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Abstract
Like any group with vested interests, the food industry resists regulation. Faced with a growing scientific consensus that salt increases blood pressure1 2 and the fact that most dietary salt (65-85%) comes from processed foods,3 some of the world's major food manufacturers have adopted desperate measures to try to stop governments from recommending salt reduction. Rather than reformulate their products, manufacturers have lobbied governments, refused to cooperate with expert working parties, encouraged misinformation campaigns, and tried to discredit the evidence. This week's BMJ finds them defending their interests as vigorously as ever.
In 1988 the BMJ published data from the Intersalt study suggesting that populations with high average intakes of salt were likely to have higher average systolic blood pressures and that salt intake predicted rise in blood pressure with age.4 The salt producers' international trade organisation, the Salt Institute, criticised the study, particularly the methods used to relate blood pressure to age, and asked the investigators to hand over their raw data for reanalysis. The investigators instead performed the reanalyses themselves: these appear on p 1249,5 confirming the previous findings. The Salt Institute sent the BMJ a letter in response to the reanalysis, and this appears on p 1283,6 along with a commentary from an independent expert (p1284)7 and an answer from the Intersalt investigators (p1285).8
The Salt Institute's letter is the latest volley in a 20 year …
... While the findings were aggressively attacked by the Salt Institute, Stamler and colleagues eventually prevailed and the findings have stood the test of time. 5 As described by Stamler and Beevers, 6 an important human consequence of the INTERSALT study, beyond its scientific impact on hypertension, was the creation of an international cadre of well-trained and motivated investigators, keen to continue epidemiological research using the same high standards as the INTERSALT study. While INTERSALT had focused on sodium, potassium, alcohol, and body weight, multiple other dietary factors of potential relevance to blood pressure were not assessed. ...
... With regard to food manufacturers and the food-processing industry, the initial resistance to the governments' recommendations for salt reduction (Godlee, 1996;Strazzullo et al., 2009) was later amended and recently many food producers and manufacturers seem to have understood the importance of low-sodium products in food markets (Lucas et al., 2011) as a favourable economic opportunity for the food industry in terms of product differentiation. Although salt also affects the texture and preservation of food and its role is very important in processed meat, cheese, and baked goods production (Doyle and Glass, 2010), participants in the food industry are investigating ways to maintain the same perceived salt intensity at lower sodium levels (Dötsch et al., 2009). ...
High salt intake is an important health risk since its consumption is often strongly related to negative health effects. In light of this, and given the social and health costs linked to overconsumption of salt, this paper highlights the main factors related to the demand for foods that have a low sodium content. Our study aims to analyse in depth
the preferences and attitudes of consumers towards food low in salt as well as assessing for the first time the willingness to pay (WTP) in order to determine whether consumers place a high value on sliced salt-reduced bread. The results show a fairly limited WTP
for bread with a low sodium content, with the relevant values being calculated at 20% over the price of normal bread. This indicates that consumers are positively interested in this kind of product but their willingness to pay more is rather limited.The findings of this study also support an argument for the first time of the role played by the physical activity and physical characteristics of the sampled consumers, showing the importance of the body mass index in significantly influencing the individual WTP for low-salt bread.
... In parallel with these actions, a 'salt debate' has filled the pages of health magazines and newspapers for years. From John Swales' original scepticism in 1988 [9] to Godlee's sharp call to reality in 1996 [10], the debate has transcended the scientific arena into public opinion and media campaigns with increasingly passionate tones [11]. The controversy has been particularly heated since the translation of the results of scientific studies into public health and policy actions [7] and the 'salt debate' has become for some a 'salt war' [12]. ...
A reduction in salt intake reduces blood pressure, stroke and other cardiovascular events, including chronic kidney disease, by as much as 23% (i.e. 1.25 million deaths worldwide). It is effective in both genders, any age, ethnic group, and in high-, medium- and low-income countries. Population salt reduction programmes are both feasible and effective (preventive imperative). Salt reduction programmes are cost-saving in all settings (high-, middle- and low-income countries) (economic imperative). Public health policies are powerful, rapid, equitable and cost-saving (political imperative). The important shift in public health has not occurred without obstinate opposition from organizations concerned primarily with the profits deriving from population high salt intake and less with public health benefits. A key component of the denial strategy is misinformation (with ‘pseudo’ controversies). In general, poor science has been used to create uncertainty and to support inaction. This paper summarizes the evidence in favour of a global salt reduction strategy and analyses the peddling of well-worn myths behind the false controversies.
... Governments in these countries have put pressure on the food industry to reduce sodium levels in foods, such as through mandatory nutritional labeling and the establishment of salt targets in specific food categories (Valenzuela & Atalah, 2011). Because food reformulation can often incur a cost for the industry (Desmond, 2006;Godlee, 1996), it is possible that fast food chains are investing in salt reduction only in products from countries that have well established nutrition-related policies . ...
SUMMARY. Sodium in breads and snacks of high consumption in Costa Rica. Basal content and verification of nutrition labeling. Bread is highly consumed by population, making it one of the main sources of sodium in the diet, despite being moderate in salt. Mean while, snacks have high sodium content, but are less
consumed by the general population. The aim of this study was to determine by direct analysis the baseline of sodium in breads and snacks most consumed in Costa Rica and verify compliance with the Central American Technical Regulation on Nutritional Labeling. Foods samples were classified by type, trade mark, method and place of production. Samples were collected in supermarkets and bakeries in the Great
Metropolitan Area between 2011and 2012. Primary sample comprised 99 breads and 84 snacks, and analytical sample
33 and 28, respectively. The sodium content was determined
by flame emission spectrophotometer. Breads showed between 496 and 744mg/100g sodium, 45% included nutritional labeling and 80% reported greater amount than found by direct analysis. Industrialized breads except the whole grain varieties, complied with regulations. In snacks, sodium content ranged from 276 to 1221mg/100g, all had
nutritional labeling and 43% reported less content, in breach
of the regulations. The study provides baseline data to initiate sodium reduction and direct analysis confirms that it is essential to know with certainty the sodium content in foods. Key words: Bread, snacks, sodium, salt, nutritional labeling, hypertension
... Subsequent government reports made no strong recommendations until the early 1990s, when dietary targets for salt were set and the government made clear recommendations for reductions in the sodium levels of manufactured foods [24][25][26]. The government later backtracked, however, as industry representatives baulked, and the task force set up to deal with the issue was disbanded [27,28]. Health advocacy groups organized themselves and began to collaborate. ...
The World Health Organization promotes salt reduction as a best-buy strategy to reduce chronic diseases, and Member States have agreed to a 30% reduction target in mean population salt intake by 2025. Whilst the UK has made the most progress on salt reduction, South Africa was the first country to pass legislation for salt levels in a range of processed foods. This paper compares the process of developing salt reduction strategies in both countries and highlights lessons for other countries. Like the UK, the benefits of salt reduction were being debated in South Africa long before it became a policy priority. Whilst salt reduction was gaining a higher profile internationally, undoubtedly, local research to produce context-specific, domestic costs and outcome indicators for South Africa was crucial in influencing the decision to legislate. In the UK, strong government leadership and extensive advocacy activities initiated in the early 2000s have helped drive the voluntary uptake of salt targets by the food industry. It is too early to say which strategy will be most effective regarding reductions in population-level blood pressure. Robust monitoring and transparent mechanisms for holding the industry accountable will be key to continued progress in each of the countries.
... Governments in these countries have put pressure on the food industry to reduce sodium levels in foods, such as through mandatory nutritional labeling and the establishment of salt targets in specific food categories (Valenzuela & Atalah, 2011). Because food reformulation can often incur a cost for the industry (Desmond, 2006;Godlee, 1996), it is possible that fast food chains are investing in salt reduction only in products from countries that have well established nutrition-related policies . ...
Salt is a major determinant of population blood pressure levels. Salt intake in Costa Rica is above levels required for good health. With an increasing number of Costa Ricans visiting fast food restaurants, it is likely that fast-food is contributing to daily salt intake. Salt content data from seven popular fast food chains in Costa Rica were collected in January 2013. Products were classified into 10 categories. Mean salt content was compared between chains and categories. Statistical analysis was performed using Welch ANOVA and Tukey-Kramer HSD tests. Significant differences were found between companies; Subway products had lowest mean salt content (0.97g/100g; p<0.05) while Popeye's and KFC had the highest (1.57g/100g; p<0.05). Significant variations in mean salt content were observed between categories. Salads had a mean salt content of 0.45g/100g while sauces had 2.16g/100g (p<0.05). Wide variation in salt content was also seen within food categories. Salt content in sandwiches ranged from 0.5-2.1g/100g. The high levels and wide variation in salt content of fast food products in Costa Rica suggest that salt reduction is likely to be technically feasible in many cases. With an increasing number of consumers purchasing fast foods, even small improvements in salt levels could produce important health gains.
... 19 In 1996, the UK government specifically rejected the recommendations on salt because of pressure from the food industry who threatened to withdraw funding to the political party in power. [20][21][22] In response, 22 experts on salt and blood pressure (mainly drawn up from the committee on medical aspects of food policy) set up an action group-CASH. ...
The United Kingdom has successfully implemented a salt reduction programme. We carried out a comprehensive analysis of the programme with an aim of providing a step-by-step guide of developing and implementing a national salt reduction strategy, which other countries could follow. The key components include (1) setting up an action group with strong leadership and scientific credibility; (2) determining salt intake by measuring 24-h urinary sodium, identifying the sources of salt by dietary record; (3) setting a target for population salt intake and developing a salt reduction strategy; (4) setting progressively lower salt targets for different categories of food, with a clear time frame for the industry to achieve; (5) working with the industry to reformulate food with less salt; (6) engaging and recruiting of ministerial support and potential threat of regulation by the Department of Health (DH); (7) clear nutritional labelling; (8) consumer awareness campaign; and (9) monitoring progress by (a) frequent surveys and media publicity of salt content in food, including naming and shaming, (b) repeated 24-h urinary sodium at 3-5 year intervals. Since the salt reduction programme started in 2003/2004, significant progress has been made as demonstrated by the reductions in salt content in many processed food and a 15% reduction in 24-h urinary sodium over 7 years (from 9.5 to 8.1 g per day, P<0.05). The UK salt reduction programme reduced the population's salt intake by gradual reformulation on a voluntary basis. Several countries are following the United Kingdom's lead. The challenge now is to engage other countries with appropriate local modifications. A reduction in salt intake worldwide will result in major public health improvements and cost savings.Journal of Human Hypertension advance online publication, 31 October 2013; doi:10.1038/jhh.2013.105.
... However, this is not always a straightforward process. For example, low-salt foods are thought to lack flavour, and therefore overcoming this may require the addition of extra ingredients, which can increase costs and the price of the food (Godlee 1996). Often, preservatives need to be added to compensate for the antimicrobial action of the salt, or foods require specific storage conditions (BNF 1999). ...
Forewords
Timeline
Introduction
Section 1: The interaction between diet and public health
Section 2: The role of government
Section 3: Trends in dietary patterns and nutrient intake
Section 4: Factors influencing food access and availability
Conclusions
Acknowledgements
References
Summary Throughout the 20th century, average life expectancy has been increasing. This is primarily a result of a change in disease patterns, as infectious diseases have declined, and chronic diseases have become the nation's main killers. A number of factors are recognised to influence the risk of chronic disease, including diet and lifestyle. Therefore, dietary guidelines have been developed to help people follow a diet that can maximise their health and longevity. These guidelines complement more detailed dietary reference values, which were first established in 1950. Since then, these values have stayed much the same, and today they are used to asses thenutritional adequacy of the diet using data from dietary surveys, such as the National Diet and Nutrition Survey. The National Food Survey is another important source of information about what the population are eating. This survey has collected data on food purchased for consumption in the home since 1940 and therefore can provide invaluable information on trends in estimated food, energy and nutrient intake for the general population. Figures estimated from the National Food Survey suggest that since the 1970s, total energy intake has been falling in line with falling levels of energy expenditure. Nevertheless, this decline in energy expenditure has left individuals prone to gaining weight, yet the dietary guidelines in use today still focus on the need to monitor intake of fat and saturates. On the face of it, the British diet has been remarkably stable over the past 60 years. However, what has been evident is a shift towards a lower fat diet with lower fat meats, such as poultry overtaking beef, pork and lamb as the most popular meats and semi‐skimmed milk dominating the milk category since its introduction in the 1980s.
There are a number of factors that have affected the trends in food consumption, some of which can be attributed to specific events; for example, the drought from 1975 to 1976 caused a shortage of potatoes, resulting in a high market price, which in turn led to a decline in potato consumption. It is beyond the scope of this Briefing Paper to explain all of the variations and changes in food intake over the past 60 years. However, this paper does provide an overview of the factors (namely government policies, advances and innovations of the food industry and consumer‐led changes) that have influenced food availability and access since the 1940s. For example, a significant policy that has had influence is the Common Agricultural Policy (CAP), which was devised by six nations of the European Economic Community in response to the effects of war, in particular world food shortages. Many of the original objectives of CAP had been met by the time the UK joined in 1973. However, through various reforms the policy has continued and has had a significant impact on food supply, food prices and the environment. More recent government policies regarding food availability have focused on improving the nutrient profile of foods and promoting a healthy balanced diet.
The food and farming industry's compliance with CAP has strongly influenced the way in which foods have been produced and the direction of the agricultural industry. For example, intensification has been essential to meet the required productivity and has relied upon the use of inorganic fertilisers, herbicides and pesticides. However, some producers have opted to produce foodstuffs organically, which has been supported by some consumers and become somewhat of a niche market.
Since their popularisation in the 1960s, the buying power of supermarkets, and fast turnover of foods, has meant it became possible to stock a larger variety of produce from across the world at more affordable prices. The increasing floor space opened a door for manufacturers and retailers to showcase a widening range of products and gave consumers an opportunity to compare products and select their preferred choice. The wide variety of food products available since the 1960s has been the result of new food technologies and more recently new ingredients and novel foods. These advances have been coupled with an increase in the ownership of domestic appliances, including fridges (1960s), freezers (1970s) and microwave ovens (from the 1980s).
Since the 1980s, there has been an increase in the proportion of women who worked; therefore, convenience became a driving factor for consumer purchasing. These social trends were reflected in the increased popularity of eating out. Convenience has remained an important determinant of consumer purchasing choice, and advances in food technology and manufacture have meant that today it is possible to cook a meal in minutes. Advances in food science and technology have also enabled health‐promoting products, so‐called functional foods, to be produced, and for many health‐conscious individuals these have proved very popular. For some consumers, the health benefits of a food have been a driver for food purchasing habits, and advertisers have taken advantage of this for decades. In particular, the association between food and health was becoming well recognised during the 1980s. This was fuelled by the publication of dietary guidelines and research reports, such as those advocating the importance of a diet low in saturates. Over the past 20 years, other ethical concerns surrounding food manufacture have been high on the agenda of food companies and consumers alike.
... The UK Department of Health has estimated the UK intake of sodium chloride at 8.2 g/person/day. Others (Godlee, 1996) refer to 9 g/person/day, calculated from data for urinary excretion of sodium. In populations with high sodium consumption there is usually no difference in sodium intake between normotensive and hypertensive individuals (Liu et al., 1979; Morgan et al., 1978; Schlierf et al., 1980; Tuomilehto, Karppanen, Tanskanen, Tikkanen, & Vuori, 1980). ...
Sodium intake exceeds the nutritional recommendations in many industrialized countries. Excessive intake of sodium has been linked to hypertension and consequently to increased risk of stroke and premature death from cardiovascular diseases. The main source of sodium in the diet is sodium chloride. It has been established that the consumption of more than 6 g NaCl/day/person is associated with an age-increase in blood pressure. Therefore, it has been recommended that the total amount of dietary salt should be maintained at about 5–6 g/day. Genetically salt susceptible individuals and hypertensives would particularly benefit from low-sodium diets, the salt content of which should range between 1 and 3 g/day. In industrialized countries, meat products and meat meals at home and in catering comprise one of the major sources of sodium, in the form of sodium chloride.
... Since the 1980s, the salt industry has tried to promote the view that salt reduction provides only a negligible benefit [41,51], but now, concerted efforts of relevant working groups and advisory panels throughout the world and the WHO are exerting pressure on them to change their strategy [49,52]. These organizations publish action plans for the implementation of salt-reducing strategies and give recommendations for a populationwide salt intake reduction. ...
We assessed the benefits and harm of reduced salt intake in patients with essential hypertension focusing on patient-relevant outcomes and blood pressure.
A systematic search of five electronic databases was performed to identify high-quality secondary literature based on randomized controlled trials (RCTs). An update primary literature search (RCTs) was performed for the time period up to 2010 that was not covered by secondary literature. Major outcomes were death, cardiovascular morbidity/mortality, hospital stays, terminal renal failure, quality of life, and adverse events. Change in blood pressure was defined as surrogate parameter.
Four different systematic reviews and two RCTs met the inclusion criteria. Only one review reported limited data on patient-relevant outcomes. Over an intervention period of up to 12 months, mean SBP was reduced by 3.6-8.0 mmHg in all reviews. For the same intervention period, a statistically significant advantage with regard to mean DBP reduction ranging from 1.9 to 2.8 mmHg was found in three reviews. The fourth publication reported a nonsignificant reduction (DBP reduction of 4.7 mmHg). None of the RCTs identified in the primary literature search update reported data on patient-relevant outcomes. However, both RCTs found blood pressure improvements with salt reduction.
A benefit from a salt-reduced diet in patients with high blood pressure is not proven with regard to patient-relevant outcomes based on systematic reviews and RCTs published up to 2010. The results indicate a blood pressure-lowering effect through reduced salt intake in hypertensive patients.
... Rather than reformulate their products, manufacturers have lobbied governments, refused to cooperate with expert working parties, encouraged misinformation campaigns, and tried to discredit the evidence. (Godlee 1996(Godlee , 1239. ...
The "salt hypothesis" is that higher levels of salt in the diet lead to higher levels of blood pressure, with attendant risk of cardiovascular disease. Intersalt was designed to test the hypothesis, with a cross-sectional study of salt levels and blood pressures in 52 populations. The study is often cited to support the salt hypothesis, but the data are somewhat contradictory. Thus, four of the populations (Kenya, Papua, and two Indian tribes in Brazil) have very low levels of salt and blood pressure. Across the other 48 populations, however, blood pressures go down as salt levels go up-- contradicting the salt hypothesis. Regressions of blood pressure on age indicate that for young people, blood pressure is inversely related to salt intake-- another paradox. This paper discusses the Intersalt data and study design, looking at some of the statistical issues and identifying respects in which the study failed to follow its own protocol. Also considered are human experiments bearing on the salt hypothesis. The effect of salt reduction is stronger for hypertensive subjects than normotensives. Even the effect of a large reduction in salt intake on blood pressure is modest, and publication bias is a concern. To determine the health effects of salt reduction, a long-term intervention study would be needed, with endpoints defined in terms of morbidity and mortality; dietary interventions seem more promising. Funding agencies and medical journals have taken a stronger position favoring the salt hypothesis than is warranted by the evidence, raising questions about the interaction between the policy process and science. Freedman__David Petitti__D_B
... The UK Department of Health has estimated the UK intake of sodium chloride at 8.2 g/person/day. Others (Godlee, 1996) refer to 9 g/person/day, calculated from data for urinary excretion of sodium. In populations with high sodium consumption there is usually no difference in sodium intake between normotensive and hypertensive individuals (Liu et al., 1979;Morgan et al., 1978;Schlierf et al., 1980;Tuomilehto, Karppanen, Tanskanen, Tikkanen, & Vuori, 1980). ...
As myofibrils consist of a three-dimensional network of long, solid protein particles with the shortest dimension of less than 20 nm, the theoretical foundations of water-holding in meat should be studied from a colloid or surface chemistry point of view. The classical hypotheses for water-holding in meat are based on electrostatic forces or osmotic forces, which cause the swelling of the myofibrils. The more recent research adds to those the structure of water, whether it is low density water induced by kosmotropic effects dominating in the system, or high density water induced by chaotropes, respectively. The phenomena in the one to three molecules thick water layers on protein surfaces do not, however, explain the bulk water-holding.The interactions of ions and non-polar kosmotropes with water and proteins have a relevant effect on water-holding. The chaotropic/kosmotropic effects of different ions will be of importance especially when reducing sodium contents in meat-based foods. Rough estimates of the surface areas of different constituents of the myofibrils showed that transverse elements have larger contact surfaces with the liquid phase than longitudinal. Therefore, more attention should be paid to heavy meromyosin, Z-line and other elements of molecular size or colloidal size. Short range surface forces seem to dominate theories of water-protein interactions, and the theoretical foundations of bulk water-holding are still lacking. Irrespective of the lack of theoretical explanation on the mechanism of water-holding in meat, the meat industry is able to control the macroscopic behaviour of meat-based ingredients rather well.
... The UK Department of Health has estimated the UK intake of sodium chloride at 8.2 g/person/day. Others (Godlee, 1996) refer to 9 g/person/day, calculated from data for urinary excretion of sodium. In populations with high sodium consumption there is usually no difference in sodium intake between normotensive and hypertensive individuals (Liu et al., 1979; Morgan et al., 1978; Schlierf et al., 1980; Tuomilehto, Karppanen, Tanskanen, Tikkanen, & Vuori, 1980). ...
http://www.elsevier.com/locate/meatsci Sodium intake exceeds the nutritional recommendations in many industrialized countries. Excessive intake of sodium has been linked to hypertension and consequently to increased risk of stroke and premature death from cardiovascular diseases. The main source of sodium in the diet is sodium chloride. It has been established that the consumption of more than 6 g NaCl/day/person is associated with an age-increase in blood pressure. Therefore, it has been recommended that the total amount of dietary salt be maintained at about 5-6 g/day. Genetically salt susceptible individuals and hypertensives would particularly benefit from low-sodium diets, the salt content of which should range between 1 and 3g/day. In industrialized countries, meat products and meat meals at home and in catering comprise one of the major sources of sodium, in the form of sodium chloride . Sodium chloride affects the flavour, texture and shelf life of meat products. The salt intake derived from meat dishes can be lowered by, whenever possible, adding the salt, not during preparation, at the table. In most cases salt contents of over 2% can be markedly lowered without substantial sensory deterioration or technological problems causing economical losses. Salt contents down to 1.4% NaCl in cooked sausages and 1.75% in lean meat products are enough to produce a heat stable gel with acceptable perceived saltiness as well as firmness, water-binding and fat retention. A particular problem with low-salt meat products is, however, that not only the perceived saltiness, but also the intensity of the characteristic flavour decreases. Increased meat protein content in meat products reduces perceived saltiness. The required salt content for acceptable gel strength depends on the formulation of the product. When phosphates are added or the fat content is high, lower salt additions provide a stable gel than in non-phosphate and in low-fat products. Small differences in salt content at the 2% level do not have marked effects on shelf life of the products. By using salt mixtures, usually NaCl/KCl, the intake of sodium (NaCl) can be further reduced.
... 7 This claim has been also extended to the evidence on the health consequences of some dietary habits, such as excess sugar or salt in diet. 8,9 Claiming that most epidemiological findings are false positives seems to suggest that epidemiology overall is junk science and in this sense echoes the claims of the industry. ...
... En Occident, on estime que 75 à 85 % du sodium ingéré quotidiennement se retrouve dans les aliments préparés. 1,2,19,20 Chez les Belges par exemple, environ 21 % de l'apport en sodium provient de la consommation de pain. 21 Un décret du ministère de la Santé belge fixe d'ailleurs la teneur maximale en sodium dans le pain à 12 g/kg. 1 Certains auteurs 1,22,23 considèrent que la réduction du sodium des aliments préparés constitue le moyen universel le plus efficace pour lutter contre l'hypertension. ...
In recent years, many studies have been published regarding the link between sodium intake and high blood pressure. Canadian, American and WHO Guidelines on the treatment of hypertension all indicate salt reduction as an efficient non-pharmacologic recommendation. However, due to the lack of clear and specific Canadian legislation on food labelling, consumers are not able to make informed choices of food products on the basis of salt content. The time has come for public health experts to join this debate.
... Rather than reformulate their products, manufacturers have lobbied governments, refused to cooperate with expert working parties, encouraged misinformation campaigns, and tried to discredit the evidence. (Godlee 1996Godlee , 1239). Drafts of our paper have been circulated in the community of salt epidemiologists. ...
The salt hypothesis is that higher levels of salt in the diet lead to higher levels of blood pressure, increasing the risk of cardiovascular disease. Intersalt, a cross-sectional study of salt levels and blood pressures in 52 populations, is often cited to support the salt hypothesis, but the data are somewhat contradictory. Four of the populations (Kenya, Papua, and 2 Indian tribes in Brazil) do have low levels of salt and blood pressure. Across the other 48 populations, however, blood pressures go down as salt levels go up, contradicting the hypothesis. Experimental evidence suggests that the effect of a large reduction in salt intake on blood pressure is modest, and health consequences remain to be determined. Funding agencies and medical journals have taken a stronger position favoring the salt hypothesis than is warranted, raising questions about the interaction between the policy process and science.
Depuis quelques années, plusieurs écrits ont souligné le lien entre la consommation de sodium et l’élévation de la pression artérielle. D’ailleurs, les lignes directrices canadiennes, américaines et de l’OMS concernant le traitement non pharmacologique de l’hypertension comprennent la réduction de l’apport en sodium alimentaire. Pourtant, l’absence d’une législation canadienne claire et spécifique sur l’étiquetage ne permet actuellement pas au consommateur de faire un choix éclairé des aliments en fonction de leur contenu en sel. Cet article invite les professionnels de la santé publique à se joindre au débat.
It is now generally accepted that lifestyle—diet, tobacco use, exercise—has a major impact on health, especially Western diseases. However, there is a world of difference between awareness of these facts and their translation into preventive action.
In the several preceding chapters we have discussed how a dominant theme of much medical research is the search for new treatments. Typically, when new treatments are developed, they are high-tech and inevitably expensive, often to the extent that they are unaffordable for many people, even in First World countries. This problem is frequently compounded by a second problem: these new treatments are often put into practice without having to meet strict standards of efficacy, and, in many cases can actually result in more harm than good. A major reason for these problems is the profit motive: increasingly researchers and physicians profit financially from their relationship with commercial firms and this influences how research is carried out and how the results are interpreted and disseminated. Overall, the degree of success of modern medicine has been a good deal less than the spokespeople for medicine claim or that they routinely promise is just around the corner.
Nutrition is an important determinant of population health, and social inequalities create nutritional inequalities even in industrialized countries where a wide variety of highquality food is available. This chapter describes the effects of food and nutrition on different health outcomes at the population level. It begins with a presentation of foodand nutrition-related diseases in developed countries, as well as childhood nutritional needs and their long-term consequences. It then examines the relationship between social inequalities, nutrition, and health, and highlights the growing problem of poverty and food insecurity within industrialized countries. The chapter concludes with a discussion of nutrition policies that are important in order to diminish nutritional and related health inequalities within and between nations.
Para manter o organismo humano funcionando de modo adequado, estima-se que o consumo de sódio deve estar em torno de 200-500 mg por dia. Porém, se consumido em excesso, o sódio causa um aumento da pressão arterial, elevando o risco de ocorrência de doenças cardiovasculares. Vários países, seguindo orientações estabelecidas pela WHO, têm tomado iniciativas no sentido de diminuir o consumo de alimentos que contenham elevada concentração de sódio. No Brasil, o Ministério da Saúde firmou o Termo de Compromisso no 004/2011 com entidades representantes da indústria alimentícia, visando estabelecer metas nacionais para redução do teor de sódio em diversos produtos, inclusive pães do tipo bisnaguinha. Devido à falta de estudos que determinem a concentração de sódio em pães tipo bisnaguinha, esse elemento foi quantificado em quatro marcas (A, B, C e D) deste tipo de pão, através da fotometria de chama. As concentrações de sódio encontradas em mg 100g-1 de produto, foram as seguintes: A - 302,90; B – 419,60; C – 430,80; D – 308,22. As concentrações de sódio de todas as marcas apresentaram-se abaixo do declarado nos rótulos dos produtos e de acordo com o estabelecido no Termo de Compromisso firmado para o ano de 2014 (430 mg 100g-1 de produto).
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For the human body to work properly, it is estimated that 200-500 mg of sodium should be consumed per day. However, if consumed in excess, sodium causes an increase in blood pressure, which in turn increases the risk of cardiovascular diseases. Following guidelines established by the WHO, initiatives have been taken by several countries to reduce the consumption of foods containing high sodium concentrations. In Brazil, the Ministry of Health signed the Term of Commitment 004/2011 with entities representatives of the food industry to establish national targets for reducing the sodium content (mg/100 g) in various products, including bisnaguinha, a type of bread. Owing to the lack of studies about quantifying the concentration of sodium in bisnaguinha, this element was quantified in four brands (A, B, C, and D) of bisnaguinha by flame photometry. The concentrations of sodium found in mg/100 g of the product were as follows: A, 302.90; B, 419.60; C, 430.80; D, 308.22. The concentrations of sodium in all brands were below those declared on the product labels and in accordance with the Terms of Compromise established for the year 2014 (430 mg/100 g of the product).
Purpose
The purpose of this paper is to investigate the effectiveness of consumer information and advice issued by the UK Food Standards Agency (FSA) in terms of consumer understanding.
Design/methodology/approach
A total of 118 female respondents in Scotland completed a questionnaire investigating their knowledge about the role of dietary salt and testing their understanding of educational material supplied by the FSA.
Findings
A significant proportion ( p <0.01) of the respondents considered themselves to be health conscious and nutritionally aware, but they were less aware of their salt intake and specific “salt in the diet” details prior to FSA information.
Research limitations/implications
The study is limited to a convenience sample of relatively advantaged consumers, so that further work is required with more vulnerable consumers.
Originality/value
A survey tool was employed that may be adapted to evaluate consumer information campaigns in any area of food policy.
Salt is one of the most valuable substances available to man, with a definitive role in the human body and in food production. However, the continued use or indeed misuse of salt has led to adverse effects on health. The increasing consumption of convenience foods has contributed greatly to a high salt intake. Highly processed, convenience foods are known to contain large quantities of salt to optimise storage stability and flavour acceptability. Current high salt intakes have therefore been attributed to processed foods, accounting for 75-85 per cent of total salt intake. Such findings and associated health implications have prompted a call from health professionals and food researchers to reduce salt intake. Effective salt reduction, however, can only be achieved with the co-operation and commitment of the food industry in the development of lower-salt processed foods.
Salt abuse in nutrition may exert harmful effects on health, increasing arterial hypertension and its cardiovascular consequences. It is a risk factor, particularly for older subjects and those having chronic diseases such as arterial hypertension, some renal diseases, and obesity. In subjects more particularly vulnerable, the maintenance of sodium balance, which is mainly aldosterone dependent, is perturbed. Although the use of salt for food preservation has greatly declined, it remains a serious risk factor. Excessive salt intake however results more often from poor dietary habits. The WHO and AFSSA have advised to reduce daily salt intake to 5 g, whereas it is currently about 9–10 g. In spite of repeated warnings, salt abuse remains the causal agent for many disease conditions, mainly arterial hypertension. That is why legislative measures should be taken in order to limit the salt content of food industry products, particularly as a preservative in foods. A large-scale public information campaign would be necessary with participation of public health partners, particularly physicians and pharmacists.
Concern about the overconsumption of unhealthy foods is growing worldwide. With high global rates of noncommunicable diseases related to poor nutrition and projections of more rapid increases of rates in low- and middle-income countries, it is vital to identify effective but low-cost interventions. Cost-effectiveness studies show that individually targeted dietary interventions can be effective and cost-effective, but a growing number of modeling studies suggest that population-wide approaches may bring larger and more sustained benefits for population health at a lower cost to society. Mandatory regulation of salt in processed foods, in particular, is highly recommended. Future research should focus on lacunae in the current evidence base: effectiveness of interventions addressing the marketing, availability, and price of healthy and unhealthy foods; modeling health impacts of complex dietary changes and multi-intervention strategies; and modeling health implications in diverse subpopulations to identify interventions that will most efficiently and effectively reduce health inequalities. Expected final online publication date for the Annual Review of Nutrition Volume 33 is July 17, 2013. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
Scientific advisory committees (SACs) are seen as "boundary organisations" working at the interface between science, policy and society. Although their narrowly defined remit of risk assessment is anchored in notions of rationality, objectivity, and reason, in reality, their sources for developing recommendations are not limited to scientific evidence. There is a growing expectation to involve non-scientific sources of information in the formation of knowledge, including the expectation of stakeholder consultation in forming recommendations. Such a move towards "democratisation" of scientific processes of decision-making within SACs has been described and often studied as "post-normal science" (PNS) (Funtowicz & Ravetz, 1993). In the current paper we examine the application of PNS in practice through a study of stakeholder consultations within the workings of the UK Scientific Advisory Committee for Nutrition (SACN). We use the theoretical insights from PNS-related studies to structure the analysis and examine the way in which PNS tenets resonate with the practices of SACN. We have selected a particular case of the SACN UK recommendations for salt as it is characterized by scientific controversy, uncertainty, vested interests and value conflict. We apply the tenets of PNS through documentary analysis of the SACN Salt Subgroup (SSG) consultation documents published in 2002/2003: the minutes of the 5 SACN SSG's meetings which included summary of the SACN SSG's stakeholder consultation and the SSG's responses to the consultation. The analysis suggests that the SACN consultation can be construed as a process of managing sources of risk to its organisation. Thus, rather than being an evidence of post-normal scientific practice, engagement became a mechanism for confirming the specific framing of science that is resonant with technocratic models of science holding authority over the facts. The implications for PNS theory are discussed.
For more than four decades, starting in the late 1960s, a sometimes furious battle has raged among scientists over the extent to which elevated salt consumption has adverse implications for population health and contributes to deaths from stroke and cardiovascular disease. Various studies and trials have produced conflicting results. Despite this scientific controversy over the quality of the evidence implicating dietary salt in disease, public health leaders at local, national, and international levels have pressed the case for salt reduction at the population level. This article explores the development of this controversy. It concludes that the concealment of scientific uncertainty in this case has been a mistake that has served neither the ends of science nor good policy. The article poses questions that arise from this debate and frames the challenges of formulating evidence-based public health practice and policy, particularly when the evidence is contested.
Clinicians are under siege from patients and politicians alleging limitations in professional self regulation. In Britain the General Medical Council's attempts to retrieve the situation are criticised by some as belated, or even unjust,1 and the emergence of clinical governance in the NHS is regarded by some as an arbitrary system for imposing uniform standards and monitoring compliance. Are such misgivings reasonable? Clinical governance should promote high quality care by making individuals accountable for setting, maintaining, and monitoring standards, to produce a hitherto elusive culture of clinical excellence.2 Systems of clinical risk management and audit should contribute to this process by facilitating greater self evaluation, open debate about clinical practice, and the routine investigation of adverse events. For clinicians to learn and improve, conclusions reached during these processes need to be documented Clinicians also need to feel safe with the process and that it will not be used against them.In practice these worthy objectives are undermined by two legal concerns relating …
Most chronic dialysis patients are volume overloaded. This has two consequences. The first is hypertension. Even though the pathophysiologic mechanism causing this blood pressure (BP) elevation is well known, many patients are treated with antihypertensive drugs. These are often ineffective and, even if they lower BP, they do not eliminate its cause and the associated cardiac damage. But at least as harmful to the heart as the pressure load is the volume load. In the early phase of dialysis, this may lead to acute pulmonary edema, which is often erroneously referred to as "heart failure." Later, it causes dilatation of the heart compartments, stretching of their walls, and regurgitation through the valves. This dilated cardiomyopathy eventually leads to liver congestion, decreased ejection fraction, and low blood pressure. It is considered to be irreversible and incorrectly called "uremic" by many authors, but can be markedly improved and even cured by judicious ultrafiltration. This may take many months, since the heart muscle needs time to become "remodeled." All these unwanted effects could be prevented by strong dietary salt restriction. We tried to analyze why this and other "old truths" are being forgotten. While the reasons are clearly multifactorial, the unfortunate introduction of the Kt/V concept seems the most important one. The claim that adequacy of dialysis can be solely defined by urea removal, disregarding all other factors, above all salt retention, has diverted the nephrologist's attention from the most important issue, giving them the false conviction that the prescribed treatment is "adequate."
Despite the fact that dietary salt restriction is the most logical measure to prevent accumulation of salt and water in patients without renal function, it is not applied in most dialysis centers. In this review, the reasons for this unlucky development are analyzed. First, it appears that many dialysis patients are slightly overhydrated, but this is often not noticed and, if so, the deleterious effects in the long run are not appreciated. These consist not only of 'drug-resistant' hypertension, but also dilatation of the cardiac compartments leading to preventable cardiovascular events. Second, there are practical reasons why salt restriction is neglected. It is very difficult to buy salt-poor food. Salt consumption is an addiction, which can be overcome, but time and efforts are needed to achieve that. Suggestions are made how to reach that goal. Finally, examples are given how cardiac damage (often considered irreversible) can be improved or even cured by a 'volume control' strategy, whose crucial part is serious salt restriction.
To assess the relation between the level of habitual salt intake and stroke or total cardiovascular disease outcome.
Systematic review and meta-analysis of prospective studies published 1966-2008.
Medline (1966-2008), Embase (from 1988), AMED (from 1985), CINAHL (from 1982), Psychinfo (from 1985), and the Cochrane Library. Review methods For each study, relative risks and 95% confidence intervals were extracted and pooled with a random effect model, weighting for the inverse of the variance. Heterogeneity, publication bias, subgroup, and meta-regression analyses were performed. Criteria for inclusion were prospective adult population study, assessment of salt intake as baseline exposure, assessment of either stroke or total cardiovascular disease as outcome, follow-up of at least three years, indication of number of participants exposed and number of events across different salt intake categories.
There were 19 independent cohort samples from 13 studies, with 177 025 participants (follow-up 3.5-19 years) and over 11 000 vascular events. Higher salt intake was associated with greater risk of stroke (pooled relative risk 1.23, 95% confidence interval 1.06 to 1.43; P=0.007) and cardiovascular disease (1.14, 0.99 to 1.32; P=0.07), with no significant evidence of publication bias. For cardiovascular disease, sensitivity analysis showed that the exclusion of a single study led to a pooled estimate of 1.17 (1.02 to 1.34; P=0.02). The associations observed were greater the larger the difference in sodium intake and the longer the follow-up.
High salt intake is associated with significantly increased risk of stroke and total cardiovascular disease. Because of imprecision in measurement of salt intake, these effect sizes are likely to be underestimated. These results support the role of a substantial population reduction in salt intake for the prevention of cardiovascular disease.
La question des effets du sel sur la santé a pris, au niveau international, une importance inédite depuis une dizaine d'années. L'Organisation mondiale de la santé, l'Union européenne et les autorités sanitaires de plusieurs pays s'intéressent aujourd'hui à cette question. En effet, ingéré en trop grande quantité, le sel favoriserait l'élévation de l'hypertension artérielle avec l'âge et serait responsable de nombreux décès dans les pays occidentaux. A partir d'une étude portant sur la manière dont les autorités françaises ont été sensibilisées à cette question et sur les types de réponses qu'elles lui ont apportée, cet article vise à dégager les différentes logiques sociales à l'œuvre dans la production des politiques nutritionnelles. L'analyse s'appuie sur des entretiens réalisés avec les principaux protagonistes du dossier et sur un corpus de textes provenant de cinq types de supports (presse écrite et audiovisuelle, documents administratifs, débats et questions parlementaires, documents provenant d'organisations professionnelles et extraits d'ouvrages). L'article présente en premier lieu la carrière du problème du sel en France en la resituant dans un contexte marqué par un intérêt accru pour la nutrition de la part des autorités sanitaires. Partant des premières prises de parole publiques sur ce sujet en 1998, il montre comment les pouvoirs publics se sont saisis du problème du sel, quelles réponses ils lui ont apportées, et comment ils les ont mises en œuvre. Il propose, en second lieu, d'expliquer la faiblesse des actions publiques engagées dans ce domaine par quatre facteurs principaux : l'existence d'incertitudes scientifiques et leurs usages stratégiques ; l'isolement des chercheurs mobilisés sur cette question ; l'existence d'obstacles techniques et économiques au niveau du secteur agro-alimentaire ; et enfin la prégnance, parmi les experts et acteurs administratifs, d'une conception globale de la nutrition, refusant de focaliser l'attention sur tel ou tel aliment ou nutriment.
Cardiovascular disease (CVD) is the leading cause of death and disability worldwide. Raised blood pressure (BP), cholesterol and smoking, are the major risk factors. Among these, raised BP is the most important cause, accounting for 62% of strokes and 49% of coronary heart disease. Importantly, the risk is throughout the range of BP, starting at systolic 115 mm Hg. There is strong evidence that our current consumption of salt is the major factor increasing BP and thereby CVD. Furthermore, a high salt diet may have direct harmful effects independent of its effect on BP, for example, increasing the risk of stroke, left ventricular hypertrophy and renal disease. Increasing evidence also suggests that salt intake is related to obesity through soft drink consumption, associated with renal stones and osteoporosis and is probably a major cause of stomach cancer. In most developed countries, a reduction in salt intake can be achieved by a gradual and sustained reduction in the amount of salt added to food by the food industry. In other countries where most of the salt consumed comes from salt added during cooking or from sauces, a public health campaign is needed to encourage consumers to use less salt. Several countries have already reduced salt intake, for example, Japan (1960-1970), Finland (1975 onwards) and now the United Kingdom. The challenge is to spread this out to all other countries. A modest reduction in population salt intake worldwide will result in a major improvement in public health.
This chapter presents analyses of relations of dietary variables to blood pressure, systolic (SBP) and diastolic (DBP), for men in the special intervention (SI) and usual care (UC) groups in the Multiple Risk Factor Intervention Trial. For each dietary factor, analyses were done at baseline, for trial years 1-6, and for change from baseline to years 1-6. Analyses were done for all participants and for men receiving or not receiving antihypertensive drug treatment and were controlled for age, race, education, serum cholesterol, smoking, special diet status, and (for specific nutrients) body mass index and alcohol intake. Nutrient data for trial years 1-6, which are based on four or five dietary recalls per man, are more reliable than the baseline or change data, which are based on only one recall. Therefore, this summary focuses on data for trial years 1-6, for SI and UC men pooled. Regression analyses confirmed direct independent relations of body mass index, alcohol intake, sodium, and ratio of sodium to potassium to SBP and DBP, and an inverse relation of potassium to SBP and DBP. Dietary starch was directly related to SBP and DBP; dietary saturated fatty acid and cholesterol and Keys score were directly related to DBP; dietary magnesium, fiber, and caffeine were inversely related to SBP and DBP; and dietary protein, polyunsaturated fatty acids, the ratio of polyunsaturated to saturated fatty acid, and other simple carbohydrates were inversely related to DBP. Method problems, all tending to produce underestimations, are also reviewed.
Stroke is directly related to blood pressure and treatment trials in older hypertensive individuals show a reduction in strokes. However, the majority of strokes occur in normotensive individuals in whom no attempt is made to lower blood pressure. We compared the effects of modest salt restriction on blood pressure in older hypertensive and normotensive people.
47 untreated elderly people (24 men, age range 60-78 years; blood-pressure range 123-205 mm Hg systolic and 64-112 mm Hg diastolic) completed a 2-month double-blind randomised placebo-controlled crossover study of modest salt restriction with slow sodium and placebo to give a salt intake of either 10 g (equivalent to the normal amount for the UK population) or 5 g.
On the normal salt intake for the UK population, supine blood pressure was 163/90 (SD 21/10) mm Hg with urinary sodium excretion of 177 (49) mmol/day. With modest sodium restriction, blood pressure fell to 156/87 (22/9) mm Hg (p < 0.001/0.004) with a urinary sodium excretion of 94 (50) mmol/day. A reduction in sodium intake of 83 mmol/day was associated with a reduction of 7.2/3.2 mm Hg. There was no significant difference in the blood-pressure fall between 18 normotensive and 29 hypertensive participants (8.2/3.9 vs 6.6/2.7 mm Hg).
A modest reduction in salt intake leads to a fall in blood pressure in both normotensive and hypertensive older people similar to that in outcome trials of thiazide-based treatment. Since the majority of strokes in older people occur below the current definition of hypertension, our results have important implications for the prevention of stroke.
The general intake of salt (sodium chloride) is much higher than the recommended allowances, in part because of added salt in food industry processed food. However, population studies have not been able to show an association between salt intake and unfavorable health outcome.
Based on population studies and randomized studies, the effect of an extreme salt reduction of 100 mmol on blood pressure in hypertensive persons is about one third of the effect of antihypertensive medications. This effect-size estimate is based on single measurements of blood pressure and is probably overestimated compared with 24-hour blood pressure measurements. Salt reduction has effects on heart rate and serum levels of renin, aldosterone, catecholamines, and lipids that may be unfavorable. Because of insufficient compliance, extreme salt reduction can only be obtained if salt in food industry processed food is eliminated. The full consequences of such elimination are not known. Other nonpharmacological interventions, such as weight reduction and diets including fruits, vegetables, and low-fat dairy foods, are probably easier to implement and more effective to decrease blood pressure than salt reduction. Furthermore, salt reduction does not seem to add to the effect size when combined with other nonpharmacological interventions. Salt sensitivity due to sodium channel mutations has been shown in a minority of blacks but not in Caucasians.
In conclusion, at present, dietary salt restriction should not be a basic component of antihypertensive therapy.
Two studies were performed to determine the quantitative relationship between salt intake and urinary volume (U(v)) in humans. In study 1, 104 untreated hypertensives were studied on the fifth day of a high- and a low-salt diet. The 24-hour U(v) was 2.2 L (urinary sodium [U(Na)] 277 mmol) on the high-salt diet and decreased to 1.3 L (P<0.001) (U(Na) 20.8 mmol) on the low-salt diet. The reduction in 24-hour U(v) was significantly related to the decrease in 24-hour U(Na) (P<0.001) and predicts that a 100-mmol/d reduction in salt intake would decrease 24-hour U(v) by 367 mL. In study 2, 634 untreated hypertensives were studied on their usual diet. There was a significant relationship between 24-hour U(v) and U(Na) (P<0.001). This predicts that a 100-mmol/d reduction in salt intake would decrease 24-hour U(v) by 454 mL. The International Study of Salt and Blood Pressure (INTERSALT) of 1731 hypertensives and 8343 normotensives on their usual diet showed that 24-hour U(v) was significantly related to U(Na) (P<0.001) and predicted that a 100-mmol/d reduction in salt intake would decrease 24-hour U(v) by 379 and 399 mL in hypertensives and normotensives, respectively. These findings document the important effect that salt intake has on U(v). The recommended reduction in salt intake in the general population is from 10 to 5 g/d. This would reduce fluid intake in the population by approximately 350 mL/d per person. This would have a large impact on the sales of soft drinks, mineral water, and beer.
Many claims about nutrition and weight loss stem from small, short-term studies, incorrect interpretations or distortions of evidence. Our knowledge of what people eat is poor; difficulties include accurate assessment of consumption, the complex composition of foods and individual variations in nutrient bioavailability. When advice appears to be ineffective, poor compliance is a likely explanation. There is no simple solution to obesity, and no fast way to create the energy deficit required for sustainable loss of fat - weight loss requires long-term commitment to permanently change eating and exercise habits. Valid advice is to reduce overall energy intake, include more vegetables, fruits and whole grain products and fewer foods high in saturated fat, sugar and salt. While mindful of the need to encourage individuals to make changes, the medical profession needs to lead the charge to advocate for changes to our obesogenic environment.
In current diets, the level of sodium is very high, whereas that of potassium, calcium, and magnesium is low compared with the level in diets composed of unprocessed, natural foods. We present the biologic rationale and scientific evidence that show that the current salt intake levels largely explain the high prevalence of hypertension. Comprehensive reduction of salt intake, both alone and particularly in combination with increases in intakes of potassium, calcium, and magnesium, is able to lower average blood pressure levels substantially. During the past 30 years, the one-third decrease in the average salt intake has been accompanied by a more than 10-mm Hg fall in the population average of both systolic and diastolic blood pressure, and a 75% to 80% decrease in both stroke and coronary heart disease mortality in Finland. There is no evidence of any harmful effects of salt reduction. Salt-reduction recommendations alone have a very small, if any, population impact. In the United States, for example, the per capita use of salt increased by approximately 55% from the mid-1980s to the late 1990s. We deal with factors that contribute toward increasing salt intakes and present examples of the methods that have contributed to the successful salt reduction in Finland.
Objectives:
To assess further the relation in Intersalt of 24 hour urinary sodium to blood pressure of individuals and populations, and the difference in blood pressure from young adulthood into middle age.
Design:
Standardised cross sectional study within and across populations.
Setting:
52 population samples in 32 countries.
Subjects:
10,074 men and women aged 20-59.
Main outcome measures:
Association of sodium and blood pressure from within population and cross population multiple linear regression analyses with multivariate correction for regression dilution bias. Relation of sample median daily urinary sodium excretion to difference in blood pressure with age.
Results:
In within population analyses (n = 10,074), individual 24 hour urinary sodium excretion higher by 100 mmol (for example, 170 v 70 mmol) was associated with systolic/diastolic blood pressure higher on average by 3/0 to 6/3 mm Hg (with and without body mass in analyses). Associations were larger at ages 40-59. In cross population analyses (n = 52), sample median 24 hour sodium excretion higher by 100 mmol was associated with median systolic/diastolic pressure higher on average by 5-7/2-4 mm Hg, and estimated mean difference in systolic/diastolic pressure at age 55 compared with age 25 greater by 10-11/6 mm Hg.
Conclusions:
The strong, positive association of urinary sodium with systolic pressure of individuals concurs with Intersalt cross population findings and results of other studies. Higher urinary sodium is also associated with substantially greater differences in blood pressure in middle age compared with young adulthood. These results support recommendations for reduction of high salt intake in populations for prevention and control of adverse blood pressure levels.
To assess further the relation in Intersalt of 24 hour urinary sodium to blood pressure of individuals and populations, and the difference in blood pressure from young adulthood into middle age.
Standardised cross sectional study within and across populations.
52 population samples in 32 countries.
10,074 men and women aged 20-59.
Association of sodium and blood pressure from within population and cross population multiple linear regression analyses with multivariate correction for regression dilution bias. Relation of sample median daily urinary sodium excretion to difference in blood pressure with age.
In within population analyses (n = 10,074), individual 24 hour urinary sodium excretion higher by 100 mmol (for example, 170 v 70 mmol) was associated with systolic/diastolic blood pressure higher on average by 3/0 to 6/3 mm Hg (with and without body mass in analyses). Associations were larger at ages 40-59. In cross population analyses (n = 52), sample median 24 hour sodium excretion higher by 100 mmol was associated with median systolic/diastolic pressure higher on average by 5-7/2-4 mm Hg, and estimated mean difference in systolic/diastolic pressure at age 55 compared with age 25 greater by 10-11/6 mm Hg.
The strong, positive association of urinary sodium with systolic pressure of individuals concurs with Intersalt cross population findings and results of other studies. Higher urinary sodium is also associated with substantially greater differences in blood pressure in middle age compared with young adulthood. These results support recommendations for reduction of high salt intake in populations for prevention and control of adverse blood pressure levels.
The Intersalt Cooperative Research Group, together with Laaser U
Intersalt: An International Study of electrolyte excretion and blood pressure. Results for 24 hour urinary sodium and potassium excretion.
A rise in blood pressure is not an inevitable consequence of aging. In some societies blood pressure remains at about 110/70 mm Hg throughout life.1 2 Dietary salt, low dietary potassium, alcohol, and body weight contribute to the increase in blood pressure with age in Western countries. The Intersalt study quantifies the effect of each of these factors while allowing for the others.1The new Intersalt paper is a valuable addition to the evidence on salt and blood pressure.3 In the original Intersalt paper the different analyses on sodium and blood pressure varied, some suggesting a strong association, others a weaker one.1 Now the position has been clarified; all the Intersalt analyses confirm salt as an important determinant of blood pressure. The average increase in blood pressure with age (from 25 to 55 years) was greater in centres with higher sodium intake, by 10 mm Hg systolic for a 100 mmol/day higher …
This article comes from the Salt Institute, the trade organisation of salt producers. It is a reanalysis of some of the data of the Intersalt study published in the BMJ in 1988. A much larger reanalysis of the study by the original authors is published on p 1249. We have published this paper from the Salt Institute because it is an interesting exampleof how special interest groups use data to advance their position. The paper is followed by highly critical commentaries from Malcolm Law, an epidemiologist who was not part of the Intersalt team, and by the authors of the Intersalt study. An editorial by Thelle reviews the current evidence on salt and health, while Godlee looks at the politics of the food industry and health promotion and Delamothe examines who owns data produced from large trials.
The 30 July 1988 issue of the BMJ contained the primary publication of the Intersalt study, as well as an editorial by Professor John Swales that provided important notes of caution about the interpretation of the findings in terms of salt's role in the aetiology of high blood pressure.1 2 Intersalt was an important epidemiological investigation of the relation of sodium intake, as reflected by urinary sodium excretion and blood pressure. As stated in the article's abstract, Intersalt could not identify an association between urinary sodium excretion and either mean blood pressure or the prevalence of hypertension. These two conclusions were strong evidence that, in contrast to widely held earlier beliefs, salt consumption was not predictive of increased blood …