Sodium content of processed foods in the United Kingdom: analysis of
44,000 foods purchased by 21,000 households1–3
Cliona Ni Mhurchu, Cathy Capelin, Elizabeth K Dunford, Jacqueline L Webster, Bruce C Neal, and Susan A Jebb
Background: In the United Kingdom, sodium reduction targets
have been set for a large number of processed food categories.
Assessment and monitoring are essential to evaluate progress.
Objectives: Our aim was to determine whether household con-
sumer panel food-purchasing data could be used to assess the so-
dium content of processed foods. Our further objectives were to
estimate the mean sodium content of UK foods by category and
undertake analyses weighted by food-purchasing volumes.
Design: Data were obtained for 21,108 British households between
October 2008 and September 2009. Purchasing data (product de-
scription, product weight, annual purchases) and sodium values
(mg/100 g) were collated for all food categories known to be major
contributors to sodium intake. Unweighted and weighted mean so-
dium values were calculated.
Results: Data were available for 44,372 food products. The largest
contributors to sodium purchases were table salt (23%), processed
meat (18%), bread and bakery products (13%), dairy products
(12%), and sauces and spreads (11%). More than one-third of so-
dium purchased (37%) was accounted for by 5 food categories:
bacon, bread, milk, cheese, and sauces. For some food groups
(bread and bakery, cereals and cereal products, processed meat),
purchase-weighted means were 18–35% higher than unweighted
means, suggesting that market leaders have higher sodium contents
than the category mean.
Conclusion: The targeting of sodium reduction in a small number
of food categories and focusing on products sold in the highest
volumes could lead to large decreases in sodium available for con-
sumption and therefore to gains in public health.
Am J Clin
Excess dietary sodium is associated with high blood pressure
(1), which increases risk of cardiovascular disease (2, 3). In 2008,
UK population dietary salt intake was estimated to be 8.6 g/d (4),
which exceeds the maximum recommended limit of 6 g/d and
remains far above the 1–2 g/d required for good health. Efforts to
lower dietary sodium intakes can improve blood pressure and
reduce risk of cardiovascular disease (5, 6). Reducing intakes to
6 g/d could prevent ’17,500 premature deaths in the United
Kingdom each year (7). However, there is little evidence of
temporal decreases over the past several decades (8, 9).
In Europe and North America, most sodium (’75%) comes
from that added to foods due to commercial processing (10).
Accordingly, efforts are underway to decrease the sodium con-
tent of processed foods (11, 12), and the UK Food Standards
Agency (FSA) has set salt reduction targets for 80 categories of
food. Review of progress and targets is undertaken on a biennial
basis (13), although this nutrition policy work recently became
the responsibility of the UK Department of Health.
Monitoring effects of public health initiatives on food refor-
mulation is challenging. Dietary assessment using diary or recall
methods substantially underestimates sodium intakes (14, 15),
whereas 24-h urinary sodium collections, considered to be the
gold standard, are challenging for participants and cannot identify
food sources of sodium. Furthermore, the constantly changing
for more flexible and up-to-date methods to monitor population
Market research companies in many countries collect pur-
chasing data from household consumer panels that scan foods at
home. Such panels are generally nationally representative, collect
data on a continuous basis, and provide estimates of national
and regularly updates nutrient data to match to purchasing data.
The combination offood-purchasingdatawith nutrientdata offers
potentially improved precision in estimating population exposure
to sodium (16). Although purchasing data are not a surrogate for
reformulation and shifts in purchasing behavior.
The primary aim of these analyses was to determine if
household consumer panel food-purchasing data could be used to
assess the sodium content of processed foods. Secondary aims
1From the Elsie Widdowson Laboratory, Medical Research Council Hu-
man Nutrition Research, Cambridge, United Kingdom (CNM and SAJ); the
Clinical Trials Research Unit, The University of Auckland, Auckland, New
Zealand (CNM); Kantar Worldpanel, London, United Kingdom (CC); and
the George Institute for International Health, Sydney, Australia (EKD, JLW,
2Supported by the Medical Research Council. Data were provided by
Kantar Worldpanel at no charge. CNM holds the Heart Foundation of New
Zealand Senior Fellowship (grant 1380). EKD is supported by a Sydney
Medical Foundation Scholarship.
3Address correspondence to C Ni Mhurchu, Clinical Trials Research
Unit, School of Population Health, The University of Auckland, Private
Bag 92019, Auckland Mail Centre, Auckland 1142, New Zealand. E-mail:
Received September 16, 2010. Accepted for publication November 30, 2010.
First published online December 29, 2010; doi: 10.3945/ajcn.110.004481.
Am J Clin Nutr 2011;93:594–600. Printed in USA. ? 2011 American Society for Nutrition
by guest on March 6, 2011
were to provide up-to-date estimates of the mean sodium con-
centration of major processed food groups and categories that
contribute sodium to the UK food supply and to compare un-
weighted mean sodium values with means weighted by annual
Analyses were undertaken with the use of 12 mo of continuous
household consumer panel data collected by Kantar Worldpanel
from 21,108 British households between October 2008 and
food and drink purchases brought into their homes. Information
recorded on products includes barcode data, purchaser, location
of purchase, total cost of shopping trip, product price, and
promotional information. Data on nonbarcoded items such as
fresh foods are collected by using barcoded show cards (pho-
tographs) and questions. Data are not collected on foods con-
sumed out of the home.
UK census data and the Broadcasters’ Audience Research
Panel Establishment Survey (the industry standard for household
demographic characteristics) are used to define and predict de-
mographic targets and to monitor the national representativeness
of Kantar Worldpanel. Key variables considered in panel se-
lection are geographic region, life stage, household size, age of
“housewife,” and social class.
Quality-control procedures are used to ensure correct data
capture, panel continuity, and barcode matching and to monitor
extreme purchasing. Eligibility criteria are run every 4 wk to
ensure the panel is limited to households meeting quality-control
criteria. Any household that has not been recording data on the
panel for the full 4-wk period is removed as are households that
havenotrecorded shoppingdata inthe lastweek. Each household
must include at least one individual who has recorded ?5 items.
Basic purchase volumes and spend criteria are set to exclude the
worst-complying households. Spend criteria are based on the size
of the household. Households are ranked on the basis of number
of items bought compared with their household size average. By
using these criteria, the poorest-complying households are ex-
cluded to maintain a similar year-to-year average number of items
bought (neutrally weighted by household size). Compliance with
scanning is encouraged by frequent e-mail, postal, or telephone
Since 2006 Kantar has also collected nutrient data from package
labels for ’100,000 UK products covering all food and drink
categories. Information on energy, total fat, saturated fat, total
carbohydrate, sugars, fiber, protein, and sodium is linked to food
purchase volumes to provide nutritional information on UK
household shopping baskets. Nutrient data are obtained for prod-
ucts new to market once 20 purchase occasions are recorded by the
panel in a 12-wk period. Package label nutrient data are collected
annually by field workers. Generic food composition data derived
from national food composition tables (17) are used for fresh
produce or in cases in which package label data are not available.
Identification of foods that contribute sodium to the UK
database were chosen on the basis of their known contribution to
sodium in the UK diet. Key food category contributors were
identified by using the UK INTERMAP study data, which
identified the main dietary sources of sodium in the United
Kingdom for men and women aged 40–59 y (18), the FSA food
classification system established for the purpose of working with
industry to achieve salt reduction in target food categories (13),
and a recent, similar Australian survey of the sodium content of
processed foods (19). A preliminary list of foods integrating all 3
systems was created, and Kantar provided purchasing data and
sodium values for all products within the following categories:
breads, grains, cereals, processed meats, processed poultry,
processed fish, dairy foods, processed vegetables and vegetarian
products, spices, flavorings, table salt, edible oils, snack foods,
convenience foods, sauces, and spreads.
Definitions of food groups and categories
Food groups and food categories were defined in a pragmatic
classification system combining 3 existing systems: the original
Kantar food product categories, the FSA salt reduction categories
(13), and categories used in a published Australian survey (19).
Foods were classified into a hierarchical system consisting of 12
food groups and 43 food categories, which broadly reflected both
the UK FSA and Australian categorization systems (19) without
necessitating extensive recategorization of the Kantar food-
purchasing data for this preliminary study.
Data management and analysis
Kantar provided the following data on all products within the
specified food categories: product description, product weight,
sodium value per 100 g (2009 fieldwork data), and number of
packages purchased by the household sample over 12 mo (un-
weighted data). Data were collated into the defined food groups
and categories, and data checks were undertaken. Package label
sodium values collected by field workers from January to June
2009 were available for 99% of products, and generic food
composition data were used for a small number of products in the
milk and bacon categories.
For some product categories [bread rolls, morning goods (buns,
teacakes, scones, crumpets, pikelets, or muffins), cakes, and pas-
tries] sodium content values were reported per serving rather than
presented for these food items. To maintain consistency with other
categories and estimate sodium content per volume purchased for
provided by Kantar on number of servings per package.
In the case of natural cheeses, product weights were missing for
a substantial number (1861; 39%) of random or variable weight
(delicatessen) purchases. Therefore, to approximate volumes pur-
chased, we estimated the average weight for the cheese category
excluding missing values (261 g) and imputed this value to replace
missing product weights.
Finally, a random sample of 100 items with zero sodium values
was rechecked to ensure zero values were correct. Nutrient data
from package labels were located for 67 items, all of which
recorded trace, zero or nil,or values ,0.1 mg/100 g. On this basis,
a decision was made to accept zero sodium values as valid.
The unweighted mean sodium concentration (mg/100 g) was
calculated for each food group and category. Weighted means
were also calculated by using data on total annual product
SODIUM IN UK PROCESSED FOODS
by guest on March 6, 2011
Sodium content of processed foods in the United Kingdom
Food group category
Proportion of annual
sodium purchasesRange Unweighted mean1
% mg sodium/100 gmg sodium/100 g
mg sodium/100 g
Bread and bakery products
Biscuits and cookies
Cakes and pastries
Cereal and cereal products
Rice and savory noodles
Meat and pastry products
Paste and spreads
Frozen processed meat
Black and white puddings4
Fish and fish products
Canned peas and beans
Other canned vegetables
Frozen vegetables and vegetarian meals
Instant mashed potatoes
Herbs, spices, and salt
Crisps or chips and snacks
Sauces and spreads
Mayonnaise and salad dressings
Sauces and stocks
Chocolate beverages and cocoa
1Mean values are averages of all recorded values.
2Weighted by purchase volumes (product weight · number of units sold over 12 mo).
3Buns, teacakes, scones, crumpets, pikelets, or muffins.
4Type of sausage consisting of meat, fat, suet, and oatmeal (and blood in black pudding).
NI MHURCHU ET AL
by guest on March 6, 2011
volumes purchased (product weight · number of units sold). In
addition, purchase volume data were used to estimate the pro-
portional contribution of food groups and categories to total
annual sodium purchases.
The 21,108 households providing food purchase data for the
analyses were representative of British households in terms of
On average, households had been part of the panel for 5.3 6 4.7
(mean 6 SD) y. Twenty-eight percent of main household con-
tacts were current smokers, and there was at least one vegetarian
in 27% of households.
Data were available for a total of 44,372 UK food products
purchased between October 2008 and September 2009 (Table 1).
The quantity reflects the variety of food choice in the United
Kingdom and diversity in product package sizes. Most of the
44,372 products were bread and bakery goods (22%), processed
meat (18%), dairy (17%), and convenience foods (11%). The
number of products per food category ranged from 32 (cooking
oils) to 5083 (cakes and pastries).
Contribution of food groups and categories to total sodium
The total annual quantity of sodium purchased was 41,454 kg,
or ’2.0 kg sodium per household/y (equivalent to ’5.4 g so-
dium per household/d or 14 g salt). The largest single contrib-
utor to annual sodium purchases was herbs, spices, and salt
(23%), predominantly attributable to table salt purchases. The
largest food group contributors to total sodium purchases were
processed meats (18%), bread and bakery products (13%), dairy
products (12%), and sauces and spreads (11%) (Figure 1).
Within these food groups, the majority of sodium purchased was
accounted for by 5 food categories: bacon [8% total (46% of
processed meat) sodium], bread [10% total (73% of bread and
bakery) sodium], milk [6% total (49% of dairy) sodium], cheese
[5% total (41% of dairy) sodium], and dried package sauces [9%
total (86% of sauces and spreads) sodium] (Figure 2).
Mean sodium content
Food groups with the highest (unweighted) mean sodium
contents were sauces and spreads (1090 mg/100 g), snack foods
(739 mg/100 g), and processed meats (590 mg/100 g) (Table 1).
Processed vegetables had the lowest mean sodium content (195
mg/100 g). Within food groups, the categories with the highest
unweighted mean sodium content were bacon (1298 mg/100 g),
FIGURE 1. Proportional contribution of major processed-food groups to
annual UK sodium purchases. “Bread & bakery products” includes bread,
morning goods (buns, teacakes, scones, crumpets, pikelets, and muffins), biscuits
or cookies, cakes, and pastries; “Cereal & cereal products” includes breakfast
cereals, cereal bars, pasta, couscous, rice, and savory noodles; “Processed meat”
includes bacon, sliced ham, sausages, meat and pastry products, cooked meat,
canned meat, paste and spreads, and processed poultry; “Dairy” includes cheese,
yogurt, yogurt drinks, milk, cream, and ice cream; “Oils” includes butter,
margarine, and cooking oils; “Fish & fish products” includes processed fish
and canned fish; “Processed vegetables” includes baked beans, canned peas and
beans, other canned vegetables, frozen vegetables and vegetarian meals, and
sour pickles; “Snack foods” includes crisps or chips and snacks; “Convenience
foods” includes pizza, ready meals, and soup; and “Sauces & spreads” includes
mayonnaise, salad dressings, sauces, stocks, and spreads.
FIGURE 2. Selected processed-food category contributions to annual UK sodium purchases.
SODIUM IN UK PROCESSED FOODS
by guest on March 6, 2011
sauces (1286 mg/100 g), and sliced ham (939 mg/100 g). Those
with the lowest were yogurt drinks (26 mg/100 g), cream (44 mg/
100 g), and milk (64 mg/100 g).
Examination of weighted mean sodium values (sodium
weighted by purchase volumes) showed that for many categories
the weighted mean was similar or somewhat lower than the
unweighted mean (Table 1). In some cases, however, weighted
means were higher than the unweighted mean, suggesting that
market leaders in these food groups contain higher sodium
concentrations than do lesser-selling products. These latter
groups were bread and bakery products (unweighted compared
with weighted mean: 257 compared with 348 mg/100 g), cereals
and cereal products (245 compared with 290 mg/100 g), and
processed meat (590 compared with 696 mg/100 g). Food cat-
egories principally accounting forthese differences include bread
(unweighted compared with weighted mean: 397 compared
with 426 mg/100 g), morning goods (275 compared with 350 mg/
100 g), breakfast cereals (274 compared with 346 mg/100 g), and
bacon (1298 compared with 1346 mg/100 g) (Figure 3). In
contrast, in the dairy food group, the unweighted mean was
substantially higher than the weighted mean (323 compared with
111 mg/100 g), possibly reflecting the predominance of milk
purchases (with associated large volumes) within this category.
These analyses show that household consumer panel data can
be used to assess the sodium content of processed foods. Table
saltisamajorcontributortosodium intheUnited Kingdom(23%
of total), but this value may not reflect actual consumption due to
wastage and other uses (eg, melting ice in winter). Apart from
table salt, more than one-third of sodium purchased (37%) comes
from only 5 processed-food categories: bacon, bread, milk,
cheese, and sauces. Accordingly, the targeting of sodium content
reductions in these categories (except for milk, where its sodium
contribution is due to volume rather than concentration) could
lead to large potential gains in public health.
The United Kingdom has had an active nationwide salt re-
duction program since 2003. Nevertheless, intakes remain well
above the maximum recommended limit of 6 g/d. Direct com-
parisons against FSA 2012 targets were possible for 14 food
categories, and in only one instance (cakes and pastries) was the
mean category sodium content below the target. Although the
(275 mg/100 g) came within target (300 mg/100 g), the weighted
mean (350 mg/100 g) exceeded the target by 17%. Similarly, the
(274 mg/100 g) was close to the target (270 mg/100 g), but the
weighted mean exceeded it by 28% (346 mg/100 g). Therefore,
for many categories, greater efforts are needed to reduce sodium
content in line with national targets for 2012.
These are the first analyses to integrate the sodium content of
UK processed foods with purchasing data to provide estimates of
purchase-weighted sodium contents. For a number of categories
(bread and bakery, cereals and cereal products, and processed
meat), purchase-weighted means were 18–35% higher than
unweighted means, which showed that market leaders have
higher sodium contents. Use of purchasing or sales data should
therefore guide reformulation efforts to target top-selling prod-
ucts within food categories to produce the greatest effect on
population sodium exposure. The use of purchasing data for
monitoring also better reflects the combined effect of product
reformulation and shifts in purchasing behavior. Although not
a substitute for food consumption data or urinary sodium anal-
population level trends.
reported that 30% of UK adults’ daily sodium intake came from
8% from milk and milk products (20). The INTERMAP study
reported that 35% of UK sodium intake came from breads, grains,
and cereals; 20% from meats, poultry and eggs; and8% from dairy
products (18). Similar findings were reported in the 2008 Family
Food Study (21). These estimates of the proportional contribution
of dietary sources to sodium intakes are quantitatively different
from those derived from our analyses, where cereals and cereal
products (bread and bakery plus cereals and cereal products
combined) accounted for 18%, processed meat for 18%, and dairy
for 12% of sodium purchased in the United Kingdom.
Differences in estimates between previous studies and our
analyses are most likely due to the exclusion of table salt from
other studies (23% of estimated total sodium in these analyses).
The exclusion of table salt from our analyses would bring our
numbers more in line with the previous studies: for example,
cereals would then account for 23% of sodium purchases, pro-
cessed meat for 24%, and dairy 15.5%. Differential wastage of
foods from various categories will also introduce differences
relative to measures of food consumption. In addition, different
(eg, convenience foods, ready meals, and sauces) into component
food categories in NDNS and INTERMAP studies are also likely
to account for some differences. Nevertheless, whereas quantita-
tively different, all studies are consistent in identifying the same
food groups as major contributors to UK sodium purchases and
Comparisons with similar data from Australia shows that for
most food groups the unweighted mean sodium content of UK
foods is substantially less than that of similar Australian foods
(19). The mean sodium content of Australian bread and bakery
products is 82% higher than that of UK products (467 compared
FIGURE 3. Unweighted compared with purchase-weighted mean sodium
content of key processed-food categories. Means are averages of all recorded
values. No formal statistical comparisons were undertaken. Weighted means
are weighted by purchase volumes (product weight · number of units sold
over 12 mo). Breakfast cereals, 965 products; morning goods, 403 products;
breads, 2210 products; cheeses, 4813 products; mayonnaise (Mayo) and
salad dressings, 510 products. Morning goods include buns, teacakes,
scones, crumpets, pikelets, and muffins.
NI MHURCHU ET AL
by guest on March 6, 2011