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Milk and yogurt consumption are linked with higher bone mineral density but not with hip fracture: The Framingham Offspring Study



Dairy foods are a complex source of essential nutrients. In this study, fluid dairy intake, specifically milk, and yogurt intakes were associated with hip but not spine bone mineral density (BMD), while cream may adversely influence BMD, suggesting that not all dairy products are equally beneficial for the skeleton. Purpose This study seeks to examine associations of milk, yogurt, cheese, cream, most dairy (total dairy without cream), and fluid dairy (milk + yogurt) with BMD at femoral neck (FN), trochanter (TR), and spine, and with incident hip fracture over 12-year follow-up in the Framingham Offspring Study. Methods Three thousand two hundred twelve participants completed a food frequency questionnaire (1992–1995 or 1995–1998) and were followed for hip fracture until 2005. Two thousand five hundred and six participants had DXA BMD (1996–2001). Linear regression was used to estimate adjusted mean BMD while Cox-proportional hazards regression was used to estimate adjusted hazard ratios (HR) for hip fracture risk. Final models simultaneously included dairy foods adjusting for each other. Results Mean baseline age was 55 (±1.6) years, range 26–85. Most dairy intake was positively associated with hip and spine BMD. Intake of fluid dairy and milk was related with hip but not spine BMD. Yogurt intake was associated with TR-BMD alone. Cheese and cream intakes were not associated with BMD. In final models, yogurt intake remained positively associated with TR-BMD, while cream tended to be negatively associated with FN-BMD. Yogurt intake showed a weak protective trend for hip fracture [HR(95%CI), ≤4 serv/week, 0.46 (0.21–1.03) vs. >4 serv/week, 0.43 (0.06–3.27)]. No other dairy groups showed a significant association (HRs range, 0.53–1.47) with limited power (n, fractures = 43). Conclusion Milk and yogurt intakes were associated with hip but not spine BMD, while cream may adversely influence BMD. Thus, not all dairy products are equally beneficial for the skeleton. Suggestive fracture results for milk and yogurt intakes need further confirmation.
Erratum to: Milk and yogurt consumption are linked
with higher bone mineral density but not with hip fracture:
the Framingham Offspring Study
Shivani Sahni &Katherine L. Tucker &Douglas P. Kiel &
Lien Quach &Virginia A. Casey &Marian T. Hannan
#International Osteoporosis Foundation and National Osteoporosis Foundation 2013
Erratum to: Arch Osteoporos
DOI 10.1007/s11657-013-0119-2
The patients in this study were followed up until 2007, not,
as stated in the article, 2005.
The first sentence of the paragraph headed Methodsin the
abstract should read Three thousand two hundred twelve
participants completed a food frequency questionnaire
(19911995 or 19951998) and were followed for hip frac-
ture until 2007.
The last sentence of the paragraph headed Assessment of
fracturein the methods section of the main text should read
Study participants were followed for hip fracture from the
date of the dietary assessment through December 2007.
The authors regret this error and any inconvenience caused.
The online version of the original article can be found at http://
S. Sahni (*):D. P. Kiel :L. Quach :V. A. Casey :M. T. Hannan
Institute for Aging Research, Hebrew SeniorLife and Harvard
Medical School, 1200 Centre St.,
Boston, MA 02131, USA
S. Sahni :D. P. Kiel :M. T. Hannan
Harvard Medical School, 1200 Centre St.,
Boston, MA, USA
K. L. Tucker
Department of Health Sciences, Northeastern University School
of Health Professionals, 316 Robinson Hall,
Boston, MA 02115, USA
Arch Osteoporos (2013) 8:132
DOI 10.1007/s11657-013-0132-5
... Dairy foods are good sources of calcium, vitamin D (in fortified dairy foods), protein, and magnesium, nutrients that have been related to bone health [5]. Our previous research [6], and that of others [7][8][9][10][11], has suggested a positive link between milk intake and bone mineral density (BMD). A recent systematic review reported that daily intake of low-or non-fat dairy products as part of a healthy habitual dietary pattern may be associated with improved BMD of the total body and at some bone sites [12]. ...
... Previous studies have reported on the association of dairy foods, primarily milk intake with bone measures. The majority of these studies were focused on DXA-derived BMD rather than TBS [6,[32][33][34][35][36][37][38][39]. A cross-sectional study [34] showed that a higher dairy intake was associated with a greater hip aBMD in men ≥ 60 y, but not in women. ...
... A cross-sectional study [34] showed that a higher dairy intake was associated with a greater hip aBMD in men ≥ 60 y, but not in women. In the Framingham Offspring Study, milk was associated with hip but not spine aBMD in men and women (mean age: 55 y) [6]. Furthermore, of the several dairy foods examined in this study only milk + yogurt + cheese intake was associated with higher L2-4 spine BMD [6]. ...
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Background Previous studies reported that dairy foods are associated with higher areal bone mineral density (BMD) in older adults. However, data on bone texture are lacking. We determined the association of dairy food intake (milk, yogurt, cheese, milk + yogurt and milk + yogurt + cheese) with spinal trabecular bone score (TBS). Methods In this cross-sectional study, a validated semi-quantitative food frequency questionnaire was used to assess dairy food intake (servings/wk). TBS, an analysis of bone texture, was calculated from dual energy X-ray absorptiometry (DXA) scans. Sex-specific multivariable linear regression was used to estimate the association of dairy food intake (energy adjusted via residual methods) with each bone measure adjusting for covariates. Results Mean age of 4,740 participants was 49 (SD: 13) years and mean milk + yogurt + cheese intake was 10.1 (SD: 8.4) servings/week in men and 10.9 (SD: 8.0) servings/week in women. There were no associations between dairy food intake and spinal TBS in adjusted models. Conclusions In this cohort of primarily healthy adults, dairy intake was not associated with bone texture.
... Previous studies on this topic have largely focused on milk intake and DXA-derived aBMD [9,[34][35][36][37][38][39][40][41]. A recent systematic review of 39 studies of various study designs (e.g., randomized trials, prospective cohort studies, case-control etc.) reported that there is only a moderate evidence for the effect of dairy foods on bone health in middle aged and older adults [12]. ...
... This was largely due to the mixed effects reported for the overall association between dairy intake and fractures in cohort studies [12]. In the FHS Offspring Study [38], milk was associated with hip but not spine aBMD in men and women (mean age: 55 years). However, no association was observed between dairy food intakes with either femur or spine aBMD in older men and women (aged 67-93 years) from the FHS Original cohort [9]. ...
... Few epidemiologic studies have examined yogurt and cheese in relation to bone health. Nevertheless, in previous studies in older adults from the Framingham Study higher yogurt intake was associated with higher aBMD [38], but cheese was not [9,38]. ...
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Previous studies reported that dairy foods are associated with higher areal bone mineral density (BMD) in older adults. However, data on bone strength and bone microarchitecture are lacking. We determined the association of dairy food intake (milk, yogurt, cheese, milk + yogurt, and milk + yogurt + cheese, servings/week) with high resolution peripheral quantitative computed tomography (HR-pQCT) measures of bone (failure load, cortical BMD, cortical thickness, trabecular BMD, and trabecular number). This cross-sectional study included participants with diet from a food frequency questionnaire (in 2005–2008 and/or 1998–2001) and measurements of cortical and trabecular BMD and microarchitecture at the distal tibia and radius (from HR-pQCT in 2012–2015). Sex-specific multivariable linear regression estimated the association of dairy food intake (energy adjusted) with each bone measure adjusting for covariates. Mean age was 64 (SD 8) years and total milk + yogurt + cheese intake was 10.0 (SD 6.6) and 10.6 (6.4) servings/week in men and women, respectively. No significant associations were observed for any of the dairy foods and bone microarchitecture measures except for cheese intake, which was inversely associated with cortical BMD at the radius (p = 0.001) and tibia (p = 0.002) in women alone. In this cohort of primarily healthy older men and women, dairy intake was not associated with bone microarchitecture. The findings related to cheese intake and bone microarchitecture in women warrant further investigation.
... The health effects of dairy products/milk have been debated for years, but epidemiological literature on dairy product intake and the risk of fracture is still limited, especially among Chinese adults [10,13,14,[17][18][19][32][33][34][35][36][37]. Our results support the conclusions of several cohort studies that dairy product intake was associated with a decreased risk of fracture among adults [14,17,34,37]. ...
... For example, Benetou and colleagues showed dairy products did not appear to play a role in preventing hip fractures in a prospective study with 29,122 participants aged 60 years and above from five European countries [19]. Studies using data from the Framingham cohort found that dairy product intake was not related to the risk of hip fracture among both middle-aged and elderly populations, but positively related to bone mineral density [33,36]. Furthermore, a study containing two large-scale cohorts found that higher milk intake was associated with higher mortality for both Swedish women and men and associated with higher fracture incidence for Swedish women [10]. ...
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Background: The current literature reports inconsistent associations between dairy product intake and fracture. This study assessed the association between dairy product intake and the risk of fracture among Chinese adults and examined the mediation effects of height and body mass index (BMI) on the association. Methods: Data in 1997-2015 from the China Health and Nutrition Survey were used. Dietary data were collected by a 24-hour dietary recall, and occurrences of fracture were obtained by self-report of participants. Cumulative average intake of daily dairy products was calculated by the sum of the dairy product intake and divided by the total waves of participating in the surveys before fracture. Cox proportion hazard regressions were performed to explore the associations between dairy product intake and the risk of fracture. Mediation analysis models were established to examine the mediation effects of height and BMI on the associations. Results: A total of 14,711 participants were included. Dairy product intake of 0.1-100 g/day was associated with a decreased risk of fracture, while no association was observed among participants with dairy product intake of >100 g/day. The indirect effects of dairy product intake on the fracture mediated by height and BMI were much smaller than the direct effects. Conclusions: Dairy product intake with 0.1-100 g/day is associated with a lower risk of fracture, and the association is mainly a direct result of nutrients in dairy products and much less a result of the mediation effects of height or BMI. Dairy product intake of 0.1-100 g/day might be a cost-effective measure for Chinese adults to decrease fracture incidence.
... In Rizzoli, [18] yogurt intake was associated with hip (trochanter) bone mineral density. Yogurt intake showed a weak positive protective trend for hip fracture, while no other dairy groups showed a significant association [53]. ...
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Older men and women are recommended to take at least 1000-1200 mg/day of calcium for bone health and prevention of fractures. Older adults have been encouraged to improve bone health by increasing their calcium intake through food rather than by taking supplements. The Objectives of the Study: To assess the effect of calcium-fortified dairy products on bone mineralization and functionality in adults aged 65 to 80 years. Full text, English only, publications was searched on PubMed and Google Scholar, published within 2011 to 2021. Three search terms were utilized on PubMed, the search resulted in five, five, and four studies. Out of these studies, two, one, and one study respectively, met pre-determined eligibility criteria for inclusion, which summed to four studies. On Google Scholar, the search resulted in 18,600 studies. Out of 60 studies, three studies met the pre-determined eligibility criteria. The total relevant publication summed up to seven studies.Two studies examined the effect of increasing the RDA of calcium. Four studies examined the effect of dairy consumption on bone health. One study investigated how fermented milk product (FMP) consumption influences bone health in postmenopausal women.Two studies shown that there was little/no evidence that increasing the RDA through dietary sources or supplements prevents fractures. Four studies shown that there was a benefit on bone mineral density with fortified dairy foods. One study suggested increase intake of yogurt reduces the risk of hip fracture in postmenopausal women.Keywords: Dairy, Calcium, Fortified, Bone, Functionality, Older Adults.
... Tolerance of dietary lactose consumption is enhanced by the presence of Bi dobacterium in LNP individuals who carry the genotypes for low functional activity of lactase and its associated regulatory elements 24,25,40 . Dairy foods are a key dietary source of important nutrients, including calcium, potassium, and vitamin D, and has been associated with bone health and reduced risk of diabetes, cardiovascular disease, colorectal cancer and mortality [42][43][44][45][46][47] . Associations of genetic disposition and two of the SNPs were found to be inversely associated with measures of obesity in the UK Biobank (Supplemental Table 10). ...
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Patterns of microbiome diversity vary across human populations largely driven by lifestyle and environmental factors. However, differences in genetically-encoded traits in the host may also be important in shaping the microbiome and related health outcomes. We report results from a GWAS of the gut microbiome in 5,202 individuals from the Multiethnic Cohort Study, including African American, Japanese American, Native Hawaiian, Latino, and White individuals. Genotyping was derived from previous studies (n = 3,337) using various Illumina Infinium arrays (660,000 to 2.5 million SNPs) and the MEGA EX array (n = 1,865). Single nucleotide polymorphism (SNP) imputation was conducted using a cosmopolitan reference panel from the 1000 Genomes Project. The stool microbiome was assessed by paired-end sequencing (Illumina MiSeq) of the16S rRNA gene (V 1 − 3 ). SNP-genera association tests were conducted using ordinal logistic regression with quintiles of bacterial abundance regressed on SNPs, adjusted for age, ancestry estimates, season of sample collection, batch, and genotyping study, using a genome-wide statistical significance threshold of p < 5*10 − 8 . We identified associations between 53 SNPs in 11 human chromosomes and 16 bacterial/archaeal genera at p < 5*10 − 8 .The SNPs in coding regions were categorized into broad categories: human genes known to be exploited by bacterial pathogens; genes involved in nutrition, obesity, diabetes, and cancer; and immune function. Most significantly, Bifidobacterium abundance was associated with 2 known SNPs on chromosome 2 (rs182549 p = 3.8*10 − 11 ; rs4988235 4.8*10 − 11 ) in the MCM6 gene that were involved in lactose intolerance overall and in Latinos (rs182549 p = 4.12*10 − 09 and rs4988235 p = 6.90*10 − 09 ) and replicated in other studies. A significant association between Coriobacteriales and CDH18 (rs7701767,p = 1.5*10 − 08 ) was also replicated in East Asian cohorts. Genetic variants in non-coding regions were primarily associated with host defenses against infection via solubilizing pathogen cell membranes, restricting growth of intracellular pathogens, and triggering inflammation though innate immune response. Fusicatenibacter was associated with a SNP (rs8067381,p = 1.63*10 − 6 ) found in non-coding regions between SOCS7 and ARHGAP23 and replicated in several East Asian cohort. Expansion into human cohorts to include racial and ethnic diversity in host genetics and microbiome interactions to support an understanding of health outcomes across the human population.
... Participants with a high yoghurt consumption (>4 servings per week) showed increased BMD at the trochanter compared to those with no intake, although no significant relationships were seen at other bone locations in the Framingham Offspring Study's 2506 men and women [39]. ...
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Probiotic fermented milks and yoghurts are acidified and fermented by viable bacteria, usually L. bulgaricus and S. thermophilus, resulting in a thicker product with a longer shelf life. They are a nutrition-dense food, providing a good source of calcium, phosphorus, potassium, vitamin A, vitamin B2, and vitamin B12. Additionally, they deliver high biological value proteins and essential fatty acids. There is accumulating evidence suggesting that yoghurt and fermented milk consumption is related to a number of health advantages, including the prevention of osteoporosis, diabetes, and cardiovascular diseases, as well as the promotion of gut health and immune system modulation. This review aims at presenting and critically reviewing the beneficial effects from the consumption of probiotic fermented milks in human health, whilst revealing potential applications in the food industry.
... However, previous studies have found correlations between some of the remaining dietary patterns and OP. For example, some studies have suggested a positive link between milk intake and BMD and that the intake of milk can he protective against bone loss [42][43][44][45][46], which were inconsistent with our results. The reason for the inconsistent results may be due to the limited sample size and racial differences. ...
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Objective: Osteoporosis (OP) is the most common bone disease. The genetic and metabolic factors play important roles in OP development. However, the genetic basis of OP is still elusive. The study aimed to explore the relationships between OP and dietary habits. Methods: This study used large-scale genome-wide association study (GWAS) summary statistics from the UK Biobank to explore potential associations between OP and 143 dietary habits. The GWAS summary data of OP included 9434 self-reported OP cases and 444,941 controls, and the GWAS summary data of the dietary habits included 455,146 participants of European ancestry. Linkage disequilibrium score regression (LDSC) was used to detect the genetic correlations between OP and each of the 143 dietary habits, followed by Mendelian randomization (MR) analysis to further assess the causal relationship between OP and candidate dietary habits identified by LDSC. Results: The LDSC analysis identified seven candidate dietary habits that showed genetic associations with OP including cereal type such as biscuit cereal (coefficient = -0.1693, p value = 0.0183), servings of raw vegetables per day (coefficient = 0.0837, p value = 0.0379), and spirits measured per month (coefficient = 0.115, p value = 0.0353). MR analysis found that OP and PC17 (butter) (odds ratio [OR] = 0.974, 95% confidence interval [CI] = (0.973, 0.976), p value = 0.000970), PC35 (decaffeinated coffee) (OR = 0.985, 95% CI = (0.983, 0.987), p value = 0.00126), PC36 (overall processed meat intake) (OR = 1.035, 95% CI = (1.033, 1.037), p value = 0.000976), PC39 (spirits measured per month) (OR = 1.014, 95% CI = (1.011, 1.015), p value = 0.00153), and servings of raw vegetables per day (OR = 0.978, 95% CI = (0.977, 0.979), p value = 0.000563) were clearly causal. Conclusions: Our findings provide new clues for understanding the genetic mechanisms of OP, which focus on the possible role of dietary habits in OP pathogenesis.
... It has been demonstrated through both observational and interventional research that consuming the recommended amount of dairy products can support bone health throughout the lifespan (16). For example, higher dairy intake was associated with elevated bone accrual during childhood (17) and adolescence (18), as well as with greater BMD in older individuals (19)(20)(21). In the context of exercise, previous research has indicated that dairy consumption alongside exercise training can push bone turnover status toward formation in young adult males (22), improve BMD and decrease bone resorption markers in female athletes (23), and induce favorable bone biomarker changes in premenopausal normal weight and overweight females (24)(25)(26). ...
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Dairy products and impact exercise have previously been identified to be independently beneficial for bone mineral properties, however, it is unknown how the combination of these two osteogenic interventions may alter acute bone turnover. Using a randomized crossover design, we compared the acute effects of consuming milk vs. an isoenergetic carbohydrate control beverage on bone biomarkers following loading exercise. Thirteen healthy female participants (Age = 20.3 ± 2.3y; BMI = 21.0 ± 1.1 kg/m2) consumed either 550 mL of 0% skim white milk (MILK) or 52.7 g of maltodextrin in 550 mL of water (CHO), both 5 min and 1 h following completion of a combined plyometric (198 impacts) and resistance exercise (3–4 sets/exercise, 8–12 reps/set, ∼75% 1-RM) bout. Venous blood samples were obtained pre-exercise, and 15 min, 75 min, 24 h and 48 h post-exercise to assess serum concentrations of bone resorption biomarkers, specifically carboxyl-terminal crosslinking telopeptide of type I collagen (CTX), receptor activator nuclear factor kappa-β ligand (RANKL), and sclerostin (SOST), as well as bone formation biomarkers, specifically osteoprotegerin (OPG) and osteocalcin (OC). When absolute biomarker concentrations were examined, there were no interaction or group effects for any biomarker, however, there were main time effects (p < 0.05) for RANKL, SOST, and OC, which were lower, and the OPG: OPG/RANKL ratio, which was higher at 75 min post-exercise compared with baseline in both conditions. In addition to assessing absolute biomarker concentrations at specific timepoints, we also evaluated the relative (% change) cumulative post-exercise response (75 min to 48 h) using an area under the curve (AUC) analysis. This analysis showed that the relative post-exercise CTX response was significantly lower in the MILK compared to the CHO condition (p = 0.03), with no differences observed in the other biomarkers. These results show that while milk does not appear to alter absolute concentrations of bone biomarkers compared to CHO, it may attenuate relative post-exercise bone resorption (i.e., blunt the usual catabolic response to exercise).
Objectives Few prospective cohort studies have evaluated the relationship between dairy product intake frequency and risk of osteoporotic fractures in Asians. This study aimed to investigate the association between habitual dairy product intake and risk of osteoporotic fractures.DesignSecondary analysis of prospective cohort study.SettingFive municipalities of Japan.ParticipantsThis study included 1,429 postmenopausal Japanese women (age ≥45 years at baseline).MeasurementsBaseline milk-intake frequency was obtained using nurse-administered questionnaires. Intakes of yogurt and cheese, and estimated calcium intake, were assessed using a validated food frequency questionnaire. Osteoporotic fracture was defined as a clinical fracture diagnosed using radiography. Hazard ratios (HRs) with 95% confidence intervals (CIs) were estimated using Cox proportional hazards models.ResultsOver a median follow-up period of 15.1 years (interquartile range [IQR], 10.1–15.4 years; total, 18,118 person-years), 172 women sustained at least one osteoporotic fracture. The proportions of participants with milk intakes <1, 1, and ≥2 cups/d were 34.4%, 48.0%, and 17.6%, respectively. After adjustment for age, frequency of yogurt intake, frequency of cheese intake, body mass index, history of osteoporotic fractures, and frequency of natto intake, the HRs compared with that for milk intake <1 cup/d were 0.71 (95% CI: 0.51–0.98) and 0.57 (95% CI: 0.35–0.92) for 1 cup/d and ≥2 cups/d, respectively. After adjustment for bone mineral density, HR significance for milk intakes ≥2 cups/d remained significant. Yogurt and cheese intakes were not related to the risk of osteoporotic fractures.Conclusion High habitual milk intake, but not a habitual yogurt or cheese intake is associated with a decreased risk of osteoporotic fractures, independent of bone mineral density, in postmenopausal Japanese women.
Yogurt is a fermented dairy food traded worldwide and eaten by all groups in different societies. Yogurt is also a good delivery system for many nutrients and bioactive ingredients and is a suitable medium for fortifying many vital compounds that have a role in improving and preventing human health. There are many developments in the technology of yogurt production; the most important of which is to increase its acceptance by improving its technological properties. Development includes supporting it with many dairy and other nondairy components to increase its health and nutritional value, as well as adding some fruits and others to improve taste and increase acceptance, as it is primarily used to deliver beneficial bacteria (probiotic) for their role in improving health. Incorporation of probiotic organisms into dairy food items to increase the nutritional status with the added therapeutic characteristics is practiced worldwide, especially in countries like Japan, United States, Australia, and Europe. Probiotics are generally mono or mixed cultures of live microorganisms which form the major component of the gut flora (e.g., Lactobacilli, Bifidobacteria). Probiotics, when ingested beneficially, affect the host by replenishing the depleted gut microflora, which may have occurred due to the use of antibiotics, illness or stress, travel or lifestyle changes; it also improves the properties of the indigenous microflora of the host. Microbial strains for probiotic use must be representative of microorganisms that are generally recognized as safe microbes. The health of women and their interest in them is important and reflects positively on society. Recent studies focus on the existence of effective methods to treat the symptoms and complications associated with women after menstruation. Because of these symptoms of health problems—followed by psychological problems that lead to economic difficulties on the family scale, which in turn reflects on society as a whole—adding types of probiotic bacteria to some additives help to solve and overcome those effects. In this chapter, we will review the most important technological developments as well as objectives of yogurt that have been addressed in the studies, and we will focus on the role of these developments and their relationship to women’s health.
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The effect of protein on bone is controversial, and calcium intake may modify protein's effect on bone. We evaluated associations of energy-adjusted tertiles of protein intake (ie, total, animal, plant, animal/plant ratio) with incident hip fracture and whether total calcium intake modified these associations in the Framingham Offspring Study. A total of 1752 men and 1972 women completed a baseline food frequency questionnaire (1991-1995 or 1995-1998) and were followed for hip fracture until 2005. Hazard ratios (HRs) were estimated using Cox proportional hazards regression adjusting for confounders. Baseline mean age was 55 years (SD 9.9 years, range 26 to 86 years). Forty-four hip fractures occurred over 12 years of follow-up. Owing to significant interaction between protein (total, animal, animal/plant ratio) and calcium intake (p interaction range = .03 to .04), stratified results are presented. Among those with calcium intakes less than 800 mg/day, the highest tertile (T3) of animal protein intake had 2.8 times the risk of hip fracture [HR = 2.84, 95% confidence interval (CI) 1.20-6.74, p = .02] versus the lowest tertile (T1, p trend = .02). In the 800 mg/day or more group, T3 of animal protein had an 85% reduced hip fracture risk (HR = 0.15, 95% CI 0.02-0.92, p = .04) versus T1 (p trend = .04). Total protein intake and the animal/plant ratio were not significantly associated with hip fracture (p range = .12 to .65). Our results from middle-aged men and women show that higher animal protein intake coupled with calcium intake of 800 mg/day or more may protect against hip fracture, whereas the effect appears reversed for those with lower calcium intake. Calcium intake modifies the association of protein intake and the risk of hip fracture in this cohort and may explain the lack of concordance seen in previous studies.
Associations between intake of specific nutrients and disease cannot be considered primary effects of diet if they are simply the result of differences between cases and noncases in body size, physical activity, and metabolic efficiency. Epidemiologic studies of diet and disease should therefore be directed at the effect of nutrient intakes independent of total caloric intake in most instances. This is not accomplished with nutrient density measures of dietary intake but can be achieved by employing nutrient intakes adjusted for caloric intake by regression analysis. While pitfalls in the manipulation and interpretation of energy intake data in epidemiologic studies have been emphasized, these considerations also highlight the usefulness of obtaining a measurement of total caloric intake. For instance, if a questionnaire obtained information on only cholesterol intake in a study of coronary heart disease, it is possible that no association with disease would be found even if a real positive effect of a high cholesterol diet existed, since the caloric intake of cases is likely to be less than that of noncases. Such a finding could be appropriately interpreted if an estimate of total caloric intake were available. The relationships between dietary factors and disease are complex. Even with carefully collected measures of intake, consideration of the biologic implications of various analytic approaches is needed to avoid misleading conclusions.
The Framingham Heart Study (FHS) was started in 1948 as a prospective investigation of cardiovascular disease in a cohort of adult men and women. Continuous surveillance of this sample of 5209 subjects has been maintained through biennial physical examinations. In 1971 examinations were begun on the children of the FHS cohort. This study, called the Framingham Offspring Study (FOS), was undertaken to expand upon knowledge of cardiovascular disease, particularly in the area of familial clustering of the disease and its risk factors. This report reviews the sampling design of the FHS and describes the nature of the FOS sample. The FOS families appear to be of typical size and age structure for families with parents born in the late 19th or early 20th century. In addition, there is little evidence that coronary heart disease (CHD) experience and CHD risk factors differ in parents of those who volunteered for this study and the parents of those who did not volunteer.
Few studies have evaluated protein intake and bone loss in elders. Excess protein may be associated with negative calcium balance, whereas low protein intake has been associated with fracture. We examined the relation between baseline dietary protein and subsequent 4-year change in bone mineral density (BMD) for 391 women and 224 men from the population-based Framingham Osteoporosis Study. BMD (g/cm2) was assessed in 1988-1989 and in 1992-1993 at the femur, spine, and radius. Usual dietary protein intake was determined using a semiquantitative food frequency questionnaire (FFQ) and expressed as percent of energy from protein intake. BMD loss over 4 years was regressed on percent protein intake, simultaneously adjusting for other baseline factors: age, weight, height, weight change, total energy intake, smoking, alcohol intake, caffeine, physical activity, calcium intake, and, for women, current estrogen use. Effects of animal protein on bone loss also were examined. Mean age at baseline (±SD) of 615 participants was 75 years (±4.4; range, 68-91 years). Mean protein intake was 68 g/day (±24.0; range, 14-175 g/day), and mean percent of energy from protein was 16% (±3.4; range, 7-30%). Proportional protein intakes were similar for men and women. Lower protein intake was significantly related to bone loss at femoral and spine sites (p ≤ 0.04) with effects similar to 10 lb of weight. Persons in the lowest quartile of protein intake showed the greatest bone loss. Similar to the overall protein effect, lower percent animal protein also was significantly related to bone loss at femoral and spine BMD sites (all p < 0.01) but not the radial shaft (p = 0.23). Even after controlling for known confounders including weight loss, women and men with relatively lower protein intake had increased bone loss, suggesting that protein intake is important in maintaining bone or minimizing bone loss in elderly persons. Further, higher intake of animal protein does not appear to affect the skeleton adversely in this elderly population.
Bone health is the resultant of bone mass, bone architecture, and body mechanics. Nutrition supports all three components, with the principal nutrients concerned being calcium, protein, and vitamin D. Potassium, magnesium, zinc, and several vitamins are also involved to varying extents. Given modern food sources, it is difficult to devise a diet that is "bone healthy" without including three servings of dairy per day, not just because of dairy calcium, but dairy protein and potassium as well.
Milk contains calcium, phosphorus, and protein and is fortified with vitamin D in the United States. All these ingredients may improve bone health. However, the potential benefit of milk on hip fracture prevention is not well established. The objective of this study was to assess the association of milk intake with risk of hip fracture based on a meta-analysis of cohort studies in middle-aged or older men and women. Data sources for this study were English and non-English publications via Medline (Ovid, PubMed) and EMBASE search up to June 2010, experts in the field, and reference lists. The idea was to compare prospective cohort studies on the same scale so that we could calculate the relative risk (RR) of hip fracture per glass of milk intake daily (approximately 300 mg calcium per glass of milk). Pooled analyses were based on random effects models. The data were extracted by two independent observers. The results show that in women (6 studies, 195,102 women, 3574 hip fractures), there was no overall association between total milk intake and hip fracture risk (pooled RR per glass of milk per day = 0.99; 95% confidence interval [CI] 0.96-1.02; Q-test p = .37). In men (3 studies, 75,149 men, 195 hip fractures), the pooled RR per daily glass of milk was 0.91 (95% CI 0.81-1.01). Our conclusion is that in our meta-analysis of cohort studies, there was no overall association between milk intake and hip fracture risk in women but that more data are needed in men.