Part D. Chapter 2: Dietary Patterns, Foods and Nutrients, and Health Outcomes - Continued
Dietary Patterns and Bone Health
Existing Evidence around Foods and Nutrients and Bone Health
Low bone mineral density and osteoporosis are common in the United States, particularly in older adults, and its contribution to disability and cost to the health care system continues to rise in parallel to longer life expectancy. As described in Part D. Chapter 1: Food and Nutrient Intakes, and Health: Current Status and Trends, more than half of women ages 60 to 69 years have low bone mass and approximately 12 percent meet established criteria for osteoporosis. The prevalence of osteoporosis increases with age; about one-quarter of women ages 70 to 79 years and about one-third of women older than age 80 years have osteoporosis. Low bone mass is less common in older men but is increasingly recognized. Among U.S. men ages 60 to 69 years, about a third have low bone mass and this increases to about 40 percent and slightly more than 50 percent for men ages 70 to 79 years and 80 years and older, respectively.
Poor bone health and osteoporotic fractures are a major cause of morbidity and mortality in the elderly and account for significant health care costs. Understanding the extent to which dietary factors can help improve bone health and reduce the incidence of fractures across all segments of the population, particularly in the elderly, is important for the health and well-being of the nation.
The most critical nutrients for healthy bone are calcium, vitamin D, and phosphorous. As part of their 2011 report on Calcium and Vitamin D, the Institute of Medicine extensively reviewed the available data and updated the Dietary Reference Intakes (DRIs) for calcium and vitamin D for men and women across life stages.206 The new reference values were based upon a strong body of evidence regarding bone growth and maintenance. At the time of the report, these bone health outcomes (in particular bone mass [bone mineral content]) were the only indicators on which there was sufficient scientific evidence to define DRIs; a thorough review of other outcomes (bone mineral density, risk of fractures, and osteoporosis) provided mixed and inconclusive results, and thus did not inform the DRIs. Part D. Chapter 1: Food and Nutrient Intakes, and Health: Current Status and Trends of this DGAC report concluded that calcium and vitamin D were shortfall nutrients of public health concern. The estimated low levels of intake in various age and sex groups place many at risk for suboptimal bone health. The DGAC asked additional questions regarding bone health that went beyond those relating to the role of specific and well-known nutrients on bone remodeling. Specifically, the DGAC considered the influence of dietary patterns and their relationship to bone health and specific bone health outcomes across the lifespan, including bone density and fractures. This approach enabled the DGAC to consider the relationship between the total diet and its component foods and nutrients, acting in combination, on bone health outcomes. This section reviews this evidence and forms the basis for the DGAC recommendation for action at individual and population level as well as its research recommendations.
Question 7: What is the relationship between dietary patterns and bone health?
Source of evidence: NEL systematic review
Limited evidence suggests that a dietary pattern higher in vegetables, fruits, grains, nuts, and dairy products, and lower in meats and saturated fat, is associated with more favorable bone health outcomes in adults, including decreased risk of fracture and osteoporosis, as well as improved bone mineral density. Although a growing number of studies are examining the relationship between dietary patterns and bone health in adults, the number of high-quality studies is modest and those available employ a wide range of methodologies in study design, dietary assessment techniques, and varying bone health outcomes.
Definitive conclusions regarding the relationship between dietary patterns and bone health outcomes (bone mineral density and bone mineral content) in children and adolescents cannot be drawn due to the limited evidence from a small number of studies with wide variation in study design, dietary assessment methodology, and bone health outcomes. DGAC Grade: Adults Limited; Children and Adolescents - Grade not assignable
Only limited evidence is available on the relationships between dietary patterns and bone health outcomes in adults and other age groups. Although there is strong evidence on the roles of vitamin D and calcium in bone health across the age spectrum, further research is needed on dietary patterns that are most beneficial.
Review of the Evidence
This systematic review included two articles that used data from RCTs and 11 articles from prospective cohort studies published since 2000 that examined the relationship between dietary patterns and bone health.207-219
The articles employ diverse methodologies to assess dietary patterns. Four articles used an index or score, six articles used factor analysis/principal components analysis, two articles used reduced rank regression, and two articles tested dietary patterns in an intervention study where bone health or fractures were either secondary or tertiary trial outcomes. Seven studies assessed risk of fracture, six studies assessed bone mineral density, bone mineral content, or bone mass, and one study examined risk of osteoporosis. The dietary patterns examined in this systematic review were defined in various ways, making comparisons between articles difficult. However, despite heterogeneity in this body of evidence, some common characteristics of dietary patterns associated with better or adverse bone health outcomes emerged, particularly in articles where patterns were defined by index or score. Articles using data-driven methods were less consistent. The following overall conclusions can be drawn:
- Patterns emphasizing vegetables, fruits, legumes, nuts, dairy, and cereals/grains/pasta/rice, and unsaturated fats were generally associated with more favorable bone health outcomes.
- Patterns higher in meats and saturated fats were generally associated with increased risk of adverse bone health outcomes.
- Results were far less consistent for added sugars, alcohol, and sodium in relation to bone health.
Although many cohort studies make extensive efforts to include participants across a wide range of race/ethnic groups and across the socio-economic continuum, there still may be some groups for which the association between dietary patterns and bone health cannot yet be determined (i.e., children, adolescents).
For additional details on this body of evidence, visit: http://NEL.gov/topic.cfm?cat=3360