Vitamin D supplements, dairy improve bone density, prevent bone loss in older adults

A combination of consuming vitamin D supplements and specific dairy foods, such as milk, yogurt and cheese, was associated with higher bone density in the spine and was protective of bone loss in the hip among older adults, according to data from The Journal of Nutrition.

“It is estimated that 10 million Americans [older than] 50 years of age have osteoporosis,” Shivani Sahni, PhD, of the Institute for Aging Research at Hebrew SeniorLife in Boston, and colleagues wrote. “Osteoporosis prevention includes regular physical exercise and adequate intakes of calcium and vitamin D. Dairy foods are good sources of calcium and vitamin D and provide more protein, calcium, magnesium, potassium, and phosphorus than any other food. Yet, [more than] 80% of the U.S. population does not meet the recommended dairy intake of three servings/day.”

“Our previous research and that of others, has suggested a positive link between milk intake and [bone mineral density],” they added. “Though, previous studies of [bone mineral density] have focused primarily on young, premenopausal women, most evaluated milk intake, and did not consider other dairy foods with different nutritional profiles or total vitamin D intake.”

Sahni and colleagues studied the association between intake of dairy foods and bone mineral density and bone loss in older men and women between the ages of 63 and 93 years (mean age, 75 years), as well as if these associations were altered by additional vitamin D intake through supplements. Dairy foods assessed included milk, yogurt, cheese, cream, fluid dairy (milk and yogurt) and a combination of milk, yogurt and cheese.

The researchers calculated baseline bone mineral density of the hip and spine recorded from 1988 to 1989 (n = 862) and follow-up bone mineral density documented from 1992 to 1993 (n = 628) from the Framingham Osteoporosis Study’s food frequency questionnaire. Dairy food intake was measured as servings per week and was converted to energy-adjusted residuals. The researchers defined the serving size for milk (skim, low fat or whole) as 237 milliliters, ice milk as 118 milliliters, cottage or ricotta cheese as 118 grams, other cheese as 30 grams, cream as 15 grams, sour cream as 15 grams, ice cream as 118 grams, cream cheese as 30 grams and yogurt as 237 grams.

Milk intake was 6.3 ± 6.8 servings per week and median vitamin D intake was 591 IU per day among vitamin D supplement users, whereas milk intake was 5.8 ± 6.1 servings per week and median vitamin D intake was 184 IU per day among non-vitamin D supplements users.

Results showed that there was no association between dairy food intake and bone mineral density (P = 0.11-0.99) or a 4-year percentage change in bone mineral density (P = 0.29-0.96). Higher intake of milk, fluid dairy and a combination of milk, yogurt and cheese was associated with greater lumbar spine bone mineral density (P = 0.011-0.009) only among vitamin D supplement users. Greater intake of the combination of milk, yogurt and cheese was associated with lower trochanter bone mineral density loss also only among vitamin D supplement users.

“This study is significant because in addition to milk intake, it also examined the association of other dairy foods such as yogurt, cheese and cream with bone mineral density and bone loss over time,” Sahni said in a press release. “Furthermore, this study clarified that the association of dairy foods with bone density is dependent on adequate vitamin intake. However, additional studies are needed to confirm these findings using serum vitamin D concentrations.”

Previous research has found other benefits of vitamin D supplementation, including reducing the risk for acute respiratory infections, such as the common cold and influenza, and reducing HCV cell replication and improving virologic response. – by Alaina Tedesco

Disclosure: The researchers report receiving support from the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health, the National Heart Lung and Blood Institute’s Framingham Heart Study, unrestricted institutional grant from the General Mills Bell Institute of Health and Nutrition, NIH's National Institute of Aging and Friends of Hebrew SeniorLife. Please see full study for complete list of the authors’ individual financial disclosures.