Subject: A recent study undercuts those “got milk” advertisements.
From watching advertisements paid for by the dairy industry promoting milk consumption, most people assume that the milk prevents osteoporosis. Yet this relationship, although seemingly obvious as milk contains calcium, has never been proven. Epidemiological studies of milk consumption and osteoporosis rates have actually argued against this theory. Switzerland which has the highest dairy consumption in the world also has the highest rate of osteoporosis. Given this, I've always wanted to see some clearer correlation before I would believe those Got Milk ads. It's always seemed like it would be easy enough to prove. A few years back, I even wrote to the Dairy Council asking for evidence of this relationship; letters which went unanswered.
With this background in mind a recent study in the American Journal of Clinical Nutrition caught my eye. Researchers at Purdue University looked at dairy intake and its affect on bone mineral density. They found a slight correlation (0.23) between dairy intake and bone mineral density in older men. They found no correlation between dairy intake and bone density in women. Calcium supplementation did have a benefit.
Am J Clin Nutr. 2004 Oct;80(4):1066-74.
Dairy intakes affect bone density in the elderly.
McCabe LD, Martin BR, McCabe GP, Johnston CC, Weaver CM, Peacock M.
Purdue University , West Lafayette , IN , USA .
BACKGROUND: Race and sex differences in the effect of diet on bone mineral density (BMD) at the hip in the elderly are unknown. OBJECTIVES: This study related cross-sectional nutrient and dairy product consumption to hip BMD in white and black men and women aged >60 y and evaluated the influence of nutrient and dairy product consumption on changes in BMD in a white cohort participating in a calcium, vitamin D, or placebo trial. DESIGN: The Health Habits and History Questionnaire was used in 289 white women and 116 white men who participated in the trial and in 265 black women and 75 black men to predict total hip and femoral neck BMD or changes in BMD. RESULTS: Blacks had higher calcium intakes than did whites (700 and 654 mg/d, respectively; P = 0.0094), and men had higher calcium intakes than did women (735 and 655 mg/d, respectively; P = 0.0007). For men, the correlation between total hip BMD and dairy calcium intake after adjustment for age, race, and weight was 0.23 (P < 0.005); this relation was not significant in women (r = 0.02, P = 0.12). Similar results were found for femoral neck BMD. In the longitudinal study, calcium supplementation reduced bone loss from the total hip and femoral neck in those who consumed <1.5 servings of dairy products/d and were <72 y old. CONCLUSIONS: Cross-sectional results indicated that higher dairy product consumption is associated with greater hip BMD in men, but not in women. Calcium supplementation protected both men and women from bone loss in the longitudinal study of whites.
Randomized Controlled Trial
PMID: 15447921 [PubMed - indexed for MEDLINE]