Milk may not do a menopausal body good

A new study has found that dairy consumption does not benefit lumbar spine or femoral neck bone density in perimenopausal and menopausal women. The findings also suggest that dairy product consumption does not prevent or reduce the risk of bone fractures.¹

Published in The North American Menopause Society (NAMS) journal Menopause, the study focused on analyzing the change in lumbar spine and femoral neck bone mineral density (BMD) and the risk of bone fracture by the frequency of dairy intakes among women across the menopausal transition.

For the analysis, researchers used data from the Study of Women’s Health Across the Nation (SWAN), a multicenter, multi-ethnic, community-based longitudinal cohort designed to examine women’s health during their menopause transitions.

The SWAN bone sub-study began collecting baseline data in 1996, with 3,302 pre- or early perimenopausal women aged between 42 and 53 years who had an intact uterus, at least one ovary, and no hormone usage in the last 3 months prior to screening from 5 clinical sites in the US (Los Angeles, Calif., Boston, Mass., Detroit, Mich., Oakland, Calif., and Pittsburgh, Penn.). After initial enrollment, women were followed up annually for collection of information on demographic, clinical, and anthropometric data.

Among 2,335 women with complete data on femoral neck and/or lumbar spine BMD at baseline, those who had osteoporosis, diabetes, and cancer were excluded. The authors also excluded women for whom data about menopausal status, dairy intake, physical activity or smoking status at baseline were missing or unknown.

Researchers included 1,955 women in the sample for assessment of the annualized rate of BMD loss and fracture analyses. Dual-energy x-ray absorptiometry scans were performed at all 5 sites to obtain BMD on both the femoral neck and lumbar spine at each annual visit. For the study, researchers analyzed total dairy foods in 4 categories of <0.5, 0.5 to <1.5, 1.5 to <2.5, and ≥2.5 servings/d or <1.5 and ≥1.5 servings/d.

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A general linear model was used to estimate the association of dairy intake with the 10-year bone mineral density loss rate and a linear mixed model was used to estimate the annualized BMD loss rate of the femoral neck and lumbar spine. The models were controlled for race/ethnicity, age, height, weight, smoking status, physical activity, alcohol consumption, calcium use, menopausal status, and total caloric intake.

Following sensitivity analyses and adjustments for hormone use, researchers found that dairy intakes across SWAN participants did not influence total calcium intake enough to impact overall femoral neck and lumbar spine BMD outcomes.

The authors of this study note several factors to consider when interpreting the results. Dairy intake was low among SWAN participants, with 65% reporting consumption of <1.5 servings per day. Second, information about milk intake during teenage years was not available in the SWAN data.

Dairy intake was particularly low among women of races other than Non-Hispanic White. “This racial disparity has been consistently suggested in the US population and could be partly attributable to lower rates of lactose intolerance among non-Hispanic White women, as compared to other racial groups,” the authors wrote.

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Reference

1. Wallace TC, Jun S, Zou P, et al. Dairy intake is not associated with improvements in bone mineral density or risk of fractures across the menopause transition: data from the Study of Women's Health Across the Nation. Menopause. 2020;27(8):879-886. doi:10.1097/GME.0000000000001555