Pam Harrison

September 23, 2016

ATLANTA (updated with commentary) — Healthy postmenopausal women who eat at least one serving of yogurt a day have a lower body mass index (BMI), less fat, and better bone density — at least at some skeletal sites — than women who never consume yogurt, new research shows.

Over time, women who ate yogurt also had less cortical bone loss than women who never ate it, and this was independent of any other factor that could account for differences in bone density, such as physical activity and total calcium intake.

"Yogurt is a source of nutrients, in particular calcium and protein, but it also contains fermented daily products and probiotics, all of which are potentially beneficial for bone health," Emmanuel Biver, MD, PhD, chief resident at the Geneva University Hospitals, Switzerland told attendees here at the American Society of Bone and Mineral Research 2016 Annual Meeting.

"So we hypothesized that yogurt consumption might attenuate bone loss in postmenopausal women, and this benefit would be independent of total dietary calcium and protein intake," he added.

"And our data suggest that there is a possible protective effect of fermented dairy products on postmenopausal cortical bone loss," he stressed.

Asked by Medscape Medical News to comment, session cochair Marian Hannan, DSc, MPH, professor of medicine, Harvard Medical School, Boston, Massachusetts, said she was "very taken" with the study and that the investigators had addressed all of her concerns.

She suggested the effects observed could have been because the women were more physically active and/or because of the protein in the yogurt, "but they controlled for physical activity" and "they did the best they could for adjusting for total protein."

"So I would take away from this study that there appears to be something to yogurt," she noted.

Geneva Retirees Cohort

Dr Biver used members of the Geneva Retirees Cohort (GERICO), made up of healthy men and women who were recruited at the age of 65 to investigate the effects of aging on bone and muscle health.

A food frequency questionnaire was taken at baseline and physical activity assessed.

This study included 733 healthy postmenopausal women who underwent bone-mineral-density (BMD) assessment at baseline and again 3 years later.

Yogurt consumption was categorized as never, less than one serving per day, and one or more servings per day, and total calcium and protein intake, as well as total energy intake, were all evaluated.

At baseline, women who consumed yogurt (over 91% of the cohort) had a 4.4% higher BMD value at the lumbar spine than women who never consumed yogurt.

BMD at the distal radius was also 3.4% greater, as was as the tibia cortical area at 5.3% greater, among yogurt consumers compared with nonconsumers, even after adjustment for BMI, physical activity, and total calcium and protein intake, Dr Biver added.

Women who consumed yogurt were also 6.4% leaner than those who never ate it, again independent of total energy intake and physical activity.

And the prevalence of low trauma fractures trended toward a lower rate, at 19% among yogurt consumers vs 29% for nonconsumers, as Dr Biver also pointed out.

More Calcium and Vitamin D in Some Yogurts Than in Milk; Gut Microbiota Also Implicated

At the follow-up assessment 3 years later, Dr Biver and colleagues also found that loss of BMD at the total hip and at the distal radius was attenuated among yogurt consumers, and this effect was again independent of BMI, physical activity, and total calcium and protein intake.

For example, the median annual change in total hip BMD was +0.1% among women who consumed at least one serving of yogurt a day; minus 0.4% for those who consumed less than one serving per day, and minus 0.6% for women who never consumed yogurt.

Significant differences were also seen in losses in the radius cortical area as well as thickness between daily consumers of yogurt and never-consumers, Dr Biver noted (= .007).

In contrast, no significant difference was seen in BMD at the lumbar spine between yogurt consumers and nonconsumers.

"As expected…total dietary calcium and protein increased in parallel with yogurt consumption," Dr Biver noted. However, total energy intake was similar between the three categories of yogurt consumers, he noted.

Senior author Rene Ruzzoli, MD, Geneva University Hospitals, Switzerland, told Medscape Medical News , "Yogurt is composed of plain milk, but in many countries, it contains additional milk powder, so for the same volume of milk, there is more calcium, more phosphorous, and more vitamin D in yogurt."

Bacteria contained in high-quality yogurt are also present to ferment the milk, and these bacteria populate the large intestine, where they improve calcium absorption and decrease inflammation, Dr Ruzzoli added.

Dr Biver also suggested that yogurt consumption may simply be a marker of a healthy lifestyle, where women who consume a nutritious diet overall would be better protected against bone loss.

On the other hand, fermented dairy products may have a favorable influence on the gut microbiota, which is now implemented in a wide range of disorders, including skeletal health.

The researchers plan to explore the latter hypothesis in greater detail.

Dr Hannan concluded: "I think they are probably correct in suggesting that [yogurt's] protective effect on bone has to do not only with protein and…with calcium but also the fermentation that happens in yogurt, all three of which we believe to be good things for bone health."

Dr Biver received a research award from the Danone Institute for his work.

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American Society of Bone and Mineral Research 2016 Annual Meeting; September 18, 2016; Atlanta, Georgia. Abstract 1112.

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