Mediterranean Diet May Help Reduce Women's Hip-Fracture Risk

Miriam E Tucker

March 30, 2016

Following a Mediterranean-style diet may reduce the risk for hip fractures among postmenopausal women, a new analysis from the Women's Health Initiative suggests.

The findings were published online March 28 in JAMA Internal Medicine by Bernhard Haring, MD, a clinical fellow in the department of medicine at the University of Würzburg, Germany, and colleagues.

The Mediterranean dietary pattern emphasizes the consumption of fruits, vegetables, fish, nuts, legumes, whole grains, and monounsaturated fat, with avoidance of red and processed meats. In the study, women in the highest quintile for adherence to this diet pattern, compared with the lowest quintile, were significantly less likely to experience a hip fracture over a follow-up period of about 16 years, although overall fracture rates didn't differ.

Adherence to other healthful dietary patterns aligning with the 2010 US Dietary Guidelines and with the Dietary Approaches to Stop Hypertension (DASH) diet also were associated with a lower hip-fracture risk, although they did not achieve statistical significance.

"The average woman should follow a healthy lifestyle, which includes adopting a healthy dietary pattern, [such as] a Mediterranean dietary pattern, and being physically active. To this point, unfortunately, the US as well as other healthcare systems largely ignore nutrition and lifestyle measures in favor of pharmacology," Dr Haring told Medscape Medical News.

Indeed, in an accompanying editorial, nutrition expert Walter C Willett, MD, chair of the department of nutrition at Harvard's TH Chan School of Public Health, Boston, Massachusetts, noted that the "wealth of evidence" linking the Mediterranean diet to cardiovascular benefits led the 2015 US Dietary Guidelines Committee to recommend it, along with "healthy American and vegan dietary patterns based on similar elements" for widespread adoption.

"Integration of the Mediterranean diet and related dietary patterns into medical practice, hospitals, schools, and other institutions has the potential to improve well-being," writes Dr Willett.

Healthful Diets and Fracture Risk

The Women's Health Initiative enrolled over 90,000 postmenopausal women aged 50 to 79 years between 1993 and 1998 at 40 US clinical centers. Haring and colleagues looked at nutrient and food intake derived from self-report through questionnaires. They were scored for adherence to the Mediterranean dietary pattern, as well as to three others: The 2010 US Dietary Guidelines, assessed by the "Healthy Eating Index 2010"; a modified version of that called the "Alternative Healthy Eating Index 2010," which accounts for type of fat, form of carbohydrate, and source of protein; and the DASH diet, which emphasizes lowering sodium content along with the other healthful patterns.

All four diets generally emphasize intake of fruits, vegetables, whole grains, and plant sources of protein and deemphasize refined starch, sugar, and red meat.

During a median follow-up of 15.9 years, a total of 2121 cases of hip fracture were documented and 28,718 cases of total fractures were self-reported. After adjustment for confounders including age, race/ethnicity, body mass index, smoking status, physical activity, physical function score, number of chronic medical conditions, and use of hormone therapy and bisphosphonates, women scoring in the highest quintile for Mediterranean diet adherence had a lower risk for hip fractures, with hazard ratio (HR) 0.80, absolute risk reduction 0.29%, and number needed to treat of 342. No association was seen for the diet and total fractures (HR, 1.01).

Higher adherence to the Healthy Eating Index 2010 and to the DASH diet also tended to be inversely related to hip fracture risk (HRs, 0.87 and 0.89, respectively), although these did not achieve statistical significance and, like the Mediterranean Diet, were not associated with total fractures. There was also no significant relationship between adherence to the alternative Healthy Eating Index 2010 and hip or total fractures (HR, 0.94).

The lack of an association with total fractures might be explained by the wide heterogeneity of fracture types in the analysis, Dr Haring told Medscape Medical News.

More Than One Reason to Go Mediterranean

Dr Willett cited a concern about the current study, that residual confounding is likely due to error introduced by assessing physical activity with via questionnaire and only at a single time point. Had physical activity been assessed better, he speculated, the results for dietary intake and hip fractures might have been nonsignificant.

Nonetheless, he writes, "At a minimum the present findings provide assurance that widely recommended eating patterns do not increase the risk of fractures, even though some of these patterns do not emphasize the intake of dairy foods."

Dr Haring told Medscape Medical News that he agrees with Dr Willett regarding the caveats, adding, "In any case, given the known benefits of a Mediterranean-type diet — eg, prevention of cardiovascular disease — integration of the Mediterranean diet and related dietary patterns is of great public-health importance."

The Women's Health Initiative is funded by the National Heart, Lung, and Blood Institute. Neither the study authors nor Dr Willett have relevant financial relationships.

JAMA Intern Med. Published online March 28, 2016. Abstract, Editorial


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