Dairy Products May Have Mixed Effects on Mortality

By David Douglas

January 14, 2019

NEW YORK (Reuters Health) - Pooled data indicate that drinking milk may prompt a slightly higher risk of coronary heart disease (CHD) mortality, while consuming fermented dairy products is associated with lower total mortality.

Dairy-product consumption is thought to increase CHD risk, but reports on the association "particularly among US adults are conflicting and controversial," researchers write in Clinical Nutrition, online December 18.

To investigate further, Dr. Maciej Banach of Polish Mother's Memorial Hospital Research Institute, in Lodz, and colleagues examined data on more than 24,000 participants in the 1999 to 2010 National Health and Nutrition Examination Surveys (NHANES) study.

During a mean follow-up of 76.4 months, there were 3,520 deaths. Among these were 827 cancer deaths, 709 cardiac deaths and 228 from cerebrovascular disease.

As Dr. Banach told Reuters Health by email, "we noticed that those individuals with the highest quartile of total dairy-products intake had a slight (2 to 3%) but significant reduction of all-cause mortality. The same 4% significant trend was observed between total dairy intake and stroke mortality. The former was also observed for cheese intake (8% risk reduction of all-cause mortality), and the latter between milk intake and stroke mortality risk (7% risk reduction)."

There was no association with deaths from cancer.

The researchers then went on to examine data from 12 studies involving more than 636,000 participants and more than 40,000 deaths. The findings were similar, and, said Dr. Banach, showed "a slight 2% but significant reduction of all-cause mortality for fermented products intake (cheese + yoghurt)."

But milk intake, he added, had a positive association with CHD mortality, with "a 4% increase for the highest quartile - which for the moment is difficult to explain. One hypothesis is that there was whole-milk intake (high-fat) in most of the individuals, therefore based on this data we suggest moderate milk intake daily, and mainly low-fat."

He and his colleagues conclude, "Based on our results it seems that the complete avoidance of dairy produces in our diet might be harmful for our health in the long-term."

They add that given the apparently beneficial effect on stroke but associated increase in CHD the "issue of daily milk intake and the possible mechanisms involved need to be still investigated and explained."

Dr. Dariush Mozaffarian of Tufts University, in Boston, who was not involved in the study, told Reuters Health by email, "The meta-analysis confirms the results of prior large studies, that dairy consumption is generally linked to better health, especially intakes of yoghourt, cheese, and other fermented dairy products."

Dr. Mozaffarian, professor of nutrition at the Friedman School of Nutrition Science & Policy, added, "This highlights the need to change our usual perspective of dairy as a single food category, and instead separately consider milk versus yoghourt, versus cheese, both for research and dietary guidelines. The differences between these foods appear more relevant than traditional categorization by fat content (e.g., low-fat, whole-fat), which appears to be relatively unimportant for health."

SOURCE: https://bit.ly/2QEHewg

J Clin Nutr 2018.