Written by: Sandeep Ravindran, Ph.D. | Issue # 96 | 2020
- Yogurt has many health benefits, but studies looking at its effects on mortality have so far been inconclusive.
- A new study of two large prospective US cohorts with long follow-up periods found that regular yogurt consumption was linked to lower mortality risk among women.
- The study also found that replacing yogurt with milk or other dairy foods was related to a greater mortality risk in women, suggesting that yogurt may represent a better food choice over other dairy products in women.
Yogurt isn’t just yummy, it’s also an excellent source of valuable nutrients—including protein, calcium, magnesium and vitamin B-12—and has been associated with various health benefits (1-9).
Given its beneficial effects on health, it’s perhaps not surprising that yogurt has been thought to increase lifespan. “Yogurt and other fermented milk products such as kefir have long been claimed to extend life expectancy by Eastern European countries such as Bulgaria,” says Dr. Karin Michels, now at the University of California, Los Angeles. “We were curious whether these claims would be supported by data,” she says.
Michels’ group has been studying the potential role of the microbiome in mediating the connection between diet and health outcomes. “Fermented foods are the most likely to influence the microbiome so we were curious to see how yogurt might affect longevity,” she says.
Previous epidemiologic studies have shown that regular yogurt intake is associated with lower risks of cardiovascular disease, type 2 diabetes, and certain cancers (10-13). However, studies looking at how yogurt consumption relates to mortality have been relatively sparse, and their results have often been inconsistent (14-18).
In a new study, Michels and her colleagues analyzed data from two large ongoing prospective cohorts of US women and men to evaluate whether yogurt consumption is associated with reduced risks of mortality (19). A total of 82,348 women and 40,278 men were included in their analysis, and the researchers used validated questionnaires to assess yogurt consumption. The cohort of women were followed from 1980 to 2012, and the men from 1986 to 2012. “Regular yogurt consumption was associated with longevity among women,” says Michels.
In addition, the researchers found that replacing one serving per day of yogurt with nuts or whole grains was associated with reduced mortality risk in women, whereas replacing yogurt with red meat, processed meat, milk, or other dairy foods was related to a greater mortality risk. In men, substituting yogurt with nuts was associated with reduced mortality risk and replacing it with red or processed meat was associated with increased mortality risk. The findings provide important information about healthier or unhealthier food alternatives to yogurt, and suggest that yogurt may represent a better food choice over other dairy products in women.
Follow-up studies will be necessary to elucidate the mechanisms by which yogurt may be influencing mortality risk. Yogurt consumption is correlated with higher intake of calcium, but Michels and her colleagues did not find a major difference in the association between yogurt intake and mortality when they adjusted for calcium intake.
One possibility is that the effects of yogurt consumption on mortality are mediated by changes to the gut microbiome. The human gut microbiota has been previously linked to changes in the immune system, cholesterol, and weight gain (20-26). In addition, studies have suggested that yogurt may modify the intestinal microbiota composition in beneficial ways, and bacteria present in yogurt, such as Lactobacillus and Bifidobacterium, may have beneficial effects on immune function that could protect against chronic diseases (27, 28). “We are currently conducting feeding studies with yogurt and kefir to more precisely study the impact of these fermented milk products on the microbiome,” says Michels.
Michels notes a few limitations of the current study. “We would have liked to be able to differentiate between the types of yogurts to get better insights into the study,” she says. “Further, the frequency of consumption in the US is generally lower than in Europe, especially among men, so it is more difficult to evaluate the impact of more frequent consumption and to evaluate a dose-response relation,” says Michels.
The study concludes that regular yogurt consumption was related to lower mortality risk among women. “Regular yogurt consumption very likely benefits human health,” says Michels. “While we were unable to differentiate between the types of yogurts, yogurt without added sugar and flavors is likely the most beneficial to health,” she says.
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