An international team of researchers are revealing that eating foods with higher microbial concentrations can contribute to modest health improvements across a range of outcomes.
The study, which utilized data from the National Health and Nutrition Examination Survey (NHANES) 2001-2018, found that consumption of fermented foods is associated with lower blood pressure, body mass indexes (BMI), waist circumference and blood plasma glucose levels.
NutritionInsight speaks with two of the study’s authors about its findings and implications.
“It is perhaps unsurprising that many nutritional studies tend to converge on the same advice,” says Dr. Colin Hill, a researcher at APC Microbiome Ireland at University College Cork and lead author of the study. “Usually this centers on eating a diversity of foods, with a focus on fresh, fermented and unprocessed foods (such as the Mediterranean diet).”
“The benefits have always been associated with the nutritional content of those food types and more recently, upon their impact on the gut microbiome. But now we are exploring the idea that the diversity of microbes in those foods could also play an important role. This could shape nutritional advice in the future.”
Dr. Joanne L. Slavin, co-author of the study and professor at the Department of Food Science and Nutrition at the University of Minnesota, US, agrees, while noting that the study reveals several health associations with the intake of live microbes, which can serve as a basis for the planning of additional studies.
“We know that live microbe intake is associated with other ‘healthy’ aspects of food such as dietary fiber, plant foods and fermented dairy,” she says. “ So our lens is broad, but helps to support that intake of live microbes has health benefits.”
In the cross-sectional study, published in The Journal of Nutrition, researchers classified over 9,000 foods and sorted them into three categories based on live microbe content. The results showed that people who ate foods with a higher abundance of microbes had better overall health across several different measures.
Not only did those who ate more fermented foods have lower BMIs and lower blood pressures, but they also had lower inflammation and lower triglyceride levels, along with higher lipoprotein density (HDL) cholesterol levels – commonly known as “good” cholesterol.
However, Slavin states that it is important to keep in mind that there are more things in many of these foods than just microbes that could also confer health benefits.
“Since we used the NHANES database, we were not able to include all fermented foods and live microbe sources in our work,” explains Slavin.
“Fermented dairy products are one of the top categories of ‘live microbes’ in the US diet, and we know that dairy products are also rich sources of protein, calcium, and vitamin D.”
Hill agrees, stating: “Once again, the implications for consumers is not that different from most reliable dietary guidelines. Individual consumers could potentially increase their consumption of fermented foods or add probiotic supplements in order to increase their intake of live dietary microbes.”
No “dirty” foods
The authors warn that there is a difference between fermented foods and “dirty” foods, or foods that are not properly prepared for consumption.
“I would stress that it is important that this is not seen as advising people to eat ‘dirty’ food,” says Hill. “Food poisoning can be a serious problem, so I would encourage people to properly cook meats and seafood, to drink pasteurized milk and only consume properly fermented foods.”
“The risk of microbial food poisoning is not trivial and people need to maintain good cooking practices.”
Slavin states that the expectation is that this study will “move the field forward,” past merely studying microbes’ effects on the microbiome to showing all of the health benefits of live microbe consumption.
“We are always building the ‘body of research’ on all food and nutrition topics and to get answers we need to define how to measure dietary exposure and agree on health outcomes,” she concludes.
“Follow-up studies should include a diverse team of food scientists, nutritionists, microbiologists and public health experts in big data and experimental design. Fermentation of foods traditionally has also been used to keep food safe, so knowledge of safe food handling procedures must also be stressed as consumers get excited about fermented foods and health benefits.”
By William Bradford Nichols with additional reporting by Jolanda van Hal