Nutrition professionals need to share the details when recommending fermented products to clients. What are the health benefits of the specific food or beverage ? Does the product contain probiotics? Live microbes?
“There are a vast array of fermented foods. This is important because it means there can be tasty, culturally appropriate options for everyone,” says Hannah Holscher, PhD and registered dietitian (RD). But, she adds, remember that these are complex products.
Holscher spoke at a webinar produced by the International Scientific Association for Probiotics and Prebiotics (ISAPP) and Today’s Dietitian. Joined by Jennifer Burton, RD and licensed dietitian/nutritionist (LDN), the two addressed the topic Fermented Foods and Health — Does Today’s Science Support Yesterday’s Tradition? Hosted by Mary Ellen Sanders, executive director of ISAPP, the presentation touched on the foundational elements of fermented foods, their differences from probiotics, the role of microbes in fermentation, current scientific evidence supporting health claims and how to help clients incorporate fermented foods in their diets.
Sanders called fermented foods “one of today’s hottest food categories.” Today’s Dietitian surveys show they are a top interest to dietitians, as the general public often turns to them with questions about fermented foods and digestive health.
Here are three factors highlighted in the webinar that dietitians should consider before recommending fermented foods and beverages.
Does It Contain Live Microbes?
Fermentation is a metabolic process – microorganisms convert food components into other substances.
In the past decade, scientists have applied genomic sequencing to the microbial communities in fermented foods. They’ve found there’s not just one microbe involved in fermentation, Holscher explained, there may be many. The most common microbes in fermented foods are streptococcus, lactobacillaceae, lactococcus and saccharomyces.
But deciphering which fermented food or beverages contains live microbes can be difficult.
Live microorganisms are present in foods like yogurt, miso, fermented vegetables and many kombuchas. But they are absent in foods that were fermented then heat-treated through baking and pasteurization (like bread, soy sauce, most vinegars and some kombucha). They’re also absent in fermented products that are filtered (most wine and beers) or roasted (coffee and cacao). And there are foods that are mistakenly considered fermented but are not, like chemically-leavened bread, vegetables pickled in vinegar and non-fermented cured meats and fish.
“The main take-home message is that it’s not always easy to tell if a food is a fermented food or not. So you may need to do more digging, either by reading the label more carefully or potentially contacting the food manufacturer,” Holscher said. “When we just think of if live microbes are present or not, a good rule of thumb is if that food is on the shelf at your grocery store, it’s very likely that it does not contain live microbes.”
Does It Contain Probiotics?
The dietitians stressed: probiotics are not the same as fermented foods.
“Probiotics are researched as to the strains and the dosages to be able to connect consumption of a probiotic to a health outcome,” Holscher said. “These strains are taxonomically defined, they’ve been sequenced, we know what these microorganisms can do. They also have to be provided in doses of adequate amounts of the live microbes so foods and supplements are sources of probiotics.”
Though fermented foods can be a source of probiotics, Holscher notes: “In most fermented foods, we don’t know the strain level designation.”
“For most of the microbes in fermented foods, we’ve just really been doing the genomic sequencing of those over the last 10 years and so we may only know them to the genus level right,” she said. For example, we know lactic acid bacteria are present in kimchi and sauerkraut.
Holscher suggests, if a client has a specific health need, a probiotic strain should be recommended based on its evidence-based benefits. For example, the probiotic strain saccharomyces boulardii is known to help prevent travel-related diarrhea, and so would be good for a patient to take before a trip.
“If you’re looking to support health and just in general, fermented foods are a great way to go,” Holscher says.
The speakers recommended looking for probiotic foods in the Functional Food Section of the U.S. Probiotic Guide.
Does Research Support Health Claims?
Fermentation contributes to the functional and nutritional characteristics of foods and beverages. Fermented foods can: inhibit pathogens and food spoilage microbes, improve digestibility, increase vitamins and bioactives in food, remove or reduce toxic substances or anti-nutrients in food and have health benefits.
But research into fermented foods has been minimal, mostly limited to fermented dairy. Dietitians should be careful making strong recommendations based on health claims unless those claims are supported by research. And food labels should always be scrutinized.
“There’s a lot of voices out there that are trying to answer this question [Are fermented foods good for us?],” says Burton. “Many food manufacturers have published health claims on their labels talking about these benefits and, while those claims are regulated, they’re not always enforced. Just because it has a food health claim on it, that claim may not be evidence-based. There’s a lot of anecdotal accounts of benefits coming from eating fermented foods and the research is suggesting some exciting potential mechanisms. But overall we know as dietitians we have an ethical responsibility to practice on the basis of sound evidence and to not make strong recommendations if those are not yet supported by research.”
Reputable health claims are documented in randomized control trials. But only “possible benefits” can be linked to nonrandomized controlled trials. And non-controlled trials are the least conclusive studies of all.
For example, Burton puts miso in the “possible benefits” category because, with its high sodium content, there’s not enough research indicating it’s safe for patients with heart disease. Similarly, she does not recommend kombucha because of its extremely limited clinical research and evidence.
“We have to use caution in making these recommendations,” Burton says.
This is why Burton advises dietitians to be as specific as possible. Don’t just tell patients “eat fermented foods” — list the type of fermented food and its brand name. She also says to give patients the “why” — what is the benefit of this fermented food? Does it increase fiber or boost bioavailability of nutrients?
“Are fermented foods good for us? It’s safe to say yes,” Burton says. “There’s a lot that we don’t know, but the body of evidence suggests that fermentation can improve the beneficial properties of a food.”