A higher intake of certain foods can reduce immune function and open the door for disease. This includes those foods high in sugar or heavily processed. Other foods, when consumed at higher rates, have the opposite effect, giving the immune system a boost.
According to a review published in July of 2023, fermented foods with probiotics fall into the second category, offering a synergistic effect on immunity that the authors state “cannot be overemphasized.”
The power of probiotics
In this review published in the International Journal of Food Science and Technology, the authors share that probiotics help promote greater immunity largely through their impact on the gut microbiome—an impact discovered back in 1907. The human gut naturally contains a variety of healthful bacteria helping the body digest food and utilize the nutrients these items contain. Probiotics are thought to enhance this effect by supplying the gut with more healthful bacteria, improving these effects.
Probiotic microorganisms with the strongest ties to improved human health include those in the Lactobacillus and Bifidobacterium species. These can be found in a number of dairy products, including yogurt, milk and cheese, in addition to other food products.
Research has connected these live microorganisms with greater resistance to infection and improved immune system regulation, also citing their beneficial effects on allergies and blood cholesterol levels. Probiotics may even offer protection against long-term diseases, such as those that impact the cardiovascular, respiratory and gastrointestinal systems.
Health benefits of probiotic fermented foods
Fermented foods provide their own health benefits, according to the review. These include a reduced risk of immune-related diseases, along with a lower risk of various metabolic, cardiovascular and cognitive disorders.
Other research supports the positive impact of fermented foods on immune system function, often through the same mechanisms as probiotics. One such piece of research was published in the journal Nutrients in 2022. It explains that while fermentation can help extend a food’s shelf life, consumption of these products is strongly associated with a reduced risk of disease and mortality. Fermented foods have also been linked with successful weight management.
Fermented foods include tempeh, kefir and sauerkraut, though they are also available in drinkable form. Kombucha is a beverage created using a fermentation process.
Synergy of probiotics and fermented foods together
Authors of the July 2023 review suggest that while probiotics and fermented foods each have their own health benefits, items containing both can provide a synergistic effect. When each is present in the same food source, the gut microbiome benefits exponentially.
Another study published in Food Control in September 2021 adds that fermented food with probiotic bacteria may help protect against viruses affecting the respiratory and alimentary tracts. Their ability to exert these effects appears to be due to stimulation of immune system function. More specifically, these combination foods seem to increase the toxicity of natural killer cells, enhance the production of pro-inflammatory substances (cytokines) and promote the growth of cells that destroy infected cells (cytotoxic T-cells).
Items that are both probiotic and fermented are referred to as probiotic fermented foods. Fermented foods with live probiotic microorganisms include sour cream, yogurt, kefir, tempeh and a majority of cheeses. Natto, miso and vegetables fermented without the use of heat also fall into this food category.
Taking probiotics safely
Fermented foods containing probiotics are generally safe to consume. However, the U.S. Food and Drug Administration (FDA) warns that the bacteria or fungi in probiotic products can be deadly for infants born very preterm or with extremely low birth weights, increasing their risk of a disease with potentially deadly consequences. For this reason, it’s advised that these infants avoid probiotics.
Probiotics already boost immune function, but when consumed along with fermented foods like kimchi or sauerkraut, the immune-enhancing effects are multiplied significantly. Make a habit of taking a high-quality probiotic and pair it with a balanced diet featuring fermented foods, and fermented foods that contain their own probiotic microorganisms, to keep your immune system functioning at its peak.