Live longer with fermented foods

What fermented foods have in common is that they were produced through the intervention of micro-organisms. Used for millennia, fermentation increases food safety and extends shelf life by inhibiting pathogenic microorganisms responsible for food spoilage. It can also improve the nutritional value and digestibility of foods. “Fermentation will transform the food, making it more flavorful, but also much richer from a nutritional point of view, explains Dr. Martine Cotinat in The magic of fermented foods. Beneficial fibers, more amino acids, vitamins, antioxidants, anti-cancer molecules, better bioavailability of minerals…are some of the gifts that fermentation offers you. »

Beyond these metabolic products, live microorganisms present in fermented foods may have direct health benefits by modulating the gut microbiota and enhancing immune function. This effect is transient, the time that these natural probiotics spend in the digestive tract. However, not all fermented foods contain live microorganisms at the time of consumption. They can be destroyed during cooking: this is the case with bread for example. But the fermentation could have produced beneficial molecules which remain in the final product.

Fermented foods cover a wide range of categories: dairy products, lacto-fermented vegetables (sauerkraut, kimchi, etc.), bread, soy derivatives (natto, miso), cold meats, wines, beers and other drinks (kombucha, kefir)… Deeply anchored in the traditional diets of all cultures, they represent approximately a third of the human diet globally. Recent data from the Swiss adult population indicate that fermented foods represent more than 20% of daily dietary intake and significantly increase the intake of essential nutrients, including calcium, vitamins A and B12, zinc and saturated fat (1).

A global analysis

In total, the researchers selected 52 cohort studies carried out on several continents, making it possible to evaluate the link between consumption of fermented foods and mortality. Among these studies we found, for example:

• large international cohorts: the PURE study conducted in 21 countries with more than 136,000 participants examined dairy consumption in relation to cardiovascular disease and all-cause mortality;
• in Japan: several cohort studies including a prospective study conducted by Japanese public health centers, called JPHC. This study, which followed more than 93,000 adults for nearly two decades, looked at the consumption of fermented dairy and fermented soy products;
• in Europe: the EPIC and MONICA studies, but also large Swedish and Dutch studies;
• in the United States: large cohorts of nurses and health professionals, etc.

Together, these studies cover a wide cultural and dietary diversity.

Benefits vary depending on the food

Only one cohort study has examined the link between fermented foods, considered as a whole, and mortality risk. It was conducted in the Netherlands and its results were inconclusive. On the other hand, taken separately, different fermented products have shown beneficial links with health.

• Fermented dairy productssuch as yogurt and probiotic drinks: their consumption modestly reduces all-cause mortality and cardiovascular mortality. For example, out of 18 studies on total mortality (over 1.17 million participants), 10 show a significant decrease in risk, while others observe a non-significant trend or a neutral effect.
• Yogurt was also analyzed separately. 13 studies involving more than 828,000 people have evaluated its consumption in relation to total mortality: five show a significant reduction in risk, five a non-significant reduction, and three a neutral effect. Conclusion: There is a moderate reduction in total mortality, classified as “slightly reduced”. Data also suggests that yogurt consumption may slightly reduce cardiovascular mortality.
• The cheese shows beneficial effects on general mortality, but data on cardiovascular health are conflicting.
• Fermented soy products like natto, show a modest association with a reduction in overall and cardiovascular mortality. For example, based on a cohort study that examined total consumption of fermented soy products, there was a statistically significant inverse association with all-cause mortality. In contrast, this study found no benefit for unfermented soy products, indicating the potential additional benefit of fermentation.

Mechanisms of action explained

The potential benefits of fermented foods are explained by the presence of compounds resulting from fermentation: bioactive peptides, polyphenols, isoflavones, nattokinase and vitamin K2.

The lactic acid produced by bacteria during lacto-fermentation also has advantages. “An important source of energy, it is capable of transforming into glucosesays Martine Cotinat. It is also known to have a very effective antimicrobial action against unwanted bacteria. »

Lactic acid bacteria also produce specific fibers: EPS or exopolysaccharides which protect the bacteria from environmental stress. “These EPS have many other interesting powers for human health, once ingested with food, explains Martine Cotinat. They not only exert a prebiotic activity by stimulating the growth of good bacteria in the intestinal microbiota, but also an anti-inflammatory, antioxidant, anticancer, antiviral (against rotavirus, adenovirus, coronavirus), hypocholesterolemic, blood thinning, regulating the immune system and antidiabetic action. »

To go further: The magic of fermented foods