In the beginning of this year, we get back to some interesting publications of 2021…
Recent years have seen a surge of interest in fermented foods, largely thanks to their suggested health benefits…
What is a fermented food?
Experts have joined forces to agree a consensus on fermented foods and their role in the human diet (1). They define fermented foods and drinks as ‘foods made through desired microbial growth and enzymatic conversions of food components’. This includes foods that are produced by fermentation but might not contain live microorganisms by the time we eat them and we can distinguish:
- Foods with live microorganisms like fermented milk, yogurt, kefir, tempeh or natto, for example.
- Foods without live microorganisms like bread, wine, cocoa or coffee beans, for example.
Over 5000 types of fermented foods are produced and consumed around the World and a huge variety of fermented foods has developed throughout history, including vegetables, cereals and breads, soybean products, dairy products, fish products, and meats.
Fermented dairy products evolved throughout the Middle East, Europe and India where animal husbandry was widespread. In much of Asia, animal agriculture was more limited and fermented foods were more often based on rice and grains, soybeans, vegetables and fish.
Traditionally, fermentation of foods was spontaneous as the result of microbes occurring naturally in the food or contamination by microbes in the environment. Nowadays, particularly in industrialized countries, defined starter cultures of microbes are more often used, and this has led to greater consistency, safety and quality of fermented products (3).
Do fermented foods have impact on health?
The gut microbiota refers to the trillions of micro-organisms – bacteria, fungi and viruses – that live in the digestive tract. A diverse and balanced microbiota is a sign of good gut health, and it is possible to change the mix and activity of the microbiota through changes in the lifestyle, such as the diet.
Fermented plant foods may have an impact: A study (2) points out subtle differences in the gut microbial diversity, between the consumers or non-consumers of fermented plant foods (kimchi, kombucha, pickled vegetables, sauerkraut,…). In light of these results, studies looking at the impact of different kinds of fermented food on the gut microbiota and health are needed.
Fermented dairy products help us absorb nutrients: Fermented dairy foods include cultured milks, cheese and yogurt. Lactic acid bacteria (LAB) that are naturally present in milk or added as starter LAB cultures convert milk sugar (lactose) to lactic acid, prevent the growth of harmful bacteria and help us absorb the nutrients better (3).
Are fermented foods probiotics?
Probiotics are specific microorganisms that remain alive within the gut after being ingested and are proven to confer a health benefit.
A fermented food may be described as a “probiotic food” only if:
- it contains live microorganisms at the time it is eaten,
- those microorganisms (bacterial or yeast strains) are well defined and have shown a health benefit in a scientific study, and
- the strains are present in the final food product in sufficient numbers to confer the health benefit.
Most fermented foods sold commercially do not fall into this “probiotic food” category (1).
Fermented foods and sustainability
Fermented foods help to address the societal, environmental, cultural and economic aspects of sustainability (3):
- In poorer regions, production of fermented foods such as yogurt provides access to safe and healthy food, creates demand for local produce, and provides employment and income opportunities.
- Fermented foods are also good news for the environment. By making use of available local produce, minimal additional agricultural input is needed in resource-poor regions. Fermentation uses little energy compared with food processing methods such as canning and freeze-drying.
- Production of yogurt, fish sauces and fermented cereals produces few waste or by-products, say the authors. Fermentation is also a good way of improving efficiency and reducing food wastage, for example by manufacturing fish sauces from highly perishable fish.
Good reasons to keep the good habits of eating fermented foods.
Sources:
(1) Marco ML, Sanders ME, Gänzle M et al. The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods. Nat Rev Gastroenterol Hepatol. 2021;18(3):196-208.
(2) Taylor BC, Lejzerowicz F, Poirel M et al. Consumption of fermented foods is associated with systematic differences in the gut microbiome and metabolome. mSystems. 2020;5(2):e00901-19. doi: 10.1128/mSystems.00901-19.
(3) Tamang JP, Cotter PD, Endo A et al. Fermented foods in a global age: East meets West. Compr Rev Food Sci Food Saf. 2020;19(1):184-217.
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