Skip to 0 minutes and 7 seconds[music] - Hello everybody, and welcome back. As we already stated during this week, superfood is not a regulated term, and it can be applied to very different foods with different properties and nutritional content. There are a few terms that are often associated with superfoods. In some cases, the meaning is intuitive such as for antioxidants, anti-inflammatory or vitamins. The meaning of other words can be less clear, and they can lead to confusion. It is the case, for instance, of prebiotics and probiotics. Probiotic is probably the term we are most familiar with, and it refers to microorganisms that can provide health benefits to their host organisms.

Skip to 1 minute and 3 secondsThis concept was introduced by a Russian biologist, Elie Metchnikoff, who used it to relation to one of the most common sources of probiotics, yogurt. Yogurt is produced by the fermentation of milk by specific strains of bacteria such as Lactobacillus delbrueckii bulgaricus. Other similar products such as kefir are produced with analogous processes by different genera of bacteria. Both yogurt and other fermented products can contain more than a single bacterial strain. Different bacteria are added either for the characteristics they give to the final product, or for the supposed beneficial effect. Why should probiotics be good for our health?

Skip to 1 minute and 57 secondsThe idea behind these claims is that when we consume them, bacteria can survive the acid in our stomach, reach our gut, and form colonies there. These colonies of good bacteria could then perform a number of useful functions such as synthesizing vitamins, and short-chain fatty acids, competing with pathogens for resources and stimulating the immune system. In order to thrive, these probiotic bacteria need both a viable habitat and an abundant source of food. This is where the second term of this lecture, prebiotic, comes into play. As probiotic bacteria live in our gut, they can benefit from the components of our diets that are not digested and absorbed in the stomach.

Skip to 2 minutes and 56 secondsTherefore, the term prebiotic indicates the molecules that can reach undigested our gut where they're metabolized by the probiotic bacteria. Most of these substances are a specific kind of fibers and they can be found, for instance, in unrefined wheat, and barley, as well as in some vegetables such as Jerusalem artichoke, and chicory root. Therefore, both prebiotics and probiotics would improve our health by modifying the population of bacteria living in our gut. Both have been associated to a range of health benefits. Are these health claims proven? As often is the case in Science, the answer is not clear-cut.

Skip to 3 minutes and 49 secondsOn one hand, multiple studies found that specific strains of probiotic bacteria are linked with positive effects on health such as activity against traveler's diarrhea or antibiotic-associated diarrhea. Other studies showed an effectiveness of a mixture of probiotics on the symptoms of irritable bowel syndrome, and linked the consumption of probiotics to increased absorption of some minerals, and regulation of bowel movements. On the other hand, the overall evidence in support of the health claims of pro and prebiotics is not very strong. When the entire body of research is analyzed, there are few proven health benefits. This is why, to the best of our knowledge in mid-2018, the European Food Safety Authority approved a health claim linked to probiotics in just one case.

Skip to 4 minutes and 56 secondsProducts such as yoghurt, kimchi, kefir, and sauerkraut have been consumed traditionally for hundreds of years, and they have good nutritional properties. They are already part of traditional eating habits in many countries, and there is no reason to either abandon them, or to think of them as a solution to some of our health problems, regardless of their labeling.

Probiotics and prebiotics

Our gut microbiome is linked with our health.

It is therefore of no surprise that foods that can influence our gut bacteria, by increasing the number of beneficial ones, received attention from scientists and consumers alike.

Yogurt and kefir are two very common sources of probiotics, and both have been named as superfoods, but is their beneficial effect proven? In contrast, prebiotic-rich foods are not commonly consumed by humans, and we are more likely to consume them in the form of supplements or nutraceuticals, but despite this difference they have the same final goal as probiotics.

In this video, we discuss the differences and links between the two concepts, and briefly review the scientific literature to find whether they can be said to be effective in improving our health.

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This video is from the free online course:

Superfoods: Myths and Truths

EIT Food