The root of the word probiotic comes from the Greek word pro, meaning "promoting" and biotic, meaning "life." The Food and Agriculture Organization of the United Nations (FAO) defines probiotics as "living microorganisms, which, when administered in adequate amounts, confer a health benefit on the host." Yes, they are actually alive, and most of these microorganisms are bacteria. How can bacteria be beneficial to us?

In the digestive system, it is important to make the distinction between what we would call "good" bacteria and "bad" bacteria. The key for optimal health is indeed keeping the right balance between the "good" bacteria and the "bad" bacteria. Probiotics are fundamental in improving digestion, and the effectiveness and intrinsic strength of the immune system. Probiotics can be found in dairy products, sauerkraut, miso soup, sourdough bread and kefir and they have been shown effective in increasing mood, helping patients with chronic fatigue syndrome and reducing psychological distress in healthy volunteers. However, probiotics have been criticized because they may easily be killed by heat and the stomach, rendering them ineffective before they’ve even been digested.

For this reason, the consumption of prebiotics is advised: chemicals that induce the growth and/or activity of "good" bacteria. So, while probiotics are “external” live bacteria, prebiotics stimulate the flora which are already present in the intestine. Prebiotics are typically non-digestible fiber compounds that, undigested, pass through the upper part of the gastrointestinal tract. Prebiotic fiber is found in many fruits and vegetables, such as the skin of apples, bananas, onions and garlic, Jerusalem artichoke, chicory root and beans.

When probiotics and prebiotics are combined, they form synbiotics. Even if this combination may sound ideal and numerous synbiotic combinations are available commercially, the benefit of synbiotics may be limited given that only specific combinations of probiotics and prebiotics support probiotic survival and growth.

At this point, many more studies are needed to clarify the beneficial effects of probiotics, prebiotics and/or synbiotics, but notwithstanding the intake of them seems a promising tool in augmenting the (human) potential of our mind, besides of our gastrointestinal tract.