Immunomodulation by probiotics: a literature survey

The primary function of food in the human diet is to provide nutrients and energy. Nutrients include macronutrients (protein, fat and carbohydrates) and micronutrients (minerals, vitamins,and trace elements). Food also has the secondary function of giving sensory satisfaction by its flavour, taste and colour. Recently identified is a third function: the capacity of food to modulate physiological systems (immune, endocrine, nervous, circulatory and digestive) beyond the accepted nutritional effects. Food components having these functions are called "functional foods" or "novel foods". This report reviews the immunomodulating properties of probiotics. Most literature on this topic is focused on beneficial health effects. In contrast, not much information is available on deleterious effects . Different probiotics may also have different effects, sometimes opposite, depending on the type. Therefore it is difficult to draw overall conclusions on the risks and benefits of probiotics. For this reason, more studies should be done to investigate these risks and benefits.The most appropriate way to conclude whether immune effects noted are beneficial or rather deleterious is to study effects of exposure in disease models. Such models include infection models, models of respiratory, skin, and food allergy and models of autoimmunity. Patterns of immune alteration due to the probiotics may interpreted in the context of the clinical effects observed, so that eventually such patterns alone would be able to indicate possible beneficial or deleterious effects of probiotics. Information on patterns of effects indicative of positive or negative consequences of the use of probiotics will eventually form the basis of designing a protocol for the evaluation of probiotics to be put on the market