A review of nondairy kefir products: their characteristics and potential human health benefits

Functional foods are foods that, in addition to having nutrients, contain in their composition ingredients that act specifically on body functions associated with the control and reduction of the risk of developing some diseases. In this sense, kefir, a group of microorganisms in symbiosis, mainly yeasts and lactic acid bacteria, stands out. The trend of ingesting kefir has been focused on the development of products that serve specific consumers, such as those who are lactose-intolerant, vegans and vegetarians, and consumers in general who seek to combine the consumption of functional products with the improvement of their health and lifestyle. This overview provides an insight into kefir, presenting the technological process to produce a nondairy beverage and evidence of the benefits of its use to reduce the risk of disease. We also discuss regulatory aspects of products fermented using kefir. Until now, the use of kefir (isolated microorganism, kefiran, or fermented product) has demonstrated the potential to promote an increase in the number of bifidobacteria in the colon and an increase in the glycemic control while reducing the blood cholesterol and balancing the intestinal microbiota, which helps in reducing constipation and diarrhea, improving intestinal permeability, and stimulating and balancing the immune system. However, the literature still has gaps that need to be clarified, such as the consumption dose of kefir or its products to cause some health benefit.