Microbial-based biofortification to mitigate African micronutrients deficiency: A focus on plant-based fermentation as source of B-group vitamins

Micronutrient deficiency is a form of malnutrition responsible for different metabolic diseases, widely shared among developing low-and middle-income African countries. While deficiencies of calcium, iron, vitamin A, zinc, and selenium have been counteracted mainly by implementing mandatory food fortification programs, little attention was given so far on strategies to decrease inadequate intake of water-soluble B-group vitamins. In this review, we summarize the physiological role of B-group vitamins, and discuss the approaches commonly used to tackle their deficiencies in Africa, namely (i) dietary diversification, (ii) supplementation, and (iii) fortification, with the main focus being here the microbial-based biofortification of food. We report the increasing evidence of plant-based African fermented foods as important sources of these vitamins and how microbial-based bio- fortification strategies may enhance their content and bioavailability during plant-based fermentation, especially seen for folate (vitamin B9), riboflavin (vitamin B2), and cobalamin (vitamin B12). The selection of pro- technological functional microbial strains from spontaneous fermentation and/or unconventional food matrices, the employment of vitamin overproducing lactic acid bacteria, as well as the implementation of adequate food processes are promising tools that could be implemented in the production of staple home-made fermented foods to counteract B-group vitamins deficiencies. Further research is needed to explore the biotechnological potential of underexploited indigenous microbial strains and the impact of fortified foods on gut host health.