Nutrition and Immunity: Key Nutrients and Trends in Nutrient Supplementation in Women and Children

Nutrition plays a critical role in promoting good immunity and health. One third of the population has at least one micronutrient deficiency, with higher vulnerability observed in women and children. A healthy diet is critical to guarantee an adequate micronutrient status and good immune response. Food components (high-quality fats and carbohydrates; many micronutrients) have been associated with antioxidant, anti-inflammatory, and immune-modulating properties. All pregnant women should be supplemented with folic acid and iron, and some may require calcium supplementation for the prevention of preeclampsia. Some women may benefit from multiple micronutrient supplementation (MMS), vitamin D, and/or omega 3. In breastfeeding babies, vitamin D supplementation is indicated for preventing deficiency, and, in areas of high vitamin A deficiency prevalence, children may need vitamin A supplementation to prevent morbidity and mortality. In adults, some evidence has shown that vitamin D or C supplementation may decrease the risk of respiratory infections and/or duration of symptoms. For COVID-19, there is some evidence of a reduction of complication events, mainly ICU admissions in adults supplemented with vitamin D, but studies show high heterogeneity. During the COVID-19 pandemic, some countries have reported an increase in the use of dietary supplements. A need for better nutrition education for the general public and health professionals is evident, as well as better targeting nutrition interventions according to adequate nutritional assessment. Countries should focus on increasing the nutrient density of the food supply, and improve food access, while decreasing the availability of ultraprocessed foods to promote health and optimal immunity.