Immune Function and Micronutrient Requirements Change over the Life Course

Abstract

As humans age, the risk and severity of infections vary in line with immune competence according to how the immune system develops, matures, and declines. Several factors influence the immune system and its competence, including nutrition. A bidirectional relationship among nutrition, infection and immunity exists: changes in one component affect the others. For example, distinct immune features present during each life stage may affect the type, prevalence, and severity of infections, while poor nutrition can compromise immune function and increase infection risk. Various micronutrients are essential for immunocompetence, particularly vitamins A, C, D, E, B2, B6, and B12, folic acid, iron, selenium, and zinc. Micronutrient deficiencies are a recognized global public health issue, and poor nutritional status predisposes to certain infections. Immune function may be improved by restoring deficient micronutrients to recommended levels, thereby increasing resistance to infection and supporting faster recovery when infected. Diet alone may be insufficient and tailored micronutrient supplementation based on specific age-related needs necessary. This review looks at immune considerations specific to each life stage, the consequent risk of infection, micronutrient requirements and deficiencies exhibited over the life course, and the available evidence regarding the effects of micronutrient supplementation on immune function and infection.

A Review of Micronutrients and the Immune System–Working in Harmony to Reduce the Risk of Infection

“…Differentiation, proliferation, functioning, and movement of innate immune cells Vitamin A For example, regulates number and function of NK cells [2,8], contributes to phagocytic and oxidative burst activity of macrophages [8] Table 1. Cont.…”

“…To combat pathogenic microorganisms, the elaborate immune defense system comprises physical and biochemical barriers, specialized immune cells, and antibodies that specifically target the pathogen (Figure 1) [2]. The immune system also helps to repair damage caused by noxious insult from external factors, such as environmental pollutants [3] and innate toxins in food (e.g., carotoxins in carrots, persins in avocados, glycoalkaloids in potatoes, and lectins in beans) [4,5].…”

Optimal Nutritional Status for a Well-Functioning Immune System Is an Important Factor to Protect against Viral Infections

“…Optimal intake of all these nutrients ideally would be achieved through the consumption of a well-balanced and diverse diet, but this can be difficult to accomplish for the general population. Indeed, it is generally accepted that nutrient inadequacies and deficiencies are widespread [46][47][48][49][50] (and references therein). Biochemical markers of nutrient status are particularly useful in assessing inadequacy or deficiency, and lead to the conclusion that intakes often are not sufficient.…”

COVID-19: is there a role for immunonutrition, particularly in the over 65s?

“…18 19 A number of potential mechanisms have been proposed, including (1) declining T cell function attributed to thymic involution and subsequent reduced output of naïve T cells 20 ; (2) ageing-associated inflammation, often referred to as 'inflammaging', which paradoxically can reduce immunity and contribute to pathogenic age-related diseases 21 ; and (3) poor micronutrient statusa bidirectional relationship between infection/immunity and nutrition whereby changes in one of these components can impact the other. 22 It is also becoming apparent that ageing can modulate immune function and cellular composition in ways that are sex-specific, possibly due to differences in how menopause and andropause unfold. 23 With regard to respiratory conditions, the combined effects of compromised immune function, frailty and length of exposure to pathogens mean that ageing populations are naturally predisposed to pulmonary disease.…”