Immunosenescence is a term describing the changes that occur to the immune system during the aging process. This may involve altered inflammatory and metabolic processes, reductions in T cell activity, and increased susceptibility to infectious disease. Certain age-related chronic illnesses have been linked to decreases in immune function and increases in circulating reactive oxygen species (ROS). 

The process of immunosenescence affects many immune functions, including losses of B lymphocytes, diminished T-cell receptor diversity, and attenuated immune cell output from bone marrow. The function of neutrophils, macrophages, and natural killer (NK) cells can also become impaired. A recently published review article explored the potential supportive role of the gut microbiome and certain nutraceuticals in the presence of immunosenescence.

The gut microbiome helps support many aspects of immune function. Short-chain fatty acids (SCFAs) produced by certain gut microbes help support immunoglobulin A production and mucosal barrier integrity, and help increase tight junction proteins. The SCFA butyrate has been shown to help modify histone activity to support epithelial gene expression. A metabolite from Bacteroides fragilis helps support the differentiation of T cells. In animal studies, reductions in lymphocytes, immunoglobulin production, and lymphoid organ sizes have been observed in germ-free mouse models. 

Nutritional status may help influence immune health during the aging process. In a clinical study involving supplementation with 1,000 mg of vitamin C daily for 6 weeks in elderly women, decreases in interleukin (IL)-6 and increases in messenger RNA of IL-10 were reported. Increases in phagocytosis and oxidative burst by granulocytes were observed in another 6-week clinical trial involving 1,000 mg of vitamin C daily in individuals between 45 and 60 years of age with type 2 diabetes mellitus and poor glycemic control. The restoration of certain aspects of immune health was observed in a trial involving elderly individuals who received 500 mg of vitamin C daily for 6 months. 

Vitamin D has been shown to support immune function through multiple pathways. It may help promote the differentiation of monocytes to macrophages and help support superoxide production and phagocytosis. A clinical trial involving healthy adults between 40 and 55 years of age reported attenuations of seasonal increases in T-cell production of interferon-gamma in the presence of 10 µg of vitamin D daily. 

Certain minerals, including zinc, may help support the aging process. Deficiencies in zinc and selenium have been linked to reductions in NK cells among older women. A trial involving older individuals residing in nursing homes reported increases in helper T cells, cytotoxic T cells, and lymphocyte production in the presence of 45 mg zinc daily for 3 months. A randomized clinical trial in elderly individuals involving 400 µg of selenium daily reported increases in NK cell activity and increases in CD4⁺ T cells. 

More studies are needed, particularly in clinical populations. However, research indicates that certain micronutrients may help support the body’s response to immunosenescence. Certain minerals and vitamins C and D may also help support antioxidative status, immune health, a normal inflammatory response, and healthy aging.

By Colleen Ambrose, ND, MAT