As the body ages, the immune system changes and goes through a remodeling process. There is a reduction in immune cell function which can lead to an increased risk of infection, viral reactivation, and risk of autoimmune disease and cancer. These changes are affected by exercise, muscle mass, and nutritional status.

In addition, chronic low grade inflammation has been shown to contribute to almost all chronic disease and has been correlated with aging. After 40 years of age the body’s cells are typically less able to produce antioxidants and soak up free radicals, making them more susceptible to damage and death. 

In a review published last month in Nutrients, researchers investigated the effects of exercise, diet, and supplementation on the immune system and aging.

Numerous studies have demonstrated the benefits of exercise on aging and the immune system. Exercise has been shown to increase natural killer cell function. In addition, cross-sectional studies on non-sedentary older adults (highly trained individuals, runners, and cyclists) have showed improved function of the adaptive immune system, including improved T-cell proliferation, reduced inflammation, and decreased thymus output.

Dietary intake of polyunsaturated fatty acids is also essential for overall health as well as for supporting immune function. Studies on omega-3 fatty acid supplementation had dosing ranges of 2 to 3.3 grams per day over a duration of a 3 to 6-month period. Supplementation with omega-3 fatty acids significantly reduce kynuerinine levels. Kynuernate is a metabolite of tryptophan, which is elevated in chronic low grade inflammation.

Accumulating research also demonstrates the association between the gut microbiome, health status and aging. There is evidence that age-related changes in the gut microbiome may be related to elevated inflammatory makers and other geriatric conditions such as sarcopenia, frailty, and cognitive decline secondary to reduced short chain fatty acid production. Also, the immune system has a tendency to decline with age, which makes one more susceptible to infections as well as increasing the risk of chronic disease. Probiotics have the potential to rebalance gut microbiota and modulate gut immune response, inhibiting the NF-κB pathway. Probiotics control microbial populations, alter cytokine expression, increase secretory IgA, increase natural killer cell activity, and reduce the risk of infections.

Previous research has demonstrated how the gastrointestinal tract changes with aging and how this impacts overall health. As one ages, the gut has an increase in interleukin 6 (IL-6) which causes the immune system to release IL-6 and trigger inflammation. Increased levels of IL-6 directly lead to increased intestinal permeability with no physical differences seen in its structure. The research also showed there was an association with a decreased immune response to microbes with aging, which may contribute to an increased susceptibility to infection.

Probiotics help encourage microbial diversity, especially if the probiotic supplement is of mixed species. In ecological terms, it is more stable to have diverse populations in any ecosystem. The same is true for the gastrointestinal microbiome.

These results suggest that nutritional supplements including both omega-3 fatty acids and probiotics can significantly reduce established biomarkers of systemic inflammation in middle-age and older adults. Other nutrients to consider for aging, inflammation and the immune system include tocotrienols, geranylgeraniol, resveratrol, quercetin, and specialized pro-resolving mediators. 

By Michael Jurgelewicz, DC, DACBN, DCBCN, CNS

Source: Weyh C, Kruger K, et al. Physical Activity and Diet Shape the Immune System during Aging. Nutrients 2020, 12(3), 622.