Acute respiratory tract infections are a major cause of morbidly and mortality. Viruses cause seasonal outbreaks and, as we are seeing now, a worldwide pandemic that is impacting public health as well as the economy. Most of the attention has been focused on isolation, wearing masks, and proper hygiene which are all important; however, public health discussions have not been focused around nutritional strategies to support optimal immune function. This is essential as poorer outcomes are associated with those with comorbidities, smoking, and the elderly population. 

In a review published two weeks ago in Nutrients, researchers demonstrated the importance of nutrition and its role in the immune system. The findings show that numerous studies have demonstrated the role of nutrition in supporting the immune system, as nutrient insufficiencies can decrease the number of lymphocytes, alter cytokine production, impair wound healing, and reduce antibody responses.

Specific vitamins, minerals, and omega-3 fatty acids support the immune system and a deficiency or insufficiency can increase the risk of infections. Vitamins and minerals help support and maintain physical barriers, support a normal inflammatory response, produce antimicrobial proteins, and support the production of cytokines and antibodies. Vitamins C and D specifically are essential for immune health. Vitamin C supports innate and adaptive immune cells, epithelial barrier function, antibody production, and is a powerful antioxidant. One meta-analysis showed a significant reduction in the risk of pneumonia, a decrease in the duration and severity of upper respiratory tract infections, and a significant decrease in the risk of infection with vitamin C supplementation at doses greater than 200 mg per day.

Vitamin D modulates the production of inflammatory cytokines and supports antigen presentation. Previous research has shown that vitamin D supplementation reduced the risk of influenza and a vitamin D deficiency has been associated with an increased risk of acute respiratory distress syndrome as well as chronic disease. The research team recommends a daily intake of at least 2000 IU per day; however, many individuals may need 5,000 - 10,000 IU per day to obtain optimal blood levels. It is also important to optimize both vitamin A and vitamin K along with vitamin D as these fat soluble vitamins have intricate interrelationships with each other.

A zinc deficiency was also shown to impact the immune system (both the innate and adaptive immune systems). A deficiency leads to impaired formation, activation and maturation of lymphocytes, and a weakening of the innate host defense. 

In addition, dietary intake of omega-3 fatty acids was demonstrated to be essential for supporting the immune system as they help resolve the inflammatory response. Several specialized pro-resolving mediators (SPMs) formed from EPA and DHA are shown to have a protective effect against lung injury and acute respiratory distress syndrome in animal studies. A recent review showed a significant improvement in blood oxygenation, reduction in ventilation requirements, organ failure, length of stay, and mortality. An intake of 250 mg of EPA and DHA is recommended but many patients may need closer to 1500 - 3000 mg to optimize their omega-3 index. 

These results demonstrate that proper nutrition, including supplementation, is a safe and effective way to support optimal immune function. It is difficult for most individuals to obtain an optimal intake of all these nutrients in the diet, therefore, supplementation should be considered. Additional nutrients to consider include tocotrienols, geranylgeraniol, resveratrol, quercetin, and melatonin. 

By Michael Jurgelewicz, DC, DACBN, DCBCN, CNS

Source: Calder P, Carr A, et al. Optimal Nutritional Status for a Well-Functioning Immune System Is an Important Factor to Protect Against Viral Infections. Nutrients. 2020 Apr 23;12(4), 1181