Nutrition has a significant impact on immunity throughout the lifespan. In the womb, a child acquires passive immunity by getting antibodies through the placenta and, after birth, through nursing (Lokossou et al. 2022). Throughout the rest of a person’s life, dietary choices will continue to strongly influence various functions of the immune system, such as innate and adaptive responses (Tourkochristou, Triantos & Mouzaki 2021). (See “Innate, Adaptive and Inflammatory Systems: An Overview,” below, for more on these key terms.)
Adequate nutrition will fortify the body’s epithelial (barrier) membranes with trained immune cells, hold microbes and pathogens at harbors, and identify and eliminate abnormal tissue growths, or neoplasms.
Fitting diet and nutrition for immunity should contain foods and other active substances that are known to stimulate and balance immune responses. What follows is a discussion of several specific diets and nutrient powerhouses that offer immune-friendly effects.
Diets and Nutrition for Immunity
Unbalanced diets may have negative, undesirable effects on immunity. For example, the high incidence of immune-related disorders in Western countries is often linked to high calorie intake, excessive carbohydrates and saturated fats, and lack of fibers in the diet. However, several diets are considered to be very beneficial for the immune system.
The Mediterranean Diet
The Mediterranean diet, one of the most immune-friendly regimes, is defined by the high intake of plant-originated foods; a balanced consumption of dairy products, eggs and sea foods; and a limited intake of red meat and sweets. This diet provides a healthy omega-6 to omega-3 ratio, with omega-3 fats coming from fish and vegetables (such as green vegetables), as well as seeds and nuts (Casas, Sacanella & Estruch 2014).
Healthy and anti-aging properties of the Mediterranean diet might be related to its immunoregulatory and antiinflammatory effects, which are mediated by isoflavones, vitamins, minerals and omega-3 fatty acids (Di Danielle et al. 2017). Omega-3 fatty acids decrease inflammation by suppressing migration of white blood cells, their adhesion to the walls of blood vessels, and the release of pro-inflammatory (inflammation-promoting) molecules (Calder 2017).
Furthermore, extra virgin olive oil, one of the key components of the Mediterranean diet, contains large quantities of polyphenols known to quench inflammation due to their antioxidant and anti-inflammatory powers (Bonaccio et al. 2017).
See “Gut Microbiota and the Mediterranean Diet,” below, for how this nutritional approach may indirectly improve immunity.
The Ketogenic Diet
The ketogenic diet, which is characterized by low carbohydrate intake and high fat consumption, has been a part of several therapeutic strategies. This diet increases the intake of fatty acids and stimulates production of ketone bodies, which act as both a fuel source and immunoregulatory molecules.
For instance, ketone bodies show the capacity to decrease inflammation and therefore have a therapeutic potential for preventing and curing allergies and autoimmune disorders (Ang et al. 2020). In addition, a ketogenic diet may help to fight infections. In fact, there is evidence that it activates a specific subtype of lymphocytes in the lungs and thus strengthens protective immunity against the flu virus (Goldberg et al. 2019). On the other hand, a high-carbohydrate diet may stimulate immune cells in patients with inflammation and autoimmunity (Zhang et al. 2019).
Calorie-Restricted Diets
Although the effects of caloric restriction on the immune system have not been studied extensively, it is well known that obesity is a strong trigger of inflammation (Zhang et al. 2019). Currently available data points out that reduced food intake can regulate immune processes. For example, a moderate food restriction has been shown to activate T lymphocytes, which protect against infection and autoimmune inflammation (Ahmed et al. 2009; Okawa, Nagai & Hase 2021). In addition, calorie restriction may stimulate antitumor immunity (Pistollato et al. 2021). Furthermore, limiting calorie intake may help rejuvenate the immune system, as calorie restriction delays T lymphocyte deterioration in studies using nonhuman primates (Messaoudi et al. 2006).
One caveat: Despite the obvious benefits of moderate calorie restriction for the immune system, undernutrition may cause a severe immunodeficiency by suppressing the growth of immune cells, the production of antibodies and the process of phagocytosis, whereby cells engulf and digest other cells, including pathogens (Alwarawrah, Kiernan & MacIver 2018).
