When It Comes to Immune Health, Does What We Eat Matter?

POST - APRIL 16, 2020

There may be no more important part of our body than our immune system. Through its nonstop work to prevent and limit the effects of harmful pathogens like bacteria and viruses, we’re able to maintain our health and recover from illnesses caused by these invaders. Our immune cells make up one of the most sophisticated, coordinated systems in the body—one that is essential for our survival.
With the recent outbreak of the novel coronavirus, also known as COVID-19, there has been an increased focus on the importance of keeping our immune systems running strong. As a result, there’s a lot of information being shared about the effect that food and dietary supplements might have on immune health. Some of this information is based in strong science, while some is…not so much.
In this article, we’ll address how the food we eat can support immune health, why many trendy supplements and “superfoods” don’t make the cut, and whether or not you can really “boost” your immune system through food. (Hint: the answer is no.) We want to be clear that the information provided here relates to healthy adults; the same conclusions may not apply to children, the elderly or those who are immunocompromised.

Is diet connected to immune health?

Yes! Many nutrients we get through the food we eat are essential for immune function, so eating a well-balanced, healthy diet allows your immune system to be the best version of itself. When we get sick and our immune system becomes more active, the demand for both energy and nutrients goes up, making adequate nutrition even more vital.

Here’s a quick list of nutrients known to be beneficial in supporting immune health, brief summaries of some of their roles in the immune system, and the foods in which you can find them:

Nutrient	Immune System Roles	Food Sources
Vitamin A	Involved in immune system development; regulates immune cell production and responses to pathogens	Beef liver, sweet potato, boiled spinach, carrots, dairy products, cantaloupe
Vitamin C	Stimulates production and function of immune cells; antioxidant capabilities	Citrus fruits and their juices, red and green peppers, broccoli, cabbage, cauliflower
Vitamin D	Tones down the inflammatory response; assists in producing proteins important for immune cell activation	Cod liver oil, fish (rainbow trout, sockeye salmon, sardines), mushrooms, fortified milk and milk alternatives, fortified cereals
Vitamin E	Antioxidant capabilities; involved in immune cell signaling and production of immune cells	Cooking oils, almonds, hazelnuts, peanuts and peanut butter, sunflower seeds
Omega-3 fatty acids	Component of immune cell membranes; involved in enhancing immune cell functions	Chia seeds, flaxseed and walnuts, cooking oils like flaxseed, canola and soybean, salmon, herring, sardines, mackerel, fortified foods
Zinc	Involved in development and function of immune cells	Oysters, beef, crab, lobster, pork, legumes, fortified cereals, chicken, nuts, seeds, dairy
Selenium	Involved in regulating inflammation and immunity; deficiency is associated with impaired production and activation of immune cells	Brazil nuts, fish (tuna, halibut, sardines), ham, shrimp, beef, poultry, grains (enriched and whole), eggs, dairy

Table source: National Institutes of Health, Office of Dietary Supplements

What can I do to support my immune system?

We know that overall good nutrition is important for maintaining optimal immune health, but there is no clear evidence that a specific food or nutrient provides a quick immune fix. Instead, eating a variety of foods, with a focus on fruits, vegetables, nuts and seafood, can provide us with many of the vitamins and minerals that play key roles in supporting the immune system. And let’s not forget the importance of non–food behaviors for maintaining a strong immune system: behaviors like frequent hand washing, maintaining a healthy weight, regular exercise, not smoking, practicing techniques for stress reduction and getting adequate sleep are all vital for ensuring that our body is properly equipped to stay as healthy as possible.
This article includes contributions from Kris Sollid, RD, and Ali Webster, PhD, RD.