Debunking myths about immune-boosting dietary habits

Is it possible to boost the immune system through diet?
Published August 9, 2021 | Updated January 25, 2023

With cold and flu season on the horizon, there’s never been a better opportunity to learn more about how your immune system works and how to keep it healthy. Read on to discover the surprising truth about the way food affects your immune response, and why “boosting” your immunity isn’t all it’s cracked up to be.

Types of immunity in the human body

In order to learn about potential immunity-boosting dietary habits, it’s important to learn a little bit about the immune system itself. The human body uses two kinds of immunity to protect itself: innate immunity and adaptive or acquired immunity.

Innate immunity refers to the body’s first line of defence against pathogens; this mechanism uses barriers such as skin, mucus, stomach acid, tears, and sweat enzymes.

Adaptive or acquired immunity refers to pathogens that are recognized by the body via bone marrow, lymph nodes, and the spleen (among others.) When foreign pathogens are present, these parts of the body create antibodies — which are specific to the virus or other type of pathogen. Your immune system remembers this information so that if you’re exposed to the same pathogens again it can create the same antibodies more efficiently.

What does an immune response look like?

Immune responses occur as a reaction to inflammation, which is the body’s reaction to illness or pain. Although it may seem backwards, the very symptoms that indicate you’re feeling ill are proof that your immune system is working. For example, the common cold brings on fever and mucus production, both of which are healthy immune responses. What makes them beneficial? A fever raises your temperature to kill the pathogen and extra mucus helps remove it from the body. In other words, if it was possible to “boost” immunity through food or supplements, you would end up feeling even more sick, not better.

Can you boost your immunity through foods or supplements?

Despite marketing claims to the contrary, it’s impossible to “boost” immunity through diet or by taking supplements. Certain items, like cayenne pepper, apple cider vinegar, green tea, kombucha, and other probiotic-right foods, are accompanied by claims about boosting the immune system, yet there is little if any science to back this up.

What role do nutrients play in immune system health?

While it isn’t possible to alter your existing immune system using diet or supplements, a healthy and varied diet plays a large part in maintaining the health of your immune system. Certain nutrients play a role in cell growth and function of the immune system, including vitamins C and D, iron, selenium, protein, and zinc. Unless your diet is extremely limited, it’s unlikely any kind of supplement is needed (an exception can be made for vitamin D, which can be hard to get in adequate amounts if you live in cooler climates.) Prebiotics and probiotics are also important for keeping your unique gut microbiome healthy, which in turn has a beneficial effect on immune response. Prebiotics are essentially the food for your gut flora, and are abundant in garlic, bananas, onions, and asparagus; however, any diet that includes fruits and vegetables should have a sufficient amount of prebiotics.

How to keep your immune system healthy (according to science)

  • Eat a healthy and varied diet, with plenty of fruits and vegetables.
  • Get plenty of quality restorative sleep, especially at the onset of an illness.
  • Limit or omit alcohol and cigarettes, particularly when you’re sick.
  • Make exercise a regular part of your routine.
  • Wash your hands after being outside, using the restroom and before preparing food.