Why is it important to have a healthy immune system?

Your immune system’s primary function is to monitor signs of invasion or danger and protect your from harmful bacteria or viruses. At the same time, immune cells should tolerate the foods you eat, your harmless gut microbiota, and the cells of your own body that you need to survive.

As Ranjit Kumar Chandra has suggested, your immune system can be understood as an umbrella that protects you against attacks from pathogenic organisms, toxins and other insults. It’s also important to remember that the immune system develops together with the gut microbiota from early life and that the microbiota is like a kind of personal trainer for the immune system, priming the body to fight infection and some diseases.

Good nutrition is important for immune and gut microbiota health. Undernourishment (e.g., poor diet) as well as overeating (e.g., an excess of foods loaded with sugars, fats and salt) can compromise the immune system, leading to greater susceptibility to infections. Other factors including age, stress, lack of sleep and rest, and chronic diseases can also cause this protective shield to unbalance.


Getting enough nutrients from a balanced diet is key to ensuring a healthy immune system

Your diet supplies you with nutrients that are the building blocks needed to ensure health and the proper functioning of immune cells, which have a high demand of energy and nutrients. Sometimes immune cell functioning involves an increased energy demand (e.g. in viral infections such as COVID-19), but it is unlikely that individual foods or nutrients offer special protection.

When it comes to diet and immune function, Andrea Hardy, who is a Canadian dietitian specializing in gut health, explained to GMFH via email that “It’s important to remember that more isn’t necessarily better. Getting adequate amounts of all nutrients and preventing deficiencies are key, especially in at-risk populations, such as the elderly, or those with chronic medical conditions, who may get a less varied diet for medical or social reasons.”

In humans, the nutrients that are needed for the immune system to work effectively include:

  • Proteins: immune cells and antibodies that fight against infections pathogens are made up of proteins.
  • Essential fatty acids: a good balance between omega-3 and omega-6 fatty acids is crucial for ensuring immune cell membranes function properly and for keeping inflammatory processes at bay.
  • Vitamins and minerals, such as vitamins B6, B12, folate, vitamins C and D, zinc, copper, iron and selenium.

All of these elements are found in a variety of plant and animal foods.

You also need to feed your gut microbiota for a well-balanced immune system. In that regard, beneficial bacteria found in probiotics—contributed by fermented foods in particular—and prebiotic fibers that fuel your gut microbiota—found in onions, garlic, bananas and artichokes—are all necessary.

Both probiotics and prebiotics can work individually or in synergy with proteins, essential fatty acids, vitamins and minerals to improve the health of your gut microbiome and the integrity of your gut barrier, preventing pathogens from entering your gut.

According to Andrea Hardy: “A wide variety of nutrients are involved in our immune function, so getting a varied diet is the best way to ensure adequacy.”

However, if you cannot meet your daily target for fresh vegetables, Andrea Hardy acknowledges that key nutrients found in fruit and vegetables still remain in canned and frozen foods, which can be used occasionally for troubleshooting.


The bottom line

Nothing you eat will stop you from getting infections and disease, but a rich and varied diet will provide support so a proper immune system and gut microbiota can function. Rather than focusing on an individual food or nutrient to support your immune defenses, it’s better to focus on a healthy, diverse and well-balanced diet that will provide the nutrients required to keep your immune system and gut microbiota in good shape.



 Chandra RK. Nutrition and the immune system: an introduction. Am J Clin Nutr. 1997; 66(2):460S-3S. doi: 10.1093/ajcn/66.2.460S.

Calder PC. Feeding the immune system. Proc Nutr Soc. 2013; 72:299-309. doi: 10.1017/S0029665113001286.

Childs CE, Calder PC, Miles EA. Diet and immune function. Nutrients. 2019; 11:1933. doi: 10.3390/nu11081933.

Calder PC, Carr AC, Gombart AF, Eggersdorfer M. Optimal nutritional status for a well-functioning immune system is an important factor to protect against viral infections. Nutrients. 2020; 12:1181. doi: 10.3390/nu12041181.

Derbyshire E, Delange J. COVID-19: is there a role for immunonutrition, particularly in the over 65s? BMJ Nutrition, Prevention & Health. 2020. doi: 10.1136/bmjnph-2020-000071.