Boosting Your Immune System Through Diet

- January 3, 2018

It’s January, which means that cold and flu season is upon us. Don’t panic! While there isn’t a magic pill to completely avoid these illnesses, there are a number of measures we can take to minimize our risk. Your immune system serves to protect you against infectious components (“pathogens”) that can cause illnesses. Therefore, strengthening your immune system can help fight illnesses more quickly or even avoid them altogether! Quality nutrition is essential to ensuring your immune system works properly. While researchers are still studying all the ways diet can protect the immune system, below are some well-studied dietary tips that can help your immune system keep you and your family healthy this season and beyond.

As a good rule of thumb, it’s best to get nutrients from food over supplements whenever you can. Because it is possible to get too much of a good thing…!


When your immune system fights potential infections (aka: “immune response”), it can be quite taxing on the body. Byproducts called “reactive oxygen species” (ROCs) can unintentionally damage healthy tissues. Fortunately, anti-oxidants can help protect against this damage. Here is a list of some helpful antioxidants and commons food sources of each.

Vitamin C
  • WHY: This vitamin helps the different types of immune cells function better and helps get rid of the harmful ROCs. And, as we learned from sailors getting scurvy, vitamin C helps your wounds heal faster and protects your skin and gums against pathogens.
  • FOODS: Commonly known sources are citrus fruits (e.g., oranges, grapefruit, lemon), but vitamin C can also be found in other fruit, such as tomatoes and kiwi. Even vegetables have vitamin C, like sweet potatoes, leafy greens, and broccoli.
Vitamin E
  • WHY: Like other antioxidants, vitamin E improves immune functioning. As such, diets low in vitamin E are associated with weaker immune systems, though deficiencies are uncommon.
  • FOODS: Nuts (e.g. peanuts, almonds), common oils: olive, canola and sunflower, and some fortified cereals (look for “d-alpha-tocopherol”). 
Vitamin A
  • WHY: This vitamin helps with the growth of immune cells. Good vitamin A intake has also been associated with a quicker recovery from illnesses. It has also been shown to help protect the digestive and respiratory tracts from infections.
  • FOODS: Orange and yellow vegetables (e.g. sweet potatoes, carrots, squash); spinach; and cereal or dairy products that are “fortified with vitamin A”.

Probiotics (“Good” Bacteria)

  • WHY: Your body naturally contains a variety of bacteria, most of which are desirable for your health. These good bacteria are called “probiotics”. Researchers are still learning about the role of these bacteria. In immune health, it is thought that probiotics likely slow down the growth of pathogens by consuming their food sources.
  • FOODS: Probiotics are found in a variety of sources, but fermented or cultured dairy products (e.g. yogurt and kefir) are the most common. Other sources include fermented soybeans (miso or tempeh) and fermented vegetables (kimchi or pickles made without vinegar).

Adequate Protein & Calories

When the immune system discovers a pathogen in your body, it kicks into overdrive to fight it. But to do so, it needs a lot of energy. If your body does not have enough calories, the immune system will not have enough energy. Similarly, your body needs enough protein to function correctly. So it is important not to try to rapidly lose weight. Talk to your doctor or dietitian if you are considering weight loss.

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