By Cami Glosz, R.D. @ University

What are some reasons why your immune system might not be working up to par?

  • Not eating enough fruits and vegetables
  • Not drinking enough water
  • Having low stores of vitamins and minerals in your body
  • Eating a lot of sugar, junk food, or fast food
  • Lots of stress
  • Not getting enough sleep
  • Not exercising
  • Smoking

Now that we know that, let’s learn which nutrients and foods are especially helpful for boosting your immune system.

Vitamin A

The precursor to vitamin A, called beta-carotene, is found in red, orange, and green fruits and vegetables. Other foods that have vitamin A are animal products, like eggs, milk, and some fish. Vitamin A is a strong immune system booster and can help prevent infections from sticking around. When you eat foods like carrots, bell peppers, cantaloupe, sweet potatoes, spinach, and kale, you are helping your body fight bad bacteria and viruses, especially in your eyes, respiratory system (lungs and breathing), and gastrointestinal system (stomach and digestive system).

Vitamin C

Vitamin C is found in many fruits and vegetables, especially citrus fruits, like oranges, lemons, limes, and grapefruit. Other good vitamin C foods include strawberries, tomatoes, and bell peppers. Vitamin C is an antioxidant, which means it helps protect the cells in your body from damaging oxygen species. Vitamin C can also help produce more of the protective cells of your immune system, so you have more of them to fight the bad bacteria. It’s best to get vitamin C from fruits and vegetables, rather than from a supplement.

Vitamin D

Vitamin D is the vitamin that you can make in your skin from sunlight. During the winter, it is harder for our bodies to make vitamin D from the sun because of the gloomy, shorter days, and our bodies are more covered up with jackets, scarves, and hats. Vitamin D is found in fatty fish, like salmon, mackerel, sardines, tuna, and cod liver oil, as well as mushrooms, fortified milk, and egg yolks. People who have low vitamin D levels are much more likely to get sick because vitamin D helps your body produce anti-microbial compounds that can protect you from bad bacteria. If you live somewhere that doesn’t have much sunlight during the winter, think about eating vitamin D-rich foods daily, or talk to your doctor about a supplement.

Vitamin E

Vitamin E is also an antioxidant, like vitamin C. This vitamin is found in nuts, seeds, spinach, avocados, sweet potatoes, and fortified cereals. It can help your immune system function better by fighting off compounds called free radicals that are damaging to your body.


Zinc is a mineral that helps to strengthen the cells in your body that fight infections. Even marginally low levels of zinc in your body can compromise your immune system. Zinc is found in meats (especially lamb, beef, and chicken), oysters, pumpkin seeds, mushrooms, and spinach. Some people take zinc supplements to help fight a cold.


Your immune system has many components that require protein to function properly. Healthy proteins include lean meats, fish and seafood, eggs, dairy, beans, nuts, and lentils. Make sure there is a protein-containing food at all of your meals!


Probiotics are good bacteria that have health benefits when you consume them in large enough amounts. Probiotics can help to make sure the bad bacteria don’t take over, which can lead to many different ailments. These good bacteria can help strengthen your immune cells and the barriers that keep out bad bacteria. Probiotics are found in fermented foods, like yogurt, kombucha, fresh sauerkraut, kefir, miso, tempeh, and kimchi. Don’t eat these foods? Ask your doctor about which probiotic supplement is best for you.


There are many other ingredients or foods that have been studied in regards to immunity. Ginger, garlic, oregano, elderberry, echinacea, and ginseng may have a beneficial effect to your immune system. Try adding ginger or garlic to flavor your meals this winter! Before starting any supplement containing these ingredients, consult your doctor.

Eat these vitamin- and mineral-rich foods to avoid catching a cold or the flu this season, and don’t forget to wash your hands!

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