According to the Linus Pauling Institute, or LPI, nutrition and the immune system are tightly linked. LPI identifies several nutrients involved in immune system function --- protein, vitamins A, D, C and E, folate, B-6, B-12, zinc, selenium, iron and copper. Additionally, the Office of Dietary Supplements, or ODS, reports that magnesium supports a healthy immune system. You can find several of these nutrients in fruits and vegetables.
Vitamins A, C and E
According to LPI, vitamins A, C and E contribute to a healthy immune system. For vitamin A, think bright red or orange and deep green. Sweet potato, pumpkin, carrots, cantaloupe, mango, spinach, broccoli, kale, collard or turnip greens, tomato, apricots and winter squash are rich sources, according to the USDA.
Kiwi, broccoli, bell pepper, hot chili peppers, strawberries, grapefruit, orange, citrus juices, papaya, Brussels sprouts, mustard greens, cauliflower, cantaloupe, rutabagas and red cabbage are just a few examples of vitamin C-rich foods.
Vitamin E is found in kale, sweet potato, spinach, lima beans, asparagus, blueberries, avocado, carrots and broccoli. It is found in higher amounts in nuts---almonds, hazelnuts, peanuts and sunflower seeds---and in vegetables oils.
Folate and B6
Folate, B-6 and B-12 are also involved in immune system function, according to the LPI. B-12 is not found in fruits or vegetables. According to the USDA, good sources of folate include orange or pineapple juice, cantaloupe, orange, strawberries, banana, spinach, broccoli, turnip greens, Brussels sprouts, asparagus, cabbage, beets and cauliflower. Potato, banana, garbanzo beans, tomato juice and avocado contain B-6. Fortified breakfast cereals are an excellent source.
Zinc, Iron and Copper
The minerals zinc, iron and copper play roles in immune system function. According to the ODS, zinc can be found in legumes and nuts --- baked beans, chickpeas, kidney beans, peas, cashews and almonds. Plant sources of iron include apricots, spinach, raisins, prune juice, prunes, potato with the skin, kidney and lima beans, lentils and cashews. Eating a vitamin C-rich food with a plant source of iron increases iron absorption. To get copper, eat lentils, mushrooms and nuts --- cashews, sunflower seeds, hazelnuts, almonds and peanut butter.
Magnesium
Magnesium also supports a healthy immune system, according to the ODS. They recommend eating a variety of legumes, nuts, whole grains and vegetables to meet magnesium needs. Examples include soybeans, spinach, potato with skin, black-eyed peas, lentils, kidney beans, pinto beans, avocado, banana, almonds, cashews or mixed nuts.
Other
Vitamin D is not found naturally in fruits or vegetables but can be obtained from fortified orange juice. Selenium can be found in other plant sources, including Brazil nuts, black walnuts, brown rice, enriched noodles and whole wheat bread.
