Fruits and Veggies to Boost Immune Health: Guest Post

Readers: This is a guest post by David Novak, for your information only. Jenna is paying forward these suggestions and thanks Novak for his contribution to Call Me Old Fashioned.

Eating fresh fruits and vegetables is the natural way to boost your immune system. Good-tasting produce are nature’s way of keeping you healthy, and a lot of fruits and vegetables are high in Vitamins A, C, E, B-6, folic acid and zinc, which are crucial in supporting the immune system. It is much more fun to eat your way to health than to take pills or supplements anyway.

Vegetables and fruits have a lot more to offer the immune system than just their vitamins and minerals. The oils, acids, antioxidants and phytonutrients –which are responsible for their various colors and flavors– are the reason why they’re so good at helping you maintain your ability to heal, your health and your immune system.

Fruits and veggies are classified as foods rich in immune- modulating properties.  These bioactive compounds are used by the body to fight infections, inflammation and they also aid in detoxification and immune cell function through several different mechanisms.  Below are a few suggestions to look for when choosing the vegetables and fruits that will boost your immune system most effectively, and with which you want to include in your diet:


Colors of fruits and vegetables are key, and the richer and denser in color, the better.  First look for “red” foods.  For example, compounds in cranberry juice have been shown to be beneficial for the prevention and treatment of urinary tract infections while also decreasing the use of antibiotics in the elderly. Red berries like, like wolf and goji, have immune-regulating properties, which increased immune cells called lymphocytes and antibodies called immunoglobulin G. Lycopene is the most potent antioxidant in tomatoes and the same pigment molecule that gives watermelon and red bell peppers their red color.

“Yellow” and “Orange” colored foods– citrus fruits like lemons and orange– have a ton of vitamin-C content, and they’ve been touted as cure-alls for the cold and flu. Although vitamin C is integral to proper immune function, citrus fruits have a lot more to offer than just one vitamin.  Actually, over 8,000 flavonoids have been identified with many coming from citrus. Some of the most common flavonoid compounds in citrus– such as rutin, apigenin, tangeretin, hesperidin and quercetin– target immune malfunctions such as cancer development and excessive inflammation.

“White” and “green” colored fruits and vegetables aid in the fight of some cancers.  Cancer is one of the ultimate immune disorders as cancerous cells need to evade multiple immune defenses and checkpoints in order to become malignant and spread. Regular consumption of cruciferous vegetable such as cauliflower, broccoli and cabbage have beneficial effects on several types of cancer through their powerful anticarcinogenic agents such as indoles, isothiocyanates and sulforaphane. Leafy green vegetables such as spinach and kale are rich in vitamin A & C, antioxidants, essential fatty acids and chlorophyll, which have immunostimulatory and immunoprotective effects while the sulfur-rich molecules in garlic work on numerous immune pathways by being antiviral, antifungal, anticarcinogenic and antibacterial.

Finally, “purple” and “blue” foods, like blueberries, are full of potent antioxidants called anthocyanins, which help to counter exercise-induced stresses on the immune system (inflammation and oxidative stress) by increasing anti-inflammatory compounds and natural killer cells – immune cells which help fight infections. Purple grapes are also full of similar anthocyanin antioxidants, and regular consumption of grape juice can increase antioxidant status as well as circulating levels of immune cells.

Good Vegetable Sources for your Immune System

Regarding the types of vegetables to choose, which are the best for immune health, you can’t go wrong with carrots.  They deliver 110% of the daily value for Vitamin A along with 250 mg of potassium and two grams of dietary fiber. The Vitamin A is useful for immune function support as well as skin and eye health.  Broccoli is an excellent source of Vitamin C, containing 220% of the daily value and it also provides 460 mg of potassium, three grams of dietary fiber, and four grams of protein. Sweet potatoes contain 120% of the daily value for Vitamin A in one potato, along with 440 mg of potassium and two grams of dietary fiber, great for your immune system.

Bell peppers are high in Vitamin C, containing 190% of the daily value for Vitamin C. Bell peppers also 220 mg of potassium and two grams of dietary fiber. Spinach, one of the leading super-foods, plays an important role in immune function because of its naturally high antioxidants. Cauliflower is also a good source of Vitamin C with 100% of the daily value contained in one-sixth of a cauliflower head. Cauliflower also contains only 25 calories yet has 260 mg of potassium and two grams of dietary fiber.

Good Fruit Sources for your Immune System

Most fruits are great for your immune health, but the below list is the best, starting with oranges.  Oranges are packed with vitamin C, and one orange has 130% of the daily value, along with 250 mg of potassium.  Blueberries are high in Vitamin B, another important immune system booster. Blueberries are easily eaten plain and are also good as a topping for yogurt or cereal.  Strawberries are another Vitamin C source with eight berries delivering 160% of daily value for Vitamin C.  Strawberries will also provide 170 mg of potassium.

Cantaloupe provides a high level of Vitamin C and Vitamin A, and vitamin A supports healthy skin – our first line of defense against illness and infection.  Cantaloupe contains 80% of the daily value of Vitamin C and 120% of the daily value of Vitamin A in one-fourth of a melon. Grapefruit are also very high in Vitamin C with one-half of a grapefruit containing 100% of the daily value. Grapefruit are also surprisingly low in calories, linked with diets and weight loss, but are also an excellent citrus fruit for boosting your immune system.  Finally, Kiwi is loaded with Vitamin C despite being very low in calories. Two kiwi delivers 240% of the daily value for Vitamin C, and provides 450 mg of potassium and four grams of dietary fiber.

These vegetables and fruits provide very tasty ways to support your immune system, and eating a variety of these is the natural way to support your immune system and give it the boost that it needs.  You’ll do yourself a favor when the next time you’re at your local market, that you stock up on nature’s immune system boosters.

David Novak is a international syndicated newspaper columnist, appearing in newspapers, magazines, radio and TV around the world. His byline has appeared in GQ, National Geographic, Newsweek, The Wall Street Journal, Reader’s Digest, USA Today, among others, and he has appeared on The Today Show, the CBS Morning Show and Paul Harvey Radio. David is a specialist at consumer technology, health and fitness, and he also owns a PR firm and a consulting company where he and his staff focus on these industries. He is a regular contributing editor for Healthline. For more information, visit

Jenna Beaulieu

About Jenna Beaulieu

Jenna is a writer who recently moved back home to the St. John Valley to settle down and nurture her roots. She’s a fan of excellent music, homemade gravy, and colored pencils (also, short books and long books, good pens, flannel, and when the June bugs don’t really come out much that year). For more about Jenna, visit her website at