However, many standard multivitamins may not contain enough vitamin C. Researchers believe that milligrams mg a day is necessary for immune health. If a person already has a deficiency, they likely need more of that nutrient than a multivitamin contains.

Although some studies suggest that supplementation with multiple immune-supporting micronutrients is beneficial, more research is needed. Currently, the strongest evidence suggests that these three micronutrients offer immune support: vitamin C, vitamin D, and zinc. Vitamin C , or ascorbic acid, is a water-soluble vitamin known for its ability to support a strong immune system.

In addition to promoting various cellular functions of the immune system, vitamin C helps the body grow and repair tissue, heal wounds, and absorb iron. Vitamin C is also an antioxidant , meaning that it fights off free radicals, which may help prevent certain cancers and heart disease.

Studies show that a vitamin C deficiency can lead to an impaired immune system and an increased risk of infection. The human body cannot make vitamin C, so it needs to come from foods or dietary supplements. The RDA for vitamin C is 90 mg for male adults and 75 milligrams for female adults.

However, many scientists believe this is not enough and recommend mg per day for maximum health benefits. While most studies show that taking vitamin C does not prevent colds in the general population, it may help reduce the symptoms and severity of a cold.

For example, one meta-analysis from found that taking extra doses of vitamin C may help reduce the duration of the common cold by up to half a day, as well as symptoms such as chest pain, a fever , and chills.

Vitamin C supplementation may be even more beneficial for people who perform heavy physical activity. Vitamin D plays a critical role in keeping the immune system strong so that the body can fight off bacterial and viral illnesses, such as a cold. Some clinical trials suggest that supplementation of international units IU , or 10 micrograms mcg , of vitamin D per day may help prevent the common cold.

Other studies show that vitamin D treatment can reduce respiratory tract infections, especially in those with a vitamin D deficiency. Some researchers also believe that there is a link between vitamin D deficiency and an increased risk of COVID hospitalization, though there is controversy about this claim.

In some cases, it has been used to minimize the impact of socioeconomic factors for at-risk groups. Many experts believe that the current vitamin D RDA of IU 15 micrograms for people up to age 70 and IU 20 micrograms for people over 70 is not enough to support healthy immune function.

However, the evidence remains inconclusive, and finding the dosage that best supports immune function requires further research. A zinc deficiency can weaken the immune system by impairing the formation, activation, and maturation of lymphocytes, white blood cells that are an active part of the immune system.

Several studies suggest that low zinc levels can increase the risk of viral infections. Some also show that zinc lozenges may shorten the duration of the common cold.

However, identifying the best dosages for supporting immune health and treating colds will require further research. We know that they play a key role in helping maintain a healthy balance of bacteria in the gut, and new research supports the idea that they have beneficial effects on immunity.

For example, one study from — carried out, it must be noted, by a company that produces probiotics — found that probiotic use may reduce the incidence and duration of upper respiratory infections. The authors call for more research to establish a relationship between probiotics and the immune system.

Many people are taking one or a combination of supplements to prevent or treat COVID But there is not enough data to support the use of any vitamin, herb, or other supplement to treat or prevent this illness.

Only vaccines , together with strict hygiene measures , are proven to help prevent COVID For severe cases of COVID, doctors may use specific medications.

Research does suggest that supplementation with vitamins and minerals can be a low-cost way to support optimal immune function. Even supplementation with vitamins C and D above the current RDAs may be beneficial to the immune system, as long as dosages stay below the recommended safety limits.

Many supplements can interact with medications and other supplements. And combining different supplements can also lead to very high amounts of certain nutrients in the body, which can have potentially severe side effects.

For example, excess vitamin C is excreted in the urine and usually causes no serious side effects. But very high amounts can cause diarrhea , abdominal pain, and nausea.

Too much vitamin D — more than 4, IU or mcg — can be harmful and lead to nausea, vomiting, kidney stones , confusion, loss of appetite, and muscle weakness. Very high levels can even lead to kidney failure, an abnormal heartbeat, and death. Vitamin D also interacts with medications, such as the weight loss pill orlistat Alli, Xenical , steroids , and cholesterol-lowering statins.

If a person has too much zinc, it can cause negative effects such as nausea, vomiting, diarrhea, and headaches. Over time, excess zinc can lead to low copper levels, decreased immunity, and lower levels of helpful cholesterol.

Zinc can also interact with other medications. Probiotics are safe for most people. However, they may worsen illnesses or cause bacterial infections in people who have very weak immune systems or are severely ill. This can involve :. There is no evidence that mega-doses of vitamins and nutrients can boost the immune system.

The best way to ensure that the immune system functions well is to have a balanced diet, get enough sleep, exercise, and take the vaccinations that are offered.

Anyone with nutrient deficiencies who is unable to have a healthy, balanced diet may find it beneficial to take a daily multivitamin.

But though some research shows that getting more than the RDAs of vitamins C and D might help support immune health, confirming this requires more research. If a person thinks they have a nutrient deficiency, they should consider speaking with a doctor about having a blood test.

This will help pinpoint any deficiencies and determine the right approach to supplementation. Before taking any supplement, a person should have a conversation with a primary care doctor who is familiar with their medical history.

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Most citrus fruits are high in vitamin C. The recommended daily amount for most adults is:. Ounce for ounce, red bell peppers contain almost 3 times as much vitamin C mg as a Florida orange 45 mg. Besides boosting your immune system, vitamin C may help you maintain healthy skin.

Beta-carotene, which your body converts into vitamin A , helps keep your eyes and skin healthy. Broccoli is supercharged with vitamins and minerals. Packed with vitamins A, C, and E, as well as fiber and many other antioxidants , broccoli is one of the healthiest vegetables you can put on your plate.

The key to keeping its power intact is to cook it as little as possible — or better yet, not at all. Research has shown that steaming or microwaving are the best ways to keep more nutrients in the food.

Garlic adds flavor to food and has long been used for medicinal purposes. Early civilizations recognized its value in fighting infections. Garlic may also slow down hardening of the arteries, and people use it to treat high blood pressure.

Ginger is another ingredient many turn to after getting sick. Ginger may help decrease inflammation, which can help reduce a sore throat and inflammatory illnesses. It may also help with nausea. Ginger may also decrease chronic pain and might even possess cholesterol-lowering properties.

Similar to broccoli, spinach is healthiest when cooked as little as possible so that it retains its nutrients. However, light cooking makes it easier to absorb the vitamin A and allows other nutrients to be released from oxalic acid , an antinutrient.

Check out some spinach recipes here. These cultures may stimulate your immune system to help fight diseases. Try to get plain yogurts rather than the kind that are flavored and loaded with sugar. You can sweeten plain yogurt yourself with healthy fruits and a drizzle of honey instead.

Yogurt can also be a great source of vitamin D , so try to select brands fortified with this vitamin. Clinical trials are even in the works to study its possible effects on COVID Research so far suggests that vitamin D deficiency may increase the risk for COVID19 and the severity of disease progression in people with the infection.

Experts therefore believe supplementation may protect people with a vitamin D deficiency. However, there is no evidence that vitamin D can treat a COVID19 infection. When it comes to preventing and fighting off colds, vitamin E tends to take a backseat to vitamin C.

However, this powerful antioxidant is key to a healthy immune system. Nuts, such as almonds , are packed with the vitamin and also have healthy fats. Adults only need about 15 mg of vitamin E each day. Sunflower seeds are full of nutrients, including phosphorous , magnesium , and vitamins B6 and E.

Vitamin E is important in regulating and maintaining immune system function. Other foods with high amounts of vitamin E include avocados and dark leafy greens. Sunflower seeds are also high in selenium.

Just 1 ounce contains nearly half the selenium that the average adult needs daily. A variety of studies , mostly performed on animals, have looked at its potential to combat viral infections such as swine flu H1N1.

You may know turmeric as a key ingredient in many curries. This bright yellow, bitter spice has also been used for years as an anti-inflammatory in treating both osteoarthritis and rheumatoid arthritis.

Research shows that high concentrations of curcumin , which gives turmeric its distinctive color, can help decrease exercise-induced muscle damage. Curcumin has promise as an immune booster based on findings from animal studies with antimicrobial properties. More research is needed. Both green and black teas are packed with flavonoids , a type of antioxidant.

Where green tea really excels is in its levels of epigallocatechin gallate EGCG , another powerful antioxidant. Research has suggested that EGCG may have antiviral properties that support the immune system. The fermentation process black tea goes through destroys a lot of the EGCG.

Green tea, on the other hand, is steamed and not fermented, so the EGCG is preserved. Papayas also have a digestive enzyme called papain that has anti-inflammatory effects. Papayas have decent amounts of potassium , magnesium, and folate , all of which are beneficial to your overall health.

Like papayas, kiwis are a rich source of essential nutrients, including folate, potassium, vitamin K , and vitamin C. The soup may help lower inflammation, which could improve symptoms of a cold. Poultry, such as chicken and turkey, is high in vitamin B6.

About 3 ounces of light turkey or chicken meat contains nearly one-third of your daily recommended amount of B6.

Vitamin B6 is an important player in many of the chemical reactions that happen in the body. Stock or broth made by boiling chicken bones contains gelatin , chondroitin, and other nutrients helpful for gut healing and immunity. Too much zinc can actually inhibit immune system function.

You may want to focus on eating a balanced diet with plenty of fresh foods and whole grains, engage in at least minutes of physical activity per week, get enough sleep, manage stress with deep breathing or talk therapy, avoid or quit smoking, and limit alcohol consumption.

Preliminary research suggests vitamin C may be involved in the development and function of white blood cells. It seems vitamin C may improve the reproduction of B- and T-cells , which are important white blood cells for the immune system.