COVID-19: Are supplements best for a strong immune system?

The coronavirus (COVID-19) outbreak has been quite the motivator for building up a strong immune system.

While shopping for essentials, you may be grabbing for vitamin C, zinc, elderberry syrup and other supplements said to give the immune system that extra boost. There currently is no full-proof protection against the coronavirus, but there is nothing wrong with using this time to develop better dietary habits for immune support.

But are supplements the best source of the nutrients you need? Mary Welkie, M.A., RD, LDN, a clinical dietitian at Levindale Hebrew Geriatric Center and Hospital, explains how to best fuel your immune system:

How much vitamin C and zinc is enough?

For a healthy immune system, a general, unprocessed, whole food diet is the way to go, Welkie says.

Your daily diet should include at least five fruits and vegetables, lean proteins, low-fat dairy, and whole grains.

"If your diet includes these types of foods, you're likely to get all the macronutrients, vitamins and minerals required for a healthy immune system," Welkie says. "Eating a variety of whole foods allows for the correct balance of nutrients. Fruits and vegetables are especially high in vitamins and minerals that aid in maintaining a healthy immune system. Therefore, buying additional vitamins or supplements wouldn't be necessary."

Vitamin C and zinc are vital to a healthy immune system, but supplementation is unnecessary for the average person. Your typical vitamin C daily supplement is about 1,000 mg, but the recommended daily amount of vitamin C for adults is 75 to 90 mg. "Although high intake of vitamin C generally isn't seen as harmful, it also isn't very beneficial due to the solubility of the vitamin," Welkie says. "This essentially means if you consume a large amount, your body doesn't store the vitamin. Rather, it will void it through your urine or sweat."

Foods that are rich in vitamin C include red peppers, oranges, broccoli, kiwi, leafy greens and strawberries.

Be careful when it comes to your zinc intake: Zinc toxicity can occur with very high intakes, which is why you should check with your doctor first before taking zinc supplements. The recommended daily amount of zinc for adults is 8 to 11 mg. Oysters, Welkie says, are the food source highest in zinc. "If you're not a fan of oysters, other good sources are red meat, poultry, beans, nuts and whole grains," she says.

Other helpful nutrients you need

Vitamins A, D and E also are key for a healthy immune system.

The recommended daily vitamin A intake is 900 mcg. Vitamin A is in orange foods like sweet potatoes, pumpkin and carrots as well as spinach. Good sources of vitamin E (recommended daily intake is 15 mg), which plays an antioxidant role in immune function, include sunflower seeds, almonds and peanut butter.

Exposure to the sun is our best natural source of vitamin D. But right now, with everyone being urged to stay home as much as possible and practice social distancing during the COVID-19 outbreak, getting adequate sunlight exposure might be difficult. Good food sources of vitamin D include fatty fishes, milk, and fortified orange juice and grains, but even these sources might not be enough to fulfill your recommended daily intake (about 400 to 800 IU for adults).

"In this case, using a vitamin D supplement may be necessary if you are deficient," Welkie says.

Other key nutrients are selenium, iron and folate. "Selenium can be found in tuna, eggs and oatmeal, but its highest source is Brazil nuts," Welkie says. "Iron aids with the delivery of oxygen throughout the body and can be found in red meat, fortified cereals, kale and spinach. Folate can be found in fortified grains, spinach and asparagus."

Always ask your doctor

Remember that all vitamins and minerals have recommended intakes that can be exceeded with supplement use. So, if you think if you may be deficient in a nutrient, speak with your doctor about it before loading up on supplements. A multivitamin may be beneficial if your diet is lacking in a particular area. "But in general, a healthful diet is the best way to obtain adequate nutrients for immune function," Welkie says.

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