Masks, hand washing, and social distancing are key fighters in fending off outside attacks. But healthy eating strengthens the warriors who keep us safe.

According to Dr. med. Manfred Eggersdorfer it is time to put nutrition in the foreground of the COVID-19 war.

“I think we have to … follow social distancing and wear masks too, but optimal nutritional status, I believe, would be an additional measure and help reduce the risk of infection,” said Dr. Eggersdorfer, Professor of Healthy Aging at the University of Groningen, the Netherlands.

Dr. Eggersdorfer spoke to Medical Daily about his research on macronutrients and virus resistance published in the journal Nutrients.

The paper covered a wealth of information on how macronutrients affect immunity. The research goes well beyond the typical advice on getting the most out of vitamin C. The main players are not only C, but also vitamin D, zinc and omega-3 fatty acids, which have been shown to boost the immune system.

The issue is underestimated on all fronts, he said.

“It is a pity that government agencies, nutritionists and scientists are no longer addressing this issue. I am … disappointed with the medical community because they really should also recommend taking care of your diet, maintaining optimal nutrition and optimal nutritional status as additional measures that will reduce the risk of infection. “

But why?

“For immunity, we need a higher intake of some nutrients in order to get the best immune system state,” he said.

vitamin C

Vitamin C revitalizes white blood cells, the killers that attack and dispose of invading microbes, said Dr. Eggersdorfer. “If you have a good vitamin C reservoir, you are more mobile and agile and can fight pathogens, viruses and bacteria better.” The usual recommended daily dose is 75-100 mg. However, doses of 200 mg or more have been shown to reduce the risk, severity, and duration of respiratory infections. Sick already? Even more – 1 or 2 grams is the way to go.

Vitamin D

Our bodies naturally produce vitamin D when we are exposed to sunlight, but low levels are common, noted Dr. Eggersdorfer firmly in his work.

Vitamin D deficiency is linked to an increased risk of respiratory infections. Studies have confirmed the benefits of vitamin D supplements. A review of 25 studies with 11,000 subjects found that supplementation can reduce the risk of infection by up to 70%.

Earlier this year, the New York Times reported an increase in sales of vitamin D supplements.

One study recommended that people at risk for COVID-19 increase their vitamin D levels quickly by taking 10,000 IU per day for short periods of time. By and large, the consensus seemed to be:

  • Vitamin D deficiency is common.

  • Vitamin D has been linked to improved results in respiratory infections.

  • Taking vitamin D is safe and inexpensive.

In September, a group from Harvard Medical School started a clinical study. They hope to recruit 2,700 people to test whether vitamin D supplementation reduces the risk of hospitalization or death. People who participated in the study took a large dose of vitamin D for two days and smaller doses for the remainder of the four weeks.

The study is expected to be completed in 2021. Clinical studies are needed to show whether a treatment is effective. While vitamin D supplements can help, they are not a proven cure or a proven preventive measure.

Especially during the winter months and during lock reorders, people are less likely to get a quality time in sunlight. This is where supplements can make up for the loss. Guidelines usually suggest 600 IU / day, but Dr. Eggersdorfer suggests that 2,000 IU / day would be a better choice.


Zinc lozenges might sound like an old woman’s story, but they can be effective in reducing the duration of cold symptoms. They work by reducing the amount of virus in the nose and throat at the beginning of a cold. A review of seven studies in 2017 compared it to an inactive diamond. The zinc lozenges reduced the length of the cold by 33%. The most effective dose was about 100 mg; higher doses didn’t work better.

But just this year, a study comparing active lozenges with inactive lozenges found that lozenges did not reduce the duration of colds. Placebo-controlled studies like this one are considered the gold standard for determining whether a treatment is effective. So the jury is still on lozenges. However, since zinc supplements increase the formation and lifespan of immune cells, this can have an overall benefit. Children, in particular, are more resistant to respiratory infections and some diarrheal infections when zinc levels are at the same level, said Dr. Eggersdorfer.

He recommends 8–11 mg / day.

Fatty fish are your friend

In addition to the vitamins, Dr. Eggersdorfer believes that people should add omega-3 fatty acids. “You can usually eat this from fish oil or fish, but we recommend 250 milligrams,” he said.

The dish

But is supplementation the only way to achieve these goals? The short answer is no. For some things, like vitamin C, getting the full 200 mg is incredibly easy. “You can achieve 200 mg if you eat maybe two oranges or an orange and a kiwi every day,” said Eggersdorfer, “to achieve an intake of 200 mg. 200 milligrams of vitamin C are possible through food. “According to a USDA report, the body doesn’t seem to be consuming much more than 200 mg of vitamin C per day, and over 3 grams (3,000 mg) might even be unhealthy. There are about a hundred milligrams of vitamin C in one large orange. As long as people avoid eating thirty oranges in a day, vitamin C is easy to get from food and difficult to overdo.

Vitamin D is another topic. Especially in winter it is not so easy to get out of the sun. For many, the supplement aisle may be the most convenient place to look. Eggersdorfer explained that zinc and omega-3 fatty acids could be obtained from meat and fatty fish. This requires commitment. One fatty fish meal per week is unlikely to provide enough omega-3 fatty acids.

Walk alone

Just as scientists know how much vitamin or mineral is too little for the human body, they also know what is too much. These are called upper limits, and while some part of a particular vitamin, like 2,000 mg of vitamin D, is good, 4,000 mg of vitamin D can do harm. Diet is a delicate balancing act, and individuals interested in supplementation should check with their doctor. A doctor can not only test the content of vitamins and minerals, but also know possible interactions with drugs and optimal values ​​for each patient.

In the grocery store

Go for a supplement that doesn’t make exceptional health claims and look for a trusted brand.

Eat To promote health

What does a health professional eat? Muesli apparently. Dr. Eggersdorfer said he started the day with nutritional supplements and a mixture of oats and grains. Afterwards there are lots of vegetables and a light dinner.

Take them home

Especially for people who are less outdoors or eat fewer fruits and vegetables in the winter, talking to a doctor about diet supplements could provide better health in the months to come. Better nutrition could protect the body and support the immune system, but wearing a mask and social distancing are proven ways to avoid getting or transmitting the coronavirus.

Sabrina Emms is a science journalist. She began as an intern on a health and science podcast on Philadelphia public radio. Before that, she worked as a researcher studying the way bones are formed. When she is not in the laboratory and at her computer, she is in the moonlight as an assistant to a pig veterinarian and bagel baker.