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How Your Diet Affects Your Risk of COVID-19

We know a lot about COVID-19. We know COVID-19 is sweeping across the world with new variants seemingly every month. We know how vaccines work to fight off a COVID-19 infection. We know how chronic COVID-19 can cause lasting impacts on the body.

But, until recently, we did not know exactly what the effects of diet on COVID-19 were. A recently published study has begun to answer that question. Here’s what we know.

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The Study:

Researchers from Johns Hopkin, Harvard, Stanford, and Columbia looked at health professionals from 6 different countries who had recovered from COVID-19. The researchers examined data from nearly 600,000 participants over the span of 9 months. The researchers found that while diet had little effect on who got COVID-19, dietary habits had profound effects on the severity of a COVID-19 infection.

At the beginning of the study, the participants completed a questionnaire about their dietary habits. The participants’ diet scores were then assessed using a healthful Plant-Based Diet Score that emphasizes vegetables, fruits, and other healthy plant food.

Over the course of the study, 31,831 participants developed a COVID-19 infection. From there, the participants with COVID-19 were divided into two groups based on the severity of their infection: minimal-mild and moderate-severe. The researchers found that those with the highest diet score had a 9% lower chance of developing COVID-19 and a 41% lower risk of developing a severe COVID-19 infection. The lead researcher said that these results were consistent across a range of sensitivity analyses accounting for outside behaviors.

The participants with the highest diet scores were those eating a diet high in plant-based foods. The lowest scores were held by participants who ate a diet with few plant-based food sources.

The researchers found that a 40% increase in vegetable consumption produced a 70% decrease in the risk of moderate-severe COVID-19. Participants who described their diet as low carb and high protein had nearly 4x the risk of developing moderate-severe COVID-19.

These statistics demonstrate that sugar was not the key to the severity of Covid-19 but, rather the increase in vegetables. No participants in the study were true vegetarians. Those who described their diet as plant-based ate the same amount of dairy products and eggs as the other group. The plant-based group ate just as much fish but less poultry and meat. The plant-based group used beans, seeds, and nuts as a major source of protein.

Why is the plant-based diet more protective?

Some speculate that the plant-based diet offers protective effects against COVID-19 due to the polyphenols that plants contain. Specifically flavonoids and bioflavonoids. Polyphenols are micronutrients that have previously been linked to health benefits. Such benefits include:

  • Boosted digestion & brain health

  • Protection against type 2 diabetes, heart disease, & some cancers.

Polyphenols are able to produce such beneficial effects because they can act as antioxidants, neutralizing the harmful free radicals that have been linked to many chronic illnesses.

Another potential answer to why the plant-based diet offers protection is due to the high fiber content that fruits and vegetables offer. Fiber is a key component of a healthy microbiome. This is because Fiber encourages the production of short-chain fatty acids and butyrate by gut microbes. Butyrate nourishes the cells of the large intestine and is absorbed into the body producing a global anti-inflammatory and protective effect throughout your body and especially the brain.

A healthy gut microbiome is also key to a healthy immune system. The microbes in the gut microbiome are in constant interaction with immune cells in the gut. These gut immune cells actually help to keep our entire immune system primed to fight off infection. Eating a diet full of processed foods instead of plants and fiber diminishes the power of the immune cells in the gut. Which ultimately leads to a diminished immune system that has less power to fight off viruses like COVID-19.

How to follow a plant-based diet?

Following a largely plant-based diet, like the ones in the study, is actually easier than you think. One example of such a diet is the Mediterranean Diet. This diet is widely regarded as the healthiest diet and studies have shown how it promotes overall health and longevity. The Mediterranean diet focuses on eating plant-based foods, fresh fruits and vegetables, and lean proteins. It also promotes eating whole foods and a few processed foods. You could consider the Mediterranean diet to be more of an eating pattern than a diet, as it doesn't have such strict restrictions.

Some key facets of the Mediterranean diet include:

  • Emphasizes olive oil and other healthy fats such as avocados

  • Whole grains

  • Legumes

  • Leafy greens

  • Emphasizes nutrient-rich foods

  • No need to count calories or carbohydrates

  • Lower intake of sugar due to the amount of other fresh foods

Alternatively, you could also explore a modified low-carb diet. A low-carb diet focuses on limiting your intake of grains, fruits, sweets, and starchy vegetables while eating more protein, natural fats, and non-starchy vegetables.

Some key facets of the Low-carb diet include:

  • Low carb diets largely consist of minimizing carbohydrate intake, especially simple and refined carbs.

  • The low-carb diet is looser in structure, most people do not eat enough fat to force your body to enter ketosis.

  • Typically, low-carb entails eating proteins and non-starchy vegetables, while limiting grains, fruits, bread, sweets, and starchy vegetables, like potatoes and peas.

  • Low-carb diets can be extremely successful in aiding and maintaining weight loss.

  • The total carbohydrate intake is <100g.

Combining both the low-carb and the Mediterranean diet is a great way to meet the high diet score like the one referenced in the above study. The emphasis is on nutrient-rich foods but with very few grains and limited starchy carbohydrates. Keeping carbohydrates between 20-50mg a day would be more in line with a Keto-Mediterranean diet. A Low-Carb Mediterranean diet allows 20-100mg a day. This number varies depending on your physical activity and other metabolic numbers. Best to consume starchy carbs such as sweet potatoes and beans after an aerobic workout.

The Low-carb Mediterranean is a great way to eat for life!

Reminder! Diet cannot replace the vaccine!

While there is no negating the importance of a healthy diet for overall health, your diet itself DOES NOT replace the need for other COVID-19 precautions like getting vaccinated or wearing a mask. Further, while studies like this one offer great new insights, there is still much to learn about the role of diet and the microbiome play in managing a COVID-19 infection.

There is no denying that diet is a very important aspect to take into account during the ongoing coronavirus pandemic, but it is not the only aspect! A healthy diet, combined with vaccinations and other COVID-19 precautions is the best way to keep yourself safe.

To learn more about your diet and how it affects your risk of COVID-19, click here to contact us! If you have any more questions about your path to optimal health, email our office at or call 276-235-3205.

The Johnson Center for Health services patients in-person in our Blacksburg and Virginia Beach locations. We also offer telemedicine for residents of Virginia and North Carolina!


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