A new study has found that those who ate right had both a lower chance of contracting COVID-19 and, on average, fared better if they caught the coronavirus.
“Eating right” meant following a Mediterranean diet, and the findings add weight to years of evidence that food choices matter with more than chronic diseases such as heart problems and diabetes. Diet – and, more specifically, how one’s diet impacts the immune system – makes a difference in our ability to fight infectious diseases brought on by viruses and bacteria.
The Mediterranean diet is heavy on fruits, vegetables, legumes (such as lentils, peas, and beans), nuts, and olive oil. Fish, poultry, eggs, and dairy products play a lesser role, and red meat a minor one. The diet is high in good fats such as omega-3 fatty acids, and it’s rich in vitamins and minerals (a.k.a. micronutrients) and antioxidants.
The study, released in late August, was a roundup that considered five studies in five countries published from 2020 to 2023, with 55,239 total participants. Food questionnaires had established whether the participants followed a Mediterranean diet. The results, in a nutshell:
- Three of the five studies reported that those on Mediterranean diets to have a 5% to 25% lower risk of contracting COVID-19. Two of the other studies showed lower coronavirus risk, but the number of cases involved didn’t reach the point of statistical significance.
- One of the four studies looking at the severity of coronavirus symptoms found symptoms to be lessened by 6% to 34% among Mediterranean dieters, depending on the symptom, with the other three studies also showing milder symptoms – but again, the numbers did not reach statistical significance.
- Among the three studies that considered the risk of severe COVID-19, one of them found a 77% lower risk among those on a Mediterranean diet; the other two saw 22% to 78% lower risk, but those results did not attain statistical significance.
The authors recognized the limitations of the studies they included in the review. Depending on the study, the caveats included low numbers of coronavirus infections, gender bias, the use of self-reported diet data, and other potentially influential factors including socioeconomic status, lifestyle, and preexisting health conditions.
Chronic inflammation plays a role in many diseases
Yet the overall message still resonates, and other studies have said the same: A healthy diet can keep you from catching bugs like the coronavirus and help you subdue them if you do. Vitamin deficiency and outright malnutrition can directly affect the body’s ability to fight off disease, and Mediterranean diets are rich in vitamins and supply good nutrition. But it looks like the more important factor for most people in wealthy countries is the role of diet in inflammation.
Inflammation keeps us alive: It’s our immune system’s response to microscopic invaders that make us sick, and it also helps heal injuries.
But inflammation becomes a problem if it smolders over time – or, worse, gets hijacked into attacking otherwise healthy tissues, which is what happens with autoimmune diseases such as rheumatoid arthritis and asthma. Recall also that the many severe coronavirus cases involved a “cytokine storm” – an inflammation tsunami.
The Mediterranean diet has proven to be anti-inflammatory. It lowers the expression of molecules that boost inflammation (TNF-alpha, IL-1, IL-6, and CRP among them) and reduces the body’s overall level of inflammation. That, the medical community has long understood, is why those on that diet generally have fewer chronic health problems (chronic inflammation is implicated in cardiovascular disease, kidney disease, type 2 diabetes, neurodegenerative diseases such as Alzheimer’s, cancers, and other health problems). The connection between inflammation and infectious disease has been harder to demonstrate – particularly inflammation related to dietary habits. A global pandemic plus a diet that’s prevalent in countries with hundreds of millions of people delivered enough patients to explore the question further.
Mediterranean diet and inflammation
Dr. Annie Moore, a University of Colorado School of Medicine internal medicine specialist who is board-certified in obesity medicine and integrative medicine, has published on anti-inflammatory diets. The body has pro-inflammatory as well as anti-inflammatory systems, and they should be in balance, she says. Those whose immune balance has tipped into inflammatory territory – diet, stress, obesity, a lack of exercise, and other factors can contribute to that – are likely more susceptible to infectious diseases.
“The Mediterranean diet is probably one tool to keep your underlying systems in harmony with each other, and that may make you less vulnerable,” Moore said.
The challenge with changing up diets is how personally and culturally ingrained our food choices are – not to mention the food business’s motivation to keep highly processed foods on our shopping lists. (You don’t see ads for blackberries and spinach during NFL broadcasts; it’s a different story with fast food and salty snacks.) Fast food tends to be inflammatory food. We buy and cook what we know, and what we know isn’t necessarily healthy, regardless of culture. Moore points out that we similarly metabolize white bread, white rice, and flour tortillas into a quick spike in blood sugar that can bring about a pro-inflammatory response.
Incremental changes can improve your diet – and your health
Switching wholesale to a Mediterranean, Whole-Foods, or American Diabetes Association diets is a big ask for most of us. Moore has a few suggestions for those who want to eat healthier, but perhaps want to ease into a new, healthier normal.
There’s a lack of awareness that red meat and, in particular, processed meats invite inflammation, so try to cut back on those, she suggests. Go with whole-grain breads, brown rice and whole-grain tortillas. Try an orange instead of orange juice. Skip the chips and snack on nuts instead. Potatoes’ nutritional value in terms of carbs may be more than skin-deep, but the skins are rich in potassium and high in fiber. Eating seasonally – more berries in the summer, more root vegetables in the fall – can keep things interesting and lower costs. Beans offer a nice blend of protein, carbohydrates, and fiber – try adding them to your diet, she says.
“Sometimes it’s easier to add healthy foods than taking other foods away,” Moore adds.
The new study also offered up some ideas specific to reducing COVID-19 risk – and, probably, that of other infectious diseases.
“Several subtypes of food were inversely associated with COVID-19 risk. Higher olive oil consumption, lower red meat consumption, lower cereal consumption, moderate amounts of alcohol, and higher intake of fruit and nuts reduced COVID-19 risk, and higher consumption of vegetables, fruits, legumes, nuts, whole grains, and fish lowered odds of severe COVID-19,” the authors reported.
Perhaps the most important reminder here is that, just as exercise is medicine, so too is food. Paying attention to what we eat, even incrementally, can make a difference in how we feel and how well we fight off disease.
Editor’s Note: The Colorado Times Recorder occasionally posts articles, like this one, from UCHealth Today, which is published by UCHealth, the hospital associated with the University of Colorado School of Medicine. Our goal is to provide as many people as possible with accurate information about medical issues that are poisoned by misinformation, particularly as discussed on social media and talk radio.
