Dietary strategies to enhance protection against COVID-19

NATION — As cold and flu season approaches, many people are looking for ways to boost their immune defenses and reduce the risk of falling ill. While COVID-19 remains a top concern, it’s also important to protect against other common viruses that circulate this time of year. One key factor in supporting immune function is nutrition.
Monique Richard, MS, RDN, LDN, a registered dietitian nutritionist and owner of Nutrition-In-Sight, recommends starting by consulting with a qualified nutrition professional to assess individual needs and develop a personalized plan. ”First, Richard suggested meeting with a registered dietitian nutritionist (RDN) or other qualified, credentialed nutrition expert to learn more about your unique needs,” she advised.
From there, she emphasized the importance of consuming a variety of nutrients that play critical roles in immune health. These include vitamins A, B (thiamine, riboflavin, pantothenic acid, B6, folate, and B12), C, D, and E, as well as minerals like zinc, magnesium, and selenium. ”Many of these are found in fruits, vegetables, whole grains, proteins and fat,” Richard noted.
However, she cautioned against relying on supplements to meet these needs, explaining, ”Keep in mind that dietary supplements for each of these nutrients do not necessarily have the same impact as the whole food and in fact can often be counter-productive especially in high doses by depleting a different nutrient.”
Richard provided the example of zinc, a mineral that is essential for immune function but can interfere with copper absorption when consumed in excess. ”For example, too much zinc can deplete copper,” she said. ”Taking a zinc supplement may not be necessary especially if you are obtaining enough in your diet, it is not advised for a prolonged period of time. This is one of many I see in practice being overconsumed and consequences are not always benign.”
To help people assess whether they are getting enough immune-supporting nutrients from their diets, Richard posed a series of questions:
How many fruit servings am I consuming in a day? Are they coming from a variety of fresh or frozen sources such as citrus fruits (oranges, grapefruit, tangerines), berries, apples, and stone fruit (plums, peaches, apricots)?
Fruits are rich in vitamin C, folate, and other antioxidants that support immune cell function and protect against oxidative stress. Eating a colorful assortment helps ensure a broad range of beneficial plant compounds.
How many servings of fresh or frozen vegetables am I consuming in a day? Are leafy greens such as spinach, arugula, kale, or turnip greens included? Are bright orange and red vegetables included, such as carrots, peppers, tomatoes, sweet potatoes, radishes, beets, etc.?
Like fruits, vegetables provide a plethora of vitamins, minerals, and phytochemicals that bolster immunity. Dark leafy greens are especially high in vitamins A, C, and folate, while red and orange vegetables tend to be top sources of beta-carotene, another immune-enhancing antioxidant.
Where do I get my protein? Beans? Frozen or fresh or canned fatty fish such as salmon, sardines, herring, or tilapia for example?
Adequate protein is critical for immune cell production and function. Legumes like beans and lentils provide zinc and folate in addition to plant-based protein. Fatty fish are among the few food sources of vitamin D, which helps regulate immune responses.
Are fat sources in my diet quality olive, avocado, or nuts and seeds sources? Full-fat dairy? Or is it mostly saturated fat from animal sources, which is then processed, breaded, and deep-fried?
The types of dietary fats consumed influence inflammation in the body, which in turn impacts immune function. Anti-inflammatory unsaturated fats from plant oils, nuts, seeds, avocados, and fish are preferable to pro-inflammatory saturated and trans fats prevalent in red meat, full-fat dairy, fried foods, and ultra-processed snacks.
Am I cooking and seasoning foods with antioxidant-rich spices and herbs such as ginger, garlic, onions, turmeric, basil, thyme, rosemary, parsley, cilantro, or scallions, just to name a few?
Many herbs and spices contain potent anti-inflammatory and antioxidant compounds that provide an extra immune boost. Using them generously in cooking is an easy way to ramp up protective benefits without excess calories, sugar, or sodium.
The common thread throughout Richard’s guidance is an emphasis on whole, minimally processed plant foods. The fiber, nutrients, and bioactive compounds they provide work synergistically to support the body’s natural defenses against infection.
A recent study published in the journal PLOS ONE found that people who closely followed a Mediterranean-style eating pattern had lower odds of testing positive for COVID-19. The researchers, led by Dr. Andre Marolop Pangihutan Siahaan of the Universitas Sumatera Utara in Indonesia, analyzed data from over 55,000 participants across six observational studies. They consistently observed an inverse relationship between Mediterranean diet adherence scores and COVID-19 infection rates.
However, it’s important to remember that a healthy diet alone is not a panacea. Dr. Siahaan emphasized that diet is just one factor influencing COVID-19 risk and outcomes. ”It is important to note that diet alone does not determine the impact COVID-19 may have on an individual,” he said. ”There are a multitude of factors that play a role including current health conditions, genetic predisposition, level of exposure, organ function, age, metabolic function, and environment just to name a few.”
Family medicine physician Dr. David Cutler also cautioned against overstating the significance of the observed correlations in the absence of clear causation. ”Even if there was an association between diet and COVID outcomes, that doesn’t imply that there’s any cause and effect relationship,” he told MNT. ”And while that might be interesting, I really don’t think it’s all that important. I think most people would agree that a Mediterranean diet is a helpful diet and it’s a good idea to follow one, regardless of whether or not it changes COVID outcomes.”
Lifestyle factors like sleep, stress management, and physical activity also play key roles in overall immune function. Getting recommended vaccines, practicing good hygiene, and following public health guidelines remain critical as well.
Nonetheless, as Richard highlights, focusing on nutrition is an important strategy for strengthening viral protection throughout the cold and flu season and beyond. By filling one’s plate with a rainbow of fruits, veggies, legumes, whole grains, and healthy fats, while limiting sugary, highly refined, and heavily processed items, anyone can give their immune system an edge.
—Elliot Mercer