Oysters! Acai berries! Miso soup! Coconut oil!
The Internet is awash with articles breathlessly rattling off lists of “Immune-Boosting Superfoods” to help us bolster our defenses against the coronavirus. In the current climate this is understandable, but not particularly helpful.
By all means, if you love oysters, acai berries, miso soup and coconuts, eat them; they’re delicious and nutritious. But know that individual foods, no matter how nutritious, won’t ward off disease — especially if you’re otherwise eating a Standard American Diet, skimping on sleep and exercise, and running on cortisol from continuous stress. (See my Covid-19 posts on sleep, stress and exercise.)
So instead of giving you yet another list of superfoods (which aren’t actually a thing), I am inviting you to take a deep breath, step back from the reductionist, quick-fix approach to eating (“Eat food X to achieve outcome Y”) and consider the bigger picture: A pattern of eating that nourishes not only your immune system, but every other cell in your body, too. It’s called the Mediterranean diet and it has solid immune-supporting and anti-inflammatory credentials (see articles here, here, here, here and here).
A strong army needs good food
Napoleon famously said, “an army marches on its stomach.” The immune system – our very own molecular army that fights disease-causing invaders such as viruses and bacteria – is no different: When it is well fed, it’s best equipped to fight disease.
Optimal nutrition doesn’t just help switch on the immune response that helps our bodies fight invaders; it also helps to switch it off once the attack is over, thus reducing the risk of chronic inflammation. Inadequate nutrition, on the other hand, impairs immune function.
Unfortunately, many of us don’t consume the nutrients our bodies need to regulate our immune response – notably vitamins A, C, D and E, zinc, selenium and omega-3 fatty acids. According to medical biophysicist Sarah Ballantyne, PhD, “many of the staple foods of the typical American diet have very little nutritional value.”
Processed foods, in particular, are nutritionally poor. “The more a food is refined, processed and manufactured, the more the nutrients … are leached out, removed, or degraded,” Ballantyne writes. “Even foods that many people think are healthy, like whole grains and low-fat dairy, are pretty weak when it comes to essential nutrients,” she states. “And every time a nutritionally weak food displaces a nutritional powerhouse, the overall nutritional value of the diet suffers.”
Sadly, most Americans don’t get the nutrients they need from food. The US government survey NHANES 2007-2010, which studied 16,444 people four years and older, found inadequate nutrient intakes across the board. Thus, 94.3% of the US population did not meet the daily requirement for vitamin D, 88.5% for vitamin E, 52.2% for magnesium, 44.1% for calcium, 43.0% for vitamin A, and 38.9% for vitamin C. Inadequate intakes extended across all of the B vitamins and several minerals, including copper, iron, phosphorus, selenium and zinc – many of which are essential to proper immune function.
It starts with food
Upon reading these numbers you’d be forgiven for rushing out to buy a megadose multivitamin and mineral supplement. But while supplements do provide useful nutrients, studies of their efficacy show mixed results. So rather than stocking up on supplements, I suggest you support your immune system by buying the most nutritious foods you can afford while cutting out inflammatory foods made with refined grains, sugar and industrially produced seed oils. Which brings us back to the Mediterranean diet.
In terms of macro-nutrients, the Mediterranean diet offers the best you could ask for:
- High-quality protein from animal and plant foods: protein is needed to produce disease-fighting antibodies and other immune factors). Foods high in protein, such as red meat, seafood and beans, also contain other immune-boosting nutrients like zinc. And fermented dairy foods like yogurt and kefir supply not only protein but immune-friendly bacteria called probiotics.
- Healthy fats, such as the monounsaturated fatty acids found in olives and some animal foods, the polyunsaturated omega-3 fats in oily fish and omega-6’s in seeds and nuts, have anti-inflammatory and immunomodulatory effects.
- Low-glycemic carbohydrates, such as vegetables, fruits and legumes, which are rich in immune-supporting vitamins and antioxidants, as well as fibers and starches that nourish the gut bacteria (our immune system’s staunchest allies).
Moreover, the Mediterranean diet is a rich source of immune-supportive micronutrients such as:
- Vitamin A (best sources of vitamin A’s retinoid (animal) form include shrimp, eggs, cheese, butter, yogurt, salmon and sardines. Carotenoid (plant) sources of vitamin A can be found in foods like sweet potato, carrots, kale, spinach, mustard greens, etc.). It’s best to get both retinoid and carotenoid vitamin A in our diet. More here on vitamin A.
- Vitamin C (bell peppers, broccoli, strawberries, Brussels sprouts, pineapple, oranges, kiwi, cauliflower, etc.). More here on vitamin C.
- Vitamin E (sunflower seeds, almonds, spinach, Swiss chard, avocado, turnip greens, asparagus, etc.) More here on vitamin E.
- Vitamin D (salmon, sardines, milk, tuna, eggs and sunshine). More here on vitamin D.
- Zinc (oysters, beef, lamb, sesame seeds, pumpkin seeds, etc.). More here on zinc.
- Selenium (tuna, shrimp, sardines, salmon, turkey, cod, etc.). More here on selenium.
All together now
Don’t worry — you don’t have to memorize all these foods and nutrients. Just eat as many different whole, fresh foods as you can, and you should obtain all the nutrients you need to stay healthy. This doesn’t just apply to immune strength; research has found that a high degree of dietary variety is associated with improved microbiome health and reduced risk of chronic diseases such as cardiovascular disease, diabetes mellitus, metabolic syndrome and certain cancers (article).
So, get out of your comfort zone and include foods you don’t usually eat: In addition to protein favorites chicken, beef and salmon, for instance, why not eat lamb, cod, sardines and liver? Instead of snacking on almonds and baking with almond flour, why not try walnuts, pecans, Brazils and macadamias and bake with hazelnut flour? And in addition to broccoli and green beans, throw in eggplants, zucchini, fennel, mustard greens and celery root. And before you dive in, sprinkle some parsley, mint, oregano or cilantro on top.