There isn’t a magic cure for the coronavirus that’s currently sweeping across the world. At least not yet, anyway. But scientists do know that our immune system is our body’s best line of defense against COVID-19, an infectious disease caused by the virus that affects the respiratory system.
While people have died from COVID-19, many have recovered, so experts know it is possible for the human body to fight it off. The Guardian reports that more than 84,000 out of more than 219,000 people are recorded as having recovered from the novel coronavirus.
So, while you’re washing your hands and shielding yourself from infection at home, here are seven nutrition tips that could help your immune system. It just makes good sense.
At the risk of sounding like your mother, you really should eat your greens. Broccoli, for example, is rich in important vitamins and minerals. According to Medical News Today, it’s so healthy, it could even be considered a “superfood.” It’s a source of antioxidants, which are said to neutralize free radicals—waste produced by cells as the body processes food and reacts to its environment. If the body cannot effectively remove free radicals, it can cause oxidative stress, which is linked to heart disease, certain forms of cancer, and respiratory diseases.
It also contains vitamin C, which may help to boost your immune system. Registered dietician Katherine Marengo, LDN, RD, writes on Healthline that to get the best out of broccoli, you should eat it as raw as possible.
She says: “Broccoli is supercharged with vitamins and minerals. Packed with vitamins A, C, and E, as well as many other antioxidants and fiber, broccoli is one of the healthiest vegetables you can put on your table. The key to keeping its power intact is to cook it as little as possible — or better yet, not at all.”
Rich in vitamin C, she says leafy green spinach is also better raw. “[Spinach is] packed with numerous antioxidants and beta carotene, which may increase the infection-fighting ability of our immune systems,” says Marengo.
Kale, asparagus, peas, and sprouts are further examples of green vegetables that are rich in vitamins and minerals.
According to many health experts, B vitamins are important for a good immune system. According to Clare Collins, a professor in nutrition and dietetics at the University of Newcastle, B6, B9, and B12 “contribute to your body’s first response once it has recognized a pathogen.”
“They do this by influencing the production and activity of ‘natural killer’ cells,” she writes for the Conversation. “Natural killer cells work by causing infected cells to ‘implode,’ a process called apoptosis.” She adds, “at a football match, this role would be like security guards intercepting wayward spectators trying to run onto the field and disrupt play.”
B6 and B9 can be found in leafy green vegetables, as well as nuts and legumes. The former can also be found in fortified cereals, and the latter in seeds and commercial bread-making flour. Vegan sources of B12 include supplements, fortified nutritional yeast, fortified cereal, mushrooms, and fortified dairy-free milk.
Green vegetables aren’t the only foods rich in vitamin C. Oranges, lemons, limes, kiwifruit, avocados, and tomatoes are also a good source.
According to Collins, if B vitamins are the security guards of the football pitch, then vitamin C is the cleaner of the grounds after the game. “When your body is fighting an infection, it experiences what’s called oxidative stress. Oxidative stress leads to the production of free radicals, which can pierce cell walls, causing the contents to leak into tissues and exacerbating inflammation.”
Along with vitamin E—found in nuts and leafy green vegetables–vitamin C can help to protect your cells from oxidative stress. It produces specialized cells, notes Collins, that mount to an immune response, including neutrophils, lymphocytes, and phagocytes.
Spending all this time inside can make you want to reach for the comfort food, and while there’s nothing wrong with indulging in your favorite snack every once in a while, opting for foods like nuts and berries could do your body some good.
Brazil nuts, for example, are rich in selenium. Registered dietician Jillian Kubala writes for Healthline, “selenium plays an important role in the health of your immune system. This antioxidant helps lower oxidative stress in your body, which reduces inflammation and enhances immunity.” Nuts are also a good source of fiber and protein.
Berries are a good source of vitamin C and contain antioxidants and soluble fiber, too. Gregory Freund—a professor at the University of Illinois’ College of Medicine—told Science Daily, “soluble fiber changes the personality of immune cells—they go from being pro-inflammatory, angry cells to anti-inflammatory, healing cells that help us recover faster from infection.”
According to Very Well Health, roughly one cup of berries, which can include raspberries, strawberries, and blueberries, can contain between 0.3 and 1.1 grams of soluble fiber.
When you’re staying inside, you’re limiting your chances of sun exposure, and therefore not soaking up as much vitamin D. The vitamin is important, says Collins, as some immune cells need it to destroy infection-causing pathogens.
Mushrooms are a good source of vitamin D. Chirag Shah MD—the co-founder of Accesa Labs, which offers vitamin D testing—told LIVEKINDLY: “mushrooms are thought to make vitamin D from a molecule called provitamin D2 with the help of the sun.”
Portobello, maitake, morel, button, and shiitake are considered some of the best mushroom sources of vitamin D. You can also get it from fortified dairy-free milk, tofu, orange juice, and supplements.
Experimenting with your cooking while you’re spending time at home? Consider adding a little garlic. Not only will the ingredient add flavor, but it’s good for you too. According to registered dietician Helen West, garlic has been “used for centuries” as a food ingredient and as a medicine.
West writes for Healthline, “garlic contains compounds that help the immune system fight germs.” When you crush or chew it, a compound called alliin turns into allicin. The allicin gives the garlic that distinctive taste (and smell) because it contains sulfur.
“Allicin is unstable,” explains West. “So it quickly converts to other sulfur-containing compounds thought to give garlic its medicinal properties.” She adds, “these compounds have been shown to boost the disease-fighting response of some types of white blood cells in the body when they encounter viruses, such as the viruses that cause the common cold or flu.”
While you’re at it, as well as garlic, consider adding legumes and beans to your dinner. These work particularly well in pasta dishes, chillis, shepherd’s pie, and stews.
Legumes—like lentils and chickpeas—contain iron, which, according to Collins, helps to kill pathogens by increasing the number of free radicals. “It also regulates enzyme reactions essential for immune cells to recognize and target pathogens,” she continues. Legumes also contain B vitamins, magnesium, and zinc. The latter helps to “maintain the integrity of the skin and mucous membranes,” says Collins.
Beans, like kidney, pinto, and black varieties, are a good source of protein. According to physician Carol DeSarkissian, MD, on WebMD, “protein is vital to build and repair body tissue and fight viral and bacterial infections. Immune system powerhouses such as antibodies and immune system cells rely on protein.”
As well as protecting yourself from the virus on the outside, you can also build up your defenses from the inside by strengthening your immune system. Many people, especially the young, develop only very mild disease. The immune system is complex and highly responsive to the world around us, so it’s not surprising that many factors affect its function. What’s important to know is that most of these factors are not hard-coded in our genes but are influenced by lifestyle and the world around us.
One thing that you can control immediately is the health of the trillions of microbes living in your gut, collectively known as the microbiome. Recent research has shown that the gut microbiome plays an essential role in the body’s immune response to infection and in maintaining overall health. As well as mounting a response to infectious pathogens like coronavirus, a healthy gut microbiome also helps to prevent potentially dangerous immune over-reactions that damage the lungs and other vital organs. These excessive immune responses can cause respiratory failure and death. (This is also why we should talk about “supporting” rather than “boosting” the immune system, as an overactive immune response can be as risky as an underactive one.)
Rather than taking supplements that claim to “boost your immune system” with no good supporting evidence, the food you eat has a big impact on the range and type of microbes in the gut. A diverse microbiome is a healthy microbiome, containing many different species that each play their part in immunity and health. Microbiome diversity declines as you get older, which may help to explain some of the age-related changes we see in immune responses, so it’s even more necessary to maintain a healthy microbiome throughout life.
The fine details of the interactions between the gut microbiome and the immune system are not fully understood. But there seems to be a link between the makeup of the microbiome and inflammation – one of the hallmarks of the immune response. Gut bacteria produce many beneficial chemicals and also activate vitamin A in food, which helps to regulate the immune system.
The best way to increase microbiome diversity is by eating a wide range of plant-based foods, which are high in fiber, and limiting ultra-processed foods including junk food. Following a Mediterranean diet has also been shown to improve gut microbiome diversity and reduce inflammation: eating plenty of fruit, vegetables, nuts, seeds and whole grains; healthy fats like high-quality extra virgin olive oil; and lean meat or fish. Avoid alcohol, salt, sweets and sugary drinks, and artificial sweeteners or other additives.
If you are concerned about getting hold of fresh produce while self-isolating or quarantined, frozen fruit, berries and vegetables are just as healthy as their fresh counterparts and will last much longer than the currently recommended two-week isolation period. Canned fruit, beans and pulses are another long-lasting option.
You can also support your microbiome by regularly eating natural yogurt and artisan cheeses, which contain live microbes (probiotics). Another source of natural probiotics are bacteria and yeast-rich drinks like kefir (fermented milk) or kombucha (fermented tea). Fermented vegetable-based foods, such as Korean kimchi (and German sauerkraut) are another good option.
Whether you’re shopping for yourself, your family or for elderly relatives or friends, choosing foods that support a healthy gut microbiome is much more important than stockpiling toilet paper. Managing your mental health, staying physically active and getting enough sleep will also help to keep your immune system in good shape. And don’t forget to wash your hands!
SOURCE: The Conversation