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Home of Sidney Kimmel Medical College

Boosting Your Immune System – Fact vs. Fiction

From mega-doses of vitamins to nutritional supplements we can’t pronounce – Jefferson experts help us understand what can actually help our immunity during the pandemic.

Green tea with cayenne pepper, probiotic-rich kombucha, scarily large pills of zinc – these are just some of the “immune-boosting” trends that have been making the rounds during the COVID-19 pandemic. Even as Pennsylvania readies itself for the “green” phase of reopening, the presence of the novel coronavirus still lingers. As people head back to the office, venture to restaurants, or enjoy of the warmth of the summer months,  it’s understandable to want to seek out treatments that will help bolster our defenses against this invisible and insidious pathogen. But often there is sparse scientific evidence to show that any of these foods and nutrients can prevent or reduce the risk of being infection. What’s more, consuming certain vitamins and minerals in excess can be toxic, interfere with medications, and even disrupt the normal functioning of our bodies.

We talked to experts at Jefferson to help weigh the science behind commonly sought after supplements that are linked to immune function, as well as provide practical tips for maintaining overall immunity.

Be Wary of Supplements

If you’re healthy, supplements generally won’t have any added benefit for your immune system. “People who are undernourished or have vitamin deficiencies may be more susceptible to contracting infections,” says Reina Marino, MD a physician at Jefferson Health’s Marcus Institute of Integrative Health. “But even in those cases, taking higher-than-necessary amounts of vitamins will not necessarily make your immune system function better. If you are concerned you’re not getting enough nutrients, I would suggest focusing on having balanced meals, and adding a basic daily multi-vitamin.”

Some of the supplements that have been flying off the shelves are vitamin C and zinc. “Vitamin C does play an important role in the immune system and helps immune cells identify and kill viruses and bacteria,” says Dr. Marino. “But the ideal way to get vitamin C is from food. Five to seven servings of fresh fruits and vegetables would provide 400 to 500mg,” she adds. Research has shown that these levels of vitamin C can help fight off infections, but adding a supplement to the mix could be overkill, and end up causing stomach upsets and diarrhea. “Similarly, zinc is a mineral that’s been shown to be important for immunity,” says Dr. Marino, “but taking too much of it can actually inhibit our body’s absorption of other essential minerals, like copper.”

On the Bright Side, Vitamin D May Help

Vitamin D plays an important role in immune function; several of our immune cells actually have receptors for vitamin D and this interaction can help transform these cells into more specialized defenses against viruses and bacteria.

“It’s been shown that having low levels of vitamin D is linked to a higher risk of acute respiratory infections,” says Dr. Marino. “Although there is no current scientific data proving that vitamin D specifically protects against COVID-19, a recent study found a possible association between low vitamin D levels, number of COVID-19 cases and deaths from COVID-19 in multiple European countries. In addition, researchers in the Phillipines found that COVID-19 patients with higher blood vitamin D levels had better clinical outcomes.” Of all the supplements, Dr. Marino recommends vitamin D, since deficiency is quite common, even in healthy adults. In fact it’s estimated that 1 billion people worldwide have low levels of vitamin D in their blood. “Taking Vitamin D daily or weekly has been found to be protective against respiratory infections as opposed to taking the supplement less frequently and researchers recommend taking 2000 IU of Vitamin D per day to support optimal immune function. This recommendation corresponds to Endocrine Society guidelines and is within the daily tolerable upper limit for adults.”

“Vitamin D is harder to get from food, and with the current guidelines urging people to stay inside, it’s also harder to get sun exposure and we need the ultraviolet energy from the sun to make vitamin D,” she says.

Most experts agree that an optimal range of vitamin D in the blood is 30-60ng/ml. “It is possible to take too much of it,” says Dr. Marino. “Vitamin D is fat-soluble, so this means it can be stored and concentrate in our fatty tissue. Too much vitamin D can lead to high levels of calcium in our blood, and can even cause kidney stones. Taking a vitamin D supplement may be a good idea, but there’s no evidence at this time to show it can prevent infection by the coronavirus. If you want to take a vitamin D supplement, Dr. Marino suggests speaking with your physician first and checking blood levels regularly to make sure that the nutrient is in the optimal range.

Stick to Fruits and Veggies

“The biggest problem with supplements is that they are not regulated,” adds Emily Rubin, RD, LDN registered dietician and director of dietetics in the division Gastroenterology and Hepatology at Jefferson Health. “So instead of focusing on supplements, people should be paying attention to their overall diet, especially fruits and vegetables.”

Many are avoiding grocery shopping right now and want to limit their time in stores. “A good rule of thumb is to go straight to the produce section, and choose brightly colored vegetables – tomatoes, broccoli, spinach, peppers, sweet potatoes – these are great sources of vitamin C and polyphenols or antioxidants that are good for overall cellular health,” says Rubin. “But frozen vegetables and fruits are just as healthy, and it’s a good way to get produce that’s not in season. Canned beans and lentils are another great source of vitamins, protein and fiber, I would just recommend getting the low-sodium options.”

“Cooking with garlic and onion is not just a great way to infuse flavor, but they’ve also been shown to have antimicrobial properties,” says Dr. Marino. “That doesn’t mean you should be eating bulbs of garlic a day, but try to incorporate a few cloves into your daily meals.”

What About Those Good Bacteria?

Seventy percent of our immune system is located in our gastrointestinal tract, and the bacteria that live there are critical for the smooth functioning of immune cells. Probiotics are a source of those good bacteria, and another method that has been touted as an boosting immunity.

“There have been some studies showing that probiotics can decrease respiratory tract infections,” says Dr. Marino. “But again, we cannot make that jump to say that probiotic supplementation can prevent coronavirus infection, or reduce the severity of symptoms.”

“I don’t often recommend the average population to take a probiotic supplement, I only suggest it to my patients who may already have GI symptoms” says Rubin. “But if you’re looking for probiotic rich foods, I suggest eating yoghurt, and there are lots of non-dairy options for those who are lactose intolerant. Sauerkraut and kimchi are another good source.”

Sleep On It

When we sleep, our immune systems continue to work, producing proteins called cytokines. Cytokines drive inflammation during infection, and therefore are critical for the immune system to respond effectively to invading germs. Studies have shown that lack of sleep can reduce the production of these cytokines, possibly increasing susceptibility to disease. Last year, a study linked good sleep to the improved function of T-cells, another essential immune player.

“It may sound like common sense, but getting good sleep is critical,” says Rubin. “It’s not just important for immunity, but for overall physical and mental wellbeing.”Lack of sleep can also increase blood-levels of cortisol, “the stress hormone.” Chronic stress and sustained high levels of cortisol have been shown to inhibit immunity. With the chaos and uncertainty surrounding us every day during the pandemic, stress levels are high. Meditation and exercise are both effective in decreasing stress.

“I know people are looking for a ‘magic-bullet’ approach right now to protect themselves against this virus,” says Dr. Marino. “But the best things you can do right now are eat right, sleep well, and be active.”

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COVID-19, Healthy You, Research & Innovation