Sales of supplements to fight flu and colds topped $13.85 billion in 2019. While the evidence is limited on the effectiveness of many of these supplements, there are some studies pointing to the benefits of certain vitamins and supplements in fighting colds and flu .
According to USA Today, zinc, vitamin C, and vitamin D are the most researched of the immunity-boosting supplements. Dr. Michael Daignault, an emergency room physician in Los Angeles says that zinc is critical for the development and function of many immune system cells. The mineral is easily obtained from diet and is found in meat, eggs, nuts, and seeds. Although no studies confirmed that zinc prevents COVID-19, sales of zinc supplements skyrocketed to an estimated $134 million during the pandemic, since many experts believe that zinc deficiency can lower your immune response, says The New York Times.
“It’s very clear. If you are zinc deficient, your immune system will not function as well,” said Dr. David Hafler, a world-renowned expert on multiple sclerosis and chair of the department of neurology and professor of immunology at Yale School of Medicine. If you choose to take a zinc supplement, the upper limit for adults is 40 mg daily, says the NYT, adding that adverse effects of zinc include nausea, vomiting, loss of appetite, diarrhea, headaches, and abdominal cramps. Zinc can also interact with other supplements, such as calcium, so it is advisable to take them two hours apart.
Daignault says that vitamin C is perhaps the best known and marketed immune supplement. “Like zinc, vitamin C plays a key role in immune system function,” he told USA Today. But evidence shows that there is no benefit in taking massive doses of vitamin C is you catch a cold. The true benefits only come if you take it as a preventive measure. You should be able to derive enough vitamin C from sweet potatoes, red peppers, broccoli, and citrus fruit. A 500 mg dose is sufficient for most adults who prefer to supplement.
Taking vitamin D may reduce the rate of upper respiratory tract infections, says research. “The majority of the vitamin D we need is synthesized in the skin by UVB rays of the sun,” noted Daignault, adding that most of us do not get enough sunlight exposure to obtain optimum levels of this vitamin. While vitamin D can be found in fish, eggs and fortified dairy products, he suggests supplementation of 1,000 IU to 2,000 IU daily.
Echinacea and elderberry supplements may also be useful to ward off colds and flu. A study published in the Journal of Functional Foods says that elderberry extract is an effective way to block viruses from entering and attaching to healthy cells. Researchers applied a serum made from elderberries directly onto cells before, during, and even after they had been infected with the influenza virus.
“We found that the serum had a direct antiviral effect against the flu virus,” said lead researcher, Dr. Golnoosh Torabian. You can buy Sambucol black elderberry extract in many forms, from juice drinks to gummies. Echinacea, a well-respected and researched herb, is an immune stimulant that increases the activity of white blood cells.
Garlic has been used for centuries as food and as medicine, according to Healthline. It enhances the immune system by boosting the disease-fighting response of white blood cells thanks to its sulfur compounds. Studies show that garlic not only reduces the length and symptoms of illness, it can also prevent you from getting sick in the first place. One study found that research participants who took garlic regularly had a 63% lower risk of getting a cold, and their colds were 70% shorter. Garlic supplements, such as Aged Garlic Extract or AGE, retain the medicinal benefits of raw or cooked garlic against colds and flu.
Daignault says that while you can get most of your immune-boosting vitamins from a diverse diet that includes fatty fish, meat, vegetables and fruit, people who don’t get enough sunshine and are deficient in vitamin D should consider supplementation. Sucking on zinc acetate lozenges may reduce the length of your cold.
“And remember, keeping up to date with your vaccinations, staying hydrated getting good sleep, practicing stress control and exercising daily should be the foundation of your immune system,” he told USA Today.
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