Foods experimentally shown to significantly improve immunity

With COVID-19, we currently don't have any therapeutics - vaccines or anti-virals are not yet available. Instead we just have techniques such as handwashing and distancing. We do however have our own built in defence system, which can be enhanced simply by the foods and drinks we choose. By strengthening our immune systems in this way, we may just be able to either avoid catching the disease in the first place or lessening its severity if we do.

Related: Researchers have found 13 herbal compounds that may inhibit coronavirus

Mushrooms. A study showed that eating common white button mushrooms for a week boosted levels of IgA by 50%, and levels stayed high for a further week before dropping back. IgA is an important part of our mucosal immunity which is important as our mucosa (mouth, eyes, gut and more) represents our largest exposure to the outside world and is the site for more than 95% of our infections. Watch a 5 min video. Shitake mushrooms can also boost immunity.

Fruits and vegetables. A study of people aged 65+ showed that increasing their intake of fruit and vegetables from 2 to 5 servings a day for 4 months almost doubled their IgG response to a pneumonia bacteria vaccine. Watch a 2 min video. And having more than 5 servings may provide additional protection.

Kale. If you take white blood cells and add a truly tiny amount of kale protein (1 billionth of a gram per liter) then IgG antibody production goes up 400%, with the effect being even greater with cooked kale. That's outside of the body though - what about inside a body? In mice, IgG production was also significantly boosted. Interestingly, the immune stimulating factor was suggested to be Rubisco, a protein involved in photosynthesis. If true, this would suggest that any plant should be immune boosting. Watch a 2 min video.

Wakame. This seaweed, commonly found in seaweed salad, was given to people with various forms of the herpes virus. All patients experiened either a lessening or even disappearance of their symptoms. Wakame was also found to significantly boost the response to an influenza vaccine in those aged 60+ years when taken for a month. Watch a 4 min video

Green tea. Healthcare workers given green tea compounds came down with the flu about 3 times less frequently than the control group. And gargling with green tea may be helpful also. Influenza rates were 7 or 8 times less frequent when green tea was gargled compared to water in elderly residents of a nursing home. In another study, people who drank 6 cups of green tea per day had up to a 15-fold increase in infection-fighting interferon production in as little as 1 week. Intriguingly, there may be a common molecular pattern involved which is shared by some cancer cells and pathogens along with plant products such as tea, apples, mushrooms, and wine. Watch a 4 min video.

Garlic. A double-blind, placebo-controlled trial looked at garlic and colds. Those randomized to garlic had 60% fewer colds, and 70% fewer days affected, suffering only one and a half days of illness instead of five. Watch a 6 min video.

Next nutrition post: What about the fructose in fruit?

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