Here's what you need to know about fighting off COVID-19: Nothing but your immune system can beat this disease. And to have a stronger immune response to the invaders (virus particles that enter your lungs, blood cells, and organs and wreak havoc and cause inflammation) you need to eat a diet high in plant-based foods. Doctors have begun recommending to patients that they switch to a mostly plant-based diet, especially those in the highest risk groups: Overweight, diabetic, over 60, and male. One doctor urges his patients to eat mostly fruit and vegetables and stay away from inflammation-causing meat, dairy, and processed food, in light of COVID-19.

Talking to doctors and nutritionists about COVID-19 and how to best have the healthiest outcome, that allows you to suffer the least symptoms or side effects: Your immune system's response is the only thing that can fight the disease. All other therapies (such as those that President Trump is getting) are in support of your immune system. If your system is weak or overtaxed with other existing conditions, including obesity or diabetes, it can over-react, creating the "cytokine storm" of inflammation that leads to a cascade of complications that make it harder for your body to self-regulate as it attempts to create antibodies to the virus (essentially molecules that recognize the virus invaders and deploy through the bloodstream to neutralize them)

Immunity is built when your body has to fight off everything from everyday aging to infections. And the building blocks of your immunity are helped by the micronutrients in your food, such as antioxidants and vitamins and minerals, and nothing delivers those better than fruits and vegetables, legumes and nuts and seeds. The flip side is also true, that studies show a diet high in red meat and processed foods can cause inflammation, and in the case of COVID-19, inflammation is the enemy. Patients who do the worst when confronted with this virus are those who are overweight, have chronic inflammation, high blood pressure or are otherwise immune-compromised. Doctors treating President Trump should have him switch from his usual fare to a mostly plant-based diet today, consisting of fruits and vegetables high in compounds that have been scientifically proven to build immunity, to help his natural defenses mount their counter-attack on the viral invaders.

We saw President Trump speaking from his hospital suite yesterday looking a little piqued by otherwise fine. That is reassuring. But the second phase of COVID-19 is when the immune system kicks in and has to fight off the virus, for best results.

Here are the foods that are shown to fight inflammation and boost immunity. Eat them now for a stronger immune system, whether you are dealing with COVID-19 or another potential disease that requires your body to be healthier now and later. That includes almost every disease known to man. To be healthier, meaning to build cells that are able to function without bombardment from toxins, oxidization, infection, and internal destruction, plant-based foods are your best bet.

13 Immune-Boosting Foods to Eat On Repeat

These foods are known to supercharge your immune system, which is your body's defense against infection and illness. It works by recognizing cells that make up your body and will fight off anything unfamiliar. It destroys germs (bacteria and viruses) and parasites. Eat these to bolster your white blood cells and the supporting teams that keep them ready for battle. Healthline compiled the list and The Beet added even more research to bolster the facts.

Citrus fruits
Getty Images

1. Citrus for Your Cells and Healing

Your body does not produce vitamin C, which means you need to get it daily to have enough to create healthy collagen (the building blocks for your skin and healing). Also known as ascorbic acid, vitamin C is a water-soluble nutrient found in leafy greens and citrus, especially grapefruit, oranges, tangerines, lemons, limes, and clementines. It acts as an antioxidant, protecting cells from damage caused by free radicals.

How much do you need a day: The recommended daily amount to shoot for is 65 to 90 milligrams a day, which is the equivalent of one small glass of orange juice or eating a whole grapefruit. Almost all citrus fruits are high in vitamin C. With such a variety to choose from, it's easy to get your fill.

Red bell pepper on chopping board, chopping
Getty Images/Westend61

2. Red Peppers to Pump Up Skin and Boost Immunity with Twice the Amount of Vitamin C as an Orange Has

Want even more vitamin C, add red bell peppers to your salad or pasta sauce. One medium-sized red bell pepper contains 152 milligrams of vitamin C, or enough to fulfill your RDA.
Peppers are also a great source of beta carotene, a precursor of vitamin A (retinol). Vitamin A is important for healthy skin, your mucous membranes and your immune system. Beta carotene helps keep your eyes and skin healthy, as well. One cooked pepper has 19 percent of your daily recommended amount of beta carotene.
How much beta carotene do you need a day: You should try to get 75 to 180 micrograms a day which is the equivalent of one medium bell pepper a day. But a red pepper has more than two and a half times your RDA for vitamin C so eat them all winter long.
Broccoli in an old metal colander
Getty Images 

Broccoli may be the most super of superfoods on the planet. It's rich in vitamins A and C as well as E. The phytochemicals in it are great for arming and strengthening your immune system.

Broccoli is a good source of lutein, a powerful antioxidant, and sulforaphane, another potent antioxidant. It contains additional nutrients, including some magnesium, phosphorus, zinc, and iron.  The key to keeping its powerful nutrients intact and ready for helping the body's immune response is to cook it as little as possible — or even eat it raw.

Lutein is one of 600 known naturally occurring carotenoids and is found in high quantities in green leafy veggies such as spinach and kale.

There's another thing you need to know about broccoli, and why it's important to not overcook it. Broccoli contains sulforaphane, a gas that is a killer to a bug in the garden–and in the body. Sulforaphane is a sulfur-rich compound found in several cruciferous vegetables like bok choy, cabbage, and kale, but broccoli delivers the most. When a bug bites into the stalk, leaf, or flowering bud of the plant it releases this sulfuric gas that kills the invaders, thereby protecting the plant. This is the same agent that gives broccoli that sulfuric smell when you cook it, so don't overcook it since you'd rather all of that end up in your body than in the kitchen air. Cook it too much and the gas escapes into your kitchen, so if you want to keep it in the plant, and delivered to your body, lightly steam the green and add it to your meal barely cooked through.

How much lutein should you eat in a day: There is no RDA for lutein, but experts say get at least 6 milligrams.

Directly Above Shot Of Garlic On Marble
Getty Images/EyeEm

4. Garlic, Eaten By the Clove

Garlic isn't just a great flavor-enhancer, it's essential for your health. Ancient humans valued garlic as an infection fighter, which is why so much of our traditional diets include it as a first ingredient (making pasta sauce for instance). Value it and use it liberally for fighting infections.
Garlic’s immune-boosting properties are tied to its sulfur-containing compounds, such as allicin. Allicin is thought to improve your immune cells' ability to fight off colds and flu, and viruses of all kinds. (Smelling more garlic on the subway? It could be smart coronavirus management.) Garlic also has anti-microbial and anti-viral properties thought to fight off infections.
How much should you eat in a day: The optimal amount of garlic to eat is more than most of us can fathom: Two to three cloves a day. While that may not be doable, realistically, some people take garlic supplements to get 300-mg dried garlic in a powdered tablet.
Close-Up Of Ginger On Wooden Table
Getty Images/EyeEm

5. Ginger is a Power Player for Immunity and Digestion

Ginger is another ingredient that has super properties when it comes to fighting off illness. It has been shown to decrease inflammation, which can help if you get swollen glands or a sore throat or any inflammatory ailment.

Gingerol, the main bioactive compound in ginger, is a relative of capsaicin, can be used in sweet or spicy dishes. It has been found to alleviate pain and fight nausea, which is the reason ginger ale was given for upset stomachs, back when it contained actual ginger. Now few store-bought formulations do. Make your own ginger tea. Gingerol is responsible for much of its medicinal properties. It has powerful anti-inflammatory and antioxidant benefits.

How much should you eat a day: Most recommendations land on 3–4 grams of ginger extract a day, or up to four cups of ginger tea, but no more than 1 gram a day if you are pregnant. Some studies have linked high dosages to an increased risk of miscarriage.

Freshly Washed Organic Spinach in a Metal Bowl
Getty Images/iStockphoto

6. Spinach, Wilted, Not Steamed (Also Kale and Dark Leafy Greens of All Kinds)

Spinach is not only packed with vitamin C but also antioxidants and beta carotene, both of which give your immune system the healthy boost it needs to fight off invaders.

Don't overcook your spinach, since the more it's cooked the less active the antioxidants will be. If you eat it raw or lightly steamed you'll keep more of the nutrients intact.

How much should you eat a day: Aim for 1 cup fresh spinach or 1/2 cup cooked per day, but this is the right moment to try the raw or slightly wilted approach. Order warm or wilted spinach salad when you go out, or make it yourself with olive oil, pine nuts, and vegan parm.

Almonds
Getty Images

7.  Almonds for the Win, Pop Them Like Candy

Vitamin E in almonds will help ward off colds and flu and is key to your immune system humming along. It’s a fat-soluble molecule, meaning it requires the presence of fat to be absorbed, so nuts are the perfect package for E to make it into your system.

How much should you eat in a day:  A half-cup serving, or 46 whole, shelled almonds, provides almost 100 percent of your RDA of vitamin E. Almonds are great for you but they don't come with a  "free" pass, since 1/4 cup is a serving and has 162 calories, so double that for your RDA and you're eating about 325 calories. Throw them into smoothies instead.

Curcuma powder on tea spoon, close-up
Getty Images/Westend61

8. Turmeric to Fight Inflammation, Put it In Your Tea or Smoothie

If you ever feel healthier for eating curry, it is probably because of the Tumeric, which is an ingredient that gives it its burnt orange color. But this highly pigmented spice is known for its anti-inflammatory qualities. The ingredient curcumin has been found to decrease muscle soreness after a hard workout. How it helps immunity? decrease exercise-induced muscle damage.

Tumeric bolsters the immune system by stimulating antibody formation and people with auto-immune diseases are told by their doctors to take 500 mg of curcumin daily to reduce inflammation and stave off soreness.

How much should you eat in a day: Try adding extra Tumeric to your diet during periods of stress or during flu season. Or take 500-2,000 mg of curcumin to help fight inflammation and power up your immune system.

Getty Images/EyeEm
Getty Images/EyeEm

9. Green Tea by the Gallon, Skip the Coffee and Sip this Instead

Whether you prefer green tea or black tea, you will benefit from the compounds called flavonoids, powerful antioxidants. Green tea has high levels of EGCG, (epigallocatechin gallate) another hard-working antioxidant.

EGCG is known to boost immune function, and originally all tea leaves contain this anti-oxidant, but when black tea is fermented it deactivates most of the EGCG. Green tea is steamed so the EGCG is still active when you drink it.

Green tea also contains L-theanine, an anti-oxidant which appears to help in the production of T-cells in your body, the killer  L-theanine may aid in the production of germ-fighting compounds in your T-cells.

How much green tea should you drink in a day: The optimal amount is three to five cups in a day, but most people won't get to that level. Any amount is better than nothing. Swap out a usual beverage daily for green tea could improve your health.

Fresh papaya exotic tropical fruit on pink background. Sun day light illumination. Minimalistic summer flat lay wallpaper. Creative food concept. Copy space template.
Getty Images/iStockphoto

10. Papaya, The Tropical Healer to Keep You Vacation-Healthy All Year Round

Papaya delivers over twice your recommended daily amount of vitamin C in one fruit -- though you're likely to eat a few slices on a salad or in a smoothie. It also contains an enzyme called papain that has anti-inflammatory effects -- and inflammation is one factor in most illnesses, so avoiding it can help your body fight off bacterial infections like sinusitis.

Papayas contain potassium, vitamin B, and folate, which is a powerful cell rebuilder. Exactly how folic acid works to build immunity is linked to its role in protein synthesis, and researchers think that any mechanism in which cells proliferate can be affected (which is why it's critical for pregnant women). People who are folate-deficient have compromised immune systems.

How much folate should you eat a day: Whether you are pregnant or not, folate (vitamin B9) is a great vitamin to keep your cells healthy and strong. The recommendation is 400 micrograms a day, or get it from legumes, spinach, papayas, and avocados.
Full Frame Shot Of Kiwi Slices
Getty Images/EyeEm

11. Kiwis, a Vitamin Powerhouse

When you think of anti-oxidants, you should think of fruits that grow in the sun, since their vitamin pack comes from having to fight off the oxidation of the strong rays that beat down on them in the tropics. Kiwis are a great example. They are full of folate, vitamin K, vitamin C, and potassium.

These vitamins in combination work in the body to build healthy cells, fight infection and keep your immune system humming along. Vitamin K deficiency is rare but when people don't have enough they suffer from weak bones and compromised immune systems. The inflammation system in the body is also dependent on vitamin K, especially your killer T cells that mobilize and fight cancer and other diseases.

How much should you eat in a day: Vitamin K is one of the unsung heroes of the body. Women should get 90 micrograms a day, and men should have 120 micrograms.

Bowl of sunflower seeds
Getty Images

12. Sunflower seeds to sprinkle on salads or eat by themselves

Most seeds are chock-o-block with nutrients since they give the plant its healthy start. But sunflower seeds are especially healthy since they provide phosphorus, magnesium and vitamin B-6 as well as vitamin E. Your immune system needs vitamin E to function at full throttle. You can also get vitamin E from avocados and spinach and broccoli.

How much should you eat in a day: Anywhere from 1 ounce (30 grams) per day to a healthy handful is considered healthy, but because they are high in sodium you might want to refrain from eating the entire bag. The raw seeds have 204 calories per quarter cup.

Miso soup, silken tofu, wakame seaweed, spring onion
Getty Images/Westend61

13. Miso, Soup or Paste to Add to Your Soups and Salad Dressings

You've had miso soup at your favorite Japanese restaurant and perhaps even thought: "This tastes incredibly healthy! If a bit salty." Both thoughts are true. Miso is a fermented paste that adds a salty umami flavor to many Japanese dishes and soup. Most miso is made in Japan, where the ingredient has been used since the eighth century.

Miso needs no preparation and adds a touch of saltiness to soups, marinades, and dressings. Some people credit miso as a factor in Japanese longevity. Japan has more centenarians per capita of the population than anywhere else in the world – and Japan has one of the lowest rates of obesity.

The nutrients in miso -- which is a soybean paste that has been fermented with salt and a koji starter -- boosts immune system function by delivering healthy probiotics to the gut, making your microbiome healthier. How does Miso benefit your immune system?  It is a "sirt" food, which are foods that contain high levels of ‘sirtuins’ or proteins that regulate cells and activate metabolism. A diet high in sirts is believed to lead to weight loss, increased wellness and longevity.

How much should you eat in a day?

Researchers believe that consuming one bowl of miso soup per day, as is the tradition in Japan, lowers the risks of breast cancer. Other than its high sodium content there is no reason to stay away from miso with all its varied health benefits. We say cheers to that.