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Stay In, Stay Healthy: What to Eat to Support Your Immune System PT 2

  • Barbara Depta
Stay In, Stay Healthy: What to Eat to Support Your Immune System PT 2


Monday in Part 1 of staying healthy while staying in, we discussed what nutrients work to support your immune function and covered the following topics:

  • Who should take supplements?
  • Can supplements fight coronavirus?
  • What plants fight inflammation and Infection?

When it comes to the best strategy, the number one thing you’ve got to fix is a nutrient deficiency.

Polyphenols like garlic and elderberry were at the top of the list for front line preventatives to boost your immune system.

If you missed Mondays blog, be sure to click the link to catch up and continue with Part 2 of Stay In, Stay Healthy: What to Eat to Support Your Immune System  


Today, we will dig deeper into what other minerals and supplements are good for a cold or flu and how you take them along with what foods support your immune system. 



How to Use Zinc for Your Immune System The Right Way

There’s no other nutrient with as high a level of research as Zinc. Many studies have shown that it works against seasonal sickness, and the studies that didn’t work help us understand how NOT to take it.

High (but not too high!) levels of zinc for a very specific, short period of time might be the rate limiting step of your immune system’s anti-viral reaction. Too much can hurt your immune system and cause other nutrient deficiencies.

I’ll elaborate so that you understand why you should not supplement with zinc regularly (unless recommended by your healthcare provider) and why you should take the maximum recommended amount right when you feel a sickness coming on.

I’m not one to take a supplement if I don’t need it, but when your body is mounting an initial immune attack, your body is not exactly in a “normal” state. 

When you’re feeling terrible from the flu, you need a ton (literally hundreds of millions!) of a white blood cell called T-lymphocytes to fight off an infection.

Making all these cells requires making a lot of DNA, among other key nutrients like methyl donors and essential building blocks. Your body has most of these in ample supply, but zinc is a different story. 

Your body keeps almost all of your zinc trapped up in other proteins or transport molecules. Zinc is, after all, a charged pro-oxidant (the opposite of an antioxidant), meaning it will damage whatever it touches.

So you’ve got to make more DNA, you’ve got most of the raw materials around, but zinc is the critical key that lets the cogs run smoothly (technically speaking, zinc is the cofactor for zinc-finger proteins). 

Just add zinc, and your immune system can make as many white blood cells as it needs to. At least that’s how one theory goes.

Obviously, this is a simplification, and I’ll be clear, this is only one reason why zinc reduces symptoms of common upper respiratory tract infections. When it comes to 2019-coronavirus, zinc might play a more direct role in interfering with the way the virus gets into your airway cells (Han 2005, Hsu 2004).

This also shows why you’ve got to take zinc at a particular time. Taking it regularly will only help if you are deficient in the first place, whereas supplementing right when your immune system needs it makes sure that you’re not accidentally poisoning yourself.

Supplement with too much, more than 40mg per day for an adult or for too long can lead to:

  1. Poor immune response
  2. Weakness and fatigue from interfering with iron metabolism
  3. Less obvious symptoms of copper and manganese deficiency; you can take a copper supplement along with your zinc if you choose to go with the supplement route.

There’s one more thing to complicate supplementing with zinc for a cold or flu. You can hardly absorb any of it.  The more you take, the more you waste.

How to get around this?

Studies show that zinc acetate may be better absorbed, but my trick is to take lozenges, an under-the-tongue spray, or just suck on a chewable tablet.  It’s not a perfect approach, but it gets the zinc where it can be used by white blood cells: in the blood, around your throat, and not in the toilet.

How do you know you’re taking zinc correctly? If you have a metallic taste in your mouth, that’s a good sign. Here are some tips to getting the right amount at the right time:

  • Get enough zinc in you foods on a regular basis from eating oysters once per week, which conveniently provides other minerals like copper that need to be taken with zinc, or other food sources - cashews, beans, pumpkin seeds, hummus, meat, and other crustaceans - which have much lower levels and must be eaten on a regular basis. 
  • Get higher levels of zinc at the first sign of an infection or after a suspected exposure to an infection, like after being in close proximity to other people where you know something’s going around. Do not take high levels of zinc for a long period of time.

I use these recommendations every flu season, and my experience mirrors what the research suggests.  Getting the right amount of zinc at the right time can potentially knock a cold or flu flat before it takes hold.


Nitric Oxide And Foods

Nitric oxide is a master regulator in your body - it’s essential for life, and especially important for heart, lung, and immune health.

In fact, almost every person at risk for a bad illness, whether that’s with Covid-19 or with the flu, is also likely to have a nitric oxide deficiency. Old age, heart disease, and lung problems in particular are the people with consistently low nitric oxide levels and consistently high rates of bad respiratory infection outcomes.

You can boost nitric oxide levels with a couple of supplements and foods, but none work better than a natural inorganic nitrate supplement. Amino acids L-arginine and L-citrulline might work for some people, beet powder is highly inconsistent, but standardized, certified red spinach extract is hands down the best supplement out there.

If you want to know how to boost nitric oxide with your foods, check out my article on it here.

If you want to stack up different nitric oxide boosting supplements to see which ones come out on top, check out our review here and the background for our rankings here.

  • Nitric oxide is a key part of the immune system’s defense (Bogdan 2001).
  • White blood cells can use N-O to create unstable molecules that damage invading pathogens (Ramachandran 2019).
  • A total of 5 studies in animals and cells show that nitric oxide can directly suppress the SARS-coronavirus from 2003, other coronaviruses, and many other infections (see references below: Liu 2017, Pertile 1996, Keyaerts 2004, Akerström 2007, and Akerström 2009). These studies use pharmaceutical nitric oxide boosters, not natural nitrates.
  • One study in 76 college students, a portion of whom had asthma, showed that daily supplementation with beetroot juice decreased the severity of cold symptoms when they were stressed during finals. Those who had asthma had the greatest benefit (Ritz 2019).

Check out our research review on Everything Health Professionals Should Know about Nitric Oxide and Covid-19 if you want to dive deep. 

I want to make it clear here, though: the link between dietary nitrates, your immune health and covid-19 is just speculation and we have no clinical trials to verify the connection. It’s an attractive hypothesis, but nothing more at the current time. 

Suffice it to say: nitric oxide could be an overlooked link in efforts to fight the 2019-coronavirus. Getting healthy levels of nitric oxide supports your entire body’s health anyway, so try getting more nitrates yourself to see if you feel any difference.

Don’t care to supplement? That’s fine! You can get nitrates from foods.

The best foods for boosting nitric oxide are:

  • Red Spinach (a type of amaranth)
  • Arugula
  • Spinach, the regular kind
  • Bok Choy
  • Rhubarb
  • Beet Juice, although it’s terribly inconsistent!

If you want to know more about how to eat to support your heart health, lung health, and immune system with whole, nitrate-rich foods, check out our article on it here.

Other Vitamins And Supplements That Matter For Immunity

Vitamin C

Vitamin C is required for the immune system to function well. It enhances white blood cell function on multiple levels and also works as an antioxidant in its own right. 

You have to take really high doses (2000mg/day) for it to have any effect at the beginning of a cold, but taking a lower dose on a regular basis might be helpful for preventing a cold in the first place, according to a Cochrane meta-analysis. This effect might be enhanced for athletes and people with very high levels of physical activity.

Read more on the best sources of vitamin C in our blog here.

Vitamin D

Vitamin D is a master regulator, it turns processes on and off throughout your body, from your bones making red blood cells to your thyroid making white (immune) blood cells. 

There is limited evidence in animals and cells that vitamin D could promote the 2019-Coronavirus via the ACE2 receptor - I’ll leave it to the scientists to figure out the details of that.

But if you’re an American who doesn’t take a vitamin supplement, chances are more than 9 out of 10 that you aren't getting enough of this critically important vitamin. Even for those who supplement, more than 60% aren’t getting enough.

A vitamin D deficiency absolutely impairs immunity, whereas supplementing in excess might possibly increase covid-19 risk. If you’re deficient, or your healthcare provider recommends it, keep taking your vitamin D3 supplement. Learn how to get it in food in our blog post here.


Selenium is one of the key nutrients for your anti-inflammatory system. Selenium is packaged into specialized proteins that help keep your glutathione - the so-called master antioxidant - functioning properly. 

Read more about selenium and why supporting your antioxidant system - not just getting eating antioxidants - is important for fighting oxidation and inflammation here.

There are a number of other ways to raise your glutathione besides getting selenium. Exercise is arguably the best, but eating a generally healthy diet can work too. If you want to learn more about the benefits of having great glutathione, click here.


Omega-3’s also have effects throughout the body, from keeping your arteries healthy to plugging directly into the inflammatory cascade. They are pretty lacking in the Standard American Diet and they get out-competed by Omega-6’s, tilting the balance of your body towards inflammation. 

For example, one study showed that supplementing with the equivalent of 1 teaspoon of targeted fish oils reduced how often schoolchildren got sick from a cold or flu and how bad that sickness got.

Certain Omega-3’s are also prescribed as a prescription drug to lower triglycerides. So if you’re a person who has a wide waistline or at a higher risk for complications, a fish oil supplement is particularly attractive.


Lastly we’ll mention ginseng. Though commonly known as an anti-fatigue and cognitive enhancing drug, it may also have a place in preventing common respiratory infections.

One meta-analysis of studies showed that those supplementing regularly lowered their risk of getting a cold by 25% and two studies showed that colds were 6 days shorter in those taking the supplement. A 6-day-shorter cold sounds like the kind of illness I want to have!

Bottom Line

  • To prevent an illness, and to lower your risk of getting a bad infection, first make sure you don’t have any nutrient deficiencies
  • Get your nutrients from whole foods
  • Supplements have no research to fight Covid-19, but specific nutrients from foods or supplements can help you live a healthier life when taken properly
  • Pay attention to specific foods, nutrients, supplements, which ones to take, and how you take them to get the maximum effect.

The research shows that the following supplements and nutrients will impact a cold, flu, or other illness the most. The benefit is that these also have a positive effect on fighting inflammation on a systemic level and have a low risk for side effects. In any case, talk to your healthcare provider before starting or stopping any supplemental regimen.

  • Garlic
  • Elderberry
  • Zinc
  • Vitamin C
  • Vitamin D
  • Omega-3’s / Fish oil

Wellness is not just how you feel, it’s how you interact with the world, especially in difficult times. In the face of adversity, it can be easy to slip away from your healthy habits, but now it’s more important than ever to have something you can rely on. And, if you’ve been looking for an opportunity to start some healthy habits, there’s no better time than now!

We want to hear from you!

We’ll be covering all these topics and more, but that’s just scratching our own itch. What do you want to know?

Want to say something? Leave a comment or question below and we’ll get back to you! Subscribe to our feed and don’t miss our best content

Want to learn more about a topic? Let us know by contacting us or getting in touch on social media!

While some media is trying to drive revenue through clickbait and fake news, we make sure to back up our claims with hard data and a sensible perspective. We believe that when you have the right information, you’re empowered to make the best decision for yourself. That’s why we break down complex science into practical takeaways you can use today. 

Wishing you the best in your health and your safety,

The Resync Team



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