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Why it’s NOT enough to boost your immune system against the flu or coronavirus

Right now, in the midst of the coronavirus crisis, I have seen lots of content online with tips about how to boost your immune system to help prevent you from getting sick. I have LOTS of thoughts about this, which I’ll go into in this post. And at the bottom, I share the reality of how to help protect yourself and others from the coronavirus. I also shared why you should care, even if you’re young, healthy and unlikely to have complications.

I also consulted multiple doctors and a registered dietitian to weigh in on whether or not you can boost your immune system, the impact of supplements, who is at risk, and what actually helps prevent spreading coronavirus.

If you love anyone besides yourself, please read this post and share with others who are not following the guidelines from the CDC. And if you are not changing your behavior and helping to educate others on how to change their behavior, you are part of the problem in our country right now.

How to Boost Your Immune System Against the Flu

Let’s get something straight: “boosting” your immune system doesn’t really work during cold and flu season or anytime of the year. That’s not the way the immune system functions. As Harvard states, “there are no scientifically proven direct links between lifestyle and enhanced immune function.” The most important thing you can do is to have a healthy lifestyle, day in, day out, for weeks, months and years. You can’t quick fix yourself into becoming immune to the flu or coronavirus.

Many products or people selling products claim they can boost or strengthen your immune system. “But the concept of boosting immunity actually makes little sense scientifically.” In fact, boosting the number of cells in your body — whether that’s boosting immune cells or others — is not always a good thing. (Source)

So, what does a healthy lifestyle look like?

Don’t smoke and limit alcohol.

Smoking increases your susceptibility to infections, including pneumonia and influenza, since the 7000+ chemicals in cigarette smoke interfere with your immune system. Per the CDC, “Smoking harms your immune system and can make the body less successful at fighting disease.” Take every effort to reduce and stop smoking. And not just because of the flu – you’re more vulnerable to many diseases as a smoker.

Eat lots of fruits and veggies.

While studies about nutrition and immune function are limited, there is some evidence that being deficient in certain nutrients can alter immune response. Harvard outlines those key nutrients as zinc, selenium, iron, copper, folic acid and vitamins A, B6, C and E. (Source) The British Dietetics Association also recommends eating a balanced diet, making sure you include copper, folate, iron, selenium, zinc, Vitamin A, B6, B12, C and D.

So, if you eat a healthy diet with fruits and vegetables, you’re less likely to be deficient in those. More on diet and specific foods below.

Maintain a healthy weight. Lose or gain weight if necessary.

Being overweight or severely underweight impacts your immune system since it inhibits proper function. Work with your doctor to find a healthy weight for you. Calculating your BMI is a good guide, but it does leave out important factors like muscle and body composition. NOTE: You’re more vulnerable to COVID-19 if your BMI is over 40.

Get 7-9 hours of a sleep a night.

Lack of sleep can impact your immune system, according to the Mayo Clinic. Too little sleep can increase your risk of getting sick when you’re exposed to a virus, whether it’s the common cold or the seasonal flu. It can also impact your ability to recover. So, if not sleeping enough impacts your ability to fight well-studied viruses, we can assume it will also impact the ability to fight off or recover from the coronavirus.

Reduce stress.

Stress causes your body to make more of the stress hormone cortisol. In short doses, cortisol reduces inflammation which in turn helps your immunity. But, chronic stress leads to too much cortisol in your bloodstream that leads to more inflammation.  Chronic stress also decreases the number of white blood cells you have, and those are directly related to your body’s natural ability to fight an infection. So, the fewer white blood cells you have (which happens with too much stress), the higher your risk for viruses. (Source)

Reducing stress is HARD. I get that. But even small efforts truly do help. You can read how I manage stress and anxiety here.

Exercise regularly.

There isn’t a direct link between exercise and immunity (yet – it’s still being studied), but we do know that exercising helps decrease stress, which over time helps decrease cortisol. But, overexercising will lead your body to a chronically stressed state, which causes its own issues, as we just discussed.

Limit alcohol

Charlie Watson, RD, shared that it’s important to have two completely alcohol-free days per week.

And remember, all of these things are habits that need to be just that – habits. The cumulative effect of these simple things is so powerful — over time. Remember, nothing can fix poor health overnight.

So what about immune boosting diets?

Foods that Boost the Immune System

There is simply not enough evidence to prove that foods can have a direct impact on your immune system in the short-term. But consistent intake of the following foods will help you maintain a strong immune system here. Are you seeing the theme these? NOTHING WILL QUICK FIX YOU INTO IMMUNITY.

I spoke with a Registered Dietician, Charlie Watson, about what food can and cannot do for your immune system. Eating the right foods can help decrease inflammation, which can then in turn help your immune system work better. But again, these are things you need to be eating regularly. You can’t megadose on any of these in the short term and expect to alter one of your body’s most complicated systems.

Citrus Fruits

Fruits like oranges and lemons are high in vitamins C and E. These antioxidants help destroy free radicals, which in turn supports the body’s immune system. Bell peppers, brussels sprouts, and strawberries are also high in Vitamin C.

Dark Chocolate

Dark chocolate — and I mean truly dark, like 70% or higher – has anti-inflammation properties from flavonoids contains (contained or found) in cocoa. (Source)

Oily Fish

Fish like salmon, anchovies, sardines and trout are high in long-chain omega-3 fatty acids that may have an anti-inflammatory effect. However, supplementing with fish oil doesn’t have proof of long-term effects on inflammation. So, it’s better to eat oily fish in moderation than supplement.

Green Tea

Green tea is high in antioxidants called catechins, which help decrease inflammation. Additionally, the antioxidants in green tea may help fight cancer, fungus and viruses. (Source)

Green leafy vegetables

Greens are high in beta-carotene (as are carrots and sweet potatoes), which is an antioxidant that reduces inflammation.

Nuts, Seeds, Beans and Lentils

These are all high in zinc, which can help boost white blood cells (and we discussed above why those are important!).

How to Boost Your Immune System Against the Flu | Rainbow chickpea salad

For more advice, check out this resource from the U.S. Academy of Nutrition and Dietetics on how to eat right during the coronavirus.

Anything food to avoid?

Yes, in certain cases, Charlie Watson, R.D., shares. “When patients are extremely immunocompromised (e.g. going through chemo and their white blood cells are low), I recommend a neutropeonic diet, which involves advice like avoiding pate, shellfish, raw meats and fish, no runny yolks for eggs, unpasteurised dairy, raw nuts, honey. Avoid anything with a higher risk of making you sick – similar to pregnancy advice!” (More info here.)

What about supplements?

You can’t rely on supplements to fix a crappy diet and you shouldn’t take extremely high doses of any supplement in an attempt to have a healthy immune system. It simply doesn’t work that way. So again, these are foods you need to be eating all the time so you are less susceptible to any illness, whether it’s a common cold, the seasonal flu, and perhaps coronavirus. A healthy diet, consistently and long-term, will help you stay healthy for day to day living and to help prevent complications if you do get a virus.

Charlie Watson emphasized, “Untested supplements and herbal remedies could actually lead to health problems and could be potentially dangerous.”

Diet & immune systems

Anna Paulsson, MD, is a radiation oncologist and works with patients who are immunocompromised. Here’s what she had to say about immune-boosting foods: I agree with what Teri has outlined in this post, but I want to emphasize that no food, group of foods or supplement will “boost your immune system” in the short term.”

She also warned, “Be very wary of those marketing supplements and foods as a way to prevent or cure infection, as those are likely companies or individuals who profit if you purchase their product. Over the long term, diet can have a profound impact on your health, but will not prevent infection with COVID-19 (or any infectious pathogen for that matter).  If you are immunocompromised, there are certain foods (many fresh fruits and vegetables) you should avoid as directed by your doctor. If you have questions about if you should be avoiding certain foods, please ask your doctor for more information.”

And, another tip: stop reading too much advice from too many unqualified “experts.” Follow the CDC, World Health Organization (WHO), National Institute of Health (NIH) and other reputable sources for guidance.

What actually works to help prevent the spread of the coronavirus

A friend of mine said, “This current surge has not much to do at all with people’s individual behavior (personal choices about diet, exercise, smoking), but rather the collective behavior as a society.” Meaning, while our individual efforts are important in maintaining our personal health, the surge we’re seeing right now has much more to do with our community.

While the information about COVID is still changing, it does seem that those who are immunocompromised – those over 60 years old, those undergoing cancer treatments, pregnant women, for example – are more likely to have serious complications from COVID-19.  Other at-risk groups includes those with diabetes, celiac disease (unless you’ve had your spleen checked/tested), Chronic kidney disease, chronic liver disease, Parkinsons, MS, MND, cerebral palsy, those going through Chemo or steroid treatment, and those with heart disease and any respiratory issues. And you’re more vulnerable to COVID-19 if your BMI is over 40.

We do know the coronavirus is extremely contagious and you can get the virus, no matter how healthy or strong your immune system is. The presentation and severity of the symptoms seems to vary based on the immune health of patients and their ability to fight infections. But again, they are also seeing very healthy, young adults having serious complications from COVID-19.

So, if you can’t really boost your immune system to prevent you from getting it or from preventing complications since you can’t citrus-fruit away an underlying health issue that makes you immunocompromised, what SHOULD you do? FOLLOW THE ADVICE FROM THE CDC. This website is updated regularly.

The Center for Disease Control (CDC) is filled with EXPERTS in disease.

They have extensive education and training in their field. Years of experience. Data. Studies. Pay attention to what they tell you. This is not a virus that can be solved with immune-boosting foods, supplements, or essential oils.

Erin Carter, MD, is a specialist in internal medicine and rheumatology who specializes in the treatment of those with autoimmune diseases. She stated that if “If you do get the virus, it is also recommended that you avoid anti-inflammatory medications like ibuprofen, naproxen, and aspirin as these types of medications can potentially make the virus worse.”

What do serious complications look like?

Difficulty breathing. Persistent pain or pressure in the chest. New confusion. Bluish lips or face. These are all emergency warning signs.

Other symptoms that will may develop first are fever cough and shortness of breath. (Here’s what to do if you are sick. Do NOT immediately go to the emergency room unless you have emergency symptoms.)

Serious complications also include respiratory failure. Respiratory failure means a breathing tube and potentially a prolonged hospitalization in the intensive care unit. Many people, especially older people, will not fully recover from this type of hospitalization and can potentially die.

Another rare complication of COVID-19, Dr. Carter shared, that can cause the virus to become deadly is something called cytokine storm. This is basically an over-activation of the immune system, otherwise known as hyperinflammation, and is one of the ways that the virus can become deadly in otherwise healthy and young people.


This cannot be understated. When you touch a surface that has the virus on it (and remember, the virus can live on surfaces for 4-14 days) and then touch your face (eyes, mouth, nose), you can infect yourself and not even know it. So, wash your hands before every meal, even if you’re at home all day. Wash your hands after you’ve been in a public space, for at least 20 seconds. (Look at your watch – 20 seconds is much longer than you think.) And until you’ve washed your hands, avoid touching your eyes, nose and mouth.

Yes, antibacterial wipes and gels are helpful when you aren’t in a position to wash your hands at a sink, but they are a second line of defense. Hand washing is the most important thing you can do to remove the virus from your body before getting infected. If you do use hand sanitizer, make sure it contains at least 60% alcohol.


The BEST way to prevent illness is to avoid being exposed to the coronavirus in the first place. The virus is mainly spread person-to-person. So if you’re within six feet of someone at a restaurant table, on a run, at a bar, at your office, you can pass the virus on to others. Respiratory droplets when someone sneezes or coughs near you can also spread it, so keep your distance from others when you’re’ outside, at the store, etc. This is especially important for people who are at higher risk of getting very sick from coronavirus.

And, remember, many times people carry the virus but do not have symptoms. They go out and pass it to others, unknowingly, and for others, it can be extremely serious and life-threatening. It’s truly a selfish behavior to think that you don’t need to follow the advice to stay home and avoid unnecessary interactions just because you feel fine.

This is going to be our most impactful effort against this virus.

How do you avoid contact with others?

Avoid unnecessary shopping trips, be extremely careful in restaurants, don’t go to bars, take precautions at the gym or just workout outside. MANY businesses are closing early, or are even closed for a period now, whether by making a responsible choice or government mandate. If that’s not happening in your community, it’s up to you to make the responsible decision. Yes, small businesses are being impacted. (I plan to address this in another post.) But the health and literal survival of so many people in our nation is also at risk of being severely impacted.

Staying home means cancelling all non-essential travel. Let’s define essential since lots of people think this is a great time to purchase a really cheap flight. Essential: absolutely necessary; extremely important. If your travel is not absolutely necessary and extremely important, CANCEL IT.

If you do venture out for recreation, which is still currently allowed in the U.S. in most areas, PLEASE still keep six feet between you and anyone else. If you want to continue to enjoy your outdoor areas, even during the time of physical and social distancing, plan to go at an off-hour, be diligent about keeping space from others and if it’s too crowded, go home. When I run or walk, I cross the street when I encounter others. And some do the same thing. But if they don’t, do you part and keep your distance.


Wipe down frequently touched surfaces daily, including tables, doorknobs, light switches, countertops, desks, phones, keyboards, sinks, etc. Even if you are staying home from work, anytime you leave the house or bring something in your house and then touch something inside your house, you increase your risk of exposure. And, if you’re still in an office setting, there are likely more people touching things, which could then pass it to you. And god forbid someone walks by your desks and coughs or sneezes when you aren’t there, but it can easily happen. So wipe your stuff down when you get into the office.

Why should you care about the coronavirus if you’re healthy and are less likely to have complications?

To simply be a good human.

It’s incredibly selfish to think “Well, if I get it, I won’t get that sick. You may be healthy and sure, the virus may not impact you all that much, but given how incredibly contagious it is, you could easily pass it to someone who is immune compromised and it could lead to very severe complications for them.

“Thus far there are no specific treatments for COVID-19, other than supportive measures and treatment of its complications. This is why preventing mass spread of this virus is of utmost importance. I cannot emphasize how important practicing social distancing is. You truly will save lives if you stay at home as much as you can during this time” says Dr. Carter. *This quote was said prior to the vaccine being released.

To protect your parents. To protect your grandparents

You could easily pass the virus to your parents and/or grandparents and for them, it can be deadly. The fatality estimates for anyone 80+ who is exposed to the virus is 8-9 percent.

Anyone over 60 should stay home unless it’s essential to leave the house and they should not have visitors, including grandchildren. People can carry the virus without any symptoms and pass it to someone without even knowing. So does 7-year-old Sally who just played on a playground (and why is she not staying inside anyway) really need to go see Granddad? Not unless she wants to risk saying goodbye to Granddad unnecessarily soon. Dramatic? No, not really. This is the reality we are in.

To protect our healthcare system

The seasonal flu hospitalizes 1-2% of people who get it. Coronavirus hospitalizes 10-15% of cases. The U.S. has about 924,100 hospital beds, 46,000-64,000 ICU beds and 51,000 specialized ICU bed. (source) So, best case, we’re looking at 1.04 million beds — if they all happened to be empty, which they’re not. A moderate pandemic would mean 1 million people are hospitalized. A severe pandemic would be 9.6 million hospitalizations. You do the math. There are simply not enough beds in the hospital to accommodate the potential number of patients needing treatment.

By these projections, there is also a shortage in ventilators (necessary to help those with respiratory failure, see above serious complication of COVID-19) and there is already a shortage in medical supplies. A shortage in medical supplies means doctors can’t protect themselves, which means they get the virus, which limits the number of doctors able to treat patients. Physicians will be forced to ration care and choose which patients to save.

No one knows just how bad this will get. But, but all of the data shows that it’s not going to get any better any time soon.

Want to educate yourself more on the reality of the situation? I highly recommend these reads:



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  • Reply
    Emily Wakefield

    *praise hands*
    Thank you for sharing this! I am an ICU nurse at a large academic center caring for COVID 19+ patients and I love the advice provided in this post. This is one of the few articles not directly from the CDC or WHO that is factually correct; it summarizes everything concisely and in a way that is easily understandable! We have been working so hard to get prepared to care for these patients, and to prepare for the large influx of new patients to come. I have felt so disheartened when I see people casually brushing off the social distancing instructions because it is SO IMPORTANT, and I am so nervous for what I know is coming. Even if people do a great job social distancing, we are going to have full ICUs in the few to several months to come. If people do not do a great job following recommendations, then we are going to have truly terrifying times to come. Thanks for posting this information!

    • Reply
      Teri [a foodie stays fit]

      First, THANK YOU for what you are doing at work every day. My heart goes out to everyone working in health care right now. I have many friends on the front line and others who are being pulled in from other specialities and are super nervous about it. Thank you thank you thank you for helping so many people every day.

      Second, THANK YOU for your incredibly kind words about this post. I have felt so disheartened by so much information out there about supplements and food being enough to protect you and I’m also seeing so many people who are just not following any of the advice. I really hope this post helps some people change their behavior or at least start to think about their actions and ponder if they’re being selifsh.

  • Reply

    Thank you for using your platform to share this vital information!

    • Reply
      Teri [a foodie stays fit]

      Thank you so much for your support. I was a little nervous to post this…but my hope is that it would help some people change their behavior and provide some clarity in a space where everyone is a “health expert.”

  • Reply

    Great post. I didn’t see a way to re-blog or anything so I pasted your link to my Facebook page.

  • Reply

    Bravo for this post! Clearly written and backed up by reputable sources. Thank you.

  • Reply
    Stop Panic Buying… How to Eat Well When You Can’t Buy Your Usual Groceries – bookinglifestyle

    […] also contributed to TeriLyn’s blog on Coronavirus and how maximise your health  where she shares some tips on looking after yourself, helping to reduce the spread and shares some […]

  • Reply

    Thank you! I work in a hospital. It’s really awful to feel the palpable tension of my coworkers terrified of dying from this without proper PPE being provided. Please also vote for improved nurse patient ratios/ increased funding for our healthcare system and reducing profit driven legal healthcare structures. I am highly doubtful of any policy change once it does kill tons of Americans.

    It should be a right not a privilege and it’s quite unfortunate in our highly developed country that isn’t the case.

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