Helpful ways to Maintain a Healthy Immune System

In Part 1 of our “boosting” immune system series, we talked about how our immune system works and what does “boosting” immune system actually means. Ultimately, what we need and want is just a healthy and effective immune system to help defend our bodies against all kinds of infections.

This Part 2 series will explore some of the helpful ways to maintain a healthy immune system without spending big bucks on health supplements.


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It is no surprise that a healthy balanced diet is key to a healthy immune system. Remember when your mom and dad telling you to “eat your fruits and vegetables!”. Turns out, they were right all along.

Like any other cells in our body, our immune cells need proper nourishment to stay functional and do their job well. We all learned about the effects of malnourishment in school. Lack of vitamin A causes vision problems; lack of vitamin C can result in scurvy; protein deficiency leads to kwashiorkor.

It is a common misconception that malnutrition occurs only in low- and middle-income countries where people are underweight. That is not true. You can be overweight and malnourished. To understand that, let’s first talk about nutrients. They can be divided into 2 categories: macro- and micronutrients.

Macronutrients are carbohydrates, proteins, and fats, which our bodies need in larger amounts. Micronutrients are the minerals, water- and fat-soluble vitamins. So, think Vitamin B, C, A, D, E, K, calcium, sodium, zinc, iron, etc. A person can be overweight or obese and be malnourished in micronutrients.

On a macronutrient front, a healthy immune system requires an adequate amount of proteins. Our bodies need proteins to make new immune cells, new antibodies. Think of proteins as part of their building blocks. Fats, more specifically healthy fats such as the Omega 3s are essential fatty acids that we obtained from our diet. These fatty acids play an important structural role in our cell membranes.

On the micronutrient front, all the micronutrients I’ve listed above play important roles in all components of our immune systems. For example, zinc is vital for the normal development and functions of our innate immunity cells, neutrophils, and natural killer cells.

Vitamin D

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Recent studies have implied that vitamin D deficiency could be a potential reason why some people more susceptible to COVID-19. Vitamin D (in the form of D3) is the vitamin your body makes via exposure to sunlight. You can also get vitamin D from your diet (egg yolks, fatty fish etc.)

Vitamin Ds are important for bone health as they facilitate calcium absorption and strengthen our bones. They also modulate innate and adaptive immune responses. Surprisingly, for a vitamin that our bodies can manufacture through sunlight exposure, about a billion people worldwide are vitamin D deficient.

So, yes or no to vitamin supplements?

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In a nutshell, it is much better to get all your nutrients from a balanced diet. That means eating your fruits, your vegetables, your proteins, and a moderate amount of carbohydrates and fats.

There is no evidence of the overabundance of any particular vitamins or minerals is beneficial in maintaining a healthy immune system. However, if your diet lacks certain micronutrients, you can consider taking multivitamin and mineral supplements. If you are healthy and stick to a balanced diet, those vitamin supplements aren’t going to have much effect on your health.

So, make sure your diet is filled with lots of colorful fruits and vegetables; obtain your protein, fats, and minerals from a variety of protein sources (think seafood, meat, poultry, etc.). A healthy diet should fulfill 3 main criteria: balance, moderation, and variety.

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Are there risks to taking supplements?

Absolutely! Overdosing on certain supplements can pose real dangers to your health.  High doses of vitamins can be toxic. For example, high levels of vitamin A may cause birth defects and damages to your nervous system, liver, and bone; too much iron (hemochromatosis) can lead to a range of symptoms from lethargy to severe liver disease.

Besides, many adults are taking herbal supplements every day whether it is for general health or relieving symptoms of diseases. While some of them might provide health benefits, there aren’t adequate reliable studies to prove that. Not to mention, we don’t know how herbal supplements can interact or interfere with other medications and/or supplements when taken together daily over long periods.

The bottom line is, never self-diagnose and consult a trusted health professional if you have any concerns.


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Exercise isn’t just for those who want to lose a few pounds. Many studies have reported the health benefits of long-term exercise regime.

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Exercise not only improves and maintains your cardiovascular health; it is also important for bone health. Other health benefits of exercise include lowered blood pressure, improve lung functions, and even happiness (the secret is in the release of feel-good chemicals in our brains).

As for immune functions, studies suggest that exercise increases the recirculation of key immune cells, which improves overall immunosurveillance. Epidemiologic studies had also linked regular physical activity with decreased mortality and cases of influenza and pneumonia.

Just like a healthy diet, a healthy exercise regime can have significant health benefits. But how much exercise and what kind of workout are needed? That depends on your conditions. And as always, don’t overdo it. Overexercising can have the opposite effects on your immune system.

If you don’t have the habit of exercising regularly, start by taking a long walk. Stuck at home? No problem, just do some low-impact bodyweight workouts in your living room. The goal is to adopt a healthy habit of exercising regularly. Target low- and moderate-intensity exercises. In general, 30 min of moderate-intensity exercise a day is good for health. And your immune system will benefit too.


There is no doubt that stress, whether physiological or psychological can impact immune functions. Chronic stress increases inflammation. Inflammation is a natural immune response in responding to acute physiological stress such as a minor injury for the elimination of invading pathogens and initiating the healing process.

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Prolonged systemic inflammation denotes dysregulation of the immune system and can trigger dormant viruses to reactivate in our bodies. An example of such a virus would be herpes simplex virus type 1, responsible for causing cold sores. Besides, elevated levels of cortisol, a type of stress hormone can hamper immune cell functions.

Needless to say, don’t stress. If you are stressing just by reading this post, take a deep breath before you continue.

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Stress is a bit of a vicious cycle. Learn to recognize stressful thinking, identify your triggers, understand that it is a process, and don’t stress about stress. Take your time to explore stress management strategies. Find out what works for you. It could be meditation, doodling, exercise, drinking a cup of tea, a stroll at the park, deep breathing exercises, etc.

Limit Alcohol consumption

Now that we know stress hampers immune functions. What is your go-to tactic to destress? If it’s alcohol, find another destress strategy. The damaging effect of alcohol consumption is well-known. Not only does excessive alcohol consumption damages our livers, but it can increase the risks of heart disease too.

As for our immune systems, too much alcohol can dull our immune systems, making us more vulnerable to germs. Studies have shown that alcohol can affect our gastrointestinal system and damages healthy gut microbiomes related to immunity.

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Don’t stress though. Moderate alcohol use, which is typically one standard drink for women, and two standard drinks for men per day is generally considered safe. However, some people shouldn’t drink at all. For example, people with chronic liver conditions such as hepatitis or fatty liver disease should avoid alcohol at all times.

If you are unsure and worried, try reducing your alcohol intake and limit your consumption according to the recommended daily amount.  The same goes for other addictive substances such as caffeine. Moderation is the basis here.


Have you ever had a sleepless night and tried to survive the next day? Remember how groggy, unproductive, and irritable you feel? That’s what lack of sleep does to you; it impacts brain function. Sleep is vital for the rest of the body too. Lack of sleep can increase blood pressure, cause migraines, affect growth hormone production, and increase risks of heart diseases.

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And yes, sleep deprivation certainly can affect your immune systems. A recent study suggested that a good quality sleep enhances the ability of immune T cells to stick to and directly kill cells infected with pathogens. Increased stress factors such as certain hormones and pro-inflammatory molecules from sleep deprivation can impair the functions of immune T cells. It simply means a lack of good sleep can impair your immune functions, making you more susceptible to infections.

In another study involving 164 healthy adults, it was found that those who slept less than 6 hours were 4.2 times more susceptible to catching a cold than those who slept more than 6 hours.

Make sure you sleep well every night. Adopt a good sleeping routine, go to bed at the same time, and wake up at the same time every day. If you have trouble sleeping, try limiting screen time before bed. That means no phone, no TV, no computer screens, and no tablets.

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Take time to prepare yourself and get into your bedtime routine, you might want to meditate, do some stretches, give yourself ample time to decompress from your day.

Make sure your bedroom environment including your pillows and mattress are well-suited for good night sleep. While sleep requirements vary from person to person, in general, adults should get 7 to 9 hours of sleep every night. Teens and younger children need even more.

If you suffer from sleep deprivation or other sleep disorders, consult with your GP or seek professional help from a sleep clinic. Cognitive-Behavioural Therapy or relaxation techniques may help to treat insomnia.

The Bottom Line

When it comes to maintaining a healthy immune system, general healthy-living strategies go a long way.

  • Eat a balanced diet and get all your nutrients from food instead.
  • Adopt a workout routine today, find out what works best for your body.
  • Enjoy the outdoor if possible, little doses of sunlight each day can help to increase vitamin D levels in your body.
  • Practice moderation when it comes to alcohol consumption.
  • Reduce stress and get adequate sleep
  • Attitude is everything. Practice mindfulness and maintain a positive outlook amidst the hard times
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Now, none of these suggestions can prevent COVID-19. While we take care of our physical and mental health, let us all stay vigilant on proper hand hygiene and physical distancing.    

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Ameline Lim, Ph.D., is a research scientist and biologist. She received her PhD from the University of New South Wales at Sydney, Australia. She has broad interests in medicine, history of science, and behavioural science. She is particularly interested in science education and the public understanding of scientific research. Her blog 'Science with Amy' celebrates the pleasures of finding things out and general curiosity.