Strengthening Immunity with Food Based Nutrients

By: Mary Ann Marsala

We are continuously surrounded by pathogens – these are the unfriendly bacteria, viruses and fungi that crowd our skin and invade our inner passageways. Most of the time, they do not adversely affect us; we ward off, neutralize or lessen the effects of them thanks to our innate and adaptive defense system. With these two forces combined, you have what we call an ‘immune system’.
The difference between the two lies in that the innate system, also known as the ‘nonspecific defense system’, which immediately responds to protect the body from foreign substances, better known as antigens. The adaptive, or specific defense system bases an attack against a particular foreign substance through the production of antibodies. In other words, the purpose of the immune system is to protect our bodies by identifying and destroying the enemy.

Understanding Immunity

The strength of our immune system can be evaluated in a variety of ways. In most cases, the immune system does a great job of keeping us healthy by preventing infections. When we are easily fatigued and experience recurring symptoms of cold and flu, it is an indication that our immune strength has become compromised, allowing for an aggressive pathogen to thrive. With the cold and flu season upon us, it is especially important that we do not encourage the proliferation of pathogens and discourage illness. How do we do this? By strengthening our bodies through adequate nutrition, sleep and relaxation and exercise.

Often times, the immune system can unintentionally attack and destroy healthy body tissue; this is what’s known as an ‘autoimmune disorder’. We know that our white blood cells help protect against harmful substances (antigens), and that the antibodies, produced by the immune system, destroy antigens. When you have an autoimmune disorder, your immune system cannot distinguish between healthy tissue and harmful substances and as a result, normal body tissue is destroyed. While it is difficult to pinpoint the exact cause of autoimmune disorder, it is important to note its existence and understand that diet and lifestyle play a critical role in its management. Autoimmune disorders can be classified as celiac disease, rheumatoid arthritis, graves disease, Hashimoto’s thyroiditis and multiple sclerosis, just to name a few.

Conventional Wisdom vs Natural Health

There is a difference between conventional medicine and natural health when it comes to immunity. What’s the difference between the two? Let’s use the cold and flu as a case in point. The purpose of the conventional approach would be to reduce the cold and flu experience by synthetic drug or vaccine; this does not look at an individual’s current immune condition. The natural health approach requires more thought, observation and education on the individual; this is where healthcare would ultimately become your responsibility rather than that of the doctor. With the case of cold and flu, we would want to do our part in preventing its occurrence. How can this be done? By utilizing specific nutrients, primarily through food, to supply the demands of our body. This is a simple, therapeutic and cost-effective way of preventing illness. When you realize that our immune system already does a great job protecting us, it would make the most sense to strengthen it. Proper immune function and its durability greatly depend on your intake of amino acids, fatty acids, vitamins and minerals; all of which come from the big three key macronutrients: protein, carbohydrates and fats. To counter deficiency and fortify your immune health it is important to consider these key nutrients for prevention and protection.

It Starts with Nutrient Density

Our bodies work hard to protect us, so it is time we return the favour.
At CrossFit Bolton, we firmly believe in a diet that is nutrient dense; these are foods loaded in nutrients and lower in calories. For instance, consider the big compound lifts (squat, deadlift, press) that we incorporate into our daily exercise. Nutrient dense foods play a similar role in that they “provide the biggest bang for your buck.” When you are grocery-shopping, shop for foods on the outer perimeter of your grocery store such as fresh fruits and vegetables, lean protein and healthy fats and avoid the inner aisles as they are filled with highly processed foods, all of which contain too much added salt, sugar, damaged fats and chemical preservatives. So which nutrients should we really be incorporating daily? Below you will find a list which emphasizes the top immune boosting nutrients.


These are definitely nutrients worth adding in larger amounts to fight off infection. Most invaders produce dangerous oxidizing chemicals in the body known as free radicals, which damage healthy cells. Antioxidants, such as vitamin A, C, E, and our very own glutathione work to disarm free radicals and weaken harmful invaders.

Vitamin A (retinol and beta carotene)

Vitamin A is an antioxidant and immune system booster. It also prevents against many forms of cancer and helps improve night vision. Great sources of vitamin A would be beef and veal liver, carrots, sweet potato, squash and pumpkin, tomatoes, cabbage and melon.

Vitamin C (ascorbic acid)

Vitamin C, a legendary antioxidant, can detoxify toxins from the body and strengthen immunity, warding off any infection that may be lingering. Vitamin C also protects us against cancer and heart disease. Foods like peppers, broccoli, oranges, lemons, limes and tomatoes are excellent sources of vitamin C.

Vitamin E

Vitamin E is an antioxidant that is great for skin health; it also improves wound healing, fertility and prevents blood clots. You will find vitamin E in food sources such as raw sunflower seeds, sesame seeds, tuna, salmon and sardines.

Glutathione – “The Mother of all Antioxidants”

Apart from diet, glutathione, at high levels, can protect us from the damages of oxidative stress and allow our immune system to function at its very best. It is found in every cell of our body, with its highest concentration located in the liver. According to Dr. Zoltan P. Rona, MD, MSc, “if there is any disease of any kind in the body, the existence of glutathione deficiency can be proven.” Glutathione prevents aging, asthma, arthritis, cancer, autoimmune disease, heart disease and diabetes to name a few. Glutathione is also “critical for the immune system and to control chronic inflammation that could lead to cellular, tissue and organ damage…it also regulates the immune system to fight infections and cancer”. (Rona, 2015).
The best food sources which will increase glutathione levels are cruciferous vegetables such as broccoli, kale, collard greens and cabbage as well as sulphur containing foods such as garlic, onions, parsley and eggs.



Zinc is an important mineral, which helps to maintain the immune system by fighting infections and speeding up healing. You can find zinc in oysters, lamb, pecans, Brazil nuts and ginger root.


Selenium is another important mineral, which has antioxidant properties to help protect us against free radicals and carcinogens. It also reduces inflammation and stimulates the immune system to ward off infection. Foods like tuna, oysters, chicken, molasses and mushrooms are a great source of selenium.

Strength through Herbs

There are many herbs that can be used to strengthen our immune system-whether it be deep immune activation or surface immune activation. What is the difference? Deep immune activating herbs have an effect upon the cellular foundations of the human immune response. These are called immunomodulators and can be found in herbs such as astragalus root or medicinal mushrooms like shiitake or reishi mushroom. Surface immune activation addresses the need to resist pathogenic microorganisms and is done so by anti-microbial herbs like Echinacea or Garlic.


Throughout time, herbalists and folk healers have used garlic to treat many diseases.  Louis Pasteur, a 19th century French chemist, was the first to demonstrate garlic’s antiseptic properties. Since this time, many studies have confirmed that garlic can be effective against bacteria, fungi, viruses and parasites. Today, garlic is frequently used to help prevent colds, flu and other infectious diseases.
Garlic is most effective when consumed raw, either crushed, diced or finely chopped. When it is handled in such a way, the garlic become ‘disturbed’, thus producing Allicin; this is the most powerful medicinal compound derived from garlic and exhibits antibacterial, antifungal and antiviral properties. When you cook with garlic, it speeds up the degradation of Allicin, eliminating all its medicinal compounds and enzymes necessary for it to be effective. For best results, crush a small amount of raw garlic and combine with your cooked food shortly before consumption.

Probiotics – Nature’s Antibiotics

As previously stated, the strength of our immunity can be evaluated in a variety of ways; gut health being one of them. Why? This is because the human gastrointestinal tract houses a large percentage of our immune cells as well as at least 500 different species of microflora – all of which play an important role in determining health and disease (Murray, Pizzorno 2012).

When gut bacteria have been altered, a state of ‘dysbiosis’ occurs, allowing for an imbalance which ultimately affects our immune health. Dysbiosis is for the most part caused by a poor diet of highly refined sugars, damaged fats, high protein intake and low fiber as well as food allergies, poor digestion, stress and the use of antibiotics or other drugs. Protecting your gut health and preventing (or even balancing dysbiosis) begins with consuming clean, nutrient dense foods that have been mentioned throughout the article. You can also consume fermented foods; these are rich in probiotics and help augment friendly bacteria. Some of the best fermented food sources are cultured coconut milk yogurt, kombucha and fermented vegetables such as sauerkraut, kimchi and pickles.  In serious cases, where immune function is decreased, nutrient dense foods alone may not be enough and supplementation with a top quality probiotic is crucial.

Include these superfoods daily to optimize your immune function this cold and flu season!



Michael T. Murray, N.D. & Joseph Pizzorno, N.D. The Encyclopedia of Natural Medicine, 3rd Edition. 2012.

David Hoffman. Holistic Herbal: A Safe and Practical Guide to Making and Using Herbal Remedies. 1990.

Elaine N. Marieb. Essentials of Human Anatomy, 11th Edition. 2015.

Patrick Holdford. The Optimum Nutrition Bible. 2004.

Dr. Zoltan P. Rona, MD, MSc. Reversing Glutathione Deficiency in Vitality Magazine. 2015.

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