Immune Health & Triathletes

This past March while we were still learning about COVID-19, most of the nutrition and health information was focused on determining the cause, its mechanism of action, its effects, and how to prevent it.  Since then, discussions and webinars that I have participated in with medical professionals and functional nutrition colleagues, has focused on how to use food and nutrients to maintain overall health and possibly reduce the severity if acquired.

It is known that anyone with preexisting health conditions such as diabetes, metabolic syndrome, and obesity had a higher risk of becoming sick if acquiring the disease. As triathletes you may have not paid much attention if you are within normal weight and generally healthy. Even so, there are always bacteria and other viruses on door handles, counter tops, and in other peoples’ respiration droplets that are expelled during cycling and running that might be coexisting fine in your body, until you become vulnerable to them.  

A Usual Situation

It’s Saturday morning.  You wake up excited for the group ride but have been feeling run down for a few days. During the ride you stop for coffee and touch the countertop when paying for your muffin, and with that same hand, you wipe your nose and mouth to catch sweat dripping down your face.  You don’t realize that your hand now has bacteria “a” on it. Bacteria “a” isn’t a superbug and usually benign if your immune system is well. However, if your body is more susceptible due to under recovery, stress, or nutrition it could put a small dent in your armor.

It’s Monday and you are feeling a little more tired than usual after a weekend of training.  The group ride on Sunday became competitive and you rode harder than planned.  It felt good and you hope to become more fit from the ride. Wednesday you are at a grocery store, the employees are wearing masks and laughing at a joke. You walk in between the two employees who were standing across the aisle. Friday afternoon you feel more fatigue and ‘off’ compared to your usual self. 

You can see where this is going…… In the current state of pathogens, if COVID19 does not pose a threat to you, still consider the ordinary viruses and bacteria that have always been here.  If you become vulnerable to them -> develop a sinus infection or cold -> your body becomes more vulnerable to acquiring other illnesses.  Be cautious with your training intensity, hygiene and recovery.

The Immune System and Nutrients to Support It

The primary goal of the immune system is to protect its host environment against pathogenic microbes, agents, and antigens.  Cells identify microbes that are not native to the host body, engulf and digest them. In addition to defending the body against foreign pathogens, the immune response works daily to manage oxidative stress.  Oxidative stress is a natural product of exercise, and is created in your body in response to environmental toxins such as mold, heavy metals, and bisphenol A.  There are many supplements that claim to support immune health. Six of the most common evidence-based recommendations are below.


1. Cruciferous, sulfur containing foods: Garlic is always on a list of immune boosting foods. It’s pungent, delicious smell and taste make it easy to add to a stir fry, ground turkey, tofu, or roasted vegetable dish. Its health benefits are due to the sulfur compounds and enzymes it contains as well as allicin.  Sulfur is required for the synthesis of glutathione, known for its detoxification and antioxidant effects. It would require a very high intake and absorption of sulfur containing foods to increase glutathione levels, however, every bite adds to overall maintenance of these pathways.

            If you don’t like garlic, increase your intake of other sulfur containing foods such as kale, red and white cabbage, Brussel sprouts, broccoli, napa cabbage and savoy cabbage. Be sure to wash all produce prior to cooking or consuming.

Allicin is an enzyme in garlic that becomes activated when garlic is crushed or chopped. To optimize the health benefit from garlic, choose whole cloves in place of chopped or diced preserved garlic.  Peel, chop and let the garlic breathe for a few minutes before tossing into a saucepan or oven. This allows allinase to catalyze the release of allicin which has antibacterial, antiviral and anticancer properties (15).

            Tip: Christopher Ranch is the most popular brand in California. Almost every garlic sold in a grocery store is white in color.  To experience an authentic taste of garlic, choose a purple variety such as bavarian purple or purple glazer sold at a farmer’s market or direct from a farmer.


If you have been searching youtube for immune enhancers, you may have heard of sulforaphane, the bioactive compound in broccoli sprouts.  It is an isothiocyanate, a type of phytochemical with antioxidant characteristics that allow them to stabilize free radicals. Free radicals are created during exercise and are a normal process of aging. However, when their numbers increase higher than the body can manage, they cause illness.

Sulforaphane is in many cruciferous vegetables, however, it was found in clinical trials, that the concentration was highest in broccoli sprouts. Recommending a specific dose is difficult because most interventions combine it with other cancer drugs. In addition, the form and dose used in clinical trials is produced in a laboratory, making it difficult to replicate in a food based supplement. (3,7,8).  That being said, sulforaphane is available in supplements sold directly to practitioners, but these products are not tested by 3rd party labs.

2. Quercetin: A flavonoid predominantly found in citrus fruit, as well as onion, red wine, berries and apples. Its mechanism of action is to modulate inflammation as the body is responding to infection or injury.  Research has highlighted anti-inflammatory behavior through inhibition of COX-2 and reduction of CRP (c-reactive protein) in healthy athletic males, but no significant changes in inflammation related to pathological conditions. It is frequently studied in relation to cancer due to its ability to protect DNA from oxidative damage.

Dose: Quercetin dihydrate 500 mg twice daily, taken for three weeks has shown to reduce the incidence of upper respiratory infections (9). Consumed with vitamin C containing food or supplement will increase uptake of quercetin. Quercetin is also recommended as an anti-histamine and may reduce the severity of some allergies.

Dose: 500 mg, 2xday
Consume with at least 250 mg Vitamin C (most brands include this in the formula)

3. Vitamin C (L-Ascorbic Acid): A water soluble vitamin and electron donor (antioxidant). It is active in many enzymatic reactions related to wound healing and supports collagen production.

Dose: 2000 mg is the upper limit daily recommended intake. Amounts up to 5 grams per day were not linked to toxic effects but may cause diarrhea. Patients with high values of urinary oxalates or frequent kidney stones should avoid doses greater than 1 gram per day.

For increased bioavailability and reduced stomach upset, choose buffered ascorbic acid identified by the “mineral ascorbates” listed in the Supplement Facts panel.

Vitamin C
Choose “Buffered” Ascorbic Acid; Upper Limit per day:     2000 mg

4. Zinc: Is an essential mineral involved in growth and development, immune function, vision, involved in enzymatic reactions and regulating gene expression. Food sources include eggs, red meat, shellfish, whole grains, legumes, and nuts (12).

  1.  The recommended dietary allowance (RDA) for males is 11 mg/day and females 8 mg/day.  These recommendations can be achieved through diet. If using supplemental forms of zinc, less than 40 mg/day (the RDA upper limit) is recommended to prevent copper deficiency. Using a higher daily dose of 75 – 180 mg/day may be used short term to reduce symptoms of the common cold.  Zinc gluconate, glycinate and aspartate are the most common forms founds in lozenges and tablets (11).
    • Requirements for vegans and vegetarians may be 50% higher than those who eat a mixed diet including animal protein.  Vegetarian foods that contain zinc include grains and legumes, both of which contain phytates that reduce the ability to absorb zinc during digestion.
    • Bioavailability of zinc is higher in animal sources due to the lack of phytates and the natural inclusion of cysteine and methionine, two sulfur containing amino acids.
RDA (19 years & older):  Males: 11 mg/day             Females: 8 mg/day
Upper Limit per day: 40 mg
Short term use to support immunity: 75 – 180mg/day

5. Elderberry (Sambucus nigra): The bioactive compounds in elderberry are anthocyanosides. Anthocyanosides are a category of phytochemicals found in purple, blue and red fruit and vegetables.

Research has shown that using elderberry extract has reduced the extent to which some viruses such as H1N1 and influenza have been able to replicate.  It does not claim to prevent the flu or COVID-19 (13,14).

  • The standard dose of elderberry referred to in literature is 600 – 900mg daily prior to travel, and 1 Tablespoon (15mL) up to four times daily to reduce symptoms of influenza.  Different brands contain different concentrations of elderberry extract. Follow instructions for use specific to each product.
Dose: 600 – 900 mg/day
Nature’s Gate: 2 – 4 x 1 tsp Gaia: 1 x 1 Tbsp

6. Mushrooms: Cordyceps (Ophiocordyceps sinensis), and Maiitake (Grifola frondosa) are used to strengthen the immune system and chronic fatigue.  Three grams of cordyceps (CordyMax Cs-4) was effective at strengthening the immune system over five weeks without any side effects noted.

       In Oriental medicine mushrooms are held in high regard, however, as a competitive triathlete, using these products that are not 3rd party tested is risky. The doses added to coffee or other supplements are not effective and a waste of money. To glean the benefits of mushrooms, first work with a practitioner to determine the root cause of your fatigue or weak immune system.  A cordyceps tincture will not provide immediate relief, however, in combination with other lifestyle changes it could support your immune response.

Disclaimer: As competitive triathletes you are sanctioned by the World Triathlon Corporation and it is your responsibility to know policies related to doping and prescription medication use. Any product that contains a Supplement Facts label is not regulated by the FDA and therefore, you assume the risk of consuming banned ingredients that may or may not be listed on the label. The following information is for education purposes but does not condone the use of the products or ingredients.  Every person should discuss with their physician or certified sports dietitian to discuss ingredients, side effects and risks. Every individual’s symptoms and goals are unique and therefore the information below may or may not be applicable to you.  If you have multiple food sensitives, autoimmune conditions, or preexisting health conditions, please consult with your practitioner. Third party certification is not a guarantee of purity, however, they are less likely to contain contaminated supplements. Look for the Informed-Choice label to know that product has been tested against the WADA list of banned substances.