How to Keep Your Immune System Strong By Chrissy Wellington M.S., C.N.S., L.D.N., C.P.T

The fall months will soon be turning to winter months and with the colder temperatures come a higher chance of getting sick.  While being an endurance athlete helps improve your immune system, we can often times push ourselves so hard that we actually weaken our immune systems after hard workouts.  The best thing you can to keep yourself healthy and able to keep swimming, biking, and running  is to follow the advice below and be sure you get the essential nutrients your body needs keep you healthy so that you can train hard through the winter months.  The healthier you stay in the off season, the more you can train, and the better triathlete you will be when the season starts back up again. 

Check out KONA Multisport home of for all of your triathlon supplies, triathlon equipment, and supplements you may need to keep you healthy this off season. 

Enhancing immunity is a thriving topic in the nutraceutcial markets today. Nutritionists agree that a poor diet is the number one reason we become susceptible to cold weather illnesses.


There is no cure for the common cold or flu, but eating well during this season may help you avoid getting sick. Science is busy discovering links between our immune system and protective components in food.

Here are some top nutritional keys to stay healthy this season:

Vitamin C

Vitamin C tops the list of immune boosters. There has been more research about the immune boosting effects of Vitamin C than perhaps any other nutrient. Vitamin C is available naturally in many fruits and vegetables.

Unlike most animals that produce their own Vitamin C, the human body does not synthesize any. Vitamin C has substantial antiviral and antibacterial benefits though it’s known for its protective aspects in creating host resistance. The most abundant vitamin C foods are guava, papaya, strawberries, kiwi, cantaloupe, orange and grapefruit.


The live cultures found in yogurt, particularly Lactobaccilus and Bifidobacteria, may be beneficial in enhancing immunity. Having a healthy supply of gut flora increases a person’s white blood cell production and activity. They may also boost the immunity while taking antibiotics, and they supply added protection to those who may have a compromised immune system.

In a recent Swedish study, those who drank a daily supplement of Lactobacillus reuteri (a specific probiotic that appears to stimulate white blood cells) took 33 percent fewer sick days than those given a placebo. Probiotic rich foods are yogurt, kefir, select cheeses and milk, sauerkraut, kim chi and tempeh.


Mushrooms are antioxidant-rich and very high in selenium. Selenium has been studied to reduce the risk of developing a severe flu. Mushrooms are also recognized for there antiviral, antibacterial, and anti-tumor effects. White button mushrooms in particular have noticeably greater immune boosting effects than other mushrooms such as, oyster and shiitake.

High Fiber Grains

Oats and barley in particular contain beta-glucan, a type of fiber with antimicrobial and antioxidant capabilities. They enhance resistance to various fungal, bacterial and viral diseases. Beta-glucan is also found in protective amounts in shiitake and maitake mushrooms. Beta-glucan enhances immunity, similarly to echinacea and astragalus root. Beta-glucan binds to macrophages and other white blood cells and activates anti-infection activity by increasing the production of free radicals.

Vitamin E

Vitamin E has been studied for its production of natural killer and B-cells, the cells that produce antibodies that destroy bacteria. The highest vitamin E foods are green leafy vegetables, sunflower seeds, almonds and blueberries.

Carrots and Sweet Potato

The antioxidant beta carotene has been studied to increase the number natural killer T-cells in our immune system. Beta carotene is a powerful antioxidant that mops up excess free radicals that can accelerate illness.


Zinc is a mineral which increases the production of white blood cells. Always include zinc from food sources rather than in a supplement form. As little as 15 to 25 milligrams a day will help to support immune function. Some of the top zinc foods are oyster, crab, grass-fed beef and beans.


Garlic is known for its antibacterial, antiviral, antifungal and immune boosting effects. Garlic stimulates the production of white blood cells and increases the efficiency of antibody production. The immune-boosting properties of garlic seem to be due to its sulfur-containing compounds. Garlic can also act as an antioxidant that reduces the build-up of free radicals in the bloodstream.

Omega-3 Fatty Acids

Omega-3 fats reduce inflammation, increasing airflow and protect the lungs from colds and respiratory infections. The omega-3 fatty acids in ground flaxseed and fish such as, salmon, tuna, sole, flounder, sardines, herring and mackerel, act as immune boosters by increasing the activity of phagocytes, the white blood cells that destroy bacteria. Other omega 3 rich foods are tofu, edamame and walnuts.


The amino acid responsible for immune boosting components in tea is, L-theanine. It is abundant in both black and green tea.  Many already know to drink green tea to help fight disease, new research is also including white tea, for its strong ability to destroy the organisms that cause disease.

Not only should you boost your intake of certain nutrients, but there are certain things you should avoid to stay healthy this season:

Excessive Sugar Intake

Eating or drinking too much refined sugar, can reduce the ability of white blood cells to kill germs. The immune-suppressing effect of sugar starts immediately after ingestion and may strengthen throughout the day. Excessive refined sugar intake can reduce the responsiveness of your immune cells and lower your immune defense.

Excessive Alcohol Intake

Excessive alcohol intake can harm the body’s immune system. Alcohol ingestion deprives the body of protective nutrients, leaving the body susceptible to invaders. High doses of alcohol suppress the ability of the white blood cells to multiply and it inhibits the action of natural killer cells. Damage to the immune system increases in proportion to the quantity of alcohol consumed. Amounts of alcohol that are enough to cause intoxication are also enough to suppress immunity.

Excessive Processed Food Intake

Foods that contain synthetic colors, dyes, artificial sweeteners, flavors and texturizers can decrease your immunity and be a factor in increasing your body’s susceptibility to cold and flu viruses. To keep your immune system at its best, it is important to avoid exposing cooking oils and fats to high heat since this can produce damaging substances.

Excessive Weight Gain

Being overweight by even 10 pounds may also suppress the immune system. Excessive weight may affect the ability of white blood cells to multiply and produce antibodies. Since the excessive consumption of fats and calories can lessen your immune system, it is important to shape your daily intake in such a way that you can become satisfied without overeating.

To stay healthy this cold and flu season eat a diet that contains a variety of fruits and vegetables. These foods ensure that you get the bioflavenoids needed to boost the immune system. Emphasize certified organic foods which are free from pesticides, heavy metals, and residues. These are among the most immune-damaging molecules we can ingest. Drink filtered water to avoid these same immune-suppressing factors that are found in most tap water.


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