PT on the Net Research

Skip the Flu Season: 4 Ways to a Strong Immune System


Learning Objectives:

  1. Learn the value of sleep and its impact on the immune system.
  2. Be conscious of the effects of sugar consumption.
  3. Comprehend the significance of fats for strengthening the immune system.
  4. Understand the effects of vitamin D levels and the immune system.

The health of our clients is very important for them to see results and to reach their goals. If our clients are sick then that equates to missed sessions and a lack of results. From a business perspective, missed training sessions equates to hurting the bottom line.

Many of our clients will opt for the flu shot from the local drug store or from their doctor, yet there are a high percentage of our clients who will become sick even after receiving a flu shot.

Are we more vulnerable because it’s the "flu season" or could it be something else? The flu virus doesn’t magically appear out of the blue and say, “Hey it’s February. We need to kick it up a notch and infect as many people as possible!” On a daily basis, we are constantly surrounded by pathogens that are jumping at the chance to invade our body and cause havoc.

This is the reason you must consider other factors during the so called “flu season.” One of the major ones is stress. Our clients are under a lot of stress. Some of them are stressed out to the max! The body is designed to deal with acute stress and small bouts of it, but when the stress becomes chronic, it snowballs into a colossal problem. When stress is prolonged, the body’s immune defenses get worn out thus leaving the body predisposed to invaders such as a virus or bacteria (Radek et al. 2010). 

In addition to stress, food can have a huge influence on our immune system. In particular, desserts and alcohol can do a real number. Studies show sugar can depress the immune system for up to 5 hours (Ringsdorf et al., 1976; Sanchez et al., 1974). And if your clients like booze, I’ve got some bad news. Alcohol such as wine and other cocktails are loaded with sugar. While sugar is problematic, the alcohol has been shown to decrease human growth hormone (HGH). The body naturally produces HGH when you sleep but when you have a glass of wine, your HGH levels goes down significantly (Ekman et al., 1996). Remember HGH is a potent fat burning hormone. That glass of wine might sound good, but it’ll make you sick and fat!

During this “flu season” it’s important to focus on keeping your clients healthy rather than trying to prevent getting the flu. Our body has the capacity to protect itself, provided that we give it what it needs.

Here are 4 simple ways to ensure a strong immune system:


There’s always a connotation that if you go to sleep early or sleep 8 hours then you’re getting old. In reality, if you don’t sleep 8 hours at night, you will get older!  The CDC has shown that there are a high percentage of us that are sleeping less than 6 hours per night. With the advent of the internet, smart phones and technology, this problem will only worsen over time.

Sleep is the most underrated therapeutic tool. But it is absolutely free! Think about it. We should be spending a third of our life sleeping. Our body is designed to rest at night, not stay up like night owls. If you go against what your body needs, the body will breakdown. It’s just a matter of time. Research shows that a lack of sleep impairs the immune function of the body (Imeri et al., 2009). Remember the last time you were sick? You probably were in bed for half the day, right? That’s because your body needs time to repair itself and fight the infection (Imeri et al., 2009).

What often happens is that people end up burning the candle at both ends. They have so much work to do that in order to finish their work, they end up sacrificing sleep. This puts any person in a weakened immune state predisposed to becoming sick.

When it comes to sleep, quality and quantity matter. A consistent sleep schedule will ensure high quality sleep. Just think about the last time you traveled to another time zone. The irregular pattern of sleep affected your quality of sleep. Strive to sleep at the same time each night. For example, try to sleep at 10pm and wake up at 6am so your body has a consistent schedule.


We tend to think of food as just calories, but food goes far beyond calories. Every time you put food in your mouth, you create a hormonal response in your body.  Depending on what you eat, you can have a favorable or unfavorable effect from the food. Sugar consumption is a food that goes way beyond “empty calories.” There is an interaction between sugar and the immune system in the body.

Your body has a defense mechanism to protect you. If a foreign invader enters the body, cells called neutrophils will respond to get rid of these foreign invaders. Think of it as Pac-man. The ghosts are invaders and Pac-man is a neutrophil. In the same way that Pac-man goes around eating up ghosts, the immune system releases these neutrophils to take care of any invaders in our body.  

Research has shown that sugar suppresses the immune system (Sanchez et. al., 1973). One particular study used sugars in the form of glucose, fructose, starch, sucrose, honey and orange juice. All of these forms of sugars depressed the activity of the neutrophils except for starch. Another interesting fact about this study was the amount of time that the immune system was depressed. The results showed that the immune system could be depressed for as long as 5 hours! Think twice before you have that orange juice for breakfast!

If you want to keep your immune system running strong, make sure to keep your sugar intake to a minimum.


Ah the "F" word. FAT!! Fat has been villainized for years as the cause of heart disease, obesity and diabetes. Saturated fats known as the “bad fats” have gotten the worst wrap. But not all fat is created equal. Saturated fats are very healthy for you and your immune system. In particular, coconut oil is classified as a saturated fatty acid, but it’s a very special fatty acid. The fatty acids that comprise coconut oil are called medium chain triglycerides (MCT’s). The MCT’s that make up coconut oil are comprised of 48 percent lauric acid, 8 percent caprylic acid and 7 percent capric acid. These acids have been shown to be highly anti-microbial (Shilling et al., 2013). In particular, lauric acid has been shown to have the most anti-bacterial and anti-viral activity (Hornung et al., 1994).

What this means is that the fatty acids in coconut oil fight germs. Simply cooking with coconut oil is a great way to protect your body from getting the cooties! Other great ways of incorporating coconut oil are:


Vitamin D is an important vitamin in the body. Actually, it’s a misnomer to call vitamin D a vitamin. In reality, it is classified as a secosteroid. Vitamin D functions as a hormone in the body and goes way beyond being just a vitamin. It helps to modulate the inflammatory response in the body. In particular, Vitamin D stimulates the antimicrobial effect of the body’s protectors called neutrophils, monocytes and natural killer cells. In addition, vitamin D stimulates the cells lining the respiratory tract which have a protective effect on the lungs (Cannell et al., 2006).

Since vitamin D’s role is so important in the immune system, it’s important to obtain the right amount on a daily basis. Unfortunately, there is an epidemic of vitamin D deficiency globally and there are many reasons why this is occurring. Factors that can affect vitamin D deficiency are: age, reduced sun exposure, use of sunscreens and lack of vitamin D in the diet.

If you go to your doctor on an annual basis, most will check vitamin D levels in your blood. The range of vitamin D is 32-100 ng/ml, but ideal levels should be 50-60 ng/ml. According to leading researcher and founder of the Vitamin D Council, Dr. James Cannell, 5000 IU should be consumed on a daily basis to obtain the optimal levels of vitamin D in the blood. For those of you that are avid exercisers the need for vitamin D increases. According to Dr. Cannell, avid exercisers should be consuming 10,000 IU per day. For instance, as triathletes ramp up volume during a training phase, many can succumb to a depressed immune system leading to upper respiratory tract (URT) infections. Increasing vitamin D levels for these athletes can be very effective, especially for those exercising more than 3 times per week.

It just plain sucks when clients become sick. They stop coming to see you and your training schedule dwindles to nothing, or they come in and workout but you get their cooties! Following the 4 recommendations will ensure that your immune system is strong so you and your clients can skip the flu this season.


Cannell J.J., Vieth R., Umhau J.C., Holick M.F., Grants B., Madronich S., Garland C.F., Giovannucci E. Epidemic influenza and vitamin D. (2006). Epidemiol Infect;134, 1129-1140.

Centers for Disease Control and Prevention. Percentage of adults who reported an average of ≤6 hours of sleep per 24-hour period, by sex and age group-United States 1985 and 2004. MMWR Morb Mortal Wkly Rep. 2005;54:933. 

Ekman AC, Vakkuri O, Ekman M, Juhani Leppäluoto J, Ruokonen A, Knip M. (1996). Ethanol decreases nocturnal plasma levels of thyrotropin and growth hormone but not those of thyroid hormones or prolactin in man. J Clin Endocrinol Metab;81(7):2627-32.

Glaser R, Kiecolt-Glaser JK.  Stress-induced immune dysfunction:implications for health. Nat. Rev. Immunol. 2005 5:243-51. 

Hornung B., Amtmann E., Sauer G. (1994). Lauric acid inhibits the maturation of vesicular stomatitis virus. J Gen Virol;75 (Pt 2):353-61.

Huang C.B., Altimova Y., Myers T.M., Ebersole J.L. (2011). Short- and medium-chain fatty acids exhibit antimicrobial activity for oral microorganisms. Arch Oral Biol;56(7):650-654. 

Imeri L, Opp MR. (2009). How (and why) the immune system makes us sleep. Nat Rev Neurosci; 10(3): 199-210.

Ringsdorf W., Cheraskin E., and Ramsey E. (1976) Sucrose neutrophilic phagocytosis and resistance to disease. Dental Survey 52, No. 12, pp. 46-48.

Sanchez A., Reeser J.L., Lau H.S., Yahiku, P.Y., Willard R.E., McMillan P.J., Cho S.Y., Magie A.R., Register U.D.  (1973). Role of Sugars in human neutrophilic phagocytosis. Am J Clin Nutr;26(11): 1180-4.

Shilling M., Matt L., Rubin E., Visitacion M.P., Haller N.A., Grey S.F., Wollverton C.J. (2013). Antimicrobial effects of virgin coconut oil and its medium-chain fatty acids on clostridium difficile. J Med Food;16(12):1079-85