Tag Archives: illness

Let’s explore two statements that even the most novice athlete, who’s ever been sick, will not find profound in any way:

  • Exercise is productive and results in beneficial training adaptations.
  • Conversely, illness is inflammatory and can interfere with our ability to train.

What is profound is what’s hidden between the lines in those two statements. There’s a very important assumption that, consciously or unconsciously, many of us make – the immune system is independent from the processes in our body that produce training adaptations and inflammation interferes with those processes.

In truth, that assumption is misplaced. Fighting illness and the beneficial adaptations we get from training are in fact two sides of the same coin.

And that’s all because of evolution.

Evolution hates re-inventing the wheel. Whenever it discovers something beneficial, it has a way of hanging on to that new trick and using it anywhere it can. And when we’re talking about something as sophisticated and calorically expensive as our immune system, evolution has made sure to get its money’s worth.

Our immune systems do a lot more than just fight off harmful invaders. Their many functions include acting as a transport system, they manage cell apoptosis to ensure our bodies are healthy and functioning normally, they sample the foodstuff in our guts to help determine what should gain entry.

And when we exercise, our immune systems handle the repair that produces many of our major training adaptations.

In fact, the fundamental principle of exercise science – the Principle of Progressive Overload – depends on the immune system. The Principle states that training actually causes damage, and if that damage is big enough, our bodies hyper-compensate and rebuild stronger to avoid the same damage in the future.

Our immune systems are responsible for that repair work and hyper-compensation. In other words, the macrophages, T-Cells and cytokines like Il-6 and TNF-α that fight viral infections are also responsible for making us stronger and faster. Hence, fighting illness and producing training adaptations are in essence two sides of the same immunological coin.

This has several important implications:

  1. Training is inflammatory – after that hard interval session or big weight lifting routine, your muscles are damaged, and the body’s healthy response to that damage is inflammation around that damaged tissue.


  1. Training Can Suppress the Immune System – excess inflammation can lead to something called Systemic Inflammatory Response Syndrome (SIRS) which is dangerous. So, when there’s a lot of damage due to training, our bodies try to keep the inflammation localized to the damaged muscles by suppressing the immune system in the rest of the body.


  1. Excessive Training Can Cause the Immune System to “Malfunction” – when you are training hard, your immune system has to do double-duty repairing damage and fighting potential infections which can put a strain on it. If that load becomes too big (like when athletes over-train) the inflammation can become aberrant and lead to inappropriate responses.

Let’s explore each of these in more depth…


Training Is Inflammatory

You just completed a hard run causing minor muscle tearing in the muscle fibers of your legs. Your body’s immediate response is to release inflammatory cytokines like IL-6 and TNF-α to promote an inflammatory response. You experience this inflammation as swelling and muscle soreness. The activated immune cells then very effectively clear out damaged tissue and begin the repair work.

The whole process is generally completed within a few days which you’ll experience as a day or two of dragging your feet followed by fresh stronger legs.

This happens every time we train hard and do damage. It’s a natural and healthy reaction. But always remember that that inflammation is very similar to the inflammation you experience when you’re sick.

Which begs the question, why don’t we feel sick after every hard workout?


Training Can Suppress the Immune System

Excess body-wide (systemic) inflammation is dangerous. In fact, this condition known as Systemic Inflammatory Response Syndrome (SIRS) is what can causes death in burn victims and people suffering from sepsis [1].

SIRS is generally only seen in the trauma ward, but there actually is evidence of this syndrome in over-trained athletes [1].

But that’s uncommon. Most of the time, our immune systems try to localize the productive inflammation to the damaged muscles and avoid inappropriate and excessive inflammation throughout the body. Anti-inflammatory cytokines such as IL-10 and TGF-β are released into the bloodstream to suppress systemic inflammation. [2]

In essence, the immune system weakens itself.

So, after periods of heavy training, we are not as effective at fighting infections. Which means, the worst time to hang out at a coffee shop, use a public restroom or sit in an airport is soon after a three-hour race or hard training session.

And to add insult to injury, there’s an important balance in our bodies between two types of T-helper cells (the Generals of our immune systems.) Type 1 T-helper cells (Th1) direct viral responses while Th2 cells are responsible for allergic reaction. Unfortunately, as part of the immunosuppression described above, the balance is shifted towards Th2 which may be why many endurance athletes experience worsening allergy symptoms when they train hard. [2]

That doesn’t mean you should worry every time you go for a run or hit the weight room. Not all training suppresses your immune system. In fact, very light training helps the immune system by improving blood flow throughout the body. It’s only heavy and exhaustive training that leads to immunosuppression.


Excessive Training Can Cause the Immune System to “Malfunction”

Immunosuppression after heavy exercise is the reason we don’t feel sick after every workout. But it doesn’t always work. Sometimes hard exercise does make us think we’re sick.

When we’re truly fighting an illness, most of the symptoms of that illness (coughing, elevated body temperature, swelling and soreness) are caused by our immune systems and not the virus or bacterial infections themselves. In fact, if the virus had its way, you’d never notice it at all. Viruses would very happily hide out in your cells using those cells to replicate itself.

So, if our immune systems “malfunction” or becomes so activated that it can no longer suppress systemic inflammation, we can feel sick whether there is an actual infection or not. Excessive levels of training can cause this malfunction.

To make this point, a 2007 study in Medicine and Science in Sports and Exercise looked at upper respiratory tract infections (URTI) in highly trained athletes. The study found that only 30% of the infections had an identifiable viral cause. Further, most of the reported cases of URTI were during heavy training periods.[3]

Undoubtedly, in some of those cases, the virus simply escaped detection. But the authors still made a strong case that at least some of the incidences were not an infection at all. They were the result of excess inflammation caused by over-training.

This is important because often athletes feel they are “tough” and can train through URTI. But what if that URTI isn’t an infection? What if instead its inappropriate inflammation due to over-training? Then “pushing through” is actually just making the problem worse. What the body needs is rest.

Taken to the extreme, it’s shouldn’t be surprising that the symptoms of severe burnout are very similar to symptoms of illness and even autoimmune disease. Doctors frequently mistake burnout for mononucleosis.


Supporting our Immune Systems

To perform at our best, we shouldn’t look at inflammation as an unhappy road block threatening to derail our training. Instead we need to see effective training and a healthy immune system as two sides of the same coin. In fact, we can’t have one without the other.

And when we’re training hard, we’re asking our immune system to do double-duty keeping us both healthy and repairing muscle damage. So, it’s our job to do everything we can to support it.

Fortunately, the things we can do to keep our immune systems healthy and the things we can do to support our training are often one and the same. Both require greater focus on proper rest and proper nutrition. A few tips to do this include:

  • Always keep an effective balance between recovery and training – this is number one. Let it get out of balance and the immune system will stop functioning properly. And that means excess immunosuppression can allow a virus to take hold, or alternately, inappropriate systemic inflammation will cause you to get sick (no virus necessary.)
  • Get your easy rides and runs – there is a J-shaped curve relationship between exercise and the immune system.[4] Hard training can suppress the immune system, but easy training can support it. Recovery rides or easy walks are great for speeding training adaptions and fighting illness.
  • Avoid exposure – your immune system is compromised after hard training. This is the time to tap into your inner-hypochondriac. Stay home and keep your hands clean.
  • Support your immune system – when it is active, your immune system is producing millions of cells and cytokines. All of which require a steady supply of amino acids. So, when you are sick or training hard, make sure you are consuming lots of healthy protein to support that cell and cytokine production. Healthy omega-3 fats are also needed for cell wall formation and prostaglandin production (important soldiers of the immune system.)
  • Reduce simple sugars, especially when you think you may be sick – simple carbohydrates are inflammatory and can contribute to excess inappropriate inflammation.[5, 6] Worse, many viruses and bacterial infections are anaerobic. Meaning they can only survive on carbohydrates. Don’t feed them!
  • Take L-glutamine when training hard – the primary fuel of our immune system is l-glutamine. Normally our bodies produce enough for our needs. The problem is during exhaustive exercise, when we’re depleting our glycogen, our bodies start using l-glutamine to fuel our exercising muscles and we can become transiently depleted. So, when doing a lot of long hard endurance work such as a six-hour bike ride, it might be worth supplementing.
  • A few other supplements – while heavy supplement use is generally a bad idea, a few supplements can help when you’re sick. There is some evidence that vitamin D and zinc can support immune function and reduce the severity of illness.[7-10]

A healthy Paleo Diet® naturally addresses many of these tips. It provides the healthy proteins and omega-3 fatty acids needed to support your immune system. It’s also very low in simple sugars and supplies better, natural sources of zinc. That makes it a great way to provide your immune system the support it needs when doing double-duty.



  1. Fehrenbach, E. and M.E. Schneider, Trauma-induced systemic inflammatory response versus exercise-induced immunomodulatory effects. Sports Med, 2006. 36(5): p. 373-84.
  2. Suzuki, K., et al., Systemic inflammatory response to exhaustive exercise. Cytokine kinetics. Exerc Immunol Rev, 2002. 8: p. 6-48.
  3. Spence, L., et al., Incidence, etiology, and symptomatology of upper respiratory illness in elite athletes. Med Sci Sports Exerc, 2007. 39(4): p. 577-86.
  4. Gleeson, M., et al., Influence of training load on upper respiratory tract infection incidence and antigen-stimulated cytokine production. Scand J Med Sci Sports, 2013. 23(4): p. 451-7.
  5. Della Corte, K.W., et al., Effect of Dietary Sugar Intake on Biomarkers of Subclinical Inflammation: A Systematic Review and Meta-Analysis of Intervention Studies. Nutrients, 2018. 10(5).
  6. Benetti, E., et al., High sugar intake and development of skeletal muscle insulin resistance and inflammation in mice: a protective role for PPAR- delta agonism. Mediators Inflamm, 2013. 2013: p. 509502.
  7. Das, R.R., Zinc and vitamin A for prevention of upper respiratory tract infection in children. Br J Nutr, 2012. 108(9): p. 1722.
  8. Veverka, D.V., et al., Use of zinc supplements to reduce upper respiratory infections in United States Air Force Academy cadets. Complement Ther Clin Pract, 2009. 15(2): p. 91-5.
  9. Jung, H.C., et al., Vitamin D(3) Supplementation Reduces the Symptoms of Upper Respiratory Tract Infection during Winter Training in Vitamin D-Insufficient Taekwondo Athletes: A Randomized Controlled Trial. Int J Environ Res Public Health, 2018. 15(9).
  10. Dubnov-Raz, G., et al., Vitamin D supplementation and upper respiratory tract infections in adolescent swimmers: a randomized controlled trial. Pediatr Exerc Sci, 2015. 27(1): p. 113-9.


Give Your Immune System a "Paleo-Boost!" | The Paleo Diet

The darker, shorter and colder days of winter are upon us and with it comes an increase in colds and flu. The first wave of patients with sore throats and congestion has already passed through my office, so now is a great time to think about how you can support your immune system. There are several key deficiencies that commonly rear their ugly heads over the fall and winter months and contribute to increased frequency and severity of colds and flu. Nothing will slow your productivity at work, in the gym, or family time at home quicker than sick days.

If you are working long hours, exercising intensely, or have kids in daycare or school, then you’ll likely be more exposed to bacteria and viruses that can leave you stuck at home in bed. The research tells us that as your cortisol stress levels increase (from busy days, meeting deadlines, or getting up early with the kids) your first-line of immune defense or innate immune system function decreases.1This leaves your immune defense team short-handed.

Staying active is a great way to enhance your immunity but the more intensely you train, the quicker you deplete critical ‘immune soldiers’ called natural killer cells (NK).2 Studies show your immune system can be depressed for 24-72 hours after intense training, which means you need to provide the right support to reduce your risk of colds and flu.3

What can you do to boost your immunity this winter? (The answer is on your dinner plate!)


If you live in a northern climate with a true fall and winter season, obtaining the right amount of vitamin D is critical for keeping your immune system firing on all cylinders. Vitamin D deficiency is associated with decreased innate immunity and increased risk for infections.4

The best part of a Paleo dietary approach is that it provides you with the most nutrient dense choices for foods. To keep your vitamin D levels from plummeting over the winter months, increase your intake with these 5 vitamin D rich foods:

  • Cod Liver Oil – 1,400 IU per tbsp. (your grandma knew best!)
  • Cold-Water Fatty Fish – trout (645 IU per 3 ounce), salmon, or mackerel
  • Medicinal Mushrooms – Portobello (375 IU per mushroom) or maitake
  • Pork – 78 IU per 3 oz. serving
  • Eggs – 44IU per egg

The Vitamin D Society recommends maintaining your vitamin D levels between 100-150 (nmol/l), so if you struggle with colds and flu, or low mood over the winter, then getting your levels tested would be beneficial.5


If you are low in Vitamin A, it will significantly impair your mucosal immunity and leave you more prone to upper respiratory tract infections (URTI).6 If you work in an office, have kids in daycare or school, or train intensely than you’ll be a much greater risk of URTI, especially through the winter months.

A Paleo Diet is loaded with nutrient dense meats that are the richest source of preformed vitamin A. You can also get significant beta-caretene (which converts to vitamin A) from fruits and veggies.

Try these 5 Paleo rich vitamin A foods to keep your immune system robust:

  • Turkey and Beef Liver – 17,000 IU and 6,400 IU per 2.6 oz., respectively.
  • Cod Liver Oil – 4,150 IU per tbsp.
  • Sweet potatoes – 1,100 IU per medium size
  • Pumpkin -1,000 IU per ½ cup
  • Carrots – 700 IU per ½ cup


Vitamin C and zinc is a powerful combo for ramping up your immune army and fighting off bacteria and viruses. Vitamin C improves the response of neutrophils and lymphocytes, important immune cells that are the ‘front-line soldiers’ of your innate immune system.7,8 Zinc is essential for optimal function of your thymus gland, responsible for developing the ‘special forces’ immune cells of your adaptive immune system.9 This is the seek and destroy arm of your immunity, crucial for knocking out foreign invaders once they’ve breached your first-line of defense.

A Paleo Diet rich in animal protein is the best dietary source of zinc, while a mix of fruit and veggies are key for boosting your vitamin C intake (some sources may surprise you!). To ensure you’re meeting your body’s increased demands throughout the fall/winter months, be sure to include the following foods:

Vitamin C

  • Yellow Bell Peppers – 345mg per large pepper
  • Broccoli – 92mg per cup (chopped)
  • Kale – 80mg per cup (chopped)
  • Orange – 70mg per fruit (medium)
  • Kiwis – 64mg per fruit

  • Oysters – 33mg per 6 oysters
  • Beef – 14mg per fillet (4.5oz.)
  • Lamb – 7mg per 3oz.
  • Pork – 4.3mg per 3oz.
  • Pumpkin seeds – 2.9mg per oz.


There is inherent ‘cross-talk’ between your gut and immune system, therefore ensuring the right balance of healthy microbiota in your intestinal tract will go a long way to fighting off colds and flus.10,11 Common fermented foods and Paleo staples like kombucha tea, sauerkraut, and kimchi, are great options for increasing ‘good’ gut bacteria. In addition, the polyphenols found in green tea also promote the growth of beneficial gut bacteria. If you struggle with frequent or persistent colds or flu, you may want to add a probiotic supplement to add further immune support.

Limiting the growth of ‘bad’ or dysbiotic gut bacteria is crucial to maintaining optimal intestinal microflora and therefore immunity. Short-chain saturated fats like butyric acid and lauric acid, found in butter and coconut oil, exert potent antmicrobial effects that help to keep bad bacteria in check.12,13

Don’t let the cold, dark months slow you down. Enhance your Paleo Diet by incorporating the foods richest in the key immune boosting nutrients – vitamin D, A, C, zinc, and probiotics – to increase your resiliency this cold and flu season.

Enjoy a healthy winter!


[1]Nieman DC et al. Influence of carbohydrate on the immune response to intensive, prolonged exercise. Exerc Immunol Rev 1998;4:64-76.

[2] Nieman DC, Pedersen BK. Exercise and immune function. Recent developments. Sports Med 1999;27(2):73-80.

[3] Walsh PH et al. Position statement. Part one: Immune function & exercise. Exerc Immunol Rev.2011;17:6-63.

[4] Youssef D et al. Vitamin D’s potential to reduce the risk of hospital-acquired infections. Dermatoendocrinol. 2012 Apr 1;4(2):167-75

[5] Heaney R, Bggerly C, Sorenson M, Vieth R. Toronto Vitamin D Disease Prevention Symposium. November 6th, 2013. Toronto, ON

[6] Semba RD. The role of vitamin A and related retinoids in immune function. Nutr Rev. 1998;56(1 Pt 2):S38-48

[7] Douglas RM et al. Vitamin C for preventing and treating the common cold. Cochrane Database Systematic Review. 2004 Oct 18;(4):CD000980.

[8] Peters EM, Goetzche JM, Grobbelaar B, Noakes TD. Vitamin C supplementation reduces the incidence of post race symptoms of upper-respiratory-tract infection in ultra marathon runners. Am J Clin Nutr 1993 Feb;57(2):170-4.

[9] Mangini S et al. A combination of high-dose vitamin C plus zinc for the common cold. J Int Med Res. 2012;40(1):28-42.

[10] Rask C et al. Differential effect on cell-mediated immunity in human volunteers after intake of different lactobacilli. Clin Exp Immunol 2013 May;172(2):321-32.

[11] Madden J.A.J. et al. Effect of probiotics on preventing disruption of the intestinal microflora following antibiotic therapy: A double-blind, placebo-controlled pilot study. Int Immunophar 2005: 5: 1091-1097.

[12] Mortesen FV, Nielsen H, Aalkjaer C, et al. Short chain fatty acids relax isolated resistance arteries from the human ileum by a mechanism dependent on anion-exchange. Pharmacol Toxicoli 1994;75(3-4):181-5. 6.

[13] Mortesen FV, Nielsen H, Mulvaney MJ, et al. Short chain fatty acids dilate isolated human colonic reistance arteries. Gut 1990;31(12):1391-4.

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