Carbohydrates and Immune Function

Following on from the first in a three part series of articles, we are now focusing on carbs and their influence on the immune system. 

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A hard training schedule can improve fitness and health dramatically, but it can also suppress your immune system.

Epidemiological evidence suggests that moderate exercise protects against upper respiratory illnesses, like the common cold, whereas regular intense exercise increases this risk, due to a suppressed immune system.

Many components of the immune system exhibit change after prolonged, heavy exertion, indicating that the immune system is suppressed and stressed. Poor nutrition choices coupled with strenuous exercises can have negative effects on the immune system.

Up until recently, carbohydrates were not thought to have had a heavy influence on the adaptations in the immune system.

Consuming carbs during workouts is viewed mainly as a performance-enhancing strategy, but evidence exists that supports the immune boosting effect of consuming carbs. People who follow carbohydrate restrictive diets, and who also participate in frequent high intensity exercise, can suffer from greater exercise related stress hormones compared with athletes following a carbohydrate-rich diet. Further studies have revealed that if blood glucose levels are low, white cells (which protect against infection and illness) multiply at very modest rates.

Two well structure studies analysed 30 marathon runners and 10 triathletes and found that immune responses to carbohydrate compared to placebo ingestion diminished the physiologic stress of long intense exercise. There was a direct correlation between the post exercise glucose levels and cortisol levels (stress hormone).  

If you are partaking in multiple high intensity sessions, especially when the recovery time between the two sessions is short, the consuming carbohydrate in the first few hours after exercises can help restore glucose levels and immune function quicker, as well s helping fuel for the next session.

It must be noted that that easy workouts lasting just 30 to 45 minutes would have minimal negative effects on the immune system, making intra-workout and potentially post workout carb consumption unnecessary, especially if your goal is to use fat as a fuel source.

As a rule of thumb, workouts lasting more than an 60 minutes or particularly intense sessions lasting 45 minutes or more are probably the ones which call for intra-session carbs consumption.

Naturally, athletes can increase their chances of staying healthy by following a diet which is adequate for carbohydrate, protein, and fat, as well as vitamins, minerals, fibre, and antioxidants.

The next article from myself will be looking at the connection between fats and the immune system.


S&C Coach