Yes, it can. According to Clinics in Sports Medicine, ‘During this open window of impaired immunity’which may last three to 72 hours, depending on the immune measure’viruses and bacteria may gain a foothold, increasing the risk for subclinical and clinical infection’ (18:537-548;1999).
The researchers in question looked at the effects of zinc, vitamin C, glutamine and carbohydrate on immunity after prolonged exercise. With regard to zinc, vitamin C and glutamine, the report stated that all the data thus far has been inconclusive; however, ‘the most impressive results have been reported with carbohydrate supplementation.
‘Physiological stress to the immune system is reduced when athletes use carbohydrate beverages before, during and after prolonged and intense exertion.’ That keeps blood sugar levels from falling too low while at the same time holding down cortisol levels. A good phosphatidylserine supplement can also help keep cortisol levels low.