The Effect Of A Ketogenic Diet On The Exercise Induced Immune Response

Abstract

PURPOSE: Ketogenic diets are popular amongst athletes, they improve fat oxidation capacity and training with low carbohydrate (CHO) availability can possibly enhance training adaptation. However, performance improvements are not observed and training with low CHO availability may increase the susceptibility to illness and infection. Therefore, the aim of this study was to examine the effect of a (short and longer) ketogenic diet on the exercise induced immune response. METHODS: in this cross-over study, 14 well trained male athletes (age 32.9±8.2 years, VO2max 57.3±5.8 ml/kg/min) were assigned to two weeks on a low CHO ketogenic (LC) diet (< 10En% CHO) and two weeks on a high CHO (HC) diet (> 50En% CHO) in a random order, with a wash-out period of >2 weeks in between. Test days were planned after 2 days and 2 weeks on both diets. During test days athletes cycled for 90 minutes at 70% VO2max and blood samples were taken at baseline, directly after exercise and 2hr after exercise. Blood samples were analysed for cortisol, immune cell differential count and homing factors. RESULTS: Total work load performed during the exercise test was lowest after 2 days on the LC diet (938.6±162.5 kJ) and improved after 2 weeks (1003.2±128.6 kJ, p=0.03), but was still lower compared to the HC diet (~1040 kJ, p>0.05). Cortisol response after exercise was higher after 2 days on the LC diet (822±215 nmol/L) compared to the response after 2 weeks on the LC diet (669±243 nmol/L) and compared to both test days during the HC diet (609±208 and 555±173 nmol/L, both p<0.001). Immune cell differential count, for T-cells, Th cells, Cytotoxic T cells, NK T cells, B cells and monocytes was significantly different between diets (p < 0.05). Differences between diets were more pronounced after 2 days on the diets compared to 2 weeks on the diets. The CCR7+ homing factor on CD4+ cells (which guides cells to lymph nodes) was higher during the LC diet, compared to the HC diet (p< 0.05) CONCLUSIONS: The short term ketogenic diet caused a higher stress response and more pronounced differences in cell differentiation, compared to the HC diet. In addition, homing of CD4+ cells to the lymph nodes was stronger on the LC diet compared to the HC diet.