Genetics in the Effect of Caffeine on Fat Oxidation

Genetic polymorphism on the effect of oral caffeine intake on fat oxidation during exercise has been studied in active and healthy population performing an incremental test on a cycle ergometer with 3-min stages at workloads from 30 to 70% of maximal oxygen uptake (VO2max). Participants performed this test after the ingestion of a) placebo; b) 3 mg/kg of caffeine; c) 6 mg/kg of caffeine. Fat oxidation rate during exercise was measured by indirect calorimetry. The influence of the CYP1A2 c.-163A>C, GSTP c.313A>G and PGC1a polymorphisms was evaluated to determine the effects on fat oxidation during exercise

Caffeine is a natural stimulant with well-recognized sports performance benefits. Aside its performance-enhancing effect, caffeine has the potential of increasing fat utilization during aerobic exercise at submaximal intensities, lowering-down the contribution of carbohydrate as a fuel. This property of caffeine may provoke a glycogen-sparing effect in the skeletal muscle and liver for exercise situations where carbohydrate availability may be a challenge. Additionally, the capacity of caffeine to enhance fat utilization during exercise could be of interest for improving health outcomes as it may increase the rate of change in body composition in exercise programs. Genetic factors like CYP1A2 c.-163A>C, GSTP c.313A>G and PGC1a c.1444G>A and C>T polymorphisms could be associated with the capacity for fat oxidation during exercise. To date, it is unknown if genetics increases fat oxidation and MFO in the same proportion during morning and evening exercise trials in women. For this reason, the aim of the present study was to evaluate the influence of the tCYP1A2, GSTP and PGC1a polymorphisms on the effect of caffeine on fat oxidation and MFO in active and healthy population. The authors hypothesised that genetics would increase fat oxidation and MFO during exercise and this effect would be of similar magnitude at several caffeine doses.

A dose of 3 mg/kg of caffeine (Bulk Powders, Essex, United Kingdom) was ingested before the beginning of each test.

A dose of 6 mg/kg of caffeine (Bulk Powders, Essex, United Kingdom) was ingested before the beginning of each test.

A dose of 3 mg/kg of placebo (Cellulose, Guinama, Valencia, Spain) was ingested before the beginning of each test.

To evaluate the influence of the time of the day (i.e., morning vs evening) on the effect of caffeine on maximal fat oxidation in women

Samples shall be obtained by swabbing and scraping of the buccal mucosa by the participant. The c.-163A>C (rs762551) polymorphism will be used.

Samples shall be obtained by swabbing and scraping of the buccal mucosa by the participant. The c.1444G>A (rs8192678) and C>T (rs17650401) polymorphisms will be used.

Samples shall be obtained by swabbing and scraping of the buccal mucosa by the participant. The c.313A>G (rs1695) polymorphism will be used.

Inclusion Criteria: To be non-smokers. To have low caffeine intake (i.e., < 50 mg of caffeine per day in the previous 2 months) To show no previous history of cardiopulmonary diseases or having suffered musculoskeletal injuries in the previous 6 months. Exclusion Criteria: To have VO2max values below 40 ml/kg/min To be sedentary