This narrative review explores the mechanisms of action and efficacy of caffeine and the potential for combinations of caffeine and other dietary compounds to exert psychological effects in excess of those expected following caffeine alone.
Key Points:
- Caffeine, when taken alone, is associated with reasonably consistent ergogenic and psychological benefits. However, its effects on mental performance are limited, and do not encompass benefits to several sport-relevant cognitive domains.
- Caffeine is typically consumed alongside other bioactive compounds.
Evidence suggests that products derived from caffeine-synthesising plants, including high polyphenol cocoa, guaraná and coffee extracts, engender mental performance benefits that exceed those expected from their caffeine content.
Similarly, multi-component energy drinks and shots may be more effective than their caffeine content.
- Further research disentangling the comparative contributions of caffeine and other co-consumed bioactive ingredients to their combined effects is required in order to inform future recommendations.
Mental Performance and Sport: Caffeine and Co-consumed Bioactive Ingredients (open access)
This one found that the consumption of skimmed milk after exercise may reduce subsequent energy intake, such that total energy intake is not different from a low-energy placebo beverage and reduced relative to a sucrose beverage.
"The main finding was that ad-libitum energy intake 60 min after beverage ingestion was reduced following skimmed milk compared to a sucrose beverage and tended to be reduced for skimmed milk compared to the placebo beverage...
"...This meant that total energy intake (ad-libitum energy intake plus the energy provided in the post-exercise beverage) was lower following skimmed milk and placebo compared to after ingestion of the sucrose beverage...
This one found distinct adiposity-related body shape phenotypes to be associated with the risk of cancer, identifying novel relationships, suggesting that cancer burden associated with adiposity and body size based on classical anthropometric traits is likely underestimated.
- Results for overall adiposity:
The hazard ratio for overall cancer risk per 1 SD increment for the overall adiposity phenotype was 1.07.
In this one, both 3mg/kg and 6mg/kg doses of caffeine ingestion increased plasma catecholamine concentration and improved the average peak power output during a repeated sprint test in trained female team-sport players.
- Both doses of coffee ingestion improved the average peak power output attained by participants during the repeated sprint test compared to placebo, with no differences between doses.
- Peak and mean power output and the fatigue index did not improve during the individual sprints.
This one suggests that a higher genetic predisposition to gut microbial relative abundance is associated with greater reductions in central adiposity and body composition in response to weight-loss diet interventions, an effect that may be modified by dietary protein.
- In this large dietary intervention trial, a higher GRS for gut microbial relative abundance was associated with 2 year reductions in waist circumference and body composition.
- The relations of the gut microbial abundance GRS with changes in fat mass were modified by the dietary protein intake at 6 months.
In this one in mice, resistance exercise was found to counteract the effects of an obesogenic diet on body composition, while also being associated with improved glucose tolerance, even after exercise cessation.
- The study wanted to investigate the preventive effects of resistance exercise on body weight, gonadal fat mass, and glucose tolerance and determine whether the beneficial effects of exercise are associated with skeletal muscle strength and endurance in mice.
- Skeletal muscle strength (as measured by grip strength) and skeletal muscle endurance (as assessed by hanging time) were increased, even after exposure to an obesogenic diet for 1 week (~280 human days) after exercise discontinuation.
This one found that Sicilian long-lived individuals have changes in circulatory fatty acids status with advancing age, characterized by a reduction in blood levels of total PUFA and trans FA with age, whereas total SFA remained unchanged throughout life.
- This fatty acid profle characterized by high MUFA content may indicate reduced peroxidation while maintaining membrane fluidity.
- "We suppose that the high consumption of the extra virgin olive oil (EVOO) may have infuenced this datum"