A new study by the University of Chichester has found that medium doses of blackcurrant extract have no consistent effect on performance or physiological responses in cyclists in a fed state.
Blackcurrant extract has previously been shown to have significant performance effects in a fasted state or following a light breakfast with morning testing.
This is the first study to assess the outcome when used following ‘normal’ meals and late afternoon or early evening testing. The findings suggest a higher dose may be required to achieve metabolic and physiological responses when having had ‘normal’ meals.
The unique study tested participants over a prolonged period of time as well as at varying times during the day to mimic the ‘real world’ settings of late-afternoon and early-evening racing.
The study compared daily doses of 300mg, 600mg CurraNZ® New Zealand blackcurrant extract and a placebo on 13 male cyclists, two hours before testing. They were assessed in a 16.1km time trial on three occasions over seven days. Participants ate a normal breakfast, a normal lunch, with no food intake three hours before the late-afternoon or early evening testing sessions.
The findings showed:
The study resulted in the publication of two papers - one focusing on performance and physiological responses, the other focusing on cardiovascular responses (links below).
The study wasn’t without its limitations, but highlights that more work is needed to determine the dosing to compensate for nutrition during the day in order to maintain a performance-enhancing effect.
Mark Willems, Professor of Exercise Physiology at the University of Chichester, who led the study, suggests that greater loading of blackcurrant may be needed when participants are competing in a fed state, rather than the idea that the berry is ineffective in these types of trials.
He says: “There is still room to play with the dosing, other clinical studies have used 600mg-700mg anthocyanin over many months. The highest dose we have used is three capsules – ie. 315 mg of anthocyanins – over a week in a fasted state.”
There were some variables in the cohort group that may have had a bearing on the outcome.
Professor Willems explains: “One of the limitations was the study cohort used trained individuals, but not highly trained athletes, so there were performance variations from person to person. Also, the study took six-seven months to complete and their training status may have changed during that period.”
Professor Willems downplayed the no-effect finding for fat oxidation, because of the impact of food intake on substrate use.
He says: “It is likely the reason we found no fat oxidation findings was by the effect of ‘normal’ meals– it would be interesting to examine with higher doses in fed-state cyclist’s.
“There was a reduction in total peripheral resistance and an increase in cardiac output. While it may have been a small effect size, these adaptations are still beneficial.
“This study does, however, throw up a question about the possible food relationship with absorption. It would be useful to know if the food matrix interferes with blackcurrant intake, but that requires measurement of metabolites.”
Professor Willems and his team are presently undertaking a study investigating the effect of acute higher doses in cyclists during a 16.1km time trial.
No Effects of New Zealand Blackcurrant Extract on Physiological and Performance Responses in Trained Male Cyclists Undertaking Repeated Testing Across a Week Period was published in Sports. https://doi.org/10.3390/sports8080114
No Effects of Different Doses of New Zealand Blackcurrant Extract on Cardiovascular Responses during Rest and Submaximal Exercise across A Week in Trained Male Cyclists was published in the International Journal of Sports Nutrition Exercise Metabolism, DOI: 10.1123/ijsnem.2020-0164