This primary conclusion is drawn from a review led by Nutrigenomix, in which the team identify a strong body of evidence linking genetic variants with caffeine’s effect on endurance performance.
“This is the kind of research that sport dietitians are looking for to better serve their athletes,” said Dr Nanci Guest, lead author of the paper, who completed her PhD in nutritional sciences at the University of Toronto.
“DNA-based personalised sports nutrition is ready for prime time, but DNA-based approaches to personalised fitness training are not despite some genetic tests making such claims.
“It’s important to ensure that the genetic test you use is grounded in solid science and not glitzy marketing”.
Dr Guest’s comments come as the industry moves away from the “one-size-fits-all” group approach and toward personalisation for the individual, moving nutrigenomics research from basic science into practice.
The raft of nutrigenomic activity from firms such as DNAfit, BASF and Spoon Guru, particularly for sports suggests that personalised assessments are already driving the next stage of growth.
But while blood panels can reveal nutritional deficiencies within a few hours, unravelling the role of genetics will take some time as the review acknowledges the lack of gene-diet interaction studies that directly measure performance outcomes in competitive athletes.
Caffeine and vitamin A
Central to the review’s argument are the variation in genes such as CYP1A2 and possibly ADORA2, which are associated with caffeine metabolism, sensitivity and response.
The research team, based at the University of Toronto and the University of Western Ontario, point to caffeine’s potency to restore cognitive or physical performance.
Its mechanism of action possibly involving the adenosine neuromodulator/receptor system may serve athletes well under conditions of jetlag, and irregular or early training or competition schedules.
The largest caffeine/exercise study to date looked at the CYP1A2 genotype, on 10 km cycling time trial in male athletes after taking 0 milligrams (mg), two mg or four mg of caffeine per kilogram (kg) body mass.
There was a 3% improvement in cycling time in the four mg dose in all subjects. However, there was a significant caffeine-gene interaction where performance improvements were seen at both caffeine doses, but only in those with the AA genotype who are caffeine “fast metabolisers”.
In that group, a 6.8% improvement in cycling time was observed at four mg/kg. Those with the CC genotype, four mg/kg caffeine impaired performance by 13.7%. Those with the AC genotype showed no effect of either caffeine dose.
Athlete health, immunity and performance
Along with anaemia-related micronutrients, vitamins C, D, calcium and choline, the review also looks at vitamin A and its link to optimal health, immunity and performance in athletes.
While, no studies examine the role of genetic modifiers of vitamin A status directly on athletic performance, its contribution to the superior visual abilities of high-performance athletes is noted.
“Upon absorption, provitamin A carotenoids are readily converted to vitamin A by the BCMO1 enzyme,” the review said.
“β-Carotene is the most abundant provitamin A carotenoid in the diet and the conversion of beta-carotene to retinal or retinoic acid is necessary for vitamin A to exert its biological functions.
The team said the rs11645428 variant in the BCMO1 gene might affect plasma carotenoid levels. Those with the GG genotype are inefficient at this conversion, and may be at higher risk for vitamin A deficiency.
“These individuals are considered low responders to dietary β-carotene so consuming enough dietary pre-formed vitamin A (or supplements for vegans), can help to ensure that circulating levels of active vitamin A are adequate to support vision, immunity and normal growth and development.”
“I consider this review to be very timely, as I navigate the variability in response to sport supplements that I see in my own research,” said Dr Dana Lis, sport scientist at the University of California at Davis.
“I also work with several high-performance athletes and teams, and I look forward to exploring more of this area of research as it moves forward, with the prospect of using genetic testing to help better understand certain aspects of an athlete’s diet.”
Source: Frontiers in Nutrition
Published online: doi.org/10.3389/fnut.2019.00008
“Sport Nutrigenomics: Personalized Nutrition for Athletic Performance.”
Authors: Nanci Guest et al