I came upon a podcast on the Canadian CBC site from their science show "Quirks and Quarks". You can listen to it here.
They interview the Canadian author of a study published in the Journal of the American Medical Association which wanted to find why there is such variation between studies on the risks associated with coffee drinking. Some studies find that there is an increase in risk of heart attack, while others seem to find a preventative effect.
This study by authors from Toronto, Harvard and Costa Rica looked at a genetic link. Some people have a so-called "fast" form of the enzyme that metabolizes caffeine while others have a "slow" form. The results were, in my opinion, astounding:
For those with the "fast" form of the gene drinking 1-3 cups of coffee each day decreased the risk of heart attack by 50%
BUT for those with the "slow" form of the gene, drinking four or more cups of coffee resulted in a four-fold increase in the risk of heart attack which is equivalent to that of a heavy smoker.
The authors note that in a multi-ethnic city such as Toronto where they live, the two forms of the gene appear each in about 50% of the population but that it is likely more prevalent in some ethnic groups. They did not mention any in particular as this is the first study of its kind, but they suggest that this is the reason for conflicting results from different studies. Some would have been conducted in groups with a high prevalence of the "slow" gene and thus found negative effects from drinking coffee. Other studies would have been conducted in populations with a high prevalence of the "fast" gene and thus foudn beneficial effects of coffee drinking.
The authors mention that that expect this study is just the beginning of a new era of personalized nutrition where we find that for genetic reasons different people need to have thier diets tailored specifically.
I can't help but think that these two forms of the gene may have an impact on athletes' performances as well. At the very least, if you believe caffeine is ergogenic (aids performance) one would expect these two forms of gene would effect either the timing of when it is ingested before a race - sooner if you have the fast form, longer before with the slow form. Alternatively, it could affect how much caffeine is beneficial to performance for similar reasons.
Have a listen to the podcast and see (ah, hear) what you think.
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