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- Alex Hutchinson (@sweatscience)
The supplement: Coenzyme Q10.
Used for: Endurance, power.
The evidence: Coenzyme Q10 is one of those supplements that has been lingering for decades, with no one quite able to prove or disprove its benefits. It’s a vitamin-like substance that we produce naturally, found in every cell in the body, and it has several key roles including fighting free radicals (i.e. it’s an antioxidant) and producing ATP, the essential cellular fuel. There are studies dating back to the 1980s claiming that CoQ10 improves everything from anaerobic threshold to aerobic power — but there are as many or more studies, using similar dosages and protocols, that didn’t find any benefit at all.
Generally, if it’s that hard to prove an effect, it means the benefits probably aren’t that great. But a study in the Journal of the International Society of Sports Nutrition last year proposed an interesting alternative. Researchers from Baylor University suggested that the problem is that most oral CoQ10 supplements simply aren’t bioavailable enough to be taken up in the muscles. So they tried a new “fast-melt” version of the supplement (whose manufacturer, it should be noted, funded the study), and they monitored CoQ10 levels both in the blood and in the muscle cells of their subjects, during a double-blind trial.
Even with the more bioavailable supplement, levels of CoQ10 didn’t rise as much in the muscles as in the blood — but they did rise, and that was correlated with increased time to exhaustion in a treadmill test.
The verdict: There’s still a lot more research to be done — but the Baylor study revives hope for a supplement that decades of ambiguous results had caused most people to write off. One intriguing hypothesis the researchers make is that supplementing with CoQ10 for too long might cause the body to slow down its own production of CoQ10, which might explain why studies lasting four to six weeks have failed to increase levels of CoQ10 found in muscles. As a result, CoQ10 might need to be taken like creatine, in shorter on/off cycles. That — like pretty much all the claims about CoQ10 — still needs to be tested before it’s worth trying.