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Caffeine, beets and beta-alanine: do they work for female runners?

Each of these supplements has been shown to be effective for male runners, but less is known about how effective they are for women

Caffeine, beets and beta-alanine have been widely accepted as legal performance aids in the running community, but is this true for everyone? Most of the research conducted on these supplements has been done with male subjects, leaving their efficacy in women up for debate. Recently, a team of researchers reviewed the available literature to answer this question, and the results are not entirely clear.

Men vs. women

The researchers pointed out the physiological differences between men and women, including differences in sex hormones and fluctuations in women’s menstrual cycles, make generalizing male data to female athletes unhelpful, and even potentially harmful. In their review, published in the International Journal of Sport Nutrition and Exercise Metabolism, the team found only nine studies on beta-alanine, 15 on caffeine and 10 on nitrate (a.k.a. beets) conducted on healthy women, and here is what the research said:

Beta-alanineevidence suggests that beta-alanine may lower the rate of perceived exertion for female runners, allowing them to run longer and achieve “greater functional adaptations.” In other words, beta-alanine can make running feel easier, so you can run more and improve your performance.

CaffeineStudies show that caffeine is an effective performance aid for women, but like men, exactly how effective depends on how responsive your body is to caffeine (fast metabolizer vs. slow metabolizer) and how much coffee you drink on a regular basis.

Nitratethe efficacy of nitrate (the active compound in beets) appears to depend on what type of activity you’re doing and which muscle group you’re looking at.


Unfortunately, the studies for all three of these supplements are missing some key pieces of information. Most notably, the researchers highlight that there is no clear consensus on dosage, timing, or even how effective these supplements really are for female athletes. In other words, none of these studies provide enough information to make strong, evidence-based recommendations to female athletes.

Additionally, the researchers point out that very few of the studies considered hormonal status and how this affects metabolism, which could have an impact on how well each of the supplements work for female athletes. Not surprisingly, their research led the team to the following conclusion: “This gap in sex-based knowledge necessitates further research on these ergogenic supplements in women with greater considerations for the effects of hormonal status.”

So the question remains: should female runners bother using the supplements at all? For now, the answer really depends on the individual. If you find any of them help you run better, then, by all means, go ahead and (safely) use them. We don’t have all the answers currently, but for now, it doesn’t appear as though they are harmful to your performance, either.