A 10-week study in Berlin found that people who consumed high doses of ecdysterone, a chemical found in spinach, performed better.
It might seem unlikely that humans could get super-human strength from spinach, like cartoon character Popeye the Sailor, but its creator Elzie Crisler Segar may have been been on to something.
Scientists at the Freie Universität Berlin's Institute of Pharmacy have recommended that ecdysterone, a hormone found in spinach, be included in the list of prohibited substances for athletes.
During a 10-week study, led by the university's Institute of Pharmacy, participants were split into four groups.
One was a control group, another received a placebo, while the third and fourth respectively received two and eight capsules containing 100 mg of ecdysterone from spinach extract every day.
"Significantly higher increases in muscle mass were observed in those participants that were dosed with ecdysterone," the study said in published notes.
"Even more relevant with respect to sports performance, significantly more pronounced increases in one-repetition bench press performance were observed," it added.
Maria Parr, one of the study's scientists, told ARD and ARTE that their "hypothesis was that we would see an increase in performance, but we didn't expect it to be that big."
"We recommended to WADA (the World Anti-Doping Agency) in our report that the substance be added to the doping list. We think that if it increases performance, then that unfair advantage should be eliminated," she added.