By Ana Sandoiu

Fact checked by Jasmin Collier

New research has examined the potential of spinach extract as an enhancer of athletic performance. The active compound in spinach extract significantly improves muscle strength, leading the study authors to recommend banning the supplement in sports.

Rich in calcium, magnesium, and iron, some people call spinach a “superfood.”

Some studies have suggested that spinach has a variety of health benefits, such as keeping cancer at bay, preventing asthma, lowering blood pressure, and helping those with diabetes manage their condition.

New research looks at another potential benefit of the plant, although the study examined an extract from spinach in the form of a dietary supplement rather than the food itself.

Specifically, researchers led by Maria Parr — a professor of pharmaceutical chemistry at the Freie Universität in Berlin, Germany — examined the effect of ecdysterone on athletic performance and muscle strength.

Ecdysterone is the main compound in spinach extract. It is a phytosteroid — that is, a steroid that occurs naturally in plants and belongs to a class called phytosterols, which are “structurally similar to cholesterol.”

Previous studies in mammals have shown that ecdysteroids have a wide range of beneficial effects. In the 1980s, researchers dubbed ecdysterone the “Russian secret,” following suspicions that Russian Olympic athletes were using it as a performance boosting supplement.

Other studies have demonstrated that ecdysterone “increases protein synthesis in skeletal muscle.” In fact, as Prof. Parr explains, previous tests in vitro and in vivo showed that ecdysterone is more potent than other steroids banned in sports, such as methandienone.

The new study paper appears in the journal Archives of Toxicology.

Studying ecdysterone and muscle strength

For their research, Prof. Parr and team carried out a double blind study involving 46 young athletes.

The researchers divided them into two groups: one that received spinach extract (the intervention group) and another that received a placebo. Neither the participants nor the researchers knew what they were taking, and the intervention lasted for 10 weeks.

During this time, the people in the intervention group received “[d]ifferent doses of ecdysterone containing supplements” to ascertain their effects on performance enhancement.

The scientists took blood and urine samples and analyzed them for ecdysterone and “potential biomarkers of performance enhancement.” They also did a “comprehensive screening for prohibited performance enhancing substances.”

Higher muscle mass and better performance

Results revealed that the participants who took ecdysterone had “[s]ignificantly higher increases in muscle mass.” In vitro experiments replicated the findings, and Prof. Parr and colleagues showed that ecdysterone interacts with the estrogen receptor beta. The tests also revealed significant “increases in one-repetition bench press performance.”

However, the blood and urine tests displayed no signs of liver or kidney toxicity.

As Prof. Parr and team explain in their study paper, “These data underline the effectivity of an ecdysterone supplementation with respect to sports performance.”

They conclude:

“Our results strongly suggest the inclusion of ecdysterone in the list of prohibited substances and methods in sports in [the] class […] ‘other anabolic agents.'”

Prof. Parr adds that the participants who took a low dose of the supplement received two pills of ecdysterone daily, which is the equivalent of anywhere between 250 grams (g) and 4 kilograms (kg) of spinach, depending on the quality of the plant.

So, to reap the benefits of such a low dose, a person would have to consume 250 g to 4 kg of spinach every day for 10 weeks. To mimic the high dose in the study, a person would have to consume anywhere between 1 and 16 kg of spinach every day for 10 weeks.