Cadets given cinnamon capsules threw a ball 30% farther in six weeks. Nobody was given a dummy capsule, and some of the sums don't add up

Cinnamon has been tested for years as a help with blood sugar, with mixed results. Its use as a fitness supplement is newer and rests mostly on animal work. Two exercise physiologists at the University of Mohaghegh Ardabili in Iran wanted to know whether it adds anything to Tabata training, the short, very hard interval format of 20 seconds of effort and 10 seconds of rest. Their trial was published online in the Journal of the International Society of Sports Nutrition on 7 October 2026.

They recruited 48 male officer cadets aged 20 to 25 at a military academy in Tehran and randomly split them four ways: Tabata sessions three times a week, cinnamon alone, both together, or neither. The cinnamon was Ceylon cinnamon (Cinnamomum zeylanicum) in capsules, 1.5 g a day in three doses with meals. All the cadets kept eating the academy's food and doing its routine drills. Before and after six weeks they took the six-event fitness test designed by the US Army (deadlift, backward medicine-ball throw, push-ups, a sprint-drag-carry shuttle, leg tucks and a two-mile run, scored out of 600), had their body composition estimated on an electrical impedance scale, and gave blood for irisin, a hormone-like protein that muscle releases during exercise.

Forty-five cadets finished. On the paper's figures every treated group improved and the untreated group stood still. The average test score rose from 430 to 467 with Tabata alone, from 444 to 497 with Tabata and cinnamon, and from 468 to 496 with cinnamon alone, while the control group went from 481 to 479. The cinnamon-only cadets, who did no extra exercise, are reported to have lost 2.2 kg, thrown the medicine ball 2.3 metres farther (7.6 to 9.9 m) and raised their irisin by about a third. The combined group lost 5.7 kg and their body fat reading fell from 21.3% to 17.3%. Food diaries showed no change in how much anyone ate.

That is the part to slow down on. There was no placebo: cadets in the cinnamon groups knew they were swallowing capsules, and the control group swallowed nothing. A fitness test rewards effort, and people who believe they are on something tend to try harder, which is exactly why supplement trials use dummy capsules. The authors list this as a limitation themselves, and say the combined effect should be read as possible or additive, not proven. The four groups also started far apart for a randomised study, from 430 points to 481, with the control group managing about nine leg tucks at the start against two or three in the Tabata group. Groups of nine to thirteen can end up lopsided like that by chance, and although the analysis adjusted for starting values, small uneven groups make shaky comparisons.

Then there are the numbers themselves, and this reading is ours, not the paper's. In the combined group body weight fell by 7% while body mass index fell by 16%. BMI is weight divided by height squared, so in adults who are not shrinking the two percentages have to match. The methods describe six weeks at three sessions a week, which is 18 sessions, but give the total as 24; the food diaries are said to have been collected after an eight-week intervention. The trial gives no registration number, so there is no public record of what the researchers planned to measure before they began. None of this proves the cadets didn't get fitter. It does mean a result this good, a spice with no training matching a good share of what hard intervals achieved, needs repeating with a placebo and a registered plan before anyone leans on it. The work was funded by the Iran National Science Foundation and the authors report no conflict of interest.