An examination into the mental and physical effects of a saffron extract (affron®) in recreationally-active adults: A randomized, double-blind, placebo-controlled study.

The short version

This randomized, double-blind, placebo-controlled trial with 62 recreationally active adults tested whether a standardized saffron extract changes how much people enjoy exercise, how they feel, how they sleep and how their heart rate varies. Saffron comes from the dried stigmas of the Crocus sativus flower, and its extract affron® is standardized to contain safranal and crocin, compounds studied for mood-enhancing effects at about 28-30 mg a day in adults with low mood or anxiety. Heart rate variability (HRV), the beat-to-beat variation in heart rate, serves as a marker of the body's calming parasympathetic activity. Adults aged 18 to 65 who exercised more than three times a week were randomly assigned for six weeks to take either 14 mg of saffron extract or a matching placebo tablet twice daily (28 mg of saffron a day). They kept exercising as usual. The main measure was the Physical Activity Enjoyment Scale, an 18-item questionnaire. The team also tracked mood with a 40-item survey, sleep and HRV with a WHOOP wrist strap, and blood levels of three brain-related chemicals at the start and end. Across everyone, saffron did not beat placebo on any measure (exercise enjoyment p = 0.276, mood p = 0.787, HRV p = 0.502, sleep time p = 0.598, meaning no real difference between groups). Enjoyment did climb within the saffron group, from 107.99 to 114.44 points (p = 0.001), but placebo also drifted upward. In an exploratory split by sex, the 22 men on saffron gained more enjoyment than the 15 men on placebo (113.81 versus 106.20 points, p = 0.009), and their HRV rose about 9% while placebo men's fell 5.7% (p = 0.001). No such differences appeared in the 9 women on saffron or the 16 on placebo. Side effects were mild and uncommon. The authors describe the male-only findings as preliminary, since the groups were small and uneven by sex, and the headline result was null. Healthy, already-active volunteers may leave little room for improvement, women's hormonal cycle phase was not controlled, and the wrist-worn tracker is less precise than laboratory sleep and heart measures. They recommend larger trials with varied doses and durations.

Key findings

• In this six-week trial of 62 recreationally active adults, a standardized saffron extract (28 mg a day) did not beat a matching placebo on exercise enjoyment (p = 0.276), mood, sleep or blood markers across all participants.
• In an exploratory analysis of 37 men, those on saffron gained more exercise enjoyment (113.81 versus 106.20 points on an 18-item scale, p = 0.009) and a larger rise in heart rate variability (HRV, the beat-to-beat variation that reflects calming nerve activity; about +9% versus -5.7%, p = 0.001).
• No differences appeared in the 25 women, and the authors treat the male-only findings as preliminary because the groups were small and uneven by sex (22 men and 9 women took saffron).
• Side effects were mild: 84% of saffron participants reported none, and the few reports were vivid dreams (2), muscle pain (1) and thirst (1).
• Because participants were healthy and already active, there may have been little room to improve, and women's menstrual cycle phase was not controlled, so a larger trial is needed to confirm any effect.

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