Two of the most popular stress-relief supplements on the market, saffron and ashwagandha, just went through one of the more rigorous evidence audits either has faced. A systematic review of randomized controlled trials asked a blunt question: do these herbs actually change stress, anxiety, and the hormones that drive them, or is the hype outrunning the data.
The review, published in the Journal of Visualized Experiments, pulled together the available randomized controlled trials testing saffron and ashwagandha against stress-related mental health outcomes. That includes perceived stress scores, anxiety symptoms, sleep quality, and in several cases, measured cortisol, the hormone most associated with the body’s stress response.
Researchers wanted to know not just whether these supplements worked, but whether the trials backing them were built well enough to trust.
Ashwagandha and the cortisol question
Ashwagandha, the root of Withania somnifera, has built its reputation largely on cortisol. The herb is thought to act on the hypothalamic-pituitary-adrenal axis, the signaling loop that governs how much cortisol the adrenal glands release under stress, rather than working through the serotonin pathways targeted by most antidepressants.
Several of the randomized trials feeding into reviews like this one have tested branded root extracts in adults with self-reported chronic stress, tracking blood cortisol before and after supplementation. Treatment groups typically see a meaningful drop in serum cortisol over sixty days, while placebo groups shift only slightly, and perceived stress and anxiety scores usually move in step with the hormone data.
That consistency is part of why ashwagandha has become a staple on stress supplement shelves. But a drop in a stress hormone on a lab panel is not automatically the same as a clinically meaningful change in how someone feels day to day, and the review’s authors were careful to separate the two.
Saffron’s case rests on mood, not cortisol
Saffron, the dried stigma of Crocus sativus, takes a different route. Its trial record leans heavily on mood and anxiety scales rather than cortisol, with several studies standardizing dosing around 28 to 30 milligrams of extract per day.
Some of the earlier randomized trials on saffron compared it directly against low-dose SSRIs in adults with mild to moderate depressive symptoms, reporting comparable improvement over six to eight weeks. Anxiety-specific trials have generally shown smaller, but still measurable, effects.
What saffron has going for it mechanistically is a plausible route to serotonin and dopamine activity, which separates it from ashwagandha’s hormone-focused story. That distinction is also why the two herbs tend to get studied, and marketed, somewhat differently despite both falling under the same stress-relief umbrella.
Where the evidence starts to wobble
A systematic review exists to stress-test the underlying trials, not just summarize their conclusions, and that is where both supplements run into trouble. Many of the randomized controlled trials behind saffron and ashwagandha are small, often fewer than 100 participants, and run for six to twelve weeks at most.
Reviewers typically apply standardized risk-of-bias tools, the kind built into Cochrane methodology, to score each trial on blinding, allocation concealment, and selective reporting. A sizable share of the saffron and ashwagandha literature scores poorly on at least one of those measures.
Dosing is inconsistent across studies too, with different extracts, concentrations, and proprietary formulations making it hard to compare one trial’s version of ashwagandha to another’s. Several trials were funded by the same companies that manufacture the branded extract being tested, a conflict of interest that reviewers are required to flag.
Combining the two isn’t backed by trials yet
Combination products pairing the two herbs have started showing up on supplement shelves, marketed as covering both the hormone and mood angles of stress at once. The review found essentially no randomized trial evidence testing saffron and ashwagandha together, which means every claim about a combined effect is extrapolated from two separate bodies of single-ingredient research rather than tested directly.
Stacking two unproven doses does not automatically produce a proven effect. In the absence of combination trials, buying both separately offers no more certainty than buying either one alone.
What the safety data actually shows
Efficacy was only half the review’s mandate. Safety was the other, and it is the part most marketing skips entirely.
Ashwagandha has drawn scrutiny over rare case reports of liver injury and documented increases in thyroid hormone levels, which matters for anyone already on thyroid medication or managing a thyroid condition. Most randomized trials report good short-term tolerability at standard doses, but the case-report signal is enough that clinicians generally advise caution during pregnancy and in people with autoimmune thyroid disease.
Saffron’s safety profile looks cleaner in the trial data, with mild gastrointestinal upset being the most commonly reported side effect at supplement doses. The toxicity concerns associated with saffron appear mainly at doses far above what any reputable supplement contains, well into the range once used historically as an abortifacient rather than anything sold as a wellness product today.
What this means before buying either one
The honest takeaway is that both saffron and ashwagandha have real, trial-supported signals for stress and mood, just not the kind of bulletproof evidence that should replace therapy, sleep, or clinical treatment for diagnosed anxiety or depression. The extract matters as much as the herb.
Trials used specific standardized formulations at specific doses, not whatever generic capsule happens to be cheapest on a shelf. Results from a branded, clinically tested extract do not automatically transfer to an unrelated product sharing the same plant name on its label.
Anyone on thyroid medication, immunosuppressants, or antidepressants should loop in a doctor before adding either supplement, given the interaction and monitoring questions the review flagged. For most healthy adults looking to take the edge off a stressful stretch, the data supports giving one of these a measured trial, taken consistently for at least six to eight weeks before judging whether it is doing anything.
The review’s broader recommendation is less about ruling out either herb and more about raising the bar for the next decade of research. It calls for larger trials with harmonized dosing, standardized extracts, and head-to-head comparisons against each other and against first-line treatments, rather than more small studies each testing a different proprietary formulation against placebo.
Until that happens, every headline claiming a definitive stress cure from either plant is getting ahead of what the trials actually support.
