Rhodiola and Holy Basil for Cortisol: What the Evidence Shows Beyond Ashwagandha

Ashwagandha gets most of the attention on this site and in the wellness aisle generally, but it is not the only "adaptogen" being marketed for cortisol and stress right now. Rhodiola rosea and holy basil, also called tulsi or Ocimum tenuiflorum, show up constantly in supplement blends promising calmer stress hormones. The evidence for these two is real but smaller and less consistent than the ashwagandha research, which makes them a useful case study in separating what is measured from what is marketed.

Rhodiola has the longer research history. A randomized, double-blind, placebo-controlled trial published in Planta Medica gave 60 adults with diagnosed stress-related fatigue either 576 milligrams a day of a standardized Rhodiola extract (SHR-5) or a placebo for 28 days. The treatment group showed improved fatigue symptoms, better performance on attention tasks, and a change in the cortisol-awakening response, the sharp rise in cortisol that normally occurs in the first half hour after waking. That is a genuine, controlled result, though it comes from one trial in people with a diagnosed fatigue condition, not confirmation that Rhodiola measurably changes cortisol in an average healthy adult managing ordinary daily stress.

Holy basil's evidence is newer and, in one respect, more directly relevant to cortisol specifically. An 8-week randomized, double-blind, placebo-controlled trial in Frontiers in Nutrition tested a standardized Ocimum tenuiflorum extract at a comparatively low dose, 250 milligrams daily, in adults reporting stress and poor sleep. Participants taking the extract showed reduced perceived stress, better subjective sleep quality, and, notably, a smaller salivary cortisol rise when deliberately exposed to an acute stressor in the lab, compared with the placebo group. That last finding is closer to a direct cortisol-reactivity result than most adaptogen studies manage.

Zooming out, a 2023 systematic review and meta-analysis in the Journal of Functional Foods pooled 25 studies across nine different adaptogenic herbs, including Rhodiola, holy basil, and ashwagandha. The strongest, most consistent signal in that pooled analysis was for ashwagandha specifically, with a measurable drop in both serum cortisol and perceived stress scores across trials. Rhodiola and holy basil had supportive individual trials but a thinner overall evidence base once pooled across fewer, smaller, and more heterogeneous studies, which is a meaningfully different evidence tier than "proven."

This is exactly where the trend-versus-proven line matters. Supplement marketing tends to present the entire adaptogen category as interchangeable, implying that if ashwagandha has decent trial support, Rhodiola and holy basil must too. The actual research does not support treating them as equivalent. Rhodiola and holy basil both have at least one legitimate, well-designed human trial behind them, which puts them well ahead of purely traditional or anecdotal claims, but neither has the depth or consistency of evidence that ashwagandha now has across multiple pooled meta-analyses.

None of this amounts to a reason to avoid Rhodiola or holy basil, and the doses used in the trials described here were generally well tolerated with no major adverse effects reported. But it is a reason to be skeptical of blanket claims that any adaptogen supplement will reliably "lower your cortisol," and a reason to check what dose and what specific extract was actually studied before assuming a product on a shelf will replicate a trial's results. As with most supplements in this category, talking to a doctor before starting, especially alongside other medications, remains the more reliable move than trusting a label alone.