Mood & mental wellbeing

Well supported

St John’s Wort (Hypericum perforatum) is the one herbal that has genuinely earned its place, and also the one that demands the most caution. The Cochrane review of 29 trials in over 5,000 patients found it superior to placebo and about as effective as standard antidepressants for mild-to-moderate depression — with notably fewer people dropping out for side effects.² That is a real result, not marketing. But read the two hard limits before you reach for it. First, the evidence is for mild-to-moderate low mood only — it is not a treatment for severe depression, and self-treating serious illness with a herb is how people get hurt. Second, and this is the big one: St John’s Wort is a powerful inducer of the CYP3A4 enzyme and the P-glycoprotein transporter, so it accelerates the breakdown of a long list of drugs — it can make the contraceptive pill fail, blunt warfarin, ciclosporin, HIV protease inhibitors and some cancer drugs, and stacked on top of an SSRI or triptan it can tip you into serotonin syndrome.³ If you take any prescription medicine, this is a conversation with your doctor or pharmacist, full stop.

Saffron (Crocus sativus) is the pleasant surprise of this list. The threads of the world’s most expensive spice have accumulated a genuinely respectable trial record: a meta-analysis of randomised controlled trials found a large effect on depressive symptoms versus placebo, and in head-to-head trials saffron performed on a par with antidepressants such as fluoxetine and imipramine in mild-to-moderate depression.⁴ A later systematic review reached the same read — consistent antidepressant and anti-anxiety signals across the studies, at the standard research dose of 30 mg/day.⁵ The honest caveats: the trials are mostly small, many come from a single research group in Iran, and the follow-up is short. But as underrated mood supplements go, this is the most interesting one on the shelf — low-risk, well tolerated, and worth an 6–8 week trial in the right person.

EPA-dominant omega-3 is where people get the fish-oil story backwards. For mood, the fraction that matters is EPA, not DHA — the reverse of the brain & cognition picture, where DHA is the structural fat the brain is built from. A comprehensive meta-analysis of trials in depression found a clear benefit, and dug out the reason the literature looks so noisy: it was the EPA-predominant formulations that carried the effect, and omega-3 worked best as an adjunct alongside treatment rather than as a solo therapy.⁶ So the practical rule is to look past the total “omega-3” number on the label and check the EPA:DHA ratio — a supplement with substantially more EPA than DHA is the one with mood data behind it. See the full fish oil guide for forms, doses and how to read a label.

Worth a look — know the target

Ashwagandha (Withania somnifera) is a stress and anxiety tool more than a mood one — and on that narrower claim the data is decent. In a randomised, double-blind, placebo-controlled trial, a standardised root extract at 300 mg twice daily cut perceived-stress scores substantially and lowered serum cortisol over 60 days.⁷ Trials on the branded KSM-66 and Sensoril extracts point the same way for stress and anxiety. What it is not is a proven antidepressant — the depression evidence is much thinner, so treat this as a way to take the edge off a wound-up, over-cortisoled state rather than a lift for genuine low mood. More on the class in our adaptogens guide.

Magnesium earns its spot honestly, in the same “fix a shortfall” way it does for blood sugar and sleep. Low magnesium status tracks with anxiety and depression, and in an open-label randomised trial, 248 mg of elemental magnesium a day produced a clinically meaningful drop in both depression (PHQ-9) and anxiety (GAD-7) scores within a fortnight — and it worked regardless of starting level, though the mechanism most plausibly runs through correcting a deficiency.⁸ It is cheap, safe and easy to trial. Glycinate or citrate are the better-absorbed, gentler-on-the-gut forms; the oxide sold cheapest is the one most likely to just loosen your bowels. Check your intake first — the full magnesium guide has the detail.

L-theanine, on its own, is the quiet one for anxiety. This is a different use from the caffeine + L-theanine stack people take for focus — here it stands alone. At 200 mg/day over four weeks in healthy adults it lowered anxiety and depression-scale scores and improved sleep quality, all without sedation.⁹ That “calm but not drowsy” profile is exactly what makes it useful for stress and the racing-mind kind of sleep-onset anxiety, and it stacks cleanly with the wind-down routine on our sleep page. The trials are in non-clinical stress, not diagnosed anxiety disorders — keep the expectation there.

Mixed — manage expectations

5-HTP is the intuitive one — a direct precursor your body converts into serotonin, so surely it lifts mood? The trial record is frustratingly thin. The Cochrane review of 5-HTP and tryptophan for depression found only a couple of small studies of adequate quality; they hinted at benefit over placebo, but the authors concluded the evidence was too weak to recommend it as a treatment.¹⁰ That leaves a real safety flag doing more work than the efficacy data: because 5-HTP raises serotonin, combining it with any serotonergic drug — an SSRI, SNRI, MAOI, tramadol or triptan — risks serotonin syndrome. If you are on anything for mood, migraine or pain, 5-HTP is not a casual add-on.

Vitamin D has one of the strongest correlations in this whole field and one of the shakiest causal stories. Low vitamin D tracks closely with depression, and a systematic review and meta-analysis found supplementation nudged negative mood in a favourable direction — but the effect was modest and the causal question stays genuinely open.¹¹ Here is the local angle, though: at Scandinavian and northern latitudes, winter vitamin D deficiency is not a rarity, it is close to the default from October to March. So for Swedish and other northern readers, correcting a real, measurable winter deficiency is sensible on its own terms — and any mood benefit is a bonus rather than the reason to do it. Test if you can; supplement the shortfall either way.

Probiotics and the gut–brain axis make the most interesting mechanistic story on the page — the vagus nerve, microbial metabolites, inflammation — and the early human data is genuinely promising: a meta-analysis of randomised trials found a small but significant reduction in depression scores.¹² The problem is that “probiotic” is not one thing. There is no agreed strain, dose or duration for mood, the trials use wildly different products, and the effect sizes are small. Fascinating field, worth watching, too soon to point at a specific bottle and say “take this.”