Guide
Does vitamin D help depression?
Updated September 15, 2026 · kept current as we cover new studies
The short answer
Short answer: not as a treatment for depression on its own. In the randomized trial we have covered, eight weeks of high-dose vitamin D3 did not beat placebo for depression in young people selected for having both major depression and low vitamin D.
Two qualifications, both from that same trial. It did modestly reduce anxiety. And in the subgroup with moderate-to-severe depression, it reduced both depression and anxiety compared with placebo, although that was an exploratory subgroup analysis and the adolescent slice of it did not clearly benefit. No safety problems, such as raised calcium, appeared.
So it is a lead worth testing in larger trials for people who are genuinely deficient and more severely depressed, not a standalone treatment, and not a reason to defer established care.
What this page covers. One randomized trial in 108 people aged 10 to 24 who all had low vitamin D. It says nothing about people whose vitamin D is normal, and nothing about doses or durations other than the one tested. Every claim above is drawn from the studies below, and each of those links to the original paper.
The trial
The direct test: high-dose vitamin D3 against placebo, in people who were both depressed and deficient.
Does vitamin D help depression?
108 young people with both major depression and low vitamin D were given supplements. The effect was real but modest.
What has been shown to help outside a therapist's office
The reason people ask about supplements is usually access. These trials test the other low-barrier options against real comparison groups.
Lifestyle medicine for depression, without a therapist
A three-arm trial of an 8-week program delivered by app, by booklet, or not at all.
Does a mental health app still work without a coach checking in?
In a three-arm trial recruiting across 13 countries, 825 adults living with chronic medical conditions used a digital wellbeing program either on their own or with weekly phone check-ins. Both versions cut combined anxiety and depression scores by roughly 3 points versus a waitlist, and the two versions were statistically indistinguishable from each other.
An app for depression after breast cancer
313 women were enrolled in a trial of a fully automated, publicly available program — because there aren't enough therapists.
Other compounds studied for mood
Where else a drug effect on depression and anxiety has been looked for.
What GLP-1 drugs do to depression and anxiety
Swedish records for ~100,000 people compared periods when the same individuals were and weren't taking GLP-1 medications.
Why depression scores are slipperier than they look
Every result above is a change in a depression score, and those scores move for reasons that have nothing to do with treatment.
Changing the wording changes your depression score
A randomized trial altered only the instructions on the PHQ-9 and GAD-7 — and the same people scored differently.
Common questions
Does vitamin D treat depression?
Not on the evidence here. In the trial we covered it did not beat placebo for depression overall, even in a group chosen for being deficient.
Did it do anything at all?
It modestly reduced anxiety in the randomized vitamin D group, and in the moderate-to-severe depression subgroup it reduced both depression and anxiety versus placebo. That subgroup finding was exploratory, which means it is a hypothesis for the next trial rather than a result to act on.
How much was used, and was it safe?
4,800 IU of vitamin D3 daily for eight weeks. No safety problems such as hypercalcaemia appeared in this trial.
Should I have my vitamin D tested?
That is a question for a clinician, and this page cannot answer it. What the trial can tell you is that its participants were selected for having low vitamin D, so its results do not extend to people whose levels are normal.
This is an educational summary, not medical or psychological advice, and it is not a substitute for consultation with a qualified professional. Read the full disclaimer.