Few Supplements Show Real Promise for Treating Depression, Study Finds

A recent study from the United Kingdom has found that while dozens of dietary supplements claim to ease depression, only a handful have substantial research supporting their effectiveness.

Researchers reviewed hundreds of clinical trials on 64 different over-the-counter supplements, including herbs and vitamins, to examine their impact on depressive symptoms. Although most supplements had limited evidence, the study identified five that received the most attention in research, with four of those—St. John’s Wort, probiotics, vitamin D, and saffron—consistently performing better than a placebo.

“I was interested in seeing whether this could be a solution for many people,” said lead author Rachael Frost, a senior lecturer and herbal practitioner at Liverpool John Moores University. “The accessibility of supplements is important—they do tend to cost less and do tend to be widely available.”

However, Frost cautioned that the review did not judge the quality of the underlying studies. While all involved human trials, the reliability of the results varied due to differences in trial size and design.

Majority of Supplements Lack Solid Evidence

With dietary supplements now a $152 billion global industry, understanding which products are truly effective is increasingly important. Many consumers are influenced by social media promotions from non-experts.

“This study is a really helpful snapshot of where we stand with supplements for depression. What stood out most to me is that they looked at 64 different products but found solid evidence for only four,” said Dr. De Borrah Wright, medical director of child and adolescent psychiatry at NYC Health + Hospitals - Kings County, who did not participate in the study. She emphasized that the findings illustrate the importance of not assuming every supplement on the shelf works as advertised.

The researchers examined 209 trials on products ranging from magnesium and folic acid to cinnamon, vitamin C, and prebiotics. Notably, 41 of the supplements had been investigated in only a single study each.

Supplements With Stronger Scientific Backing

Certain supplements have undergone more thorough investigation. Omega-3 fatty acids were the most studied, appearing in 39 trials, but generally did not outperform placebo for depression relief. By contrast, St. John’s Wort—a herb commonly used in Europe—was found in many trials to ease depression, with some research suggesting benefits comparable to prescription antidepressants.

Saffron, while promising, still requires more data before experts can fully recommend it. Probiotics and vitamin D showed potential as well, though vitamin D’s benefits were clearer in people with deficiencies, and taking it in high doses poses health risks.

Several other supplements—including folic acid, lavender, zinc, tryptophan, rhodiola, and lemon balm—showed limited but positive early evidence.

How Supplements Might Relieve Depression

Some of these supplements, like St. John’s Wort and saffron, appear to affect brain chemicals such as serotonin and dopamine, which are closely linked to mood regulation. Vitamin D may play a role due to its receptors in brain regions involved in mood, while probiotics are thought to influence mental health via the gut-brain axis.

“Taking probiotics and also getting them from food can be good,” said Thea Gallagher, a clinical psychologist at NYU Grossman School of Medicine.

Safety, Regulation, and Practical Advice

For individuals with mild or moderate depression, experts believe trying certain supplements is usually low-risk. Adverse effects reported in the studies were relatively rare, according to Frost. However, supplements can interact with medications—for example, St. John’s Wort can interfere with birth control and blood thinners—and quality varies widely, as supplements are not closely regulated by the U.S. Food and Drug Administration.

Dr. Wright recommends choosing brands with third-party testing seals, such as USP or NSF, for better safety and quality assurance.

Stay Critical and Prioritize Overall Wellbeing

While a few supplements have promise, their benefits relative to prescription antidepressants such as SSRIs remain uncertain. Experts caution that social media endorsements may not be reliable and that most supplements alone are unlikely to resolve depression.

“It’s kind of the wild wild west with understanding supplements,” said Gallagher. “If you’re trying to avoid prescription medication, it’s essential to maintain healthy habits like eating regular, nutritious meals, getting enough sleep, and exercising 150 minutes per week.”

In summary, while some supplements may help alleviate depressive symptoms—especially in cases of deficiency or as part of broader lifestyle changes—people experiencing depression are encouraged to adopt a cautious, well-informed approach and to consult healthcare professionals about treatment options.