Natural Support for Depression? Here’s What the Science Says

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A recent review explored the available scientific evidence behind over-the-counter (OTC) products used to help manage symptoms of depression in adults aged 18 to 60 years.

A team of investigators led by Rachael Frost, Ph.D., an herbalist and senior lecturer in Health and Social Care at Liverpool John Moores University, reviewed 209 clinical trials covering a wide range of vitamins, herbs and supplements, narrowing in on products commonly sold in many countries. While many of these products aren’t officially approved to treat depression, people often turn to them for support — especially as natural or nonprescription options.

“Although antidepressants are more easily accessible, they require help seeking with a medical practitioner in order to receive them, and views and experiences of their perceived effectiveness, desirability and side effects are mixed,” wrote investigators. “Consequently, it is unsurprising that prior to, or whilst receiving treatment, people often find ways to self-manage depressive symptoms, most commonly using herbal medical products (HMPs) and vitamins and minerals rather than practitioner-directed modalities.”

Depression significantly affects individuals’ quality of life and increases the risk of serious health issues like heart disease and diabetes. It also has a major societal and economic impact, contributing to missed work and costing the global economy an estimated $4.7 trillion. These widespread effects highlight the urgent need for effective strategies to prevent and manage depression in adults.

“Once you start looking into which OTC product might be helpful, the list becomes endless,” Frost explained. “This is particularly the case if you read online blogs or look at social media promotion of various products. How do we know what is evidence-based? What products are effective? Are they safe?”

The trials included in the study were identified using a database search of MEDLINE, PsycINFO, AMED, CENTRAL and Embase from inception to December 2022. Most research was conducted in Iran, Germany, the U.S., Australia, the U.K. and China. Nearly all studies (187) were double-blind and most required patients to have a diagnosis of depression at baseline.

The strongest evidence existed for omega-3 fatty acids, Saint-John’s-wort, saffron, probiotics and vitamin D, all of which showed promising results in managing mild to moderate symptoms. Other natural ingredients like lavender, lemon balm, chamomile and Echium also showed potential benefits, but investigators believe more research is needed in these areas.

Lesser-known products such as folic acid, zinc, tryptophan and Rhodiola had limited but encouraging data. Many of these were studied in combination with prescription antidepressants or psychological therapy.

Importantly, most OTC products reviewed did not raise major safety concerns, whether taken alone or alongside other treatments. Among those that included adverse events (69%), most (85%) reported no significant events. However, investigators did point out that reporting of side effects in these trials needs to be improved.

This review had several strengths, including identifying more clinical trials on OTC products for depression than previous studies. Unlike other reviews that focused on one product or age group, this one used a broad scoping review method to map the evidence across many products and summarized ongoing trials. It focused on participants with diagnosed depression or clear symptoms, offering more targeted insights.

However, investigators noted a few limitations, including that some relevant trials may have been missed due to inconsistent product labeling or outdated search strategies, as the literature search only extended through 2022. Only 10% of studies were double-screened, which could introduce bias. Additionally, while non-English studies were included, translations were sometimes done with Google Lens, which may not have been fully accurate.

They encourage future reviews to use broader language search terms, consider including traditional Chinese medicine and aim for more thorough screening processes to improve completeness and accuracy.