In an evolving health landscape, emerging research continues to highlight concerns that could impact everyday wellbeing. Here’s the key update you should know about:
From St John’s Wort to vitamin D: This review uncovers which over-the-counter products have real scientific backing for relieving depression, and which still need proof.
Study: Understanding the research landscape of over-the-counter herbal products, dietary supplements, and medications evaluated for depressive symptoms in adults: a scoping review. Image credit: Yuliia Ushakova/Shutterstock.com
A study published in Frontiers in Pharmacology aimed to document the research evidence available for over-the-counter (OTC) products for treating depression in adults. Researchers point out the need for further research on everyday herbal products, such as lavender, chamomile, lemon balm, and Echium, used to alleviate depressive conditions, to assess their safety and efficacy.
Depression: Prevalence, symptoms, and treatment
Depression is a mental health condition characterized by persistent low mood, loss of pleasure or interest in activities, insomnia, and fatigue, which impacts overall daily life. An increased prevalence of depression, including major depressive disorder (MDD), has been documented worldwide. For example, 11.3% of the UK population experience mild depressive symptoms, 4.2% have moderate depressive symptoms, and 3.3% experience severe depressive symptoms.
Besides genetic and stress factors, deficiencies in monoamine neurotransmitters, increased production of glucocorticoids, and elevated hypothalamic-pituitary-adrenal (HPA) axis activity led to MDD. Impaired neurogenesis from reduced brain-derived neurotrophic factor (BDNF) and gut microbial dysbiosis affecting the function of the HPA axis could cause depression. Therefore, robust strategies are needed to manage and prevent depressive symptoms in adults effectively.
According to the National Institute for Health and Care Excellence (NICE) guidelines, individuals diagnosed with depression are advised to do exercise regularly, undergo psychological therapies, and some are prescribed antidepressants. Although many strategies are available to combat depression, only 13.4% of residents of Great Britain suffering from depression receive any form of treatment. The particular challenge in accessing psychological therapies is their long waiting times.
Previous studies have shown that many people manage their depressive symptoms on their own through herbal medical products (HMPs) and vitamins and minerals rather than practitioner-directed strategies. These patients also use OTC homeopathic preparations to alleviate their depressive symptoms. However, while some individuals use homeopathic remedies, the review did not include trials evaluating homeopathic products. There are no specific OTC medicines licensed to treat these conditions. HMPs, such as St John’s Wort and saffron, and omega-3 supplements are most popular among consumers due to the perception of safety and naturalness.
About the review
The current review investigated the research landscape to identify the areas with a higher volume of literature and those with a limited number of studies. Therefore, it helped recognize the existing gaps in research, allowing scientists to conduct future studies on products for depressive symptoms.
All available trial evidence for OTC products for anxiety, insomnia, and depression was considered. All relevant articles were obtained from five databases: MEDLINE, PsycINFO, AMED, Embase, and CENTRAL, from inception to December 2022. Due to the large volume of studies, researchers synthesized data based on overall and specific product types. The analysis used methods called vote counting to summarize product effectiveness across studies.
Review findings
The current review considered 209 articles that evaluated products for depression symptoms and fulfilled various other research criteria, including participants who were between 18 and 60 years of age. Trials considered in this review were mainly performed in Iran, Germany, Australia, the US, the UK, and China. The median size of participants recruited in trials was 70. In most trials, participants were required to have a depression diagnosis at baseline, while certain studies followed a symptom scale cutoff for participant recruitment.
The Hamilton Depression Rating Scale, the Montgomery-Åsberg Depression Rating Scale, and the Clinical Global Impression Scale were common depression scales used in the selected studies.
It must be noted that all considered studies focused on evaluating the efficacy of dietary supplements and a small number of single chemical medicines, but not homeopathic products, for alleviating depressive symptoms. Since 1973, a general increase in the number of trials evaluating dietary supplements for depression has been observed, peaking in 2019 with an average of 3.2 trials per year.
Many studies on omega-3s, St John’s Wort, probiotics, saffron, and vitamin D have been conducted to evaluate their efficacy against depression symptoms. However, considerable deviation in extracts, methodology, formulations, and dosage was noted.
Many studies revealed the use of St John’s Wort as a monotherapy to treat depressive symptoms of people with no comorbidities. Based on vote counting, St John’s Wort demonstrated higher efficacy, sometimes even more effective than prescription antidepressants.
Saffron products have been assessed across a broader range of comorbid conditions than St John’s Wort, including postpartum, menopause, cardiovascular disease, and type 2 diabetes. In contrast to a placebo, saffron exhibited a prominent antidepressant effect. Comparisons with prescription medications generally found similar levels of effectiveness.
Vitamin D has been mainly evaluated as an adjunct to prescribed medication and/or cognitive behavioural therapy. Across placebo comparisons, vitamin D was more often effective than not.
Contradictory or mixed findings have been documented for melatonin, magnesium, curcumin, cinnamon, Echium, vitamin C, vitamin D, and vitamin D combined with calcium, reflecting the need for further well-designed trials. One omega-3 trial reported specific safety concerns. Overall, 85% of trials that reported safety outcomes did not identify safety concerns, but 31% of studies lacked sufficient safety reporting details.
Many ongoing trials are assessing the therapeutic potential of vitamin D, three omega-3s, and a range of HMPs to treat depression.
Conclusion
The current review highlighted many dietary supplements and herbal medical products that are being assessed to treat depression. The authors highlighted gaps in research about a smaller number of trials with large sample sizes, and indicated the need for further replications of results to validate the accuracy. More research is required to optimize the dosage and herbal preparation. Further evaluation on folic acid, lavender, tryptophan, zinc, rhodiola, bitter orange, lemon balm, and chamomile is required to assess their antidepressant potential.
The authors also recommend further exploration of OTC products as adjuncts to psychological therapies to support an integrative approach.