In the United States, it is estimated that more than one in five adults (20%) live with a mental illness. This statistic covers what is referred to as "any mental illness," defined as a mental, behavioral or emotional disorder that can vary in its impact from mild to severe. In the United States, women are more likely to have a mental illness than men (27.2% vs. 18.1%) and younger adults are more likely to have a mental illness than older adults. In 2021, 34% of all adults 18 to 25 years of age had a mental illness, compared to 28% of adults 26 to 49 years of age and 15% of all adults 50 years of age and older [2]. The prevalence of mental illness in adolescents (12 to 17 years of age) is also increasing [3].

In the United States, it is estimated that more than one in five adults (20%) live with a mental illness. This statistic covers what is referred to as "any mental illness," defined as a mental, behavioral or emotional disorder that can vary in its impact from mild to severe. In the United States, women are more likely to have a mental illness than men (27.2% vs. 18.1%) and younger adults are more likely to have a mental illness than older adults. In 2021, 34% of all adults 18 to 25 years of age had a mental illness, compared to 28% of adults 26 to 49 years of age and 15% of all adults 50 years of age and older [2]. The prevalence of mental illness in adolescents (12 to 17 years of age) is also increasing [3].

Depression is one of the most common mental illnesses reported in the United States. In 2021, 21 million U.S. adults (8.3%) had at least one major depressive episode. This rate was highest in those 18 to 25 years of age (18.6%). Major depressive episodes resulting in severe impairment affected 5.7% of all U.S. adults in 2021. That same year, 5 million adolescents—representing about 20% of those 12 to 17 years of age—reported major depressive episodes. This rate was much higher in girls than boys, at 29% and 11.5%, respectively [2].

A separate, large meta-analysis pooled data from more than 200 studies in people with depression. That analysis determined that certain forms of exercise, including walking or jogging, strength training, mixed aerobic exercises, yoga, and tai chi or qi gong, offered the greatest benefits. Here, we will review the evidence for these last three forms of physical activity, all of which contain a meditative component.

The evidence to date indicates that practicing yoga for one to two months can improve symptoms of depression in people with mild or new-onset depression. Additionally, it appears to be beneficial as an adjunct therapy in people who are taking conventional antidepressants. Importantly, most of these studies evaluated the use of "Western yoga," which tends to entail a greater focus on physical yoga poses [17].

Small clinical studies have evaluated acupuncture for postpartum depression, suggesting that there may be a small benefit when acupuncture is added to conventional antidepressants [28]. Generally, research with traditional acupuncture during pregnancy has not identified any safety concerns for the unborn baby. However, there is one specific acupoint (SP6) which may be unsafe to stimulate during pregnancy, as it has been associated with an increased risk for early contractions and miscarriage [29].

Expressive therapies combine some form of artistic expression with some form of therapy. This artistic expression can include art, music, dance, drama, poetry, or creative writing. Two specific forms of expressive therapy—art and music—have shown benefit for symptoms of anxiety and depression.

The best evidence for both forms of expressive therapy is in the management of depression. Various forms of art therapy can improve symptoms of depression, from adolescents to the elderly. Research has shown that art therapy, in the form of regular sessions over 10 to 20 weeks, can offer modest benefit as an adjunct to conventional antidepressants or as monotherapy [32,33]. Similarly, music therapy has shown benefit for symptoms of depression across various age groups. This therapy may include listening to and/or making music, with or without the presence of a therapist. In most cases, the patients in these studies were already taking a conventional antidepressant [34,35].

There is also a large body of evidence showing that music therapy can benefit people with symptoms of anxiety. In these studies, music therapy had a small to medium benefit in a variety of patients, including postpartum adults, people with a variety of underlying health conditions, and adolescents. These benefits appear to be short-term, however, and do not seem to continue after the therapy has ended [36]. Some small clinical studies have also shown modest benefit with art therapy, particularly in the elderly or in women with various anxiety disorders. In most of these studies, 10 to 12 art therapy sessions occurred over about three months [37,38].

Particularly for patients who already enjoy music and/or art, these expressive therapies could be considered as safe adjunctive modalities for managing symptoms of depression and anxiety.

Clinical research shows that light therapy, delivered at a brightness of 3,000–10,000 lux, reduces symptoms of seasonal depression and may be similarly effective to fluoxetine 20 mg daily [50]. Higher intensity light therapy appears to be more effective than dimmer therapy, and blue and green wavelengths appear to be more beneficial than red wavelengths [50,51]. In most studies, patients have been exposed to a light placed 12–18 inches away from the face for 30 minutes to 3 hours each day.

St. John's wort (Hypericum perforatum) is a plant with a yellow, star-shaped flower. Extracts of the plant are known to affect the neurotransmitters serotonin, dopamine, and norephinephrine, possibly limiting their reuptake. It has been extensively studied for the treatment of mild or moderate depression, with most studies showing evidence of benefit.

Due to its popularity and the amount of research conducted to date, St. John's wort is discussed in some clinical guidelines, including those from the American College of Physicians (ACP). Although the ACP acknowledges the available evidence, it stops short of recommending this extract for the treatment of depression due to the fact that it may be difficult for patients to obtain a product of adequate quality and with the appropriate amount of hypericin and hyperforin. Conversely, an international guideline from the World Federation of Societies of Biological Psychiatry (WFSBP) and Canadian Network for Mood and Anxiety Treatments (CANMAT) Taskforce recommends St. John's wort at doses of 600–1,800 mg daily as monotherapy for mild-to-moderate forms of MDD [54].

St. John's wort is notorious for its ability to interact with many prescription drugs. This herb can induce cytochrome P450 (CYP) 3A4, which is responsible for metabolizing many drugs. This can reduce the levels and efficacy of a wide range of medications, including birth control, immunosuppressants, and certain anticoagulants [54]. Also, because St. John's wort has serotonergic activity, it can cause serious interactions with other serotonergic drugs, and even increase the risk for serotonin syndrome [54,55].

Saffron, derived from the flower of Crocus sativa, is perhaps best known for its use as a vibrant red-orange spice. However, it has recently been gaining popularity for use in the treatment of both depression and anxiety.

The most extensive evidence to date is for the use of saffron extract for the treatment of depression, either alone or in combination with conventional antidepressants. Clinical research shows that taking saffron extract 30 mg daily, or taking dried saffron stigma 100 mg daily, for up to three months improves symptoms of depression when compared with a control group. When compared with a variety of antidepressants, including SSRIs, it seems to have a comparable effect [60,61]. When used in combination with an SSRI, some research suggests that saffron may provide a further modest reduction in depressive symptoms [62].

The evidence for anxiety, on the other hand, is less robust. Only a couple of small clinical studies have evaluated saffron for this purpose. Although both suggest that saffron may modestly improve symptoms of mild-to-moderate anxiety, more research is needed to confirm this finding [63,64].

The same international guideline that recommends St. John's wort for the treatment of depression (from WFSBP and CANMAT) also provisionally recommends saffron 30 mg daily for either monotherapy or as an adjunct treatment in mild to moderate depression [54].

When it comes to anxiety, the strongest available evidence has evaluated only one specific lavender oil extract (Silexan) that is taken by mouth. This extract has been studied at doses of 80–160 mg orally daily for up to 2.5 months, and research shows that it improves anxiety when compared with placebo [70,71]. Lavender oil aromatherapy has also been evaluated for the management of both chronic and situational anxiety, for which it seems to moderately reduce symptoms when compared with a control group [70,72,73].

Although kava appears to be generally safe when taken by mouth, it has been associated with multiple reports of hepatotoxicity. It is not entirely clear whether these cases of liver damage have been directly related to kava extracts; however, analyses of the reports suggest that the risk may be higher with higher doses and a prolonged duration of use. Some reports have also suggested that the extraction method for kava, or contamination of the kava plant, may increase the risk of liver damage [87,91]. In general, patients with liver dysfunction, or patients who are using other medications that can cause liver damage, such as alcohol, should avoid kava.

Ashwagandha extracts may be unsafe for use during pregnancy. Although there has been little to no research conducted on the safety of taking ashwagandha during pregnancy, there is a hypothetical concern that it has miscarriage-causing (abortifacient) activity [68].

The U.S. Food and Drug Administration (FDA) strongly recommends against the use of CBD during pregnancy [107]. Research on the use of CBD during pregnancy is currently limited to animal studies. However, these studies have detected an increased risk of developmental toxicity [104]. Additionally, due to the widespread issues with product quality, there is a risk that taking a CBD supplement may expose the fetus to THC. THC can cause serious adverse effects to the fetus, including low birth weight, birth defects, placental abruption, and an increased risk for requiring intensive care after birth. It can also cause long-term developmental issues [108].

Of these vitamins, folic acid has the most convincing evidence of benefit for the treatment or prevention of depression. Although folic acid alone does not seem to be beneficial in the management of depression, clinical studies have found that taking folic acid 0.2–15 mg daily in conjunction with a conventional antidepressant can improve treatment response in adults with MDD when compared with taking the antidepressant alone [111].

Due to the limited evidence of benefit and lack of clarity as to the impact of vitamin D deficiency, the international guideline from WFSBP and CANMAT provides only a weak recommendation for the use of vitamin D, in doses of 1,500–4,000 IU daily, as an adjunct or monotherapy for adults with MDD. This recommendation also focuses on people who are likely to have a vitamin D deficiency due to inadequate sun exposure and notes that the benefits may be greater in winter months [54].

This mineral has also been evaluated for use in depression, with more promising (although preliminary) findings. Observational research suggests that higher dietary intake of zinc is associated with a lower rate of depression than lower intake [127]. Additionally, some small, lower-quality studies show that taking an oral zinc supplement at doses of 7–25 mg daily for up to 12 weeks in conjunction with a conventional antidepressant may increase the benefits of the antidepressant [128].

S-adenosyl-L-methionine (SAMe) is naturally formed in the body, where it serves a wide variety of functions. Clinical research shows that taking SAMe 800–1,600 mg daily in divided doses for one to three months can improve symptoms of depression when compared with placebo and may be equally effective to tricyclic antidepressants [131]. Additionally, one clinical trial shows that adding SAMe 400–800 mg twice daily to a conventional antidepressant can modestly improve remission rates when compared with taking the antidepressant alone [132].