In the United States the term nutritional supplement is used interchangeably with the term dietary supplement. Nutritional supplements were officially defined under the Dietary Supplement Health and Education Act of 1994 (DHSEA) as a product meant to supplement the diet, and includes items marketed in pill, tablet, capsule, powder or liquid form.

In order to qualify as a nutritional supplement under the established definition, the item in question must contain at least one (or a combination) of the following ingredients: an herb other than tobacco (e.g., lemon balm), a botanical (e.g., chamomile flowers), a mineral (e.g., magnesium), a vitamin or precursor (e.g., beta carotene, which is a precursor to vitamin A), an amino acid (e.g., tryptophan), or a concentrate, metabolite, constituent or extract thereof. By law such products may not be marketed as a conventional food and must be labeled as supplements.

The Food and Drug Administration (FDA) categorizes nutritional supplements as foods and therefore it does not regulate them. Unlike pharmaceutical companies, companies producing nutritional supplements are not required to seek the approval of the FDA, and the FDA does not evaluate their effectiveness.

The term phytomedicinals (from the Greek phyto, meaning plant) refers to herb and plant preparations that are used or have been used for centuries for the treatment of a variety of medical conditions. Thousands of herbal drugs are being marketed today; the most common with psychoactive properties are listed in Table 34-1. Ingredients, to the extent they have been identified, are listed, as are indications, adverse events, dosages, and comments, particularly on interactions with commonly prescribed drugs used in psychiatry. For example, St. John’s wort (wort is an old English word meaning root or herb), which is used to treat depression, decreases the effectiveness of certain psychotropic drugs such as amitriptyline, alprazolam, paroxetine, and sertraline, among others. Kava kava, which is used to treat anxiety states, has been associated with liver toxicity.

Adverse effects are possible, and toxic interactions with other drugs may occur with all phytomedicinals. Adulteration is common, and there are few or no consistent standard preparations available for most herbs. Safety profiles and knowledge of adverse effects of most of these substances are lacking. Because of the paucity of clinical trials, all of these agents should be avoided during pregnancy; some may act as abortifacients. Because most of these herbs are secreted in breast milk, they are contraindicated during lactation.

Clinicians should always attempt to obtain a history of herbal use during the psychiatric evaluation.

It is important to be nonjudgmental in dealing with patients who use phytomedicinals. Many do so for various reasons: (1) as part of their cultural tradition, (2) because they mistrust physicians or are dissatisfied with conventional medicine, or
(3) because they experience relief of symptoms with the herbal treatment. Because patients will be more cooperative with traditional psychiatric treatments if they are allowed to continue their herbal preparations, psychiatrists should try to keep an open mind and not attribute all effects to suggestion. If psychotropic agents are prescribed, the clinician must be extraordinarily alert to the possibility of adverse effects as a result of drug–drug interactions because many phytomedicinals have ingredients that produce actual physiologic changes in the body.