Introduction

Currently, approximately 1 in 4 adult Americans have been diagnosed with a mental disorder, which translates into about 58 million affected people [1]. Though the incidence of mental disorders is higher in America than in other countries, a World Health Organization study of 14 countries reported a worldwide prevalence of mental disorders between 4.3 percent and 26.4 percent [2]. In addition, mental disorders are among the leading causes for disability in the US as well as other countries. Common mental health disorders include mood disorders, anxiety disorders such as post-traumatic stress disorder (PTSD), panic disorders, eating disorders, attention deficit disorder/attention deficit hyperactivity disorder (ADD/ADHD), and autism. However, the four most common mental disorders that cause disabilities are major depression, bipolar disorder, schizophrenia, and obsessive compulsive disorder (OCD) [3,4].

Typically, most of these disorders are treated with prescription drugs, but many of these prescribed drugs cause unwanted side effects. For example, lithium is usually prescribed for bipolar disorder, but the high-doses of lithium that are normally prescribed causes side effects that include: a dulled personality, reduced emotions, memory loss, tremors, or weight gain [5,6]. These side effects can be so severe and unpleasant that many patients become noncompliant and, in cases of severe drug toxicity, the situation can become life threatening.

Researchers have observed that the prevalence of mental health disorders has increased in developed countries in correlation with the deterioration of the Western diet [7]. Previous research has shown nutritional deficiencies that correlate with some mental disorders [8,9]. The most common nutritional deficiencies seen in mental disorder patients are of omega-3 fatty acids, B vitamins, minerals, and amino acids that are precursors to neurotransmitters [10-16]. Compelling population studies link high fish consumption to a low incidence of mental disorders; this lower incidence rate has proven to be a direct result of omega-3 fatty acid intake [10,17,18]. One to two grams of omega-3 fatty acids taken daily is the generally accepted dose for healthy individuals, but for patients with mental disorders, up to 9.6 g has been shown to be safe and efficacious [19-21]. Western diets are usually also lacking in fruits and vegetables, which further contributes to vitamin and mineral deficiencies.

This article will focus on the nutritional deficiencies that are associated with mental disorders and will outline how dietary supplements can be implemented in the treatment of several disorders (see Table 1 for an overview). The mental disorders and treatments covered in this review do not include the broad and complex range of disorders, but however focuses on the four most common disorders in order to emphasize the alternative or complementary nutritional options that health care providers can recommend to their patients.