NUTRITION
Excerpt from:
Hiingle, M. Nutrition. In Lake, J and Spiegel, D (ed.),
Clinical Manual of Complementary and Alternative Treatments in Mental Health.
Washington, DC: American Psychiatric Press, Inc. 2006.
A wise healer once said, “Let food be thy medicine and medicine be thy food.” Unfortunately, the “food as medicine” philosophy of Hippocrates has largely been neglected in modern Western medicine, where a physician's tools are often limited to expertise in advanced surgical techniques and a prescription pad. While many doctors agree that food choices play an important role in the prevention and treatment of disease, nutrition as a healing modality remains largely overlooked by the conventional medicine practitioner. However, this may be about to change. The obesity epidemic and its associated health risks led to revived interest in the role of nutrition in health and wellbeingThere is growing demand for practitioners who are able to offer sound, practical advice to their patients regarding optimal dietary choices addressing medical or psychiatric problems. There is extensive evidence supporting the role of nutrition in the prevention and treatment of many diseases that are leading causes of morbidity and mortality in the industrialized countries, including cardiovascular disease, stroke, diabetes, and cancer. A growing body of scientific evidence also recognizes the use of nutrition therapy in the prevention and management of mental illness.
Dietary Trends and Disease
Most of us are familiar with the phrase 'you are what you eat.' This most basic argument for healthy eating rings especially true in today's world of expanding food choices and diminishing food quality. The past century has seen major changes in the way we produce, process, and distribute food, all of which influence food quality, food choices and our health. During the twentieth century a significant increase in the lifetime risk of major psychiatric disorders was observed, a trend that cannot be completely explained by new diagnostic criteria, changes in attitude toward mental illness, reporting bias, or other artifact. (Logan 2003; Rogers 2001; Silvers and Scott 2000) However, increased risk may correlate with a population-wide shift to a more processed and refined diet, suggesting that changes in dietary habits may be causally related to the increased prevalence of many psychiatric disorders. If this hypothesis is borne out, identifying influential dietary factors is an important step in reducing the risk of developing many psychiatric disorders.
The Connection Between Physical and Mental Health
For most medical illnesses, research findings suggest that good nutrition is an effective means to reduce symptoms or slow disease progression. Despite this, the role of diet in the treatment of mental illness remains poorly defined. Researchers have noted that psychiatric illness is often accompanied by physical illness. For example, obesity is common in mentally ill populations. As a result, when treating mental illness, the health of the body must be considered in addition to that of the mind. (Rogers 2001) Although mental health problems are clearly related to medical illness, and both have known dietary risk factors, the nature of this relationship is less clear (i.e.,does poor diet contribute to physical decline, leading to mental illness, or vice versa?). Since physical co-morbidities may precede mental illness or occur as direct or indirect results of mental illness, a reasonable approach is to treat physical and psychiatric symptoms concurrently. (Rogers 2001)
Identifying Dietary Risk Factors
The most compelling evidence to date supporting the role of specific nutrients in maintaining mental health is derived from epidemiological and correlational studies, which suggest that certain dietary factors play key roles in mental health, including essential fatty acids (EFAs), carbohydrates and proteins, alcohol, B vitamins, and caffeine. Research findings also point to a strong correlation between obesity and mental health problems. The following sections review these findings and provide guidelines for the application of nutritional counseling in the clinical setting.
Evidence Supporting the Use of Nutrition in Psychiatric Treatment
Most data on dietary factors that are related to major depression are obtained from epidemiological studies. Cumulative results suggest that several key nutrients (EFAs, CHOs, and folate) may have protective effects.
Essential fatty acids play a central role in physical and mental health. The following section is a brief summary of current research evidence for the importance dietary n-3 EFAs in mental health. A more thorough review is provided in Part II, chapter 6. Population studies indicate significant differences in the prevalence of major depression across countries, a pattern very similar to cross-national comparisons of mortality from cardiovascular causes. This finding suggests that common dietary risk factors may play a role in both diseases. (Hibbeln 1998; Noaghiul and Hibbeln 2003) Analysis of national dietary patterns in relation to international variations in prevalence suggests that an important common dietary risk factor is intake of fish, and other foods rich in n-3 fatty acids. (Peet 2004) Epidemiologic studies suggest that fish consumption worldwide is inversely correlated with prevalence of depression (Silvers and Scott 2002) however the data are inconsistent (Hakkarainen et al, 2004). Fish consumption is also negatively correlated with the risk of seasonal affective disorder (SAD) and post-partum depression, and predicts improved mental health status in general. (Logan 2003; Hibbeln 1998) While these findings do not prove causation, the idea that fish intake play a role in depression is consistent with clinical studies showing that higher levels of DHA in red-blood cell membranes and higher serum EPA to AA ratios are inversely correlated with severity of depressive symptoms. (Hibbeln 1998; Noaghiul and Hibbeln 2003) Causal links between certain essential fatty acids and depression is poorly defined, and it is unclear whether the changes in lipids are etiologically related to depression or a result of the neurobiological changes that take place during depression. (Bruinsma and Taren 2000) In summary, research findings suggest that regular consumption of n-3s (fish, soy, leafy greens, nuts and seeds) should be encouraged in depressed patients.
Carbohydrates and Proteins
Carbohydrate intake is associated with improved mood in both depressed and non-depressed individuals, and depressed mood often stimulates the consumption of 'comfort foods,' usually rich in both carbohydrates and fat. (Benton and Donohoe 1999; Christensen 1997 Many theories have been advanced in efforts to explain possible physiologic mechanisms of behavioral effects associated with carbohydrate consumption in humans, but there are no definitive findings to date. (Christensen 1997)
Folate
Epidemiologic studies confirm early observations that folate plays a significant role in mood regulation. A meta-analysis of population studies shows that low folate status is common in depressed patients, and that serum folate levels in this population were significantly lower than levels associated with other psychiatric disorders or healthy individuals. (Morris 2002; Rogers 2001) The elderly and substance abusers are at greatest risk for folate (and other B vitamin) deficiency, due to age-related gastric atrophy and inadequate intake,respectively. . (Selhub et al. 2000) Although it is unclear whether low folate status actually causes depression, antidepressant trials have demonstrated that increasing serum folate levels in depressed patients improves the efficacy of antidepressants and increases response in previously refractory patients. (Alpert 2000; Morris 2002) These findings support the view that low folate status is widespread in the depressed population, and that changes in psychological functioning (including changes in mood) is an important indicator of low folate. (Benton and Donohoe 1999)