Depression and Anxiety: Nutritional Considerations

Diet may influence mood in several ways. For example, certain amino acids and other nutrients act as building blocks in the production of brain chemicals. Dietary carbohydrate and protein can influence the rate at which brain chemicals are built. Further, weight loss in obese persons is associated with improvement in mood.

Diabetes is associated with depression. Poor control of blood sugar may worsen depression and decrease the effectiveness of antidepressant medications. Studies have shown that depression often improves as blood sugar improves. In addition, individuals who are depressed are at an increased risk for diabetes.

The following nutrients are under investigation for their role in depression and/or anxiety:

• Folate and other B-vitamins: Low blood levels of folate and vitamin B₁₂ are associated with depression and may decrease the effectiveness of antidepressant medications. Increased dietary (and perhaps supplemental) intakes of these vitamins may be important in preventing or treating depression. Limited evidence suggests that elderly patients with depression respond better to antidepressant medication when given supplemental vitamins B₁, B₂, and B₆, compared with antidepressant treatment alone. These observations may help explain why consuming a traditional Chinese diet, which is high in folate, is associated with lower rates of depression.
• Omega-3 fatty acids: Depression is associated with lower levels of omega-3 fatty acids. Some, but not all, studies have found that in countries where intake of these fatty acids is higher, depression is less common. Controlled clinical trials have found improvements in depression when fish oils were administered along with standard antidepressants. It is not known whether botanical sources of omega-3s, such as flax oil, have the same effect.
• Botanical treatments: St. John's Wort is effective in as many as 50 to 70 percent of patients with mild depression. However, they have not shown to be effective in patients with severe depression. Passion flower (Passiflora incarnata), chamomile (Matricaria recutita), and lemon balm (Melissa officianalis) contain flavonoids that may have anti-anxiety effects. Kava is an herbal treatment with evidence of a significant anti-anxiety effect. However, it is no longer available, due to reports of liver failure in rare cases when high doses were taken.
  

The following treatments may be helpful, but require more study:

• S-adenosylmethionine (SAMe): SAMe is involved in the production of certain brain chemicals and proteins. In limited trials, SAMe has shown effects similar to those of medication in treating depression and may have fewer side effects.
• Inositol: Inositol is a substance found in many foods, including whole grain cereals and legumes. Limited studies have suggested that supplements at doses of 12 to 18 grams per day may reduce anxiety symptoms as effectively as anti-anxiety medications, with a low incidence of side effects.