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Abstract
The body of evidence linking diet and mental health is growing at a rapid pace. As well as its impact on short and long-term mental health, the evidence indicates that nutrition may play a contributing role in the development, management and prevention of specific mental health problems such as depression, schizophrenia, attention deficit hyperactivity disorder, Alzheimer’s disease and some anxiety disorders .
Depression and nutrition
Many studies have linked the intake of certain foods like (low intakes of fish or deficiencies of both folate and vitamins B and impaired levels of the essential amino acid tryptophan nutrients) with depression. Many studies have shown that patients diagnosed with depression exhibit nutrient related biophysiological differences when compared to individuals without depression. However, it is not wholly clear whether these are causative of depression, or a result of disordered eating as a result of the condition.
There is an evidences of possible mechanisms for links between fatty acid and folic acid with development of depression .
The few controlled clinical trials of vitamin therapy in addition to standard psychotropic medication have all reported positive effects on patients’ mental state. While results of trials using tryptophan to treat depression have been conflicting.
Fatty acids :
The polyunsaturated fats (PUFAs) include the “essential fatty acids” (EFAs), linoleic acid (omega 6) and alpha linolenic acid (omega 3). These are referred to as structural fats because they are the main component in cell walls. Like essential amino acids (protein) they cannot be made by the body but must be derived from the diet. When essential fatty acids are eaten by animals and humans, they are digested and then elongated or converted into different types of fatty acids – the elongation makes them long chain fatty acids. Linoleic acid is first converted to gamma-linolenic acid (GLA); then to dihomogamma-lionlenic acid (DGLA) before being further elongated to become arachidonic acid (AA). Alpha-linolenic acid is also converted to eicosapentaenoic acid (EPA); then to docosa- hexaenoic acid (DHA).
Clinical trials using PUFA supplementations in depression
Unipolar depression has been the subject of many clinical trials using polyunsaturated fatty acids (PUFA) as a supplementary therapy.
Stoll et al.( 1999) then Su et al.( 2003) gave indicative data of antidepressant effect of omega-3 fatty acids,. Nemets et al.(2002) reported a 4-week parallel-group, double-blind addition of either placebo or ethyl-EPA to ongoing antidepressant therapy for 20 patients with recurrent unipolar depressive disorder. Improvement in the group receiving EPA while Silvers et al.(2005) found no support for 3 g/day of fish oil supplementation of antidepressant medication, despite significant increases in both EPA and DHA in erythrocyte membranes. Also Peet and Horrobin (2002) studied the effects of ethyl-EPA in patients with ongoing depression despite apparently adequate treatment with standard antidepressant drugs. The group taking 1 g/day showed strong beneficial effects on items rating depression, anxiety, sleep, lassitude, libido, and suicidality. The group taking 2 g/day showed little evidence of efficacy, whereas the group taking 4 g/day showed nonsignificant improvement.
Post-partum depression and fatty acids
The use of omega-3 fatty acids as an antidepressant in pregnancy would be attractive given the growing evidence that conventional antidepressants may have an adverse effect upon the child .This, along with the promising results of omega-3 fatty acid therapy obtained in major depressive disorder, has prompted researchers to investigate their use in postpartum depression.