Monday, March 16, 2009

Vitamin B


Vitamin B comes in many varieties. Three of those, B6, B12, and folate (B9) have been related to depression. B6 in its active form is called pyridoxal 5′-phosphate (PLP). PLP, through some biochemical reactions, is related to serotonin levels, and serotonin is related to moods and sleep cycles.

It has been shown that depressed patients have lower levels of vitamin B12, PLP, and folate. However, B6 studies are still relatively new in the exploration of effects on depression. A couple of studies (5, 6) have shown positive effects, but inconclusive, of B6 treatment, as an antidepressant augmentation, in patients with schizophrenia and depression.

A recent study of depression in the SUN cohort (1) demonstrated an association of depression with low folate levels in smoking men and low B12 levels in women. The study did not find any significant association with B6 levels. Similar results were found in another study (2) where low folate levels were associated with depression in Japanese males. Yet another study (3) also showed a significant association between low folate levels and depression; this study further hypothesises that insufficient folate levels may be a consequence, rather than a cause, of depression and that there may be some sort of negative feedback type cycle with low folate further decreasing appetite.

Folate and B12 are involved in biochemical reactions which affect neurological functioning (7). In the relationship between these vitamins and depression, deficiencies are markers for low homocysteine levels and low homocysteine levels are associated with depression.

A 2008 study (4) of the effects of B6 on depression suggested that the intake method of B6, dietary versus supplemental, may be significant, but that more studies need to be done to verify the hypothesis.

The recommended daily intakes of B6, B12, and folate are 1.3-2.0mg, 2.4 µg, and 400 – 1000 µg, respectively (for both men and women).

Sources of B12 include beef (3oz-2.1µg), salmon (30z-2.4µg), milk (80z-0.9µg), and cheese (brie, 10z-0.5µg).

Sources of B6 include fortified cereal (3/4c-2g), baked potato (0.7g), banana (0.68g), chick-peas (1/2c-0.57g), and chicken (half breast-0.52g).

Sources of folate include fortified cereal (3/4c-400µg), spinach (1/2c, cooked-100µg), and black-eyed peas (1/2c-105µg).

References: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

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