Levels of vitamin E have been reported to be lower in patients suffering major depression but it was not known whether this is due to inadequate dietary intake or a result of depression.
An Australian team measured plasma alpha-tocopherol levels in 49 adults with major depression, and also looked at usual dietary intake of vitamin E by investigating diet history in a subset of the group.
This was designed to check whether these subjects had a lower dietary intake of the vitamin than healthy people.
Diet analysis indicated that 89 per cent of subjects met or exceeded the recommended intake for vitamin E, and so dietary intake was unlikely to be responsible for the low alpha-tocopherol levels, write the researchers in this month's European Journal of Clinical Nutrition (vol 59, pp304-306).
Yet they found that the subjects had significantly lower levels of the vitamin than has previously been reported for healthy Australians.
In addition, alpha-tocopherol levels were inversely related to depression score.
"While it cannot be determined from our study, it seems possible thatthe lower vitamin E in blood may be a marker of increased physiologicalstress (possibly increased oxidative stress) in depression," lead author Dr Alice Owen from the Smart Foods Centre in the University of Wollongong, Australia told NutraIngredients.com.
Previous studies have shown that antioxidant vitamins may protect the brain against damage caused by free radicals and other reactive oxygen species produced during basic cellular metabolism.
"We hope to see further research examining the role of oxidative stress in the pathophysiology of depression, which will hopefully allow the scientific community to develop new treatment strategies," added Dr Owen.
She noted however that there is no evidence so far to suggest that increasing vitamin E status through supplements will be of therapeutic value.
Owen's team will shortly release results from further research looking at the effect of a nutritional supplement in adults with major depression.