people over the age of 65 for 2-3 years. At the beginning of the study
none of the subjects were depressed. However, at the end of the study it
was discovered that those people who had lower levels of vitamin B12 and
folate in their blood - and higher levels of a substance called
homocysteine - had a significantly higher risk of depression than other
people in the study.
"Predictive value of folate, vitamin B12 and homocysteine levels in
late-life depression," Kim JM, Stewart R, et al, Br J Psychiatry, 2008;