Forty-five hospitalised patients with DSM-III-R diagnosis of mania, were found to have a mean red-cell folate level of 193 nmol/l, as compared to 896 nmol/l in the control group (P < 0.00001). Assessment of serum folate in both groups showed no significant differences in the levels. Furthermore the manic patients and the controls were matched by the socio-economic status. This indicated that the reduced red-cell folate in mania is associated with the illness and not due to reduced absorption or dietary deficiency of folate. Considering previous studies that showed reduced red-cell folate in depression, our findings suggest that reduced red-cell folate occurred in both phases of bipolar disorders.
Epidemiological studies have reported inconsistent findings for the association between B vitamins and breast cancer (BC) risk. We investigated the relationship between biomarkers of folate and vitamin B12 and the risk of BC in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. Plasma concentrations of folate and vitamin B12 were determined in 2,491 BC cases individually matched to 2,521 controls among women who provided baseline blood samples. Multivariable logistic regression models were used to estimate odds ratios by quartiles of either plasma B vitamin. Subgroup analyses by menopausal status, hormone receptor status of breast tumors (estrogen receptor [ER], progesterone receptor [PR] and human epidermal growth factor receptor 2 [HER2]), alcohol intake and MTHFR polymorphisms (677C > T and 1298A > C) were also performed. Plasma levels of folate and vitamin B12 were not significantly associated with the overall risk of BC or by hormone receptor status. A marginally positive association was found between vitamin B12 status and BC risk in women consuming above the median level of alcohol (ORQ4-Q1 = 1.26; 95% CI 1.00-1.58; Ptrend = 0.05). Vitamin B12 status was also positively associated with BC risk in women with plasma folate levels below the median value (ORQ4-Q1 = 1.29; 95% CI 1.02-1.62; Ptrend = 0.03). Overall, folate and vitamin B12 status was not clearly associated with BC risk in this prospective cohort study. However, potential interactions between vitamin B12 and alcohol or folate on the risk of BC deserve further investigation.