Folic acid, riboflavin, thiamine, and vitamin B-6 status of a group of first-time blood donors

Reference intervals for long-term status measures of folate, riboflavin, thiamine, and vitamin B-6 were determined in a select group of adults. Reference subjects had no adverse medical history and did not use tobacco, alcohol, or nutritional supplements, and their diets met greater than or equal to 70% of the Australian recommended dietary intake for nutrients. Red blood cell concentrations of thiamine and folate were measured by microbiological methods. Vitamin B-6 and riboflavin status were measured on the basis of the erythrocyte aspartate transaminase activity coefficient and erythrocyte glutathione reductase activity coefficient, respectively. A survey of first-time blood donors, which was conducted in Australia in 1995, revealed a significant prevalence of low red blood cell thiamine concentrations (13%) when compared with the calculated normal reference intervals. However, the most important finding in the survey was that the group of healthy nonanemic adults (first-time blood donors) was found to have a median red blood cell folate concentration 24% below the median concentration of the carefully selected (nonsupplemented) reference group. Plasma total homocysteine concentrations indicated folate deficiency in the reference group. Therefore, the 2.5th percentile cutoff for reference group red blood cell folate concentrations may have underestimated the prevalence of folate deficiency in the survey group. These data, coupled with the lack of Australian food-composition data for folate in particular, reinforce the need for monitoring nutritional status by both dietary and biochemical means. We recommend consideration of mandatory fortification of the Australian food supply with folic acid.