Folate intake, plasma folate and homocysteine status in a random Finnish population

To assess the folate status of Finnish adults using plasma folate and homocysteine as biomarkers and to evaluate dietary and supplementary folate intakes.

Plasma folate, vitamin B(12) and total homocysteine (tHcy) were determined in a random sample of 643 subjects aged 25-74 y living in the Helsinki area. The methylenetetrahydrofolate reductase (MTHFR)-genotypes were analyzed from a subsample (n=394). Dietary intake data by 24 h recall and use of vitamin supplements were collected.

Plasma folate was normal (>/=5 nmol/l) in 99% of subjects and optimal (>/=8 nmol/l) in terms of a minimum tHcy in 90%. Mean plasma folate of non-supplement users was 13.7 and 12.9 nmol/l and tHcy 11.3 and 9.2 micro mol/l for men and women, respectively. Elevated tHcy (>14 micro mol/l) was found in 11% of subjects. Homozygote frequency for MTHFR genotype TT was 5.0% and their plasma tHcy was 14.8 micro mol/l compared to the mean of the other subjects, 10.5 micro mol/l, P<0.05. The mean dietary folate intake was 241 micro g/day (29 micro g/MJ of energy) for men and 205 micro g/day (33 micro g/MJ) for women, respectively. The main dietary sources of folate were vegetables 12%, wholemeal ryebread 11%, fruits 10%, and potato 10%. Regular supplement users (n=97) received on average 207 micro g folic acid per day from supplements.

The folate status of Finnish adults seems to be adequate according to energy adjusted folate intake, plasma folate and homocysteine. The MTHFR homozygote frequency was low compared to other countries. Regular use of supplementary folic acid less than 300 micro g increased plasma folate, but supplemental folic acid over 300 micro g was required to lower tHcy values significantly.