Bioavailability of food folates is 80% of that of folic acid.
BACKGROUND
The bioavailability of natural food folates is lower than that of synthetic folic acid, but no agreement exists as to the extent of the difference.


OBJECTIVE
In a 4-wk dietary intervention study, we determined the aggregate bioavailability of food folates from fruit, vegetables, and liver relative to that of folic acid.


METHODS
Seventy-two healthy adults were randomly divided into 4 treatment groups. Group A (n = 29) received a high-folate diet with 369 mug food folate/d and a placebo capsule; groups B, C, and D (n = 14 or 15) received a low-folate diet with 73 microg food folate/d and folic acid capsules. These capsules contained 92 microg folic acid/d for group B, 191 microg for group C, and 289 microg for group D. In addition, all 72 subjects daily ingested a capsule with 58 microg [(13)C(11)]-labeled folic acid. We measured the percentage of [(13)C(11)]-labeled folate in plasma folate at the end of the intervention and ascertained the changes in serum folate concentrations over the 4 wk of the intervention.


RESULTS
Bioavailability of food folate relative to that of folic acid was 78% (95% CI: 48%, 108%) according to [(13)C(11)]-labeled folate and 85% (52%, 118%) according to changes in serum folate concentrations.


CONCLUSIONS
The aggregate bioavailability of folates from fruit, vegetables, and liver is approximately 80% of that of folic acid. The consumption of a diet rich in food folate can improve the folate status of a population more efficiently than is generally assumed.
Winkels
Renate M
RM
Wageningen Centre for Food Sciences, Wageningen, Netherlands. renate.winkels@wur.nl
Brouwer
Ingeborg A
IA
Siebelink
Els
E
Katan
Martijn B
MB
Verhoef
Petra
P
D000328:Adult; D004032:Diet; D004305:Dose-Response Relationship, Drug; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage* / Q000138:chemical synthesis / Q000493:pharmacokinetics*; D005502:Food; D005504:Food Analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009753:Nutritive Value
D005492:Folic Acid