Adding folic acid to foods is not currently permitted in many European markets, including the Netherlands, but it is added to flour in the US, Canada and Chile in order to prevent neural tube defects in babies.
Ireland is currently consulting on whether it too should encourage the introduction of some fortified foods or implement mandatory fortification as a means of stemming its high rate of birth defects.
The new study shows that milk could be another application for increasing intake of the vitamin, as well as the bread and cereal products that are already enriched with folic acid through fortified flour in some markets.
Miriam Verwei, a postdoctoral student, and colleagues from Wageningen University and TNO Nutrition and Food Research recruited 69 healthy adults for a four-week, double-blind, placebo-controlled intervention study.
In addition to a fully controlled diet, the subjects consumed 500ml of pasteurised or UHT milk, either fortified with 200mcg of folic acid or not fortified.
The consumption of fortified milk increased folate concentrations in serum and in red blood cells and lowered plasma homocysteine concentrations in the subjects, write the researchers in this month's edition of the European Journal of Clinical Nutrition (vol 59, issue 8, pp906-913).
"Milk is therefore a suitable matrix for fortification to enhance the folate status in humans," they report.
The scientists had hypothesised that the presence of folate-binding proteins (FBP) in pasteurised milk might increase the bioavailability of folic acid from fortified milk (the proteins are partly denatured in UHT milk).
However they found no such benefit, possibly because the pasteurised milk contained few of the folate-binding proteins.
Nevertheless Verwei said the findings showed that milk would be a good food source to fortify.
"Folic acid is really highly accessible from milk, and our findings were comparable to other studies testing other products," Verwei told NutraIngredients.com.
However to compare whether milk or bread would be a more effective source of the vitamin, a comparative study would be required, she added.
"What is important is to reach the biggest part of the population. It depends on the region's eating habits which product is best."