Original Communication
European Journal of Clinical Nutrition (2005) 59, 906–913. doi:10.1038/sj.ejcn.1602159; published online 1 June 2005
Bioavailability of folic acid from fortified pasteurised and UHT-treated milk in humans
Guarantor: M Verwei.
Contributors: The study was designed by HvdB, JJMC and CEW. The practical work was prepared by JJMC, carried out by RJdJ with the assistance of MV, and supervised by CEW. ES was involved in the dietary aspects of the trial. RJdJ carried out the data analysis with assistance of CEW, JJMC and TvV. All authors contributed to the final version of the manuscript.
R J de Jong1,2, M Verwei1,2,3, C E West1,2,4,5, T van Vliet3, E Siebelink2, H van den Berg1 and J J M Castenmiller1,2
- 1TNO-WU Centre for Micronutrient Research, Zeist and Wageningen, The Netherlands
- 2Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
- 3Physiological Sciences, TNO Nutrition and Food Research, Zeist, The Netherlands
- 4Division of Gastroenterology and Hepatology, University Medical Centre Nijmegen, The Netherlands
Correspondence: M Verwei, TNO Nutrition and Food Research, Physiological Sciences Department, PO Box 360, 3700 AJ Zeist, The Netherlands. E-mail: Verwei@voeding.tno.nl
5This article is dedicated to the coauthor Professor Clive E West who passed away on August 27, 2004.
Received 6 July 2004; Revised 8 March 2005; Accepted 29 March 2005; Published online 1 June 2005.
Abstract
Objective
The aim of this study was to investigate whether milk fortified with folic acid enhances the folate status of humans and whether the presence of folate-binding proteins (FBP) in pasteurised milk affects the bioavailability of folic acid from fortified milk. In untreated and pasteurised milk, folate occurs bound to FBP, while FBP is (partly) denatured in ultra-high-temperature (UHT)-treated milk. The effect of FBP on folate bioavailability is still unclear.
Design, subjects and setting
Healthy, free-living subjects (n=69) aged 18–49 y participated in a 4-week double-blind, placebo-controlled dietary intervention study.
Intervention
In addition to a fully controlled diet, the subjects consumed each day 500 ml of pasteurised or UHT milk, either fortified or not with 200 
g folic acid.
Results
Consumption of fortified milk increased folate concentrations in serum and in red blood cells (RBC) by 6.6–7.0 nmol/l (P<0.001) and 32–36 nmol/l (P<0.01), respectively. Similarly, plasma homocysteine concentrations were lowered 0.88–0.89 mol/l (P=0.001) in subjects who consumed fortified milk. The bioavailability of folic acid from pasteurised milk relative to that of folic acid from UHT milk was 74–94% (NS), depending on the parameter used.
Conclusions
Milk fortified to supply an additional 200 g of folic acid/s substantially increased folate status, and decreased plasma total homocysteine concentrations in young, healthy subjects. Milk is therefore a suitable matrix for fortification to enhance the folate status in humans. No significant effect of endogenous FBP was found on the bioavailability of folic acid from milk.
Keywords:
folic acid, fortified milk, bioavailability, folate-binding proteins, homocysteine, humans
