Folates in bread: retention during bread-making and in vitro bioaccessibility
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Bread is an important folate source in several countries. However, bread-making was reported to cause losses of endogenous bread folates (~40%) as well as added synthetic folic acid (~30%). Furthermore, the bread matrix is suggested to inhibit absorption of folates.
To (1) estimate retention of both, endogenous folates and synthetic fortificants, during bread-making, (2) assess in vitro folate bioaccessibility from breads and a breakfast meal and (3) assess in vitro folate uptake.
Retention of folate forms was assessed by preparing fortified (folic acid and [6S]-5-CH3-H4folate) wholemeal breads and collect samples from dough, proofed dough and the bread. In vitro folate bioaccessibility was assessed using the TNO gastrointestinal model TIM. In vitro folate uptake was assessed using a novel Caco-2 cell/stable isotope model. Folate content in samples was measured using LCMS.
Bread-making resulted in losses of 41% for endogenous folates and up to 25 and 65% for folic acid and [6S]-5-CH3-H4folate fortificant, respectively. 75% of endogenous bread folates and 94% of breakfast folates were bioaccessible as assessed by TIM. From [6S]-5-CH3-H4folate-fortified bread, relative folate uptake into Caco-2 cells was 71 ± 11% (P < 0.05) when compared with a standard solution.
Retention of folic acid fortificant during bread-making was substantially higher compared to retention of [6S]-5-CH3-H4folate fortificant. Data from the TIM and Caco-2 cell trials suggest an inhibiting effect of the tested bread matrices on in vitro bioaccessibility of folates, whereas folate bioaccessibility from a breakfast meal is almost complete.
KeywordsFolates TNO gastrointestinal model TIM Bread-making In vitro bioaccessibility Caco-2-cell/stable isotope model
We thank R. Havenaar and M. Verwei at TNO for carrying out TIM experiments and K. Damstedt and I. Börjesson (Cerealia R&D, Järna, Sweden) for bread-making. A. Kamal-Eldin and M. Jägerstad are acknowledged for valuable comments on the manuscript. We thank P. Artursson at Uppsala University for donation of Caco-2 cells, L. Babul at SLU for folate-binding protein and H. Nygaard Lærke at University of Aarhus for porcine bile. Non-labelled folate standards were kind gifts from Merck Eprova AG, Schaffhausen, Switzerland. This study was supported by the Swedish Research Council Formas and the Cerealia Foundation R&D.
Conflict of interest statement
The authors declare that they have no conflict of interest.
- 3.Smith AD, Kim Y-I, Refsum H (2008) Is folic acid good for everyone? Am J Clin Nutr 87:517–533Google Scholar
- 4.Becker W, Pearson M (2003) Riksmaten 1997–98, Kostvanor och näringsintag i Sverige (Riksmaten 1997–98. Dietary habits and nutrient intake in Sweden). National Food Administration. UppsalaGoogle Scholar
- 7.Pfeiffer CM, Rogers LM, Bailey LB, Gregory IJF (1997) Absorption of folate from fortified cereal-grain products and of supplemental folate consumed with or without food determined using a dual-label stable-isotope protocol. Am J Clin Nutr 66:1388–1397Google Scholar
- 8.Colman N, Green R, Metz J (1975) Prevention of folate deficiency by food fortification. II. Absorption of folic acid from fortified staple foods. Am J Clin Nutr 28:459–464Google Scholar
- 9.Finglas PM, Witthöft CM, Vahteristo L, Wright AJA, Southon S, Mellon FA, Ridge B, Maunder P (2002) Use of an oral/intravenous dual-label stable-isotope protocol to determine folic acid bioavailability from fortified cereal grain foods in women. J Nutr 132:936–939Google Scholar
- 10.Verwei M, Freidig AP, Havenaar R, Groten JP (2006) Predicted serum folate concentrations based on in vitro studies and kinetic modeling are consistent with measured folate concentrations in humans. J Nutr 136:3074–3078Google Scholar
- 11.Verwei M (2004) Bioaccessibility of folate from several liquid and solid food products. Thesis. Wageningen University. WageningenGoogle Scholar
- 13.Arkbåge K, Verwei M, Havenaar R, Witthöft C (2003) Bioaccessibility of folic acid and (6S)-5-methyltetrahydrofolate decreases after the addition of folate-binding protein to yogurt as studied in a dynamic in vitro gastrointestinal model. J Nutr 133:3678–3683Google Scholar
- 15.Enghardt-Barbieri H, Lindwall C (2005) Swedish Nutrition Recommendations Objectified (SNO)—basis for general advice on food consumption for healthy adults. National Food Administration, UppsalaGoogle Scholar
- 18.Konings EJM (1999) A validated liquid chromatographic method for determining folates in vegetables, milk powder, liver and flour. J AOAC Int 82:119–125Google Scholar
- 20.Ashokkumar B, Mohammed ZM, Vaziri ND, Said HM (2007) Effect of folate oversupplementation on folate uptake by human intestinal and renal epithelial cells. Am J Clin Nutr 86:159–166Google Scholar
- 26.Konings EJM, Roomans HHS, Dorant E, Goldbohm RA, Saris WHM, van den Brandt PA (2001) Folate intake of the Dutch population according to newly established liquid chromatography data for foods. Am J Clin Nutr 73:765–776Google Scholar
- 28.Dietrich M, Brown CJP, Block G (2005) The effect of folate fortification of cereal-grain products on blood folate status, dietary folate intake, and dietary folate sources among adult non-supplement users in the United States. J Am Coll Nutr 24:266–274Google Scholar
- 29.van Oort FVA, Melse-Boonstra A, Brouwer IA, Clarke R, West CE, Katan MB, Verhoef P (2003) Folic acid and reduction of plasma homocysteine concentrations in older adults: a dose–response study. Am J Clin Nutr 77:1318–1323Google Scholar