Bioavailability of folic acid from fortified pasteurised and UHT-treated milk in humans

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 ¼ 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 mg 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 (Po0.001) and 32-36 nmol/l (Po0.01), respectively. Similarly, plasma homocysteine concentrations were lowered 0.88-0.89 mmol/l (P ¼ 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 mg 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.

Red cell or serum folate: what to do in clinical practice?

“…For instance, in different studies of healthy populations using the same follow-up interval (de Jong et al [ 75 ] and Schorah et al [ 76 ]), the population with the lower baseline folate concentration (8.6 vs. 19.7 nmol/L) demonstrated the greater increase (64% vs. 47%). Analysing data from 13 studies, Wald et al found a greater proportional increase in serum folate for those with lower baseline concentrations [ 87 ].…”

Analytical Methods to Assess the Bioavailability of Water‐Soluble Vitamins in Food–Exemplified by Folate

“…The numerous approaches, having specifi c advantages and limitations, can provide information on folate bioavailability to different extents (Table 2.2 ). In food -related research, it is diffi cult to carry out double -blind randomized controlled intervention trials [58] . It is important to control compliance, choice of the intervention period (preferably three or more months, especially when slowresponding erythrocyte folate concentrations are used for status assessment), and choice of suitable endpoint/status parameters when designing an intervention study.…”

“…It is important to control compliance, choice of the intervention period (preferably three or more months, especially when slowresponding erythrocyte folate concentrations are used for status assessment), and choice of suitable endpoint/status parameters when designing an intervention study. High bioavailabilities of endogenous folates from vegetables and fruits [59,60] , rye cereal products and orange juice [61] , folic acid -fortifi ed milk [58,62] , and folic acid -fortifi ed breakfast rolls [63] have been reported using different intervention models. Also, the effects of dietary polyglutamyl folates [64] and different folate supplements [65] on folate status have been studied.…”

Nutridynamics – studying the dynamics of food components in products and in the consumer

“…It was suggested from animal experiments that the addition of FBP-rich foods to folate-rich foods could enhance the bioavailability of folates, but the outcome of such a combination would depend on interactions with other components of the diet [44]. Although milk is a suitable matrix for folic acid fortification to enhance folate status, no significant effect of endogenous FBP was found on the bioavailability of folic acid from milk [45].…”