Tetrahydrofolates Are Greatly Stabilized by Binding to Bovine Milk Folate-Binding Protein

Abstract

The dietary supply of folates and their measurement are both affected, potentially, by the instability of some folates. Labile folates appear to be stabilized by binding to folate-binding protein (FBP); this paper reports measurements of that stabilization. The degradation rates of the very labile tetrahydrofolate (H(4)folate) and moderately labile 5-methyltetrahydrofolate (5-CH(3)H(4)folate) were measured with the compounds free or bound to either soluble or immobilized bovine milk FBP. Complexation increased stability from 2- to> 1000-fold, depending on buffer and temperature conditions. H(4)folate at 4 degrees C and pH 6.7 appeared to be quite stable for > 100 d when bound to soluble FBP but had a half-life of < 1 h when free. Stabilization of milk folates may be a role of FBP and would improve the bioavailability of milk folate to newborns and other consumers.

Folate intakes and folate biomarker profiles of pregnant Japanese women in the first trimester

“…Milk contains folatebinding protein (FBP). As it has been reported that FBP may increase the bioavailability of dietary folate (Jones and Nixon, 2002;Jones et al, 2003), adequate milk consumption may be partly responsible for higher serum folate concentrations in pregnant Japanese women. RBC folate concentrations varied widely between subjects, especially in the high folate group.…”

Pterin and Folate Salvage. Plants and Escherichia coli Lack Capacity to Reduce Oxidized Pterins

“…The dihydropterin intermediates of folate synthesis could well be largely protein bound, and in this state resist oxidation. This is the case for tetrahydrofolates in mammals (Suh et al, 2001;Jones and Nixon, 2002). For the breakdown product H 2 PtCHO, a sufficiently high side chain reductase activity could intervene to reduce it to H 2 PtCH 2 OH almost as it formed, preempting the chance of ring Figure 6.…”

Milk fermented with selected strains of lactic acid bacteria is able to improve folate status of deficient rodents and also prevent folate deficiency

“…In addition, 5-methylTHF and 10-formylTHF are commonly the folate forms synthetized by bacteria and the most used for cellular metabolic reactions . Moreover, fermented milk is considered an adequate matrix among dairy products for folate enrichment because folate binding proteins of milk improve folate stability and the bioavailability of 5-methylTHF (Jones & Nixon, 2002). These observations would explain the effectiveness of oral administration of fermented milk rich in natural folate to prevent readily folate deficiency avoiding adverse health outcomes of the population associated with low folate status.…”