Search

BackgroundThere is increasing recognition that personalized approaches may be more effective in helping people establish healthier eating patterns and exercise more, and that this approach may be particularly effective in adolescents. ObjectiveThe objective of this study was to investigate the use of a smartphone app (FoodWiz2) in supporting healthy lifestyle choices in adolescence. MethodsParticipants (N=34: 11 male, 23 female) aged 16-19 years in full- or part-time education were recruited from sixth form colleges, schools, and other further education establishments in Norfolk and Suffolk, United Kingdom, between February and May 2015. Participants recorded food intake and exercise using a paper diary for 4-5 weeks and then used the app for the same duration. Initial nutrition education and general support were provided during the paper diary use, but the app included personalized messages sent in response to app activity. At the end of each study phase, participants completed an online questionnaire to describe their experience of using the paper diary and app. ResultsRecord completion declined throughout the study, possibly affected by examination pressure. Food intake data showed increased fruit consumption and significantly reduced consumption of chocolate snacks (P=.01) and fizzy drinks (P=.002) among participants using the app. Questionnaire responses indicated that the app was generally preferred to the paper diary, in particular, the app was seen as less boring to use (P=.03) and more acceptable in social settings (P

Single [sup.13][C.sub.6]-labeled doses of pteroylmonoglutamic acid (PteGlu: 634 nmol; n = 14), (6S-)5-formyltetrahydrofolic acid (431-569 nmol; n = 16), or [[sup.15][N.sub.1-7]]-intrinsically labeled spinach (mainly 5-methyltetrahydrofolate) (588 nmol; n = 14) were fed to fasting adult volunteers. Plasma-labeled 5-methyltetrahydrofolic acid responses were monitored for 8 h. There was a slower rate of increase in plasma-labeled 5-methyltetrahydrofolic acid and longer time to peak (171 [+ or -] 9 min; mean [+ or -] SEM) following an oral dose of [[sup.13][C.sub.6]]PteGlu than either [[sup.13][C.sub.6]5-formyltetrahydrofolic acid (54 [+ or -] 10 min) or [[sup.15][N.sub.l-7]]spinach folate (60 [+ or -] 13 min) suggesting saturated metabolic capacity for the biotransformation of PteGlu. Mathematical modeling generated a significantly higher mean 'apparent absorption' for 5-formyltetrahydrofolic acid (38%) and spinach folate (44%) than for PteGlu (24%). The high 'relative absorption' of reduced folates to PteGlu was unexpected given that PteGlu itself, from [sup.14]C-tracer mass balance experiments, is almost completely absorbed. Although it is ubiquitously accepted that a physiological dose of PteGlu is reduced and methylated in the epithelial cells of the small intestine, and that essentially only 5-methyltetrahydrofolic acid is exported into the hepatic portal vein (HPV), as is the case for absorbed reduced 1-carbon-substituted folates, modeling indicated greater liver sequestration when PteGlu was used as the test dose, suggesting that PteGlu enters the HPV unaltered and that the liver is the primary site of initial metabolism. Because of the observed differential plasma response and the hypothesized difference in the site of initial metabolism, the historical use of PteGlu as a 'reference folate' in studies of folate bioavailability is seriously questioned. KEY WORDS: * pteroylmonoglutamic acid * folate * absorption * isotopes * modeling

Folic acid fortification, mandatory in the United States, is currently being considered by the UK. The hypothesis that the matrix of some cereal-product vehicles may result in low fortificant bioavailability was tested using a dual oral/intravenous (i.v.) isotopic-label approach, which was evaluated concurrently. Fifteen women received 225 [micro]g oral folate (capsules, fortified white bread and fortified branflakes), mainly as folic acid labeled with [sup.13]C on 6 carbons of the benzoyl ring ([sup.13][C.sub.6]-PteGlu), followed by i.v. injection of 100 [micro]g folic acid labeled with [sup.2]H on 4 hydrogens of the glutamic acid group ([sup.2][H.sub.4]-PteGlu). The urinary excretion ratio (UER) in intact folate of the percentage of labeled oral dose excreted divided by the percentage of i.v. dose excreted was used as the primary index of absorption. The geometric mean (95% confidence interval) UER for folic acid capsules was 3.68 (1.90, 7.14) at 24 h and 2.18 (1.24, 3.83) at 48 h. Because these were significantly in excess of 1.0, indicative of 100% absorption of the oral dose, it was concluded that oral and i.v. labeled folic acid are handled differently by the body and that 'absolute' absorption cannot be calculated. Compared with the 48-h UER for folic acid capsules, the 'relative' 48-h UER for white bread and branflakes was 0.71 and 0.37, respectively, indicating that some cereal-based vehicles may inhibit absorption of fortificant. However, even the validity of this 'relative' approach is questioned. J. Nutr. 132: 936-939, 2002. KEY WORDS: * folic acid * bioavailability * absorption * stable isotope * cereal

A letter to the editor is presented in response to the articles "Folate intake of the Dutch population according to newly established liquid chromatography data for foods" by Erik J.M. Konings in a 2001 issue along with the author's response.

Folic acid (pteroylmonoglutamic acid) has historically been used as the reference folate in human intervention studies assessing the relative bioavailability of dietary folate. Recent studies using labelled folates indicated different plasma response kinetics to folic acid than to natural (food) folates, thus obviously precluding its use in single-dose experiments. Since differences in tissue distribution and site of biotransformation were hypothesised, the question is whether folic acid remains suitable as a reference folate for longer-term intervention studies, where the relative bioavailability of natural (food) folate is assessed based on changes in folate status. Healthy adults aged 18-65 years (n 163) completed a 16-week placebo-controlled intervention study in which the relative bioavailability of increased folate intake (453 nmol/d) from folate-rich foods was assessed by comparing changes in plasma and erythrocyte folate concentration with changes induced by an equal reference dose of supplemental (6S)-5-methyltetrahydrofolic acid or folic acid. The relative increase in plasma folate concentration in the food group was 31 % when compared with that induced by folic acid, but 39 % when compared with (6S)-5-methyltetrahydrofolic acid. The relative increase in erythrocyte folate concentration in the food group when compared with that induced by folic acid was 43 %, and 40 % when compared with (6S)-5-methyltetrahydrofolic acid. When recent published observations were additionally taken into account it was concluded that, in principle, folic acid should not be used as the reference folate when attempting to estimate relative natural (food) folate bioavailability in longer-term human intervention studies. Using (6S)-5-methyltetrahydrofolic acid as the reference folate would avoid future results' validity being questioned.