Gender and body size affect the response of erythrocyte folate to folic acid treatment

The recommended dietary allowance (RDA) differs between men and women for some vitamins, but not for folate. The RDA for folate is derived mainly from metabolic studies in women. We assessed if men differ from women in their response of erythrocyte folate to folic acid supplementation. We used data from 2 randomized placebo-controlled trials with folic acid: a 3-y trial in which subjects ingested 800 mu g/d of folic acid (294 men and 112 women) and a 12-wk trial in which 187 men and 129 women ingested 0, 50, 100, 200, 400, 600, or 800 mu g/d of folic acid in a parallel design (n = 38-42 per treatment group). In the 3-y trial, the erythrocyte folate concentration increased 10% (143 nmol/L, [95%Cl 46, 241]) less in men than in women. In the 12-wk trial, regression analysis showed that the response of erythrocyte folate upon folic acid intake for men was 47 nmol/L lower than for women (P for beta(gender) = 0.022); for an intake of 800 mu g/d folic acid, this resulted in a 5% lower response in men than in women. Differences in lean body size explained 56% of the difference in response of erythrocyte folate between men and women in the 3-y trial and 70% in the 12-wk trial. Men need more folic acid than women to achieve the same erythrocyte folate concentration, mainly because men have a larger lean body mass. This could be an indication that the RDA for folate should be higher for men than for women, or that the RDA should be expressed per kilogram of lean body mass

Bioavailability of Food Folates is 80% of that of folic acid 1-3

Background: The bioavailability of natural food folates is lower than that of synthetic folic acid, but no agreement exists as to the extent of the difference. Objective: In a 4-wk dietary intervention study, we determined the aggregate bioavailability of food folates from fruit, vegetables, and liver relative to that of folic acid. Design: Seventy-two healthy adults were randomly divided into 4 treatment groups. Group A (n = 29) received a high-folate diet with 369 µg food folate/d and a placebo capsule; groups B, C, and D (n = 14 or 15) received a low-folate diet with 73 µg food folate/d and folic acid capsules. These capsules contained 92 µg folic acid/d for group B, 191 µg for group C, and 289 µg for group D. In addition, all 72 subjects daily ingested a capsule with 58 µg [13C11]-labeled folic acid. We measured the percentage of [13C11]-labeled folate in plasma folate at the end of the intervention and ascertained the changes in serum folate concentrations over the 4 wk of the intervention. Results: Bioavailability of food folate relative to that of folic acid was 78% (95% CI: 48%, 108%) according to [13C11]-labeled folate and 85% (52%, 118%) according to changes in serum folate concentrations. Conclusions: The aggregate bioavailability of folates from fruit, vegetables, and liver is 80% of that of folic acid. The consumption of a diet rich in food folate can improve the folate status of a population more efficiently than is generally assumed

Use of faecal markers in screening for colorectal neoplasia: a European group on tumor markers position paper

Contains fulltext : 97497.pdf (publisher's version ) (Closed access)Several randomized controlled trials have shown that population-based screening using faecal occult blood testing (FOBT) can reduce mortality from colorectal neoplasia. Based on this evidence, a number of countries have introduced screening for colorectal cancer (CRC) and high-risk adenoma and many others are considering its introduction. The aim of this article is to critically review the current status of faecal markers as population-based screening tests for these neoplasia. Most of the available faecal tests involve the measurement of either occult blood or a panel of DNA markers. Occult blood may be measured using either the guaiac faecal occult blood test (gFOBT) or a faecal immunochemical test (iFOBT). Although iFOBT may require a greater initial investment, they have several advantages over gFOBT, including greater analytical sensitivity and specificity. Their use results in improved clinical performance and higher uptake rates. Importantly for population screening, some of the iFOBTs can be automated and provide an adjustable cutoff for faecal haemoglobin concentration. However, samples for iFOBT, may be less stable after collection than for gFOBT. For new centres undertaking FOBT for colorectal neoplasia, the European Group on Tumour Markers recommends use of a quantitative iFOBT with an adjustable cutoff point and high throughput analysis. All participants with positive FOBT results should be offered colonoscopy. The panel recommends further research into increasing the stability of iFOBT and the development of improved and affordable DNA and proteomic-based tests, which reduce current false negative rates, simplify sample transport and enable automated analysis