Biomedical subjects

Mette Bach Kristensen

Publications and source records attributed to Mette Bach Kristensen.

4 recordsLinked to original sources

PubMed2006

Total zinc absorption in young women, but not fractional zinc absorption, differs between vegetarian and meat-based diets with equal phytic acid content.

Zn bioavailability is often lower in vegetarian diets mainly due to low Zn and high phytic acid contents. The objective of the present study was to determine the fractional and total absorption of Zn from a vegetarian diet in comparison with meat diets with equal concentrations of phytic acid. A randomized cross-over design, comprising three whole-day diet periods of 5 d each, with a vegetarian diet or diets containing Polish-produced meat or Danish-produced meat, was conducted. Twelve healthy female subjects completed the study. All diets had a high content of phytic acid (1250 micromol/d) and in the meat diets the main meals contained 60 g pork meat. All main meals were extrinsically labelled with the radioactive isotope 65Zn and absorption of Zn was measured in a whole-body counter. The mean Zn content of the whole-day diet was: Polish meat diet 9.9 (SE 0.14) mg, Danish meat diet 9.4 (SE 0.19) mg and vegetarian diet 7.5 (SE 0.18) mg. No difference was observed in the fractional absorption of Zn (Polish meat diet: 27 (SE 1.2) %, Danish meat diet: 27 (SE 1.9) % and vegetarian diet: 23 (SE 2.6) %). A significantly lower amount of total Zn was absorbed from the vegetarian diet (mean Zn absorption of Polish meat diet: 2.7 (SE 0.12) mg/d (P<0.001), Danish meat diet: 2.6 (SE 0.17) mg/d (P=0.006) and vegetarian diet: 1.8 (SE 0.20) mg/d). In conclusion, the vegetarian diet compared with the meat-based diets resulted in lower amounts of absorbed Zn due to a higher content of Zn in the meat diets, but no difference was observed in the fractional absorption of Zn.

Adult↗

PubMed2005

Pork meat increases iron absorption from a 5-day fully controlled diet when compared to a vegetarian diet with similar vitamin C and phytic acid content.

Meat increases absorption of non-haem iron in single-meal studies. The aim of the present study was to investigate, over a 5 d period, the potential increasing effect of consumption of pork meat in a whole diet on the fractional absorption of non-haem iron and the total absorption of iron, when compared to a vegetarian diet. A randomised cross-over design with 3 x 5 d whole-diet periods with diets containing Danish-produced meat, Polish-produced meat or a vegetarian diet was conducted. Nineteen healthy female subjects completed the study. All main meals in the meat diets contained 60 g of pork meat and all diets had high phytic acid content (1250 mumol/d). All main meals were extrinsically labelled with the radioactive isotope (59)Fe and absorption of iron was measured in a whole body counter. The non-haem iron absorption from the Danish meat diet was significantly higher compared to the vegetarian diet (P=0.031). The mean fractional absorption of non-haem iron was 7.9 (se1.1), 6.8 (se 1.0) and 5.3 (se 0.6) % for the Danish and Polish meat diets and vegetarian diet, respectively. Total absorption of iron was higher for both meat diets compared to the vegetarian diet (Danish meat diet: P=0.006, Polish meat diet: P=0.003). The absorption ratios of the present study were well in accordance with absorption ratios estimated using algorithms on iron bioavailability. Neither the meat diets nor the vegetarian diets fulfilled the estimated daily requirements of absorbed iron in spite of a meat intake of 180 g/d in the meat diets.

Absorption↗

PubMed2005

The importance of dietary composition for efficacy of iron absorption measured in a whole diet that includes rye bread fortified with ferrous fumerate: a radioisotope study in young women.

Fe absorption is affected by many dietary factors. The objective of the present study was to measure the effects of high v. low content of vitamin C, meat and phytic acid in whole diets with Fe-fortified bread on the efficacy of Fe absorption. Thirty-two healthy women with low Fe stores were randomised to three groups, each of which was given two of six test diets containing either low/high amounts of vitamin C, meat or phytic acid, respectively, in a cross-over design. Each diet was served throughout a 5 d period. Fe-fortified rye bread, extrinsically labelled with (59)Fe, was given with all main meals. Fe absorption was determined from whole-body counter measurements of (59)Fe retention. The fractional non-haem Fe absorption (corrected to a 40 % standard absorption by measurements from the reference dose) was 1.9 % v. 3.4 % (P=0.04) for the low/high vitamin C diets, 3.0 % v. 3.5 % (P=0.58) on the low/high meat diets and 4.9 % v. 3.8 % (P=0.24) on the low/high phytic acid diet, respectively. The total Fe absorbed (geometric mean with standard error) varied from 0.43 (se 0.11) mg from the diet with lowest bioavailability to 1.09 (se 0.18) mg from the diet with highest bioavailability (P<0.001). The present whole-diet study indicates that diet composition is a strong predictor of Fe absorption. In the diet with a low content of enhancers and a high content of inhibitors, vitamin C improved non-haem Fe absorption. The total Fe absorption varied 2.5-fold after small alterations of the content of enhancers and inhibitors in the diet.

Absorption↗

PubMed2004

A decrease in iron status in young healthy women after long-term daily consumption of the recommended intake of fibre-rich wheat bread.

BACKGROUND: Fibrerich bread and cereals are included in the recommendations of a healthy diet. OBJECTIVE: To measure the effects of long-term consumption of the recommended intake of fibre-rich wheat bread on the iron status of young healthy women with adequate iron stores. DESIGN: Four-months intervention study including healthy female subjects assigned into two groups provided daily with 300 g of fibre-rich wheat bread, prepared with or without phytase as a supplement to their habitual diet. SUBJECTS: Forty-one women aged 24.8 +/- 3.8 years (mean +/- SD) and an average BMI of 22.0 +/- 2.9 kg/m2 participated. Baseline values for serum ferritin were 45 microg/L, 22-83 (geometric mean, range) and for haemoglobin 132 g/L, 119-148 (arithmetic mean, range), respectively. RESULTS: Distribution of energy intake from protein, fat and carbohydrate, and daily intake of dietary fibre and iron were similar in the two groups and within the recommended levels. There was no effect of the phytase added to the wheat bread on the iron status of the subjects, but an effect of the intervention period. Serum ferritin and haemoglobin levels were significantly reduced by 12 +/- 1.1 microg/L (27%) (P < 0.001) and 2 +/- 0.8 g/l (1.5%) (mean +/- SE) (P < 0.05) respectively, after four months of intervention. CONCLUSIONS: The present long-term study indicates that consumption of the recommended daily intake of fibre-rich wheat bread results in an impairment of iron status in women with initially sufficient iron stores. Reduction of the phytic acid concentration in the bread was not sufficient to maintain iron status.

Adult↗