PubMed Health⌕ Search

Biomedical subjects

L Davidsson

Publications and source records attributed to L Davidsson.

At least 19 recordsLinked to original sources
PubMed1998

A comparison of iron absorption in adults and infants consuming identical infant formulas.

Fe absorption was estimated in adults and infants from the erythrocyte incorporation of Fe isotopes added to infant formula. Fe absorption was measured in adults using radioisotopes, and in infants with a stable-isotope technique. In adults, the geometric mean Fe absorption from a ready-to-feed soya formula with its native phytic acid content was 2.4%. This increased to 6.0% (P < 0.05) after almost complete dephytinization. In infants, mean Fe absorption values were 3.9 and 8.7% respectively from the same products (P < 0.05). In adults, mean Fe absorption from a spray-dried soya formula containing 110 mg ascorbic acid/l was 4.1%, increasing to 5.3% (P < 0.05) when ascorbic acid was doubled to 220 mg/l. In infants, mean Fe absorption values were 5.7 and 9.5% (P < 0.05) from the same products. Mean Fe absorption from a milk-based formula was 6.5% in adults compared with 6.7% in infants. All meals in the adult and infant studies were fed using an identical meal size of 217 g. Increasing the meal size threefold in adults did not change fractional Fe absorption. Mean Fe absorption values for each meal were lower in adults than in infants but the relative inhibitory effect of phytic acid and the enhancing effect of ascorbic acid were similar. We conclude that Fe absorption studies in adults can be used to assess the influence of enhancers and inhibitors of Fe absorption in infant formulas fed to infants. Further studies, however, are required to extend these findings to weaning foods and complete meals.

Adult↗
PubMed1998

Influence of ascorbic acid on iron absorption from an iron-fortified, chocolate-flavored milk drink in Jamaican children.

The influence of ascorbic acid on iron absorption from an iron-fortified, chocolate-flavored milk drink (6.3 mg total Fe per serving) was evaluated with a stable-isotope technique in 20 6-7-y-old Jamaican children. Each child received two test meals labeled with 5.6 mg 57Fe and 3.0 mg 58Fe as ferrous sulfate on 2 consecutive days. Three different doses of ascorbic acid (0, 25, and 50 mg per 25-g serving) were evaluated in two separate studies by using a crossover design. Iron isotope ratios were measured by negative thermal ionization mass spectrometry. In the first study, iron absorption was significantly greater (P < 0.0001) after the addition of 25 mg ascorbic acid: geometric mean iron absorption was 1.6% (range: 0.9-4.2%) and 5.1% (2.2-17.3%) for the test meals containing 0 and 25 mg ascorbic acid, respectively. In the second study, a significant difference (P < 0.05) in iron absorption was observed when the ascorbic acid content was increased from 25 to 50 mg: geometric mean iron absorption was 5.4% (range: 2.7-10.8%) compared with 7.7% (range: 4.7-16.5%), respectively. The chocolate drink contained relatively high amounts of polyphenolic compounds, phytic acid, and calcium, all well-known inhibitors of iron absorption. The low iron absorption without added ascorbic acid shows that chocolate milk is a poor vehicle for iron fortification unless sufficient amounts of an iron-absorption enhancer are added. Regular consumption of iron-fortified chocolate milk drinks containing added ascorbic acid could have a positive effect on iron nutrition in population groups vulnerable to iron deficiency.

Animals↗
PubMed1998

Sodium iron EDTA [NaFe(III)EDTA] as a food fortificant does not influence absorption and urinary excretion of manganese in healthy adults.

NaFe(III)EDTA is a promising iron (Fe) compound for food fortification programs because of its high Fe bioavailability from meals containing dietary inhibitors of Fe absorption such as phytic acid. However, this Fe compound is not currently used in any large-scale fortification program because of concern over its possible negative influence on the metabolism of other essential minerals or its possible influence on the absorption of potentially toxic elements, such as manganese (Mn). In this study, Mn absorption and urinary excretion were studied in adults after intake of an Fe-fortified weaning cereal labeled with 54Mn. In a crossover design, the fortification of the weaning cereal with Fe as NaFeEDTA was compared with ferrous sulfate. Manganese absorption was measured by extrapolation from whole-body retention data 10-30 d after intake, and urinary excretion of 54Mn was measured over 7 d. No significant differences in 54Mn absorption or urinary excretion were found; 1.1 +/- 0.15 and 0.91 +/- 0.35% of the ingested dose was absorbed from the cereal fortified with NaFe(III)EDTA and FeSO4, respectively. Urinary excretion of 54Mn was very low; the total radioactivity in urine represented 1.1 +/- 0.55% of the absorbed dose with NaFe(III)EDTA and 0.72 +/- 0.53% of the absorbed dose with FeSO4. Until now, Fe-fortification programs have met with only limited success. The introduction of NaFeEDTA as a food fortificant could be a useful tool to provide bioavailable Fe to vulnerable groups in the population and thus aid in combating Fe deficiency.

Absorption↗
PubMed1998

The influence of meat on nonheme iron absorption in infants.

During weaning the infant has a high iron requirement, and highly available dietary iron is needed to ensure optimal iron status. Muscle tissue has been identified as an enhancer of nonheme iron absorption in adults, although the influence of meat on nonheme iron absorption in infants has not been previously reported. The effect of the addition of 25 g of meat (lean beef) on nonheme iron absorption from a home-prepared vegetable purée meal (80 g of vegetables) was investigated in infants in the present study. The meals did not differ in their contents of other known enhancers or inhibitors of nonheme iron absorption. Incorporation of stable isotopes of iron (57Fe and 58Fe) into red blood cells 14 d after intake was used to measure iron absorption, using a cross-over design in eight healthy infants 43-49 wk of age. Nonheme iron absorption was significantly increased (p = 0.002) from the vegetable purée with added meat (geometric mean 15.0%) compared with the puréed vegetables (geometric mean 9.9%). These results thus suggest that meat is also an enhancer of nonheme iron absorption in infants and that nonheme iron absorption from weaning foods can be increased by the addition of meat.

Adult↗
PubMed1997

Bioavailability in infants of iron from infant cereals: effect of dephytinization.

Iron bioavailability from an infant cereal made of wheat flour with a low extraction rate (70%) and cow milk was measured in infants by using a stable-isotope technique. A dephytinized infant cereal was prepared by adding commercial phytase during manufacture, resulting in degradation of 88% of the native phytic acid. Paired comparisons were made to evaluate the effect of phytic acid on iron bioavailability. Both infant cereals contained identical amounts of ascorbic acid and had a molar ratio of ascorbic acid to iron of 2:1. Iron was added as ferrous sulfate. No difference in iron bioavailability was observed in this study; the geometric mean was 8.7% (range: 3.8-16.9%) and 8.5% (range: 3.4-21.4%) from the cereal with native phytic acid (0.08% phytic acid) and the dephytinized cereal (0.01% phytic acid), respectively. Dephytinization of infant cereals containing a relatively low native phytic acid content and high amounts of ascorbic acid is thus unnecessary to ensure adequate bioavailability of iron.

6-Phytase↗
PubMed1996

Zinc and calcium apparent absorption from an infant cereal: a stable isotope study in healthy infants.

Fractional apparent absorption of Zn and Ca from a wheat-milk-based infant cereal was studied in six healthy infants (18-30 weeks old). Mineral absorption was measured by a stable-isotope technique based on faecal excretion of the isotopes. Each test meal (40 g cereal) was extrinsically labelled with 70Zn and 42Ca before intake. All faecal material passed during the 21 d following intake of the labelled test meal was collected on trace-element-free nappies. Individual stool samples were analysed for their content of 70Zn and 42Ca by thermal ionization mass spectrometry. Apparent absorption was calculated as intake minus total faecal excretion of the isotopes over 68-92 h after administration. The fractional apparent absorption values for Zn and Ca were 33.9 (SD 16.4) % (range 19.2-63.9%) and 53.5 (SD 12.6) % (range 36.7-71.7%) respectively. Re-excretion of absorbed 70Zn (> 68-92 h to 21 d after intake of the labelled meal) was 0.44 (SD 0.38) % of administered dose while only one infant re-excreted detectable amounts of 42Ca (1.74% of administered dose). The analysis of individual stool samples confirmed that 72 h is a sufficient time period for complete collections of non-absorbed isotopes in faecal material from infants during the weaning period and that re-excretion of initially absorbed 70Zn and 42Ca (> 68-92 h to 21 d after intake of the labelled meal) is negligible.

Calcium↗
PubMed1996

Zinc absorption in adult humans: the effect of protein sources added to liquid test meals.

The influence of different protein sources on Zn absorption was evaluated in healthy adults by radioisotopic labelling of single meals, followed by whole-body retention measurements 14 d after intake. Semi-synthetic liquid diets were used for the evaluation of different animal-protein sources and dephytinized soyabean-protein isolate (< 0.01 g phytic acid/kg). Zn absorption was measured in the same subjects from identical test meals containing no added protein. No statistically significant differences were found in the Zn absorption from test meals containing bovine whey, casein or egg albumen when compared with test meals without added protein. Bovine serum albumin (BSA) and soyabean-protein isolate (< 0.01 g phytic acid/kg) significantly reduced the mean absorption of Zn from 45-49% (no added protein) to 38.0 (SD 10.9) (BSA, P < 0.05) and 33.9 (SD 12.6)% (soyabean-protein isolate < 0.01 g phytic acid/kg, P < 0.01). These results demonstrate that Zn absorption is inhibited by certain protein sources, such as BSA and dephytinized soyabean-protein isolate, while other proteins have little or no effect.

Adult↗
PubMed1996

Dietary fiber in weaning cereals: a study of the effect on stool characteristics and absorption of energy, nitrogen, and minerals in healthy infants.

We evaluated the effect of increased dietary fiber (DF) content in weaning cereals based on wheat/soy (8.0 and 1.8% DF) and wheat/milk (5.3 and 2.0% DF) in healthy, formula-fed infants 7-17 weeks old. The study had a cross-over design, each infant acting as his or her own control. Stool characteristics and anthropometry were monitored over 4-week periods in groups of 34 (wheat/soy) and 23 (wheat/milk) infants. Absorption of zinc (Zn) and calcium (Ca) was studied by measuring the fecal excretion of stable isotopes during 72 h (70Zn and 42Ca) in a subgroup of the infants consuming wheat/soy cereals. Iron (Fe) bioavailability was evaluated by analysis of the incorporation of 58Fe into erythrocytes 14 days after administration. Fractional absorption (X +/- SD: 8.0 versus 1.8% DF) was 45.3 +/- 27.5 versus 41.2 +/- 19.4% of 70Zn and 63.4 +/- 15.8 versus 64.4 +/- 10.6% of 42Ca. Bioavailability of 58Fe varied between 1.0% and 5.4% (8.0% DF) and from <0.9% to 9.1% (1.8% DF). No significant difference in energy (95.3 +/- 2.0% versus 95.7 +/- 1.2%) or nitrogen (92.6 +/- 2.3% versus 93.0 +/- 1.6%) apparent absorption from the total diet was found during consumption of cereal with 8.0 and 1.8% DF. The intake of cereal decreased with higher DF content in the wheat/soy product: 34 +/- 23 g/d (8.0% DF) versus 42 +/- 23 g/d (1.8% DF), p < 0.01. While consuming the 8.0% DF product, 11 infants were reported to have "gritty stools"; no other differences were observed between different groups in stool characteristics or anthropometry. These results demonstrate no negative effect on the absorption of energy and nutrients with higher dietary fiber intake in primarily formula-fed infants. The impact of increased dietary fiber levels remains unknown in less well-nourished infants.

Aging↗
PubMed1995

Zinc absorption in adult humans: the effect of iron fortification.

The effect of Fe fortification on the absorption of Zn was studied by radioisotopic labelling of single meals, followed by measurements of whole-body retention of 65Zn at 14 d after intake. Healthy adult volunteers participated in the study. Weaning cereal, wheat bread and infant formula, foods that are all frequently Fe-fortified, were evaluated in the study. The amounts of Fe added as FeSO4 were similar to the levels in commercial products in Europe and the USA, and were 200 or 500 mg Fe/kg (weaning cereal), 65 mg Fe/kg (white wheat flour) and 12 mg Fe/l (infant formula). For comparison, Zn absorption was measured in the same subjects, from identical test meals containing no added Fe. No statistically significant differences were found when Zn absorption from the Fe-fortified test meals was compared with that from non-Fe-fortified test meals. Fractional Zn-absorption values from Fe-fortified v. non-fortified meals were 31.1 (SD 11.9) v. 30.7 (SD 7.0)% (weaning cereal; 200 mg Fe/kg), 37.7 (SD 16.6) v. 30.2 (SD 9.9)% (weaning cereal; 500 mg Fe/kg), 36.5 (SD 14.4) v. 38.2 (SD 18.1)% (bread; 65 mg Fe/kg flour) and 41.6 (SD 8.1) v. 38.9 (SD 14.5)% (infant formula; 12 mg Fe/l). The addition of Fe to foods at the currently used fortification levels was thus not associated with impaired absorption of Zn and the consumption of these Fe-fortified foods would not be expected to have a negative effect on Zn nutrition.

Adult↗
PubMed1995

Manganese absorption in humans: the effect of phytic acid and ascorbic acid in soy formula.

The absorption of manganese from soy formula was studied in adult volunteers by extrinsic labeling of test meals with 54Mn, followed by whole-body retention measurements for approximately 30 d after intake. Eight subjects participated twice in each of the two studies, acting as his or her own control. Soy formula containing the native content of phytic acid was compared with a similar dephytinized formula: geometric mean manganese absorption increased 2.3-fold from 0.7% (range: 0.2-1.1%) to 1.6% (range: 1.0-7.2%) (P < 0.01) with the dephytinized formula. In addition, the effect of the ascorbic acid content of the phytic acid-containing formula was investigated. Manganese absorption was not influenced by an increase in the ascorbic acid from 625 mumol/L (110 mg/L) to 1250 mumol/L (220 mg/L): the geometric mean manganese absorption was 0.6% (range: 0.3-1.0%) and 0.6% (range: 0.3-1.1%), respectively. In conclusion, fractional manganese absorption was approximately doubled by the dephytinization of soy formula but was not influenced by an increase in the ascorbic acid content of a soy formula containing the native amount of phytic acid.

Adult↗
PubMed1994

NaFe3+EDTA as a food fortificant: influence on zinc, calcium and copper metabolism in the rat.

The general acceptance of NaFe3+EDTA for food Fe fortification has been partly restricted by concern over the influence of EDTA on the metabolism of other nutritionally important trace elements and minerals. We have investigated the influence of NaFe3+EDTA, and of increasing dietary levels of Na2EDTA, on Zn, Cu and Ca metabolism in rats fed on Zn-sufficient and Zn-deficient soya-bean-isolate-based diets. With the Zn-deficient diets, changing the dietary Fe compound from FeSO4 to NaFe(3+)-EDTA significantly (P < 0.05) increased mean apparent Zn absorption from 50.2 to 67.4%, urinary Zn excretion from 2.0 to 4.0% of intake, and Zn retention from 48.2 to 63.4%. Increasing the dietary EDTA level to 1000 mg/kg further increased Zn absorption to 78.1%, urinary Zn excretion to 15.6% of intake and Zn retention to 62.5%. Increased Zn retention was accompanied by a significant increase in weight gain indicating that the extra Zn was available for normal metabolic processes. With rats fed on the Zn-sufficient diet, NaFe3+EDTA and Na2EDTA similarly increased the absorption, urinary excretion and retention of Zn but to a lesser extent. NaFe3+EDTA, however, had no influence on the absorption, urinary excretion and retention of Cu and Ca, and additional Na2EDTA caused only minor increases in Cu absorption and retention and in the urinary excretion of Ca. We conclude that using NaFe3+EDTA as a food fortificant would have no detrimental effect on the metabolism of Zn, Cu and Ca and, in some situations, could improve Zn absorption and retention from low-bioavailability diets.

Animals↗
PubMed1994

A double stable isotope technique for measuring iron absorption in infants.

A stable isotope technique has been developed which uses 57Fe and 58Fe as labels and which enables the simultaneous measurement of Fe absorption from two test meals in infants. The method was evaluated by measuring Fe absorption from a commercial whey-adjusted infant formula in nine healthy infants aged 13-25 weeks. Each infant was fed 210 ml formula, labelled with either 57Fe or 58Fe, on four consecutive mornings, in random order. The total Fe content in each feed was 2.5 mg Fe; either as 2.5 mg 57Fe, or 0.6 mg 58Fe plus 1.9 mg Fe with normal isotopic composition. Isotopic enrichment of Fe in erythrocytes was measured by thermal ionization mass spectrometry 14 d after the last administration, and Fe absorption was calculated based on isotope ratio shifts, total circulating Fe and intake of each isotope. Geometric mean absorption for the 57Fe and 58Fe labels was 6.72 and 6.58% respectively, and the absorption of the two isotopes was not significantly different (Student's paired t test). By this technique, paired comparisons of Fe absorption can be obtained and systematic studies of the influence of dietary factors on Fe absorption during infancy can be conducted.

Child, Preschool↗
PubMed1994

Sodium iron EDTA [NaFe(III)EDTA] as a food fortificant: the effect on the absorption and retention of zinc and calcium in women.

The iron fortificant NaFeEDTA could have a potential negative effect on the metabolism of other minerals. We have used stable isotopes to monitor zinc and calcium metabolism in 10 women consuming a single meal of high-extraction wheat rolls (100 g flour) fortified with 5 mg Fe as either FeSO4 or NaFeEDTA. Six-day chemical balances were made simultaneously to study apparent zinc and calcium retention from the complete diet containing the differently iron-fortified breads (200 g flour; 10 mg added Fe/d). Mean 70Zn absorption from the bread meal increased from 20.9% with FeSO4 to 33.5% with NaFeEDTA (P < 0.05) whereas mean 44Ca absorption was 53.3% from both breads. When NaFeEDTA-fortified bread was consumed, there was a small but significant increase in urinary excretion of 70Zn and 44Ca. There was a similar small increase in urinary zinc excretion during the 6-d balance, although the apparent retention of zinc and calcium was not different. Thus, we found no negative overall effect of NaFeEDTA consumption on the metabolism of zinc and calcium. In contrast, the results suggest that NaFeEDTA added to low-bioavailability diets might increase zinc absorption as well as provide iron with high bioavailability.

Absorption↗
PubMed1994

Minerals and trace elements in infant nutrition.

Little information is available on absorption and metabolism of minerals and trace elements during infancy. The lack of data is related to the methodological problems involved in these studies. By using stable isotopes as labels, studies can be conducted in infants without introducing exposure to radiation, or any other risk, and studies on bioavailability of minerals and trace elements during early life can therefore be performed. This paper discusses results from studies of trace element/mineral absorption and metabolism in infants, based on stable isotope techniques.

Calcium↗
PubMed1994

Influence of lactoferrin on iron absorption from human milk in infants.

Lactoferrin (Lf) is a major iron (Fe)-binding protein in human milk and has been proposed to facilitate Fe absorption. The potential effect of Lf on Fe absorption was investigated by measuring Fe absorption in infants fed breast milk (with its native content of Lf) and the same milk from which Lf had been removed (> 97%) by treatment with heparin-Sepharose. Eight breast-fed infants (2-10 mo; mean age 5 mo) were fed 700 to 1000 g of each milk in a randomized, cross-over design with each child acting as his/her own control. The milk was labeled with 8.6 mumol (0.5 mg) of 58Fe and Fe absorption was measured by quantifying the incorporation of the isotope into red blood cells 14 d after intake using thermal ionization mass spectrometry. Fractional Fe absorption was significantly lower (p < 0.05) from breast milk than from Lf-free breast milk. The geometric mean (range) was 11.8% (3.4-37.4%) for breast milk and 19.8% (8.4-72.8%) for Lf-free breast milk. These results do not support a direct role for Lf in the enhancement of Fe absorption from human milk at this age. In addition, Fe absorption (11.8%) from human milk fed over several feeds was lower than that previously reported for single feed studies.

Biological Availability↗
PubMed1994

Iron bioavailability studied in infants: the influence of phytic acid and ascorbic acid in infant formulas based on soy isolate.

The influence of phytic acid and ascorbic acid content of soy formula on iron (Fe) bioavailability was investigated in infants by analysis of the incorporation of stable isotopes of Fe into red blood cells 14 d after administration using a double stable isotope technique. Paired comparisons were made with each infant acting as his or her own control. The geometric mean fractional Fe incorporation into red blood cells increased from 5.5 to 6.8% (p < 0.05) when soy formula with the native content of phytic acid was compared with a 83% dephytinized formula. A more pronounced effect was shown with soy formula containing no phytic acid; the mean fractional Fe incorporation increased from 3.9 (native phytic acid) to 8.7% (zero phytic acid; p < 0.001). A significant (p < 0.01) effect was also demonstrated when the Fe:ascorbic acid molar ratio in the native phytate-containing formula was increased from 1:2.1 to 1:4.2; mean fractional Fe incorporation increased from 5.9 to 9.6%. These results demonstrate that the Fe bioavailability from soy-based infant formulas can be similarly increased by either removing phytic acid or increasing the ascorbic acid content.

Ascorbic Acid↗