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Biomedical subjects

P J Aggett

Publications and source records attributed to P J Aggett.

At least 19 recordsLinked to original sources

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

Committee report: childhood diet and prevention of coronary heart disease. ESPGAN Committee on Nutrition. European Society of Pediatric Gastroenterology and Nutrition.

Coronary heart disease is a major cause of morbidity and mortality in Europe, particularly northern, central, and eastern Europe. Several strategies have been recommended for children and adolescents to promote a healthy lifestyle and thereby reduce the risk of coronary heart disease in later life. The European Society of Pediatric Gastroenterology and Nutrition (ESPGAN) Committee on Nutrition reviewed some of these strategies, and our conclusions and recommendations are reported herein.

Adolescent

Zinc.

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Erythrocytes

Symptomatic zinc deficiency in experimental zinc deprivation.

An evaluation of indices of poor zinc status was undertaken in five male subjects in whom dietary zinc intake was reduced from 85 mumol d-1 in an initial phase of the study to 14 mumol d-1. One of the subjects developed features consistent with zinc deficiency after receiving the low zinc diet for 12 days. These features included retroauricular acneform macullo-papular lesions on the face, neck, and shoulders and reductions in plasma zinc, red blood cell zinc, neutrophil zinc and plasma alkaline phosphatase activity. Alcohol induced hepatitis, which was suspected in this subject, may have caused a predisposition to altered zinc metabolism and possible zinc deficiency which was exacerbated by subsequent zinc deprivation. The report supports the value of neutrophil zinc concentration as an indicator of poor zinc status.

Adult

Recent advances in methodology for analysis of phytate and inositol phosphates in foods.

This review summarises the methods available for the analysis of phytate and structurally related molecules, i.e., inositol polyphosphates. Phytate has been determined by colorimetry, low pressure ion exchange column chromatography, phosphorus-31 fourier transform nuclear magnetic resonance spectroscopy (31P FT NMR), near-infrared reflectance spectroscopy and high performance liquid chromatography (HPLC). Among these techniques anion exchange column chromatography and HPLC were shown to be best suited for separation of inositol phosphates. Since inositol phosphates do not have a characteristic absorption spectrum, their detection in HPLC analysis is limited to methods employing monitoring of refractive index, post column reaction products, conductivity or indirect detection although other detection methods may be feasible. As refractive index detection under isocratic eluent conditions is relatively easy to manipulate, anion-exchange HPLC methods using a low capacity column or ion-pair HPLC methods are recommended for the analysis of inositol phosphates in nutritional studies.

Chromatography

Homeostatic regulation of zinc absorption and endogenous losses in zinc-deprived men.

The mechanisms involved in the homeostatic regulation of zinc were studied in five male subjects by using stable 70Zn as a marker. When dietary zinc was reduced from 85 to 12 mumol/d, adaptation was achieved by a mean (+/- SEM) reduction in urine zinc of 48 +/- 7% and in fecal zinc of 46 +/- 12% over 25 d in four subjects. The latter was caused by an increase in the efficiency of zinc absorption from 38 +/- 3% to 93 +/- 1% after 15 d of zinic deprivation and by a reduction in intestinal endogenous losses of zinc. In a fifth subject, who had some evidence of a resolving alcohol-induced hepatitis, urine and fecal zinc were reduced by 64% and 41%, respectively, in 15 d and zinc absorption increased from 46% to 93%. More information on adaptive responses is needed to enable current dietary recommendations to be reconsidered.

Absorption

Reduced erythrocyte superoxide dismutase activity in low birth weight infants given iron supplements.

Erythrocyte superoxide dismutase (ESOD) activity reflects copper utilization and the risk of copper deficiency. To investigate the possible effects of inorganic iron on the metabolism of copper in low birth weight infants, we have measured ESOD activities in three groups of infants receiving different iron supplements. Fifty-five low birth weight infants were randomly assigned to receive daily from 28 d either 13.8 mg (HiFe), 7 mg (MidFe), or no elemental iron (NatFe) as iron edetate. At 27 d, 8, 12, and 20 wk postnatal age, infants were weighed and measured and hematologic indices, plasma ferritin, zinc, and copper concentrations, and ESOD activities were assayed. Anthropometrical and hematologic indices and plasma copper and zinc concentrations did not differ among treatment groups at any time, but at 20 wk, plasma ferritin concentrations [(micrograms/L) mean; SD] were lower in the NatFe group (17; 2.0) than in the HiFe group (32; 1.9: 95% confidence interval for mean difference 6.6 to 22.0, p less than 0.01). ESOD activities (U/g Hb) were similar in HiFe (1447; 263), MidFe (1552; 322), and NatFe (1538; 382) groups at 27 d, but by 20 wk activities in the HiFe group (1537; 211) were lower than in the MidFe (1789; 403: 95% confidence interval 38 to 466, p less than 0.05) and NatFe (1858; 304: 95% confidence interval 150 to 492, p less than 0.01) groups. The lower ESOD activities found in the HiFe group at 20 wk may reflect altered copper metabolism induced by the iron supplement, but the clinical importance of this observation is unknown.

Copper

Intestinal absorption and losses of copper measured using 65Cu in zinc-deprived men.

The absorption and intestinal losses of endogenous Cu in response to a low Zn diet were studied in five young male subjects using stable 65Cu as an oral tracer. The subjects received a semi-purified formula diet providing 85 mumol (5.6 mg) Zn/d during 15-day baseline and repletion phases and 12 mumol (0.8 mg) Zn/d during an intervening period of 25 days. Thirty-eight mumol (2.4 mg) Cu/d was provided throughout the study. In four of the subjects, the mean +/- SEM luminal disappearance of 65Cu was 37 +/- 4 per cent during the baseline phase and was unaffected by Zn deprivation (32 +/- 7 per cent) or repletion (30 +/- 7 per cent) as were intestinal losses of endogenous Cu [7 +/- 4, 8 +/- 3, 8 +/- 3 mumol/d (0.4 +/- 0.1, 0.5 +/- 0.1, 0.5 +/- 0.1 mg/d) during baseline, Zn deprivation and Zn repletion phases, respectively]. In a fifth subject, who had some evidence of a resolving alcohol-induced hepatitis, the luminal disappearance of 65Cu was 31, 44 and 42 per cent and the intestinal losses of endogenous Cu 11, 2 and 6 mumol/d (0.7, 0.1 and 0.4 mg/d) during the baseline, Zn deprivation and Zn repletion phases respectively. Plasma Cu concentrations, however, fell throughout the study in all the subjects, despite consistently positive Cu balances. There may be subtle effects of a low dietary intake of Zn on Cu metabolism which were not revealed by the methods used in this study.

Adult

Zinc deficiency and zinc repletion: effect on the response of rats to infection with Trichinella spiralis.

The expulsion of a primary infection of Trichinella spiralis was studied in rats fed diets containing (per kg diet) either 3 mg Zn [zinc deficient (Zn-)] or 40 mg Zn [zinc adequate (Zn+)]. A dose of 2000 muscle larvae (ML) impaired weight gain (mg/g body wt) in all groups compared with uninfected controls [eg, 0-7 d postinfection (dpi): infected Zn-, -105 +/- 10 (means +/- SEM); uninfected Zn-, 54 +/- 19 (p less than 0.001)]. In a study with 20.5 ML/g body wt, some Zn- rats were transferred at the time of infection to the zinc-adequate diet. [This was the zinc-repleted group (ZnR).] Both groups retained a group of pair-fed controls (Zn-PF and ZnRPF). The percentage dose established at 7 dpi was similar in all groups (32.5-39.3%) but at 13 dpi recoveries were 19.4 +/- 2.2% for Zn-, 0.1 +/- 0.1% for Zn-PF, 1.6 +/- 0.9% for ZnR, 0.6 +/- 0.2% for ZnRPF, and 4.1 +/- 2.2% for Zn+ (p less than 0.001). Up to 13 dpi, all groups except ZnR lost weight. These results show that zinc deficiency impairs the expulsion of T spiralis in rats.

Animals

Zinc deprivation and zinc repletion: effect on the response of rats to infection with Strongyloides ratti.

The course of a subcutaneous weight-related infection with Strongyloides ratti was followed in rats fed diets containing either 3 mg Zn/kg diet [zinc deficient (Zn-)] or 40 mg Zn/kg diet [zinc adequate (Zn+)]. At 19 d postinfection (dpi) the proportions of larvae persisting in the intestines as adult worms were 52 +/- 2% (means +/- SEM) for Zn-, 39.5 +/- 2.5% for pair-fed Zn- (Zn-PF), and 31.6 +/- 3.2% for Zn+ (p less than 0.001, analysis of variance); some Zn- rats were then transferred to the zinc-adequate diet [This was the zinc-repleted group (ZnR).] Both groups retained a group of pair-fed controls (Zn-PF and ZnRPF). Between 19 and 28 dpi ZnR animals gained weight faster than did Zn- animals and had heavier thymuses relative to body weight. Zinc deficiency enhances the establishment of S ratti larvae in the intestine of rats and alters the characteristics of intestinal expulsion of the nematodes; however, spontaneous cure was achieved by 38 dpi in both Zn- and control groups.

Animals

Zinc metabolism in celiac disease.

The turnover of a radiolabeled (65Zn) pool of endogenous zinc was monitored by using a whole-body counter in eight patients with celiac disease (CD) and analyzed by using a two-compartment model. The biological half-life of the first compartment (1-3 wk postadministration) was similar in healthy volunteers (122 +/- 34 d, means +/- SD) and untreated patients (97 +/- 21 d). The second compartment in the patients (3-12 wk postadministration) was shorter (159 +/- 22.5 d. p less than 0.001) than were reference values (218 +/- 27 d) but increased (291 +/- 71 d) after the patients started gluten-free diets. The percentage absorption of 65Zn (9.25 kBq) from a test meal containing 31 mumol (2 mg) zinc was similar in untreated patients (30.0 +/- 13%) and healthy volunteers (32.5 +/- 12.4%). These data show that in mild untreated CD increased turnover and loss of endogenous zinc occurs whereas the absorption of zinc from a customary zinc intake may be normal. The pathophysiological basis of this loss was not investigated.

Adult

Routine L-ascorbic acid supplementation does not alter iron, copper, and zinc balance in low-birth-weight infants fed a cows'-milk formula.

The effect of ascorbic acid (AA) [284 mumol (50 mg) twice daily] on the net intestinal absorption and maximum apparent retention of Fe, Cu, and Zn was investigated by metabolic balance studies in a randomised crossover study of six low-birth-weight (LBW) neonates fed a cows'-milk-based formula containing (mumol/L) Fe, 126; Cu, 11; Zn, 87; and AA, 400. Absorption +/- SD (Fe, -5.0 +/- 7.5; Cu, 0 +/- 0.4; Zn, -0.8 +/- 3.4) (mumol kg-1 day-1) was not altered by AA (Fe, -4.1 +/- 4.6; Cu, 0.3 +/- 0.6; Zn, -1.1 +/- 2.7) neither was retention (without AA: Fe, -6.0 +/- 8.4; Cu, -0.1 +/- 0.3; Zn, -2.4 +/- 4.2; with AA: Fe, -4.9 +/- 4.7; Cu, 0.1 +/- 0.6; and Zn, -2.7 +/- 3.1). Supplements of AA administered as in the circumstances of routine care of LBW neonates do not enhance the absorption and retention of Fe, nor do they impair these aspects of the metabolism of Cu and Zn.

Animals