ALBERT

Notes: Summary Background: The knowledge of magnesium requirements of premature infants is still very limited, although it is essential for the optimal composition of suitable formulas. Aim of the study: The study concept was 1) to assess physiological magnesium balance data of healthy term infants and longitudinal results from formula-fed premature infants and 2) to deduce conclusions on the magnesium content of the formulas. Methods: Premature infants (n = 14, birth weight ≤ 1500 g, gestational age ≤ 32 weeks) were studied in conventional balance trials with 1) a semi-elemental diet (A), 2) preterm infant formula (B), and 3) infant formula (C). In addition, healthy term formula-fed (n = 11, D) and breast-fed (n = 14, E) infants were investigated. Analysis was performed by flame atomic absorption spectroscopy. Results: The median magnesium intake ranged between 4.84 mg/kg × d−1 (breast-fed infants) and 16.33 mg/kg × d−1 (premature infants). The term breast-fed infants retained nearly as much magnesium as term formula-fed infants (3.37 vs. 3.97 mg/kg × d−1), due to a low percental fecal and urinary excretion. A higher magnesium retention was observed in the premature group: A: 7.97 mg/kg × d−1, B. 5.3 mg/kg × d−1, 3.) 5.54 mg/kg × d−1. Conclusion: In view of the high percental magnesium retention in formula-fed premature infants, excessive supply should be avoided. The long-term effects of lower intakes have to be monitored.

Notes: Summary We reviewed 15 studies reporting on the fatty acid composition of colostrum lipids from 16 geographic regions: 11 European studies and one study each from Central America, the Caribbean, Australia and Asia. The contents of essential fatty acids, saturates and polyunsaturates were similar in the southern European countries Spain, Slovenia and France. Colostrum of St. Lucian women was high in saturates and low in oleic acid, reflecting a high-carbohydrate, low-fat diet. Abundant fish intake was reflected in high contents of docosahexaenoic acid and total n-3 long-chain polyunsaturated fatty acids in St. Lucia. Two French studies published with an interval of two years showed a very similar colostrum fatty acid composition, whereas two German studies obtained with an interval of 14 years showed higher docosahexaenoic acid and arachidonic acid contents in the later study, with an unchanged n-6/n-3 long-chain polyunsaturated fatty acid ratio. Studies from Spain reported a decline of α-linolenic acid in colostrum over a time period of 13 years. Colostrum of Australian women contained the lowest polyunsaturated/saturated and n-6/n-3 long-chain polyunsaturated fatty acids ratios (0.28 and 1.58) and the lowest contents of linoleic and α-linolenic acids (7.8 and 0.4 wt. %). In contrast, the contents of docosahexaenoic acid, eicosapentaenoic acid and total n-3 long-chain polyunsaturated fatty acids (0.6, 0.4 and 1.4 wt. %) were higher in Australian than in European samples. Fatty acid composition of human colostrum appears to be markedly influenced by geographic differences in maternal dietary composition.

Notes: Summary The metabolic strengths, weakness, opportunities and threats of the metabolic ability to split water brought about a proliferation of biological systems, produced a toxic oxygenic environment, and were responsible for the development of antioxidant defence mechanisms. Evolution is driven by heritable adaptions which improve environmental ‘fit’. Hence aerobic respiration, using oxygen as a nutrient, came to predominate in biological systems, and antioxidant defence mechanisms which prevent and neutralise toxic oxygen intermediates have become widespread, varied, coordinated and effective. Antioxidant defences are nor infallible however. In humans, reactive oxygen species-induced damage is associated with the ageing process, and with chronic diseases including cancer and coronary heart disease. Interestingly, some important antioxidants, including ascorbic acid and the tocopherols, cannot be synthesised by humans and must be taen in the diet. Another antioxidant, uric acid, is found in much higher concentrations in humans than in other mammals, and levels are also affected by diet. In humans, therefore, antioxidant defence against toxic oxygen intermediates is species specific and heavily influenced by nutrition. In this article, the atmospheric and metabolic changes which produced both the threat and opportunity offered by an oxygenic environment are outlined. An overview of oxygen toxicity, and adaptations to oxidative stress in terms of evolution of antioxidant defences, is presented. Finally, suggested benefits underlying our curious inability to manufacture ascorbic acid, and the possible role of uric acid in human antioxidant defence, are briefly discussed with particular reference to nutrition and toxicology.

Notes: Summary Background: Many epidemiological studies have identified a protection against cancer associated with consumption of fruit and vegetables. One factor is this protection may be the enhancement of cellular DNA repair activity by micronutrients, such as carotenoids, found in these foods. Aims of the study: To measure the capacity of lymphocytes isolated from volunteers supplemented with β-carotene, lutein or lycopene to recover from DNA damage induced in vivo by treatment with H2O2. Methods: Healthy volunteers were given supplements of lutein (15 mg/day), lycopene (15 mg/day) and βcarotene (15 mg/day), each for 1 week, the supplementation periods being separated by 3-week wash-out periods. Blood samples were taken at the beginning and end of each supplementation, and at 1 week and 3 weeks during the wash-out period. Carotenoid levels were measured in plasma. Lymphocytes were isolated and frozen. Subsequently, they were treated with 100 μM H2O2 and incubated for up to 24 h; DNA damage was measured with the comet assay (single cell gel electrophoresis) after 0, 2, 4, 8, and 24 h. Results: Increases of 2- to 3-fold in mean plasma lutein and β-carotene concentrations were seen at the end of the respective supplementation periods; they returned virtually to basal levels after wash-out. Lycopene concentrations were less affected by supplementation, and were more variable. H2O2-induced DNA strand breaks were apparently only slowly rejoined by the lymphocytes. The rejoining of breaks in the first few hours appeared substantially faster in lymphocytes following supplementation with β-carotene, but no such effect was seen with lutein. In those individuals who showed increases in lycopene concentrations, the recovery was significantly faster. Lymphocytes that were not treated with H2O2 showed a transient increase in DNA breakage to about double the background level in 2 h, presumably as a result of exposure to atmospheric oxygen; this effect, too, was relieved by supplementation with lycopene or β-carotene. Conclusions: While certain carotenoids appear to enhance recovery from oxidative damage, this is probably in fact an antioxidant protective effect against additional damage induced by atmospheric oxygen, rather than a stimulation of DNA repair.

Notes: Summary Obesity could well become the most common health problem of the 21st century. There are more opportunities to consume large quantities of food: big portions of tasty, varied food, at reasonable prices, are available everywhere. Moreover, our bodies are better adapted to combat weight loss than to combat weight gain, since for thousands of years our species evolved in circumstances where nutrients were in short supply. The response of each individual to diet and other environmental factors varies considerably, depending on the characteristics of his/her body weight control mechanism. The differentiating element in the future, especially as regards the dietary and pharmacological control of obesity, will be knowledge of an individual's possible response depending on his/her genetic background. Obesity can occur as a result of genetic or acquired changes in three main types of biochemical processes, which are the main focus of this review: a) feeding control, which determines the sensations of satiety and hunger through processes that depend on a interplay between internal signals (notably leptin) and environmental factors; b) energy efficiency, in particular the activation of thermogenesis mediated by uncoupling proteins (UCPs) that makes it possible to dissipate part of the energy contained in food as heat instead of accumulating it as fat, and c) adipogenesis, the process by which cells specialised in fat storage (adipocytes) are formed, which is controlled by an interplay of transcription factors, including memebers of the C/EBP, PPARγ and ADD families. The knowledge of a growing numbers of genes and molecules implicated in these three types of processes and of their metabolic relationships is leading toward a molecular understanding of the body weight regulatory system and is paving the way for new methods of obesity control, especially pharmacological but also nutritional and possibly involving genetic intervention.

Notes: Summary Background: Quantitative information on conversion of β-carotene to vitamin A in humans is limited. Aim of the study: Our laboratory has developed a stable isotope method for studying the conversion of β-carotene (β-C) to vitamin A. Methods: Two dosage levels (a pharmacological dose, 126.0 mg β-C-d 8, and a physiological dose, 6.0 mg β-D-d 8) were used 2.5 y apart in an adult female volunteer to study dose effects on the conversation of β-C to vitamin A. Blood samples were collected over 21 d. β-C and retinol were extracted from serum and isolated by high performance liquid chromatography. The retinol fraction was derivatized to a trimethylsilyl ether which was analyzed by gas chromatograph/mass spectrometry with electron capture negative chemical ionization. Results: The retinol-d 4 response in the circulation peaked at 24 hours after the β-C-d 8 dose, with a higher percent enrichment after the pharmacological dose than after the physiological dose. By using retinyl acetate-d 8 as the vitamin A reference, the retinol-d 4 formed from 6 mg of β-C-d 8 (11.2 μmol) was calculated to be equivalent to 1.6 mg of retinol (i. e., 3.8 mg of β-C was equivalent to 1 mg of retinol). However, the retinol-d 4 formed from 126 mg of β-C-d 8 (235 μmol) was equivalent to 2.3 mg of retinol (i. e., 55 mg β-C was equivalent to 1 mg retinol). Conclusion: These results provide evidence that it is feasibile to use stable isotope reference method to study retinol equivalence of β-C and that there may be a dose-dependence on bioconversion of β-carotene to retinol.

Notes: Summary The potsitive effect of glutamine on lymphocyte proliferation has previously been described. Its dipeptide glycyl-glutamine (GlyGln) is more stable than pure glutamine in aqueous solutions. The aim of our study was to investigate the relationship between lymphocyte proliferation and varying concentrations of glycyl-glutamine in vitro. Isolated human lymphocytes were stimulated with the mitogens phytohaemagglutinin (PHA), Concanavalin A (ConA), pokeweed mitogen (PWM), and Staphylococcus aureus (SAC). Glycyl-glutamine was added to yield final cincentrations of 0–2 mmol/l. Overall minimal concentrations of 0.01 mmol/l glycyl-glutamine were sufficient to enhance lymphocyte proliferation over baseline (glutamine-free) levels. No difference was found between concentrations in the “physiological” range of 0.4 mmol/l and very low concentrations (0.04–0.1 mmol/l) with SAC, ConA and PWM. Increasing the concentration beyond 0.4 mmol/l (up to 2.0 mmol/l) offered further gain with PHA-stimulation only. Lymphocyte proliferation under in vitro polyclonal stimulation is maintained even at very low concentrations of glycyl-glutamine. Raising the concentration above the equivalent of physiological levels does not seem to provide further benefit.

Notes: Summary Aim of the study. An allergen-reduced dietary intervention programme with strict dietary requirements was implemented over the first four months of life in an unselected population-based infant cohort and compared to a non-intervention cohort (the ZUFF study). Recommendations for the dietary programme in the intervention cohort were extended, but not strictly implemented, until the end of month six. The intervention was based on breastfeeding, a moderate whey hydrolysate formula (pHF), and delayed introduction of weaning foods with a high allergenicity. This study was a prospective, controlled, and unblinded study, the first to assess the effects of an allergen-reduced, pHF-based early nutritional programme in a broad unselected infant population. Because overall healthy development of the infant is a major objective of any nutritional programme, the study evaluated the effects of the dietary intervention on infant growth and general health status rather than specific allergic manifestations. Part I of this paper gave results for nutritional behaviour only, and Part II gives results for growth and general health status during the intervention period through the sixth month of life. Methods. Assignment of study infants was to demographically comparable intervention (Z) or control (FF) cohorts according to place of birth. In the intervention cohort (Z=564), the recommended dietary regimen was breastfeeding and – if exclusive breastfeeding was not possible – supplementation with a moderately hydrolysed, allergen-reduced infant formula (pHF). Weaning foods were delayed until four months of age or later in case of weaning foods with high allergenicity. In the control cohort (FF=566), there was no specific intervention. Imbalances between cohorts in confounding (adjuvant) factors that could influence health related outcomes were integrated as covariates into the logistic regression of the main analyses. Growth parameters included weight, length, head circumference, BMI, and Z scores (SDS). General health status was assessed by clinically significant findings in gastrointestinal, respiratory, or skin symptoms. Results. Growth at 6 weeks and at 3 and 6 months was similar for Z and FF. Significantly fewer Z than FF infants had clinically noteworthy health findings at 3 months (Z=27% versus FF=37%, odds ratio=0.63, CI=0.48–0.82) and 6 months (Z=33% versus FF=49%, odds ratio=0.51, CI=0.40–0.66). This corresponds to a 30% reduction in overall health concerns at 6 months for the intervention cohort. At 3 and 6 months, differences between cohorts in most measures of general health status were strongly influenced by a lower incidence of skin symptoms in the Z cohort. Within FF, there were fewer exclusively breastfed (eBF) infants with health problems at 3 months compared with those who were partially (pBF) or non-breastfed (nBF) (eBF=31%, pBF=40%, nBF=39%, p〈0.05). In contrast, in the Z intervention cohort, the number of infants with health concerns was similar for exclusively breastfed infants and for those in whom mother's milk was supplemented or replaced by pHF (eBF=29%, pBF=25%, nBF=26%, ns). In a subanalysis of overall health findings in infants without a family risk of allergies, there were again significantly fewer Z than FF infants with any health or any skin problem. Conclusion.An allergen-reduced dietary recommendation that includes a moderate whey hydrolysate infant formula (pHF) has no negative effects on growth parameters up to 6 months of life in an infant population unselected for atopic risk. The dietary intervention produced improvements in general health status when compared with a control cohort that received infant formula with unhydrolysed proteins (IF), and high allergenic weaning foods at an earlier age. The difference between cohorts was principally due to fewer adverse skin findings. In infants following our allergen-reduced feeding recommendation, 3-month general health status was comparable between those who were exclusively breastfed and those in whom breastfeeding was supplemented or replaced by pHF. Our results demonstrate that a pHF feeding recommendation during the first 4 to 6 months of life – when exclusive breestfeeding is not possible – is a safe and feasible regimen not only in high-allergic risk populations but in general unselected infant population. The general use of pHF formula in non- or partly breastfed infants could therefore be considered an important contribution to optimised infant nutrition.