Dietary fat and fat types as early determinants of childhood obesity: a reappraisal.

BACKGROUND: The growing prevalence of childhood overweight and obesity has renewed interest in determining the influence of the maternal and infant diet on the risk of developing excess fat mass later in life. APPROACH: Review of available human and animal data reporting the effects of dietary fat and fat types early in life on adipose development. RESULTS: Rodent studies tend to show that maternal high-fat feeding during pregnancy and lactation results in increased adiposity of the offspring. Nevertheless, today there is a lack of population-based studies investigating this potential detrimental effect of maternal high-fat intake. Most epidemiological studies, performed so far, do not find any association between the level of dietary fat intake of infants and children and body weight and/or fatness. Regarding fat types exposure to high levels of dietary n-6 fatty acids during gestation and post-natal life, has been shown to promote obesity in mice. Nevertheless, other rodent studies do not demonstrate such an effect. CONCLUSION: There is no evidence supporting a restriction of fat intake during the first two post-natal years but the potential detrimental effects of maternal high-fat intake during gestation should be further investigated. The role of dietary fat types as early determinants of childhood obesity has so far been poorly studied. Robust evidence to support the adipogenic effects of n-6 fatty acids enriched-diets is currently lacking but this hypothesis is of importance and should be further evaluated in different animal models as well as in longitudinal human studies.

Changes of gut microbiota and immune markers during the complementary feeding period in healthy breast-fed infants.

INTRODUCTION: Little is known about changes in intestinal microbiota during the important period of complementary feeding (weaning). This descriptive study investigated changes of selected gut microbiota and markers of gut permeability and the immune system in breast fed infants during the complementary feeding period. METHODS: 22 healthy, exclusively breast fed infants (from birth to 4 months) with no antibiotic intake during the month prior to the study, were followed from 4 to 9 months of age. Faecal and saliva samples were collected at the start of the study (V0) and at monthly intervals (V1-V5) for measurement of selective gut microbiota (bifidobacteria, lactobacilli, vancomycin-insensitive lactobacilli, enterobacteria, enterococci, Clostridium perfringens) using semi-selective media. Immune markers (alpha-1-antitrypsin, eosinophil cationic protein (ECP), secretory IgA and TNF-alpha were measured in saliva and secretory IgA and TNF-alpha in faecal samples. RESULTS: High stool bifidobacteria counts at the start of the study (7.99 1 1.95 log10 CFU/g faeces) remained stable throughout the 5 months of complementary feeding while counts of enterobacteria and enterococci increased with age (P < 0.05 and P = 0.02 respectively). Vancomycin-insensitive lactobacilli increased significantly during weaning for V0 to V3 (P < 0.01), and then decreased slightly (V4). Faecal Clostridium perfringens remained below the detection limit during the study and parameters measured in saliva did not change. Faecal ECP decreased significantly from 1.011.4 (V0) to 0.510.9 mg/mg protein (V5) P = 0.03. CONCLUSION: Age and/or diet modifications during complementary feeding had no impact on faecal bifidobacteria counts but increased those of enterobacteria and enterococci. Transient increases in faecal lactobacilli and vancomycin-insensitive lactobacilli counts were observed. The reduction in faecal ECP may indicate a decrease in gut permeability (reinforcement of gut mucosa integrity) during the weaning period with age [corrected]

Calcium supplementation of chocolate: effect on cocoa butter digestibility and blood lipids in humans.

BACKGROUND: The digestibility of cocoa butter was reported in animal but not human studies to be low (60-70% and 89-94%, respectively). These differences could be due to the much higher ratio of calcium to fat (by wt) in the diet of rats (0.04-0.18) than in that of humans (0.01). OBJECTIVE: We investigated whether supplementation of chocolate with 0.9% calcium (by wt), as an integral part of a Western diet, reduces absorption of cocoa butter and hence the digestible energy value of chocolate. We also assessed the effect of calcium supplementation on the blood lipid profile. DESIGN: Ten men were fed control diets containing 98-101 g chocolate/d with or without a 0.9%-Ca supplement (0.9 g Ca/d) for 2 periods of 2 wk each. The study was conducted with use of a randomized, double-blind crossover design under free-living conditions but with strict control of food intake. RESULTS: Calcium supplementation of chocolate increased fecal fat 2-fold (from 4.4 to 8.4 g/d; P < 0.0001) and reduced the absorption of cocoa butter by 13.0%. This was due mainly to an increase in the excretion of palmitic and stearic acids (3.4 g/d), which reduced the absorbable energy value of the chocolate by approximately 9%. This supplementation also reduced plasma LDL cholesterol by 15% (P < 0.02); HDL cholesterol was unchanged. CONCLUSIONS: Calcium supplementation can be used as a means of reducing the absorbable energy value of chocolate. Supplementation with 2.25% CaCO3 had no effect on the taste of chocolate, was well tolerated by the subjects, and reduced LDL cholesterol in a short-term study.

Digestibility of cocoa butter from chocolate in humans: a comparison with corn-oil.

OBJECTIVE: To compare, in humans, the digestibility of moderate amounts of cocoa butter (30.7 g/d) consumed in the form of chocolate as part of a normal western diet with that of a well-absorbed fat (corn oil); and hence determine whether, by virtue of its apparent low absorption, cocoa butter can be considered to be a low calorie fat. DESIGN: Randomised, two-period crossover metabolic study, conducted under free-living conditions, but with strict control over food intake. SETTING: Metabolic Unit, Nestlé Research Center Lausanne. SUBJECTS: Twelve healthy men were selected from volunteers at the Nestlé Research Center and all subjects completed the study. INTERVENTION: Two treatment periods of two weeks each: cocoa butter and control periods, with strict dietary control separated by a two week wash out period. RESULTS: No differences (P>0.05) were observed in faecal weight (wet or dry), faecal fat nor in defecation frequency between treatments (cocoa butter and corn oil). Cocoa butter at a dose of 30.7 g/d in the form of black chocolate, consumed between two meals, was found to have a similar digestibility to that of corn oil (99 % of corn oil digestibility). CONCLUSION: Cocoa butter, consumed as back chocolate within a normal mixed diet, has a high digestibility, similar to that of corn oil, and a digestible energy value of 37 kJ/g in man. Thus, cocoa butter cannot be considered to be a low-calorie fat. SPONSORSHIP: Nestec Ltd, Switzerland. European Journal of Clinical Nutrition (2000) 54, 120-125

Dissociation of systemic GH-IGF-I axis from a genetic basis for short stature in African Pygmies.

OBJECTIVES: To test the hypothesis that the primary cause of short stature in African Pygmies resides in low levels of insulin-like growth factor I (IGF-I), and to evaluate whether any observed alterations in their systemic IGF-I status can be dissociated from the effects of malnutrition and/or altered immune status. SETTING: Expedition to camps of partially sedentarized African Pygmies and neighbouring Bantu farmers living in the equatorial rain forest of Eastern Cameroon. DESIGN: Serum assays for hormonal and immune status were conducted for individuals (children, adolescents, young and old adults) showing no overt clinical nor biochemical signs of malnutrition, as judged from anthropometry, clinical examinations and serum assays of albumin, pre-albumin, retinol-binding protein, transferrin, iron, zinc, magnesium and calcium. RESULTS: African Pygmies did not differ from Europeans or Bantus in mean serum IGF-I concentrations, nor in the relationship between serum IGF-I and its major binding protein (IGFBP-3). However, although in both African groups the immunoglobulins IgG, IgM and IgE as well as the C-reactive protein and ceruloplasmin were above the normal range of European references, the Pygmies differed from their Bantu neighbours in their much higher IgG and IgM serum levels. A plot of serum IGF-I against these immunoglobulins in Pygmies revealed a reverse sigmoidal relationship, with the low IGF-I values associated with serum levels of IgG and IgM which clearly exceeded those found in the Bantus. CONCLUSIONS: This study indicates that in growing and adult African Pygmies showing no clinical nor biochemical signs of nutritional deficiency, serum IGF-I and IGFBP-3 (hence IGF-I bioavailability to its receptors) are essentially normal, and that low circulating levels of IGF-I in Pygmies reside in differential exposure and/or responsiveness to environmental challenge (e.g. infections) rather than in an inherited defect in the systemic growth-hormone (GH)-IGF-I axis.

Relative importance of carbohydrate and protein sources in the differential effects of soy-based vs casein-based formulas on bone minerals in rats.

Studies reported here examine the extent to which differences in the source of protein (soy vs casein) and of carbohydrate (absence or presence of lactose) may be responsible for differential effects of soy-based and casein-based infant formulas on bone minerals. Growth and bone minerals were measured in rats fed casein-based or soy-based diets with or without lactose. Analysis of variance indicated that presence of lactose in the diets increased calcium, phosphorus, magnesium, and zinc concentrations in the vertebrae (P less than 0.02) and also increased magnesium (P less than 0.01) and zinc (P less than 0.05) in femur and tibia-fibula. In contrast, the source of protein had an effect only on bone magnesium concentration, with the soy protein resulting in lower magnesium retention in all bones studied (P less than 0.05). These data suggest that differences in lactose content rather than in the source of protein may be mainly responsible for the differential effects of milk-based and soy-based infant formulas on bone minerals.

Effects of foods rich in polyphenols on nitrogen excretion in rats.

The extent to which tea, cocoa and carob (foods rich in polyphenols) influence fecal nitrogen (N) excretion was investigated in rats. The studies took into account the methylxanthine contents of tea and cocoa as well as the poor digestibility of cocoa nitrogen. Balance measurements indicated that all three food sources significantly increased fecal nitrogen excretion relative to methylxanthine-matched control diets (p less than 0.01). In the case of cocoa, virtually all the increase could be attributed to the poor digestibility of cocoa protein itself (estimated to be only 28-30% of total N in cocoa powder). There appeared to be no other effects. With extracts of tea and carob, however, the increased excretion of N in feces resulted either from a decreased digestibility of other dietary protein, through interaction with their polyphenols, or from a stimulation of the excretion of endogenous (body) nitrogen. With respect to the latter possibility, a preliminary investigation with the stable isotope of nitrogen (15N) showed that tea produced a marked increase in the excretion of endogenous nitrogen. These studies, therefore, indicate that foods rich in polyphenols have varying effects on N excretion in feces and that, in the case of tea at least, the loss of endogenous nitrogen may be a major contributing factor.