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If an increased consumption of alpha-linolenic acid (ALA) is to be promoted in parallel with that of n-3 long-chain-rich food, it is necessary to consider to what extent dietary ALA can be absorbed, transported, stored, and converted into long-chain derivatives. We investigated these processes in male hamsters, over a broad range of supply as linseed oil (0.37, 3.5, 6.9, and 14.6% energy). Linoleic acid (LA) was kept constant (8.5% energy), and the LA/ALA ratio was varied from 22.5 to 0.6. The apparent absorption of individual FA was very high (>96%), and that of ALA remained almost maximum even at the largest supply (99.5%). The capacity for ALA transport and storage had no limitation over the chosen range of dietary intake. Indeed, ALA intake was significantly correlated with ALA level not only in cholesteryl esters (from 0.3 to 9.7% of total FA) but also in plasma phospholipids and red blood cells (RBC), which makes blood components extremely reliable as biomarkers of ALA consumption. Similarly, ALA storage in adipose tissue increased from 0.85 to 14% of total FA and was highly correlated with ALA intake. As for bioconversion, dietary ALA failed to increase 22:6n-3, decreased 20:4n-6, and efficiently increased 20:5n-3 (EPA) in RBC and cardiomyocytes. EPA accumulation did not tend to plateau, in accordance with identical activities of delta5- and delta6-desaturases in all groups. Dietary supply of ALA was therefore a very efficient means of improving the 20:4n-6 to 20:5n-3 balance.

Small birth weight and excess of early protein intake are suspected to enhance later adiposity. The present study was undertaken to determine the impact of diets differing in protein content on short-term growth, adipose tissue development, and the insulin-like growth factor (IGF) system in piglets. Normal (NW) and small (SW) birth weight piglets were fed milk-replacers formulated to provide an adequate (AP) or a high protein (HP) supply between 7 and 28 d of age. The fractional growth rate was higher (p Ͻ 0.01) in SW than in NW piglets. At 7 d of age, the lower (p Ͻ 0.05) weight of perirenal adipose tissue relative to body mass in SW than in NW piglets did not involve significant changes in plasma IGF-I, leptin, or insulin-like growth factor binding protein levels, but involved differences (p Ͻ 0.05) in the expression of IGF-I and leptin in adipose tissue. Growth rates did not differ between AP and HP piglets. At 28 d of age, HP piglets had lower (p Ͻ 0.001) relative perirenal adipose tissue weight but did not differ clearly from AP piglets with regard to the IGF system. It remains to be determined whether piglets fed such a high protein intake will stay subsequently with a low adiposity. (Pediatr Res 65: 45-50, 2009)

With genetic selection, the increase in litter size has led to higher variation in within-litter birth weights in pigs. This has been associated with a reduction in mean birth weights and a rise in the proportion of piglets weighing less than 1 kg at birth. Low birth weight pigs exhibit lower postnatal growth rates and feed efficiency, which may be explained by an inadequate digestion and/or nutrient use as a consequence of prenatal undernutrition. It is now documented that there is a relationship between birth weight and subsequent pattern of growth and development of tissues and organs. During the neonatal period, the rapid somatic growth is accompanied by tremendous anatomical, physiological and chemical composition changes. The present review focuses primarily on the influence of low birth weight on adipose tissue and the gastrointestinal tract growth and development during the suckling period. The importance of the somatotropic axis, insulin, thyroid hormones, glucocorticoids, epidermal growth factor and leptin in the regulation of these developmental processes is also considered.

ABSTRACT:Our study aimed at investigating the impact of the level of protein in milk formula on intestinal structure, barrier function, and its nervous regulation in normal and LBW neonates using a porcine model. Normal birth weight (NBW) or LBW piglets were fed from d7 to d28 of age either with a high protein (HP) or with an adequate protein (AP) formula or stayed with their mother [mother fed (MF)]. The proximal jejunum and distal ileum were sampled at d28 for morphometry analysis and ex vivo permeability measurement in Ussing chambers. Formula feeding induced a trophic effect on the jejunum and ileum of both NBW and LBW piglets, which exhibited longer villi than MF animals, irrespective of the type of formula. In NBW piglets, intestinal permeability was not altered by formula feeding. On the contrary, LBW piglets fed with HP formula, but not AP, exhibited a greater ileal permeability than MF piglets. Feeding the HP formula also disturbed jejunal and ileal regulation of permeability by acetylcholine and vasoactive intestinal peptide (VIP) in LBW compared with MF LBW piglets. In conclusion, the level of protein in formulas did not modify intestinal structure and function in NBW individuals but dramatically modified intestinal barrier function physiology in LBW individuals. (Pediatr Res 69: 4-9, 2011) T he health benefits of breast feeding have been recognized for a long time. However, many infants are still formulafed for periods of their first months of life. Formulation is an area of intensive research to improve the nutritional quality of milk formulas. However, the amount of protein per energy content is generally higher in formula than in human milk to meet the protein and amino acid requirements of infants (up to 40 and 66% more proteins than human milk for healthy neonates and preterm and LBW babies, respectively) (1). Epidemiological data point out an increased risk of developing metabolic disease and obesity later in life with accelerated growth in early life (2). High protein (HP) formulas are suspected to be one of the major factors of such accelerated growth (3). Therefore, the actual tendency is to reduce protein content in formulas toward the minimal level (4), although HP formulas are still recommended for premature and LBW babies (5).Several studies have established that formula-feeding impacts intestinal development. Using endoscopic techniques to obtain biopsies from healthy infants, Thompson et al. (6) observed that crypt length was increased by 30% in formulafed infants. More extensive studies undertaken in rats also concluded to a trophic effect of formula-versus breast-feeding on the intestine (7,8). Besides structural modifications, formula feeding also impacts intestinal epithelial barrier function. The epithelium lining the intestine plays an integrated role in maintaining intestinal barrier function through the proteins forming the tight junctions (TJs), which constitute a selective barrier and regulate the passage of molecules according to their size. Intestinal barrier function is ...

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Early postnatal nutrition is involved in metabolic programming, an excess of protein being suspected to enhance early growth and the propensity to later develop insulin resistance and type 2 diabetes mellitus. The aim of the present study was to test the hypothesis that excessive protein intake during the suckling period would overstimulate the endocrine pancreas in the short term and alter durably its maturation, contributing to the later disruption of glucose homeostasis. Normal-birth-weight and low-birth-weight piglets were fed isoenergetic formulae providing an adequate-protein (AP, equivalent to sow milk) or a high-protein (HP, þ 48 %) supply between 7 and 28 d of age and were fed a standard diet until 70 d of age. During the formula-feeding period, the HP formula did not modify postprandial insulin secretion but transiently increased fasting insulin and the homeostasis model assessment-insulin resistance index (HOMA-IR, P, 0·05). Fasting insulin and HOMA-IR were restored to AP piglets' values 1 month after weaning. The structure of the endocrine pancreas was not affected by the protein content of the formula. The weight at birth had no major effect on the studied parameters. We concluded that a high-protein supply during the suckling period does not interfere with insulin secretion and endocrine pancreas maturation in the short term. It has no consequences either on glucose tolerance 1 month after weaning. The present study demonstrated that up-regulation of postprandial insulin secretion is not involved in higher growth observed in piglets fed a HP formula.

Our data suggests estrogen to modulate the regulation of hepatic lipid metabolic pathway by dietary fatty acids. Besides, PPARalpha invalidation resulted in unexpected regulations by ALA of its known targets and was compensated partly in females, which was therefore less sensitive to the detrimental effects of a SFA-rich diet.