Biomedical subjects

E L Lien

Publications and source records attributed to E L Lien.

At least 19 recordsLinked to original sources

PubMed2001

Comparison of AIN-76A and AIN-93G diets: a 13-week study in rats.

Either purified or cereal-based diets may be used for toxicity testing in rats. Purified diets have advantages in terms of flexibility of formulation to meet specific study objectives and also assurance of relatively low levels of contaminants (e.g. heavy metals and pesticides). The American Institute of Nutrition recommended that the widely used purified diet AIN-76A be replaced by two newer diets, AIN-93G (for use during rapid growth, pregnancy and lactation) and AIN-93M (maintenance diet). The present study compared AIN-76A and AIN-93G by feeding these diets for 13 weeks to male and female rats. A cereal-based diet was also included for reference purposes. The groups fed purified diets had higher serum cholesterol and triglyceride levels than the chow-fed group. An increased incidence and severity of renal tubular mineralization in the purified diet groups was not observed in this study (in contrast to other published studies where rats were fed AIN-76A). Several histopathologic observations, including eosinophilic gastritis and mucification of gastric glands of the glandular stomach, occurred at higher rates in the AIN-76A group than the other dietary treatments. Hepatocellular fatty changes occurred in the purified diet groups at a significantly higher rate than in the chow diet group. In conclusion, AIN-93G is an appropriate diet for use in rat safety evaluation studies.

Animal Feed↗

PubMed2001

Extent of thermal processing of infant formula affects copper status in infant rhesus monkeys.

BACKGROUND: Infant rhesus monkeys are excellent models in which to study the effect of infant formulas on trace element absorption and status. Infants fed powdered formula from birth exhibit normal growth and have blood variables similar to those of breast-fed infants. OBJECTIVES: The objectives were to evaluate the effects of feeding ready-to-feed (RTF) formulas exposed to different heat treatments to infant monkeys, and, for one of these formulas, to compare the effect of fortification with 2 iron concentrations. DESIGN: From birth to age 5 mo, infant monkeys (n = 6/group) were fed one of the following formulas exclusively: 1) 12 mg Fe/L processed in cans (RTF-12), 2) formula in glass bottles with 12 mg Fe/L and manufactured by an ultrahigh-temperature (UHT) process (UHT-12), or 3) formula manufactured by a standard thermal process (STP), containing either 8 (STP-8) or 12 (STP-12) mg Fe/L. All formulas had similar copper concentrations (0.6 mg Cu/L). Anthropometric measures and venous blood samples were taken monthly. RESULTS: Weight and length gain did not differ among groups; however, the STP-12 group weighed less than the UHT-12 group at ages 2, 4, and 5 mo. Hemoglobin values were significantly lower in the RTF-12 group than in all other groups at ages 4 and 5 mo and serum ferritin was lower in the RTF-12 group than in the STP-12 group at age 5 mo. Copper status was lower in STP-12 infants than in STP-8 infants. There was a progressive and significant decline in plasma copper, ceruloplasmin, and Cu/Zn superoxide dismutase activity in infants fed canned formula (RTF-12). Furthermore, coat color changed from normal brown to silver. These outcomes suggest that the canned formula induced copper deficiency in infant monkeys. CONCLUSIONS: Excessive heat treatment of formula can have a pronounced negative effect on copper status. High iron concentrations did not improve iron status but may adversely affect copper status.

Animals↗

PubMed2000

A randomized trial of different ratios of linoleic to alpha-linolenic acid in the diet of term infants: effects on visual function and growth.

BACKGROUND: There are nutritional recommendations that the ratio of linoleic to alpha-linolenic acid (LA:ALA) in formula for term infants be between 5:1 and 15:1. These recommendations were made in the absence of data on functional or clinical outcomes. OBJECTIVE: We compared the fatty acid status, visual evoked potential (VEP) acuity, and growth of term infants fed formula containing an LA:ALA of 10:1 or 5:1 with those of a breast-fed reference cohort. DESIGN: Formula-fed infants were allocated randomly in a double-blind fashion to receive formula with an LA:ALA of either 10:1 (16.9:1.7; n = 36) or 5:1 (16.3:3.3; n = 37) from near birth to 34 wk of age. Increased ALA was attained by replacing soy oil with low-erucic acid cannola oil. A parallel group of breast-fed infants was also recruited. Infant growth and fatty acid status were assessed at 6, 16, and 34 wk of age. VEP acuity was assessed at 16 and 34 wk. RESULTS: Infants fed the 5:1 formula had greater docosahexaenoic acid (DHA) concentrations in plasma and erythrocyte phospholipids than did infants fed the 10:1 formula, but DHA concentrations of infants fed the 5:1 formula remained less than those in breast-fed infants. The VEP acuity of all formula-fed and breast-fed infants was not significantly different at 16 and 34 wk of age. At birth, infants fed the 5:1 formula were heavier, were longer, and had a greater head circumference than infants assigned to the 10:1 formula group; this differential was maintained throughout the trial. The rate of gain in weight, length, and head circumference was not significantly different between the 2 formula-fed groups, although breast-fed infants had lower weight and length gains than did formula-fed infants between 16 and 34 wk of age. CONCLUSION: Lowering the LA:ALA in formula from 10:1 to 5:1 by using low-erucic acid canola oil resulted in a modest increase in plasma DHA but had no effect on VEP acuity or growth rate.

Dietary Fats↗

PubMed2000

Dietary 20:4n-6 and 22:6n-3 modulates the profile of long- and very-long-chain fatty acids, rhodopsin content, and kinetics in developing photoreceptor cells.

The objective of this study was to determine whether addition of dietary 20:4n-6 and 22:6n-3 to a conventional infant formula fat blend influences membrane long-chain and very-long-chain fatty acid composition, rhodopsin content, and rhodopsin kinetics in developing rat photoreceptor cells. The dietary fats were formulated based on the fat composition of a conventional infant formula providing an 18:2n-6/18:3n-3 ratio of 7:1 (SMA, Wyeth Nutritionals), which served as the control fat blend. This dietary fat blend was modified to contain 20:4n-6 [arachidonic acid (AA)], 22:6n-3 [docosahexaenoic acid (DHA)], AA + DHA, or an 18:2n-6/18:3n-3 ratio of 4:1 (alpha-linolenic acid). Dams were fed diets from birth, and rat pups were fed the same diet after weaning. Retinas and rod outer segments were prepared in the dark from pups at 2, 3, and 6 wk of age for fatty acid analysis of individual phospholipids, rhodopsin content, and rhodopsin disappearance kinetics after light exposure. Feeding AA + DHA in the diet increased 22:6n-3 levels in phosphatidylcholine and phosphatidylethanolamine. In phosphatidylcholine, total n-6 tetraenoic very-long-chain fatty acids and total n-3 pentaenoic and n-3 hexaenoic very-long-chain fatty acids increased after feeding AA and DHA, respectively. Developmental changes were characterized by a decrease in 20:4n-6 in the major phospholipids, whereas 22:6n-3 increased with age in rod outer segments. The highest rhodopsin content occurred in the retina of rats fed diets containing AA and/or DHA. The kinetics of rhodopsin disappearance after light exposure was highest in rats fed DHA at 6 wk of age. This study demonstrates that small manipulations of the dietary level of 20:4n-6 and 22:6n-3 are important determinants of fatty acid composition of membrane lipid and visual pigment content and kinetics in the developing photoreceptor cell.

Animals↗

PubMed1999

The effects of dietary alpha-linolenic acid compared with docosahexaenoic acid on brain, retina, liver, and heart in the guinea pig.

The aim of this study was to compare two different strategies to elevate brain, retina, liver, and heart docosahexaenoic acid (DHA) levels in guinea pigs. First, we used an increasing dose of alpha-linolenic acid (ALA) relative to a constant linoleic acid (LA) intake, and second, we used two levels of dietary DHA provided in conjunction with dietary arachidonic acid (AA). The percentage DHA and AA of total phospholipids in retina, liver, and heart, and in the brain phosphatidylethanolamine and phosphatidylcholine was studied in female pigmented guinea pigs (3 wk old) fed one of five semisynthetic diets containing 10% (w/w) lipid for 12 wk. The LA content in the diets was constant (17% of total fatty acids), with the ALA content varying from 0.05% (diet SFO), to 1% (diet Mix), and to 7% (diet CNO). Two other diets (LCP1 and LCP3) had a constant LA/ALA ratio (17.5:1) but varied in the levels of dietary AA and DHA supplementation. Diet LCP1 was structured to closely replicate the principal long chain polyunsaturated fatty acids (PUFA) found in human breast milk and contained 0.9% AA and 0.6% DHA (% of total fatty acids) whereas diet LCP3 contained 2.7% AA and 1.8% DHA. At the end of the study, animals were sacrificed and tissues taken for fatty acid analyses. We found no significant effects of diets on the growth of guinea pigs. Diets containing ALA had profoundly different effects on tissue fatty acid compositions compared with diets which contained the long chain PUFA (DHA and AA). In the retina and brain phospholipids, high-ALA diets or dietary DHA supplementation produced moderate relative increases in DHA levels. There was no change in retinal or brain AA proportions following dietary AA supplementation, even at the highest level. This was in contrast to liver and heart where tissue DHA proportions were low and AA predominated. In these latter tissues, dietary ALA had little effect on tissue DHA proportions although the proportion of AA was slightly depressed at the highest dietary ALA intake, but dietary DHA and AA supplements led to large increases (up to 10-fold) in the proportions of these PUFA. Tissue uptake of dietary AA and DHA appeared maximal for the LCP1 diet (replicate of breast milk) in the heart. There were no significant changes in the plasma levels of 11-dehydrothromboxane B2 (a thromboxane A2 metabolite) for any diet. The data confirm that dietary ALA is less effective than dietary DHA supplementation (on a gram/gram basis) in increasing tissue DHA levels and that tissues vary greatly in their response to exogenous AA and DHA, with the levels of these long chain metabolites being most resistant to change in the retina and brain compared with liver and heart. Dietary DHA markedly increased tissue DHA proportions in both liver and heart, whereas the major effect of dietary AA was in the liver. Future studies of the effects of dietary DHA and AA supplementation should examine a variety of tissues rather than focusing only on neural tissue.

Animals↗

PubMed1999

Dietary supplementation with arachidonic and docosahexaenoic acids has no effect on pulmonary surfactant in artificially reared infant rats.

Despite the potential use of long chain polyunsaturated fatty acid (LCPUFA) supplementation to promote growth and neural development of the infant, little is known about potential harmful effects of the supplementation. The present study determined whether supplementation with arachidonic acid (AA) and/or docosahexaenoic acid (DHA) in rat milk formula (RMF) affects saturation of pulmonary surfactant phospholipids (PL). Beginning at 7 d of age, infant rats were artificially fed for 10 d with RMF supplemented with AA at 0, 0.5, and 1.0% of total fatty acid, or supplemented with DHA at 0, 0.5, and 1.0%, or cosupplemented with AA and DHA at levels of 0:0, 0.5:0.3, and 1.0:0.6% of the fat blend. Lung tissue PL contained 43 weight percent palmitate (16:0) of total fatty acids in infant rats fed the unsupplemented RMF. The supplementation with AA at both 0.5 and 1.0% decreased the weight percentage of 16:0 and stearate (18:0), indicating a decrease in saturation of PL. The observed decreases were accompanied by increases in AA and linoleic acid (18:2n-6). Surfactant phosphatidylcholine (PC) consisted of 71 weight percent 16:0 in the unsupplemented group, and this highly saturated PC was not altered by the cosupplementation with AA and DHA although there was a slight increase in DHA. Similarly, the cosupplementation did not change fatty acid composition of surfactant PL when compared with the unsupplemented group. The cosupplementation slightly decreased the weight percentage of 16:0 with a proportional increase in 18:0 leading to an unchanged weight percentage of total saturated fatty acids. These results suggest that, unlike lung tissue PL, the composition of saturated fatty acids in surfactant PL, particularly PC, is resistant to change by dietary AA and DHA supplementation. This, together with the unchanged concentration of total fatty acids in surfactant PC, indicates that LCPUFA cosupplementation causes no effect on pulmonary surfactant.

Animals↗

PubMed1999

Effect of reducing the phytate content and of partially hydrolyzing the protein in soy formula on zinc and copper absorption and status in infant rhesus monkeys and rat pups.

BACKGROUND: Although soy formulas have been designed to meet the nutrient requirements of human infants, they also contain phytate, which may negatively affect trace element absorption. OBJECTIVE: We evaluated the effect of removing phytate on zinc and copper absorption and status in infant rhesus monkeys and suckling rat pups and evaluated differences between intact and partially hydrolyzed soy protein. DESIGN: In monkeys, regular and low-phytate soy formulas were fed exclusively for 4 mo and whole-body absorption and retention of 65Zn, 67Cu, 59Fe, 54Mn, and 47Ca were determined at different time points with a whole-body counter. Subsequently, zinc and copper absorption from several human infant formulas and the effect of phytate concentration were evaluated in suckling rat pups by using 65Zn and 64Cu. Finally, infant rhesus monkeys were fed low-phytate formulas with intact or hydrolyzed soy protein for 4 mo and plasma zinc and copper were measured monthly. RESULTS: In the first monkey study, zinc absorption at 1 mo was higher from low-phytate soy formula (36%) than from regular soy formula (22%), whereas there was no significant difference between groups in the absorption of other minerals. Plasma copper was significantly lower in monkeys fed low-phytate soy formula from 2 to 4 mo. In rat pups, zinc absorption was significantly higher from low-phytate soy formula (78%) than from regular soy formula (51%) and hydrolysis of the protein had no significant effect. Phytate content or protein hydrolysis did not significantly affect copper absorption. In the second monkey study, plasma copper concentrations were highest in monkeys fed the low-phytate, hydrolyzed-protein soy formula. CONCLUSION: Reducing the phytate content and partially hydrolyzing the protein in soy formula had a beneficial effect on zinc and copper absorption and status in infant rhesus monkeys.

Animals↗

PubMed1999

Dietary lipids influence intestinal adaptation after massive bowel resection.

BACKGROUND: Certain lipids, primarily long chain fatty acids and especially long chain polyunsaturated fatty acids (LCPUFAs) from marine oils, stimulate gut adaptation after resection. The goal of this study was to define the degree of resection that provides an optimal model for adaptation and to determine if dietary LCPUFAs improve intestinal adaptation after resection. METHODS: One hundred and fifty-g male Sprague-Dawley rats were divided into groups receiving 60%, 70%, and 80% bowel resection. After resection, each group was subdivided into two dietary groups and pair fed diets containing either safflower oil or docosahexaenoic acid (DHA) and arachidonic (AA). RESULTS: After 2 weeks, mucosal mass, protein, DNA, and disaccharidase activity were measured in the remaining intestine. Rats receiving 80% resection responded with the highest level of intestinal adaptation. Within the 80% resection group, diet containing DHA and AA stimulated adaptation significantly more than safflower diet. A second study further evaluated the effect on LCPUFAs on intestinal adaptation. Diets included a control group 10% soy oil, and three diets differing in their AA-DHA fat blend ratio at 5% AA and 3.3% DHA, 15% AA and 10% DHA, and 45% AA and 30% DHA. The addition of LCPUFAs to diets enhanced intestinal adaptation in a linear, dose-dependent manner after an 80% small bowel resection. Rats fed a diet containing 30% DHA-45% AA had significantly enhanced mucosal mass compared to rats fed a diet containing 10% soy oil, and considerably higher compared to rats fed 3.3% DHA-5% AA. CONCLUSIONS: These studies suggest that modification of dietary LCPUFAs may enhance intestinal adaptation in short bowel syndrome.

Adaptation, Physiological↗

PubMed1999

Evaluation of a long-chain polyunsaturated fatty acid supplemented formula on growth, tolerance, and plasma lipids in preterm infants up to 48 weeks postconceptional age.

BACKGROUND: The last trimester of pregnancy is a period of rapid accretion of long-chain polyunsaturated fatty acids, both in the central nervous system and the body as a whole. Human milk contains these fatty acids, whereas some preterm infant formulas do not. Infants fed formulas without these fatty acids have lower plasma and erythrocyte concentrations than infants fed human milk. Preclinical and clinical studies have demonstrated that single-cell sources (algal and fungal) of long-chain polyunsaturated fatty acids are bioavailable. A balanced addition of fatty acids from these oils to preterm formula results in blood fatty acid concentrations in low birth weight infants comparable to those of infants fed human milk. METHODS: In the present study the growth, acceptance (overall incidence of discontinuation, reasons for discontinuation, overall incidence and type of individual adverse events), and plasma fatty acid concentrations were compared in three groups of infants fed a long-chain polyunsaturated fatty acid-supplemented preterm infant formula, an unsupplemented control formula, or human milk. The study was prospective, double-blind (formula groups only), and randomized (formula groups only). Two hundred eighty-eight infants were enrolled (supplemented formula group, n = 77; control formula group, n = 78; human milk group, n = 133). RESULTS: Anthropometric measurements at enrollment, at first day of full oral feeding, and at both 40 and 48 weeks postconceptional age did not differ between the formula groups, whereas the human milk-fed group initially grew at a lower rate. The incidence of severe adverse events was rare and not significantly different between formula groups. The groups fed either human milk or supplemented formula had long-chain polyunsaturated fatty acid concentrations higher than those in the control formula group. CONCLUSIONS: The results of this study demonstrate the safety and efficacy of a preterm formula supplemented with long-chain polyunsaturated fatty acids from single-cell oils.

Aging↗

PubMed1998

Interaction of n-3 long-chain polyunsaturated fatty acids with n-6 fatty acids in suckled rat pups.

The addition of long-chain polyunsaturated fatty acids (LCP: C20, and C22) to infant formula may permit fatty acid accretion rates similar to breast-fed infants, and may have long-term outcome benefits, such as improved visual acuity and cognitive development. Although fish oil may provide a source of n-3 LCP, sources of n-6 LCP have been more difficult to identify. The present study evaluates the effects of n-3 and n-6 LCP derived from single-cell oils on liver, plasma, and brain fatty acid levels in a neonatal animal model. Newborn rat pups were suckled for 14 d by dams receiving diets containing n-3 LCP alone or combinations of n-3 LCP and increasing doses of linoleic acid (18:2n-6) or arachidonic acid (20:4n-6). Dietary groups received 2% n-3 LCP and 1, 2, or 5% of either 18:2n-6 or 20:4n-6. The 20:4n-6 source also contained modest levels of 18:2n-6. At the termination of the study, liver, plasma, and brain were obtained from the rat pups and the phospholipid fatty acid profiles determined. The results indicate complex interactions of n-3 and n-6 fatty acids. Groups receiving dietary 20:4n-6 incorporated higher levels of n-6 LCP into tissues than did the groups receiving 18:2n-6. The brain was relatively resistant to changes in fatty acid composition compared with the liver and plasma. As expected, tissue n-3 LCP levels were reciprocally related to n-6 levels. The present results document that single-cell LCP oils are bioavailable in a neonatal animal model. The use of 20:4n-6 is a more effective means of supporting n-6 status than the use of 18:2n-6. These results may have implications for the addition of LCP to infant formula.

Animals↗

PubMed1998

Modification of milk formula to enhance accretion of long-chain n-6 and n-3 polyunsaturated fatty acids in artificially reared infant rats.

Artificially reared infant rats were used to determine the effects of long-chain polyunsaturated fatty acid (LCPUFA) supplementation on blood and tissue concentrations of arachidonic acid (AA) and docosahexaenoic acid (DHA). Beginning at 7 d of age, infant rats were fed for 10 d with rat milk formulas supplemented with AA at 0, 0.5 and 1.0%, or supplemented with DHA at 0, 0.5 and 1.0% of total fatty acid. The supplementation of AA increased accretion of the fatty acid in tissue and blood phospholipids with a maximum increase of 9% in brain, 15% in liver, 25% in erythrocytes, and 43% in plasma above the values of unsupplemented infant rats. Rat milk formula containing 1.0% of AA had no added benefits over that containing 0.5% of AA. The supplementation of DHA increased phospholipid DHA by a maximum of 24% in brain, 87% in liver, 54% in erythrocytes, and 360% in plasma above the unsupplemented control. The increase in tissue and blood DHA was concentration-dependent on formula fatty acid. Brain phosphatidylcholine and phosphatidylethanolamine were similarly enriched with AA and DHA by supplementation of the corresponding fatty acids. In general the observed increase of AA was accompanied by a decrease in 16:0, 18:1 n-9, and/or 18:2n-6, whereas the increased DHA was associated with a reduction of 18:1n-9, 18:2n-6, and/or 20:4n-6. Clearly, infant rats were more responsive to DHA than AA supplementation, suggesting a great potential of dietary manipulation to alter tissue DHA concentrations. However, the supplementation of DHA significantly decreased tissue and blood AA/DHA ratios (wt%/wt%), whereas there was little or no change in the ratio by AA supplementation. Although the physiological implications of the levels of AA and DHA, and AA/DHA ratios achieved under the present experimental conditions are not readily known, the findings suggest that artificial rearing could provide a suitable model to investigate LCPUFA requirements using various sources of AA and DHA in rats.

Animals↗

PubMed1998

Docosahexaenoic acid increases thyroid-stimulating hormone concentration in male and adrenal corticotrophic hormone concentration in female weanling rats.

Circulating levels of thyroid-stimulating hormone (TSH), growth hormone (GH), adrenal corticotrophic hormone (ACTH) and prolactin (PRL) were assessed in suckling rats in the postweaning period after rats were fed diets that reflect the fat composition of a current infant formula with or without the addition of 1.2 g/100 g fatty acid arachidonic acid [20:4(n-6)] and 0.7 g/100 g fatty acid docosahexaenoic acid [22:6(n-3)] or both 20:4(n-6) and 22:6(n-3). At 2 wk of age, no effect of diet on circulating levels of TSH, ACTH, GH or PRL was apparent. By 6 wk of age (3 wk postweaning), male rats consuming the diet containing 22:6(n-3) had significantly elevated levels of TSH, and females had significantly higher ACTH concentrations than males. No effect of diet was observed on circulating GH or PRL levels. Male pups had higher levels of TSH than females (P < 0.0001), whereas female pups from the 22:6(n-3) diet treatment exhibited much higher levels of ACTH than all male pups from any of the other diet treatments. These results suggest that metabolic controls, functioning through endocrine mechanisms, can be altered by changing the 20:4(n-6) to 22:6(n-3) balance in the diet.

Adrenocorticotropic Hormone↗

PubMed1997

During neuronal and glial cell development diet n-6 to n-3 fatty acid ratio alters the fatty acid composition of phosphatidylinositol and phosphatidylserine.

Brain development was examined in the neonatal rat in response to feeding increased levels of 18:3n - 3, 20:4n - 6 or 22:6n - 3 at levels proposed for infant formula. Diets varying in n - 6 to n - 3 fatty acid ratio, with or without 20:4n - 6 and 22:6n - 3 alone or in combination, were fed to nursing dams at parturition and subsequently to weaned pups until six weeks of age. Neuronal and glial cells were isolated from the frontal, cerebellar and hippocampal brain regions of rat pups at birth, one, two, three and six weeks of age. Fatty acid analysis of inositol- and serine- phosphoglycerides indicated that small changes in dietary n - 6 to n - 3 fatty acid ratio significantly affect neuronal and glial cell membrane composition. Fatty acid composition of phosphatidylinositol and phosphatidylserine was distinct and exhibited change with age. Individual brain regions and cell types varied in amount and rate of 20:4n - 6 and 22:6n - 3 accretion. Alteration of brain fatty acid composition reflected the fatty acid composition of the diet fed. If analogous changes occur during human brain development, feeding infants 20:4n - 6 and 22:6n - 3 or a reduced 18:2n - 6 to 18:3n - 3 ratio may alter fatty acid profiles of brain cells.

Animals↗

PubMed1997

Electrolyte composition of human breast milk beyond the early postpartum period.

The electrolyte composition of breast milk beyond 6 months postpartum has not been extensively examined, particularly chloride concentrations. A total of 140 samples of breast milk from 30 breast-feeding mothers were collected and analyzed. Mean mother's values +/- standard error of sodium (141 +/- 17 mg/L), potassium (480 +/- 11 mg/L), and chloride (452 +/- 32 mg/L) were found to be stable after 4 months postpartum until weaning commenced. Considerable variability was found for each constituent, equally divided between intra-individual and inter-individual for chloride and potassium, and predominantly intra-individual for sodium and lactose. In light of reported nutritional deficiency states involving electrolytes in exclusively breast-fed infants, it is possible that the variability of breast milk electrolyte concentrations may adversely affect infant nutrition in selected cases of older exclusively breast-fed infants.

Chlorides↗

PubMed1997

Small changes of dietary (n-6) and (n-3)/fatty acid content ration alter phosphatidylethanolamine and phosphatidylcholine fatty acid composition during development of neuronal and glial cells in rats.

It has been suggested that the fat composition of infant formula should provide arachidonic acid [20:4(n-6)] and docosahexaenoic acid [22:6(n-3)] or increased alpha-linolenic acid [18:3(n-3)] to optimize the (n-3) and (n-6) fatty acid content of brain during infant development. This experiment examined the effects of feeding increased levels of 18:3(n-3), 20:4(n-6) and 22:6(n-3) on brain development in neonatal rats. Diets varying in (n-6) and (n-3) fatty acid content with or without 20:4(n-6) or 22:6(n-3), at levels proposed for infant formula, were fed to nursing dams from parturition and subsequently to weaned pups until 6 wk of age. Neuronal and glial cells were isolated from the frontal region, cerebellum and hippocampus of the brain. Fatty acid analyses of ethanolamine- and choline-phosphoglycerides indicated that small changes in the dietary (n-6)/(n-3) ratio significantly altered neuronal and glial membrane fatty acid composition. Brain regions and cell types varied in amount and rate of 20:4(n-6) and 22:6(n-3) accretion. Fatty acid composition of individual phosphoglycerides was distinct and exhibited changes with age. Inclusion of both 20:4(n-6) and 22:6(n-3) in the diet resulted in alteration of brain fatty acid composition reflecting the fatty acid composition of the diet. If analogous developmental changes occur in human brain, then these results imply that addition of 20:4(n-6) and 22:6(n-3) or a reduced 18:2(n-6):18:3(n-3) ratio in infant formula may result in fatty acid profiles of neuronal and glial cells in formula-fed infants similar to those observed in breast-fed infants.

Aging↗

PubMed1997

Formula containing randomized fats with palmitic acid (16:0) in the 2-position increases 16:0 in the 2-position of plasma and chylomicron triglycerides in formula-fed piglets to levels approaching those of piglets fed sow's milk.

Human and pig milk fat contains a high proportion of palmitic acid (16:0) which is largely esterified to the 2-position of the triglycerides. In contrast, the 16:0 in most nonmilk fats and in infant formulas is mainly esterified at the triglyceride 1,3 positions. Gastric and pancreatic lipases hydrolyze fatty acids from the dietary triglyceride 1- and 3-positions to produce unesterified fatty acids and 2-monoglycerides which are absorbed and re-esterified. In this study, we determined whether formula with chemically randomized oils, which equally distributes 16:0 among all the positions of triglycerides, influences growth or the distribution of fatty acids in plasma and liver lipid of formula-fed piglets compared with piglets fed formula with native oils or sow's milk. After feeding from birth to 18 d, piglets fed formula with palm olein randomized with canola oil (co-randomized) had higher weight gain per liter of formula intake and higher 16:0 in the chylomicron triglyceride 2-position than piglets fed formula with randomized or native palm olein oil blended with canola oil. The fatty acid distribution of formula triglycerides is an important determinant of pathways of 16:0 absorption, and consequently of plasma lipid fatty acids in formula-fed piglets.

Animals↗

PubMed1997

The effect of triglyceride positional distribution on fatty acid absorption in rats.

BACKGROUND: Human milk contains palmitic acid predominantly in the triglyceride sn-2 position, and differs from the palmitic acid positional distribution found in most infant formulas (predominantly positions sn-1 and sn-3). Following lipolysis by pancreatic lipase, 2-monoglycerides and free fatty acids are produced. All 2-monoglycerides are well absorbed, including 2-monopalmitin, thus providing one reason for the efficient absorption of palmitic acid in breast-fed infants. If infants are fed fat blends with palmitic acid located in the sn-1 and sn-3 positions, the resulting free fatty acids may form poorly absorbed calcium soaps. Therefore, many infant formulas contain only modest levels of palmitic acid. METHODS: Fat absorption studies were conducted in rats with preparations containing various amounts of palmitic acid in the triglyceride sn-2 position. Determining total fat absorption, specific fatty acid absorption, and the presence of calcium-fatty acid soaps. RESULTS: Betapol, a new triacylglycerol, similar to human milk in its palmitic acid content and positional distribution, demonstrated excellent absorption characteristics compared to fat blends derived from either palm olein or oleo (similar in fatty acid profile to Betapol, but with most palmitic acid in the sn-1 and sn-3 positions). A five-point dose response was used to further evaluate the relationship of positional distribution and fat loss. Palmitic acid excretion and fecal fatty acid soaps were negatively correlated to the presence of palmitic acid in the sn-2 position. CONCLUSION: These studies provide evidence that palmitic acid can be efficiently absorbed, avoiding fatty soap formation of it is present in the sn-2 position.

Animals↗

PubMed1997

Assessment of the efficacious dose of arachidonic and docosahexaenoic acids in preterm infant formulas: fatty acid composition of erythrocyte membrane lipids.

The nutritional requirements of preterm infants for the long chain polyunsaturated essential fatty acids, arachidonic acid (AA) and docosahexaenoic acid (DHA), have not been clearly defined. The present study evaluated preterm infants of less than 2.3 kg birth weight fed a commercial formula (Preemie SMA) devoid of AA and DHA and compared this control group with similar infant groups fed one of three formulas containing a range of 0.32 to 1.1% AA and 0.24 to 0.76% DHA. An analogous group of infants fed their mothers' breast milk and a breast milk fortifier (when indicated) was also studied. Erythrocyte membrane phospholipids were isolated from blood samples collected at 12 d of age and after a further 4 wk of feeding. Infants fed the formula without AA and DHA showed a reduction in AA level in erythrocyte phosphatidylcholine, and a reduced level of DHA in phosphatidylethanolamine in comparison with infants fed breast milk or infant formula containing AA and DHA. Supplementing infant formula with increasing levels of AA and DHA produced a clear dose response in the levels of AA and DHA found in erythrocyte membrane phospholipids. From comparison of membrane phospholipid fatty acid composition it appears that a formula level of 0.32-1.1% AA and 0.24-0.76% DHA provides sufficient levels of these fatty acids to achieve a similar fatty acid composition to that of infants fed human milk for most of the lipid fractions examined.

Analysis of Variance↗