Essential fatty acid deficiency in an infant receiving prolonged parenteral alimentation

Platelet characteristics in extremely preterm infants after fatty acid supplementation: a randomized controlled trial

BACKGROUND

Two risk factors for severe retinopathy of prematurity (ROP) in extremely preterm infants are thrombocytopenia and low levels of arachidonic acid (AA) and docosahexaenoic acid (DHA). To date, these risk factors have not been linked.

METHOD

Infants born < 28 weeks gestational age (GA) from 2016 to 2019 were randomized to postnatal enteral AA/DHA supplementation or standard care (controls). Levels of AA and DHA, platelet counts ( < 100 × 109/L defined as thrombocytopenia) and platelet-related proteins in the infants' first four weeks of life were evaluated for their association with severe ROP.

RESULTS

The mean birthweight of 178 included infants was 806 ± 200 grams, and the mean GA was 25.6 ± 1.4 weeks. During the first four postnatal weeks, 20.2% of AA/DHA-supplemented infants had thrombocytopenia versus 27.7% of controls (p = 0.29). In infants with thrombocytopenia, fewer AA/DHA-supplemented infants developed severe ROP than non-supplemented controls, 29.4% (5/17) versus 65.4% (17/26) (p = 0.031). Thrombocytopenia and serum levels of AA and DHA correlated with several platelet-related proteins involved in angiogenesis and ROP, such as platelet-derived growth factor subunits A and B and vascular endothelial growth factor.

CONCLUSIONS

AA and DHA supplementation is associated with less severe ROP in thrombocytopenic infants, possibly by modulating platelet activation and function.

IMPACT

Postnatal enteral supplementation with arachidonic acid (AA) and docosahexaenoic acid (DHA) to extremely preterm infants reduces the risk of severe retinopathy of prematurity (ROP) in infants with thrombocytopenia. The impact of AA and DHA might be, at least in part, mediated through altered platelet activation. We found that AA and DHA may reduce the risk of severe ROP, possibly by modulating platelet-related proteins involved in angiogenesis. Our findings strongly support that supplementing AA and DHA to extremely preterm infants is crucial and can significantly impact their health.

Composite lipid emulsion use and essential fatty acid deficiency in pediatric patients with intestinal failure with high parenteral nutrition dependence: A retrospective cohort study

BACKGROUND

Reports of essential fatty acid deficiency (EFAD) in patients receiving parenteral nutrition (PN) and a composite lipid (mixed oil intravenous lipid emulsion [MO ILE]) are predominantly when managed by lipid restriction. The objective of this study was to determine the prevalence of EFAD in patients with intestinal failure (IF) who are PN dependent without lipid restriction.

METHODS

We retrospectively evaluated patients, ages 0-17 years, followed by our intestinal rehabilitation program between November 2020 and June 2021 with PN dependency index (PNDI) of >80% on a MO ILE. Demographic data, PN composition, PN days, growth, and plasma fatty acid profile were collected. A plasma triene-tetraene (T:T) ratio >0.2 indicated EFAD. Summary statistics and Wilcoxon rank sum test evaluated to compare between PNDI category and ILE administration (grams/kilograms/day). P < 0.05 was considered significant.

RESULTS

Twenty-six patients (median age, 4.1 years [interquartile range (IQR) = 2.4-9.6]) were included. The median duration of PN was 1367 days (IQR = 824-3195). Sixteen patients had a PNDI of 80%-120% (61.5%). Fat intake for the group was 1.7 g/kg/day (IQR = 1.3-2.0). The median T:T ratio was 0.1 (IQR = 0.1-0.2) with no values >0.2. Linoleic and arachidonic acid were low in 85% and 19% of patients, respectively; however, Mead acid was normal in all patients.

CONCLUSION

This report is the largest to date on the EFA status of patients with IF on PN. These results suggest that, in the absence of lipid restriction, EFAD is not a concern when using MO ILEs in children receiving PN for IF.

Toxicity and Its Mechanism Study of Arecae semen Aqueous Extract in Wistar Rats by UPLC-HDMS-Based Serum Metabolomics

Background

Arecae semen (AS) is officially recorded in Chinese Pharmacopoeia and it is known for its multiple functions, including antidepressive, antioxidant, anti-inflammatory, and cholesterol-lowering effects, which have been confirmed by modern pharmacological study. Previous study in our laboratory showed that long-term oral administration of Arecae semen (AS) is officially recorded in Chinese Pharmacopoeia and it is known for its multiple functions, including antidepressive, antioxidant, anti-inflammatory, and cholesterol-lowering effects, which have been confirmed by modern pharmacological study. Previous study in our laboratory showed that long-term oral administration of Hypothesis. The aim of this work was to characterize the metabolome, evaluate the metabolic changes, and study the mechanisms of the toxicity induced by different treatment doses of ASAE via metabolomics.

Methods

Wistar rats were administered orally two different doses of ASAE (1500 and 4500 mg/kg/d) for 30 days. The investigation was carried out to evaluate the safety of ASAE. And, the UPLC-HDMS-based serum metabolomics in conjunction with multivariate statistical techniques was applied to investigate the serum metabolite profile and potential markers of toxicity induced by different doses of ASAE.

Results

Coupled with blood biochemistry and histopathology results, the significant difference in metabolic profiling was observed between 1500 and 4500 mg/kg/d dosages of ASAE-treated rats and normal rats by using pattern recognition analysis, indicating that changes in serum metabolites must have occurred. Some significant changed metabolites such as arachidonic acid, linoleic acid, stearic acid, and LPC (18 : 1) have been found and identified. These biochemical changes in serum metabolites are related to the perturbation of linoleic acid metabolism, arachidonic acid metabolism, glycerophospholipid metabolism, and purine metabolism, which may be helpful to further understand the cardiotoxicity and neurotoxicity of ASAE.

Conclusion

The study shows that the metabolomic method may be a valuable tool for studying the essence of toxicity induced by traditional Chinese medicine.

Pancreatic Malnutrition in Children

Exocrine pancreatic insufficiency in children can lead to lifelong complications related to malnutrition and poor growth. The clinical presentation can be subtle in the early stages of insufficiency as the large functional capacity of the pancreas is gradually lost. The pediatrician plays a crucial role in the early identification of these children to ensure a timely referral so that a diagnosis can be made and therapy initiated. Early nutritional therapy allows for prevention and correction of deficiencies, which leads to improved outcomes and survival. When insufficiency is suspected, the workup should start with an indirect test of exocrine pancreatic function, such as fecal elastase, to establish the diagnosis. Once a diagnosis is established, further testing to delineate the etiology should be pursued, with cystic fibrosis being high on the differential list and assessed for with a sweat test. Assessment of anthropometry at every visit is key, as is monitoring of laboratory parameters and physical examination findings that are suggestive of malabsorption and malnutrition. The mainstay of management is administration of exogenous pancreatic enzymes to facilitate digestion and absorption. [Pediatr Ann. 2019;48(11):e441-e447.].

Choline and DHA in Maternal and Infant Nutrition: Synergistic Implications in Brain and Eye Health

The aim of this review is to highlight current insights into the roles of choline and docosahexaenoic acid (DHA) in maternal and infant nutrition, with special emphasis on dietary recommendations, gaps in dietary intake, and synergistic implications of both nutrients in infant brain and eye development. Adequate choline and DHA intakes are not being met by the vast majority of US adults, and even more so by women of child-bearing age. Choline and DHA play a significant role in infant brain and eye development, with inadequate intakes leading to visual and neurocognitive deficits. Emerging findings illustrate synergistic interactions between choline and DHA, indicating that insufficient intakes of one or both could have lifelong deleterious impacts on both maternal and infant health.

Essential Fatty Acid Requirements and Intravenous Lipid Emulsions

Linoleic acid (LA) and α-linolenic acid (ALA) must be supplied to the human body and are therefore considered essential fatty acids. This narrative review discusses the signs, symptoms, diagnosis, prevention, and treatment of essential fatty acid deficiency (EFAD). EFAD may occur in patients with conditions that severely limit the intake, digestion, absorption, and/or metabolism of fat. EFAD may be prevented in patients requiring parenteral nutrition by inclusion of an intravenous lipid emulsion (ILE) as a source of LA and ALA. Early ILEs consisted solely of soybean oil (SO), a good source of LA and ALA, but being rich in LA may promote the production of proinflammatory fatty acids. Subsequent ILE formulations replaced part of the SO with other fat sources to decrease the amount of proinflammatory fatty acids. Although rare, EFAD is diagnosed by an elevated triene:tetraene (T:T) ratio, which reflects increased metabolism of oleic acid to Mead acid in the absence of adequate LA and ALA. Assays for measuring fatty acids have improved over the years, and therefore it is necessary to take into account the particular assay used and its reference range when determining if the T:T ratio indicates EFAD. In patients with a high degree of suspicion for EFAD, obtaining a fatty acid profile may provide additional useful information for making a diagnosis of EFAD. In patients receiving an ILE, the T:T ratio and fatty acid profile should be interpreted in light of the fatty acid composition of the ILE to ensure accurate diagnosis of EFAD.

Essential Fatty Acid Status in Surgical Infants Receiving Parenteral Nutrition With a Composite Lipid Emulsion: A Case Series

Infants requiring prolonged parenteral nutrition (PN) may receive intravenous (IV) lipid in the form of soybean oil, fish oil, or a composite lipid emulsion (CLE) (i.e., SMOFlipid®). Soybean oil lipid-dose restriction is a popular method of treating and reducing the risk of intestinal failure-associated liver disease (IFALD) that may influence dosing strategies of other IV fat emulsions. Here we present 4 infants receiving PN with SMOFlipid® as their IV lipid source and examine trends in essential fatty-acid status, triglycerides, and dosing strategy. The infants on restricted doses of CLE developed biochemical essential fatty-acid deficiency (EFAD) that resolved with a dosage increase or by transition to a pure fish-oil lipid emulsion. Three of the 4 infants originally prescribed CLE were diagnosed with IFALD and started a pure fish-oil lipid emulsion after treatable causes of cholestasis were excluded. One of the 4 infants presented with hypertriglyceridemia that resolved upon transition to pure fish-oil lipid emulsion. Misapplication of lipid restriction protocols to CLE regimens render infants at risk for EFAD. CLE should be dosed within recommended ranges to prevent EFAD. Restricted protocols warrant close monitoring of essential fatty-acid status in infants receiving prolonged PN, particularly in those with minimal or no enteral intake. Hypertriglyceridemia and cholestasis are known adverse effects of CLE and require monitoring.

Redefining essential fatty acids in the era of novel intravenous lipid emulsions

The essentiality of fatty acids was determined by the Burrs in the 1920s. It is commonly accepted that provision of linoleic (LA) and alpha-linolenic acids (ALA) prevents and reverses essential fatty acid deficiency (EFAD). Development of alternative injectable lipid emulsions (ILE) low in LA and ALA has raised concern about their ability to prevent EFAD. This review provides biochemical evidence coupled with observations from animal and human studies that aim to characterize which fatty acids are truly essential to prevent EFAD. Retroconversion pathways and mobilization from body stores suggest that arachidonic and docosahexaenoic acids (ARA and DHA - the main derivatives of LA and ALA, respectively) also prevent EFAD. Our group first proposed the essentiality of ARA and DHA by feeding mice exclusively these fatty acids and proving that they prevent EFAD. Survival for 5 generations on this diet provides additional evidence that growth and reproductive capabilities are maintained. Moreover, the use of fish oil-based ILE, with minimal LA and ALA and abundant DHA and ARA, for treatment of intestinal failure-associated liver disease, does not result in EFAD. These findings challenge the essentiality of LA and ALA in the presence of ARA and DHA. Evidence discussed in this review supports the idea that ARA and DHA can independently fulfill dietary essential fatty acid requirements. The imminent introduction of new ILE rich in ARA and DHA in the United States highlights the importance of understanding their essentiality, especially when provision of ALA and LA is below the established daily minimum requirement.

Essential fatty acid deficiency during parenteral soybean oil lipid minimization

OBJECTIVE

To determine if parenteral lipid minimization in infants results in essential fatty acid (EFA) deficiency.

STUDY DESIGN

Prospective study of infants >30 days old and >34 weeks postmenstrual age receiving parenteral lipid minimization (<1.5 g kg^-1 per day) with either soybean oil or fish oil and >90% of total nutritional intake parenterally in the 14 days before a serum EFA sample. Nonparametric tests were used for statistical analyses with significance at 0.05.

RESULTS

Fifteen samples on soybean oil and nine on fish oil were included. Energy and macronutrient intakes and weight gain were similar between groups. Biochemical EFA deficiency occurred in 60% receiving soybean oil but none receiving fish oil (P<0.01). Average daily weight gain was 49% less in EFA deficient infants than EFA sufficient infants (P=0.02).

CONCLUSION

Infants on lipid minimization with parenteral soybean oil, but not fish oil, are at high risk of biochemical EFA deficiency with slower weight gain.

Essential Fatty Acid Deficiency in 2015: The Impact of Novel Intravenous Lipid Emulsions

The fatty acids, linoleic acid (18:2ω-6) and α-linolenic acid (18:3ω-3), are essential to the human diet. When these essential fatty acids are not provided in sufficient quantities, essential fatty acid deficiency (EFAD) develops. This can be suggested clinically by abnormal liver function tests or biochemically by an elevated Mead acid and reduced linoleic acid and arachidonic acid level, which is manifested as an elevated triene/tetraene ratio of Mead acid/arachidonic acid. Clinical features of EFAD may present later. With the introduction of novel intravenous (IV) lipid emulsions in North America, the proportion of fatty acids provided, particularly the essential fatty acids, varies substantially. We describe a case series of 3 complicated obese patients who were administered parenteral nutrition (PN), primarily using ClinOleic 20%, an olive oil-based lipid emulsion with reduced amounts of the essential fatty acids, linoleic and α-linolenic, compared with more conventional soybean oil emulsions throughout their hospital admission. Essential fatty acid profiles were obtained for each of these patients to investigate EFAD as a potential cause of abnormal liver enzymes. Although the profiles revealed reduced linoleic acid and elevated Mead acid levels, this was not indicative of the development of essential fatty acid deficiency, as reflected in the more definitive measure of triene/tetraene ratio. Instead, although the serum fatty acid panel reflected the markedly lower but still adequate dietary linoleic acid content and greatly increased oleic acid content in the parenteral lipid emulsion, the triene/tetraene ratio remained well below the level, indicating EFAD in each of these patients. The availability and use of new IV lipid emulsions in PN should encourage the clinician to review lipid metabolism based on the quantity of fatty acids provided in specific parenteral lipid emulsions and the expected impact of these lipid emulsions (with quite different fatty acid composition) on measured fatty acid profiles.

Discovery of essential fatty acids

Dietary fat was recognized as a good source of energy and fat-soluble vitamins by the first part of the 20th century, but fatty acids were not considered to be essential nutrients because they could be synthesized from dietary carbohydrate. This well-established view was challenged in 1929 by George and Mildred Burr who reported that dietary fatty acid was required to prevent a deficiency disease that occurred in rats fed a fat-free diet. They concluded that fatty acids were essential nutrients and showed that linoleic acid prevented the disease and is an essential fatty acid. The Burrs surmised that other unsaturated fatty acids were essential and subsequently demonstrated that linolenic acid, the omega-3 fatty acid analog of linoleic acid, is also an essential fatty acid. The discovery of essential fatty acids was a paradigm-changing finding, and it is now considered to be one of the landmark discoveries in lipid research.

Hair loss in long-term or home parenteral nutrition: are micronutrient deficiencies to blame?

PURPOSE OF REVIEW

To review the key nutritional factors associated with hair loss in long-term parenteral nutrition patients.

RECENT FINDINGS

The phenomenon of unexplained hair loss is multifactorial, and nonstandard definitions are applied. Deficiencies of essential fatty acids resulting in alopecia and other symptoms appear to have been eliminated by regular use of lipid-containing parenteral nutrition. Zinc is the most frequently suspected deficiency with rapid clinical responses reported from zinc therapy. Alopecia in some infants on parenteral nutrition has been relieved in a few weeks by selenium supplementation as selenite. There may be a relationship between iron depletion and diffuse hair loss in home parenteral nutrition patients at higher risk of anaemia. A serum ferritin level of 70 μg/l should be targeted when hair loss is unexplained. However, there is limited data correlating cessation of hair loss with iron therapy and insufficient evidence to recommend iron supplementation in patients without anaemia. Parenteral nutrition-associated biotin deficiency has not been reported since the vitamin has been routinely added to parenteral nutrition. However, marginal biotin status, associated with diffuse hair loss, could still be prevalent.

SUMMARY

Micronutrient status is infrequently monitored and current recommendations for supplementation are nonspecific for hair loss in long-term parenteral nutrition. Studies are required to determine the incidence of marginal zinc, selenium, iron or biotin deficiencies that could manifest as hair loss.

Vitamin D receptor: key roles in bone mineral pathophysiology, molecular mechanism of action, and novel nutritional ligands

The vitamin D hormone, 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)], binds with high affinity to the nuclear vitamin D receptor (VDR), which recruits its retinoid X receptor (RXR) heterodimeric partner to recognize vitamin D responsive elements (VDREs) in target genes. 1,25(OH)(2)D(3) is known primarily as a regulator of calcium, but it also controls phosphate (re)absorption at the intestine and kidney. Fibroblast growth factor 23 (FGF23) is a phosphaturic hormone produced in osteoblasts that, like PTH, lowers serum phosphate by inhibiting renal reabsorption through Npt2a/Npt2c. Real-time PCR and reporter gene transfection assays were used to probe VDR-mediated transcriptional control by 1,25(OH)(2)D(3). Reporter gene and mammalian two-hybrid transfections, plus competitive receptor binding assays, were used to discover novel VDR ligands. 1,25(OH)(2)D(3) induces FGF23 78-fold in osteoblasts, and because FGF23 in turn represses 1,25(OH)(2)D(3) synthesis, a reciprocal relationship is established, with FGF23 indirectly curtailing 1,25(OH)(2)D(3)-mediated intestinal absorption and counterbalancing renal reabsorption of phosphate, thereby reversing hyperphosphatemia and preventing ectopic calcification. Therefore, a 1,25(OH)(2)D(3)-FGF23 axis regulating phosphate is comparable in importance to the 1,25(OH)(2)D(3)-PTH axis that regulates calcium. 1,25(OH)(2)D(3) also elicits regulation of LRP5, Runx2, PHEX, TRPV6, and Npt2c, all anabolic toward bone, and RANKL, which is catabolic. Regulation of mouse RANKL by 1,25(OH)(2)D(3) supports a cloverleaf model, whereby VDR-RXR heterodimers bound to multiple VDREs are juxtapositioned through chromatin looping to form a supercomplex, potentially allowing simultaneous interactions with multiple co-modulators and chromatin remodeling enzymes. VDR also selectively binds certain omega3/omega6 polyunsaturated fatty acids (PUFAs) with low affinity, leading to transcriptionally active VDR-RXR complexes. Moreover, the turmeric-derived polyphenol, curcumin, activates transcription of a VDRE reporter construct in human colon cancer cells. Activation of VDR by PUFAs and curcumin may elicit unique, 1,25(OH)(2)D(3)-independent signaling pathways to orchestrate the bioeffects of these lipids in intestine, bone, skin/hair follicle, and other VDR-containing tissues.

Nutrition and Wound Healing

The relationship between nutrition and wound healing--after injury or surgical intervention--has been recognized for centuries. There is no doubt that adequate carbohydrate, fat, and protein intake is required for healing to take place, but research in the laboratory has suggested that other specific nutritional interventions can have significant beneficial effects on wound healing. Successful translation into the clinical arena, however, has been rare. A review of normal metabolism as it relates to wound healing in normoglycemic and diabetic individuals is presented. This is followed by an assessment of the current literature and the data that support and refute the use of specialized nutritional support in postoperative and wounded patients. The experimental evidence for the use of arginine, glutamine, vitamins, and micronutrient supplementation is described. Most of the experimental evidence in the field supporting the use of specialized nutritional support has not been borne out by clinical investigation. A summary of the clinical implications of the data is presented, with the acknowledgment that each patient's plan of care must be individualized to optimize the relationship between nutrition and wound healing.

The role of nutrition in the management of lower extremity wounds

From 3000 BC, healers have understood the importance of nutrition in wound care and used nutritional supplements to aid healing. Many of the teachings from Hippocrates, the father of modern-day medicine, clearly state his firm belief that good health can be achieved through nutrition. In the early 1900s when advances in biochemistry were frequent, many of the essential constituents of nutrition were characterized, which formed the basis for many animal and human wound-healing experiments. This led to the discovery of vitamin C, zinc, and many other components essential for the orderly progression of healing. Modern-day research has concentrated on finding nutritional components that can enhance healing through supra-physiological doses, such as in the use of the amino acids arginine and carnitine. However, clinicians need to be aware that approximately 50% of patients admitted to the hospital are malnourished, requiring dietary supplementation; appropriate nutritional assessment and advice therefore should be an integral part of all wound management. This review provides an up-to-date commentary on the role of nutrition in wound care, with specific emphasis on lower limb wounds, from a historical perspective, and within it both the biomedical approach and current herbalist practices are considered.

Lipid requirements of infants: implications for nutrient composition of fortified complementary foods

Dietary lipids have traditionally been considered as solely part of the exchangeable energy supply. The main consideration in infant nutrition has been the amount of fat that can be tolerated and digested by infants and young children. The significance of the composition of dietary fat has received little attention. Presently, there is a growing interest in the quality of dietary lipid supply in early childhood as a major determinant of growth, infant development and long-term health. Thus, the selection of dietary lipids during the first years of life is now considered to be critically important for health and good nutrition throughout the life course. Over the past decades interest has focused on the role of essential lipids in central nervous system development and of fatty acids and cholesterol in lipoprotein metabolism throughout life. Lipids are structural components of all tissues and are indispensable for cell and plasma membrane synthesis. The brain, retina and other neural tissues are particularly rich in long-chain PUFA. Some (n-6) and (n-3) fatty acids are precursors for eicosanoid formation; these are powerful mediators of numerous cell and tissue functions. Recommendations for infant nutrition and implications of these for the nutrient composition of complementary foods are presented and discussed. There is more to fat than its role as a key fuel in energy metabolism and body energy storage; lipids are essential for tissue growth, cardiovascular health, brain development and function throughout the life course.

Nutrition and wound healing

The relationship between host nutrition and wound healing has been the subject of study and experimentation for centuries. Despite the many years of study and a substantial knowledge base of the specific processes and factors involved, wound healing remains enigmatic. There is still much to learn about the wound-specific nutritional interventions that are available to improve wound healing. Nutrition profoundly influences the process of wound healing. Nutritional depletion exerts an inhibitory effect, and nutritional supplementation with such positive effectors as arginine can stimulate wound healing. Within this paradigm, the physician should be able to recognize patients who may be expected to have wound healing difficulties and offer early intervention to avoid wound failure.

Essential fatty acid composition of plasma phospholipids and birth weight: a study in term neonates

BACKGROUND

Essential fatty acids (EFAs) in umbilical cord blood samples are associated with attained birth weight in premature infants and low-birth-weight neonates.

OBJECTIVE

The objective was to investigate relations between the EFA composition of cord and maternal plasma phospholipids and birth weight in term neonates.

DESIGN

This was a cross-sectional study in 627 singletons born at term. The plasma phospholipid EFA composition of the mothers was determined by gas-liquid chromatography at study entry (< or = 16 wk gestation), at delivery, and in cord plasma at birth. Birth weights were normalized to SD scores.

RESULTS

In cord plasma, the dihomo-gamma-linolenic acid concentration was positively related to weight SD scores. Both arachidonic acid (AA) and docosahexaenoic acid (DHA) were negatively related to weight SD scores. EFA-status indicators showed similar negative associations, whereas eicosatrienoic acid concentrations were positively related to neonatal size. In maternal plasma, proportions of n-3 long-chain polyenes (LCPs) and n-6 LCPs decreased during pregnancy. Larger decreases in AA, DHA, n-3 LCP, and n-6 LCP fractions were observed in mothers of heavier babies. Higher concentrations of LCPs in maternal plasma were, however, not related to a larger infant size at birth.

CONCLUSIONS

A lower biochemical EFA status in umbilical cord plasma and a larger decrease in maternal plasma LCP concentrations are associated with a higher weight-for-gestational-age at birth in term neonates. Our findings do not support a growth-stimulating effect of AA or DHA; however, they do suggest that maternal-to-fetal transfer of EFAs might be a limiting factor in determining neonatal EFA status.

Essential fatty acid metabolism in the micropremie

Lipids are structural components of all tissues and are indispensable for cell membrane synthesis. The brain, retina, and other neural tissues are particularly rich in LCPUFAs, affecting neural structural development and function. LCPUFAs serve also as specific precursors for eicosanoid production (prostaglandins, prostacyclins, thromboxanes, and leukotrienes). These autocrine and paracrine mediators are powerful regulators of numerous cell and tissue functions (e.g., thrombocyte aggregation, inflammatory reactions, and leukocyte functions, vasoconstriction and vasodilatation, blood pressure, bronchial constriction, uterine contraction). Dietary lipid intake affects cholesterol metabolism at an early age and is associated with cardiovascular morbidity and mortality in later life. Over recent years, the role of fatty acids in modulating signal transduction and regulating gene expression have been described, emphasizing the complex of fatty acid effects. Dietary fatty acids, especially LCPUFA, can have significant effects in the modulation of developmental processes affecting the clinical outcomes of extremely premature infants.

Essential fatty acids in early life: structural and functional role

Essential fatty acids (EFA) are structural components of all tissues and are indispensable for cell membrane synthesis; the brain, retina and other neural tissues are particularly rich in long-chain polyunsaturated fatty acids (LCPUFA). These fatty acids serve as specific precursors for eicosanoids that regulate numerous cell and organ functions. Results from animal and recent human studies support the essential nature of n-3 EFA in addition to the well-established role of n-6 EFA for human subjects, particularly in early life. The most significant effects relate to neural development and maturation of sensory systems. Recent studies using stable-isotope-labelled tracers demonstrate that even preterm infants are able to form arachidonic acid (AA) and docosahexaenoic acid (DHA), but that synthesis is extremely low. Intracellular fatty acids or their metabolites regulate transcriptional activation of gene expression during adipocyte differentiation, and retinal and nervous system development. Regulation of gene expression by LCPUFA occurs at the transcriptional level and is mediated by nuclear transcription factors activated by fatty acids. These nuclear receptors are part of the steroid hormone receptor family. Two types of polyunsaturated fatty acid responsive transcription factors have been characterized, the peroxisome proliferator-activated receptor (PPAR) and the hepatic nuclear factor 4alpha. DHA also has significant effects on photoreceptor membranes involved in the signal transduction process, rhodopsin activation, and rod and cone development. Comprehensive clinical studies have shown that dietary supplementation with marine oil or single-cell oils, sources of LCPUFA, results in increased blood levels of DHA and AA, as well as an associated improvement in visual function in formula-fed premature infants to match that of human milk-fed infant. Recent clinical trials convincingly support LCPUFA supplementation of preterm infant formulations and possibly term formula to mimic human milk composition.

Essential fat requirements of preterm infants

The interest in factors that modify early infant development has led investigators to focus on n-3 and n-6 long-chain polyunsaturated fatty acids (LCPUFAs) in the past 2 decades. The presence of docosahexaenoic acid (DHA) and arachidonic acid (AA) in breast milk, compared with their absence from infant formulas available in the United States, has prompted clinical trials designed to examine whether LCPUFA enrichment of infant formula has beneficial effects on maturational events of the visual system. These trials have shown significant functional advantages of LCPUFA supplementation for preterm infants, whereas benefits for full-term infants remain controversial. The growth and safety of preterm infants was not compromised by LCPUFA enrichment, although these issues remain to be resolved in clinical trials with full-term infants.

Relation between polyunsaturated fatty acids and growth

Although it was discovered in the late 1920s that polyunsaturated fatty acids (PUFA) are essential for proper growth and development in animals, their nutritional importance in humans has not attained general interest until the 1990s, when the role for growth and development has been extensively studied in both humans and animals. It is now known that PUFA regulate various developmental and physiological processes, and that they are of essential importance for early human growth and development. Thus, linoleic acid is the precursor of arachidonic acid, from which hormone-like compounds, such as prostaglandins and leukotrienes, are formed, whereas alpha linolenic acid is the precursor of docosahexaenoic acid, which is an essential compound in cell membranes and occurs in particularly high concentration in the photoreceptors. In this paper the role of PUFA for human growth will be reviewed.

Requirements for long-chain polyunsaturated fatty acids in the preterm infant

Dietary long-chain polyunsaturated fatty acids have demonstrable beneficial effects on early development. The effects on neural development are of particular interest. Human milk is the best and only time-proven source of fat and essential fatty acids in the infant diet. Technologic procedures based on chemical and physical separation of the unsaturated fatty acids have permitted the isolation of concentrated sources of docosahexaenoic acid and arachidonic acid for clinical use. Virtually all infant formulas in developed countries have increased the levels of gamma-linolenic acid, and several manufacturers in Europe and in Japan have added docosahexaenoic acid, or docosahexaenoic acid plus arachidonic acid, or have also included gamma-linolenic acid in formulas for preterm and term infants. The efficacy of this practice for preterm infants seems fairly well established. The use of stable isotope methods to evaluate biosynthesis of long-chain polyunsaturated fatty acids from dietary precursors may help to better define optimal amounts and relationships of fatty acids in infant formula.

Physical findings in nutritional deficiencies

Manifestations of deficiencies of protein, calories, vitamins, and trace elements are described. These findings are placed in the context of the functions, food sources, and causes of deficiency of each micronutrient.

Role of essential fatty acids in the function of the developing nervous system

The basis for n-3 fatty acid essentially in humans includes not only biochemical evidence but functional measures associated with n-3 deficiency in human and nonhuman primates. Functional development of the retina and the occipital cortex are affected by alpha-linolenic acid deficiency and by a lack of docosahexaenoic acid (DHA) in preterm infant formulas and, as reported more recently, in term diets. Functional effects of n-3 supply on sleep-wake cycles and heart rate rhythms support the need for dietary n-3 fatty acids during early development. Our results indicate that n-3 long-chain polyunsaturated fatty acids should be considered provisionally essential for infant nutrition. DHA may also be required by individuals with inherited metabolic defects in elongation and desaturation activity, such as patients with peroxisomal disorders and some forms of retinitis pigmentosa.

Effect of supplementation of milk fat with peanut oil on blood lipids and lipoproteins in infants

Three different groups of infants were fed with different formulae based on milk fat. Group I received cow's milk fat formulae with 20% butter fat whereas groups II and III received a formulae which was supplemented with 50 and 33% of peanut oil supplementation in 20% milk fat respectively. Anthropometric measurements, cholesterol, triglyceride, lipoproteins and plasma fatty acids were followed up to a period of 6 months. The results indicated that cow's milk-fed infants had higher cholesterol levels (P < 0.01) than the other two groups. No significant differences with respect to high-density lipoproteins (HDLs) were found, whereas low-density lipoproteins (LDLs) and very low-density lipoproteins (VLDls (VLDls) were found to be increasing up to a period of 6 months. No significant differences were observed with respect to saturated fatty acids and oleic acid (18:1) levels whereas linoleic acid (18:2) clearly showed a proportional relationship between the intake and plasma levels, indicating a positive correlation. Arachidonic acid (20:4) did not, however, show a proprotionate relationship with respect to linoleic acid (18:2) intake. The triene/tetraene, oleic/linoleic, linoleic/arachidonic and total n6 fatty acids were all normal indicating normal activity of desaturase and elongase enzymes for the optimal utilisation of linoleic acid. Thus, the present study suggests that a vegetable oil such as peanut oil could be used in milk fat to improve the essential fatty acid (EFA) status of infants.

Essential fatty acid metabolism and requirements for LBW infants

Humans are unable to synthesize linoleic acid (LA) (18:2 omega-6) and alpha-linolenic acid (LNA) (18:3 omega-3). Most formulas provide ample LA, yet infants are at risk for omega-3 deficiency unless they are fed human milk. Neonates born at 30 weeks received human milk or were randomized to three formulas: formula A, based on corn oil, similar to old commercial formula; formula B, based on soy oil supplied LNA; or formula C, a product similar to B with added marine oil to provide docosahexaenoic acid (22:6 omega-3). The fatty acids of plasma and red blood cells had marked diet-induced differences. The rod photo-receptor tests demonstrated higher threshold and decreased sensitivity in the omega-3-deficient infants. Visual acuity also showed improved function of the brain cortex in the human milk and group C infants at follow-up at 57 weeks. These results suggest that omega-3 fatty acids are needed for optimal development of visual function.

Treatment with IGF-I peptides improves function of the remnant gut following small bowel resection in rats

The effects of 7 days' s.c. infusion of 111-700 micrograms/day IGF-I on gut growth and absorptive function were examined in growing rats following removal of 70 or 80% of the jejuno-ileum, and compared with the responses to the analogues, LR3IGF-I and des(1-3)IGF-I, which bind poorly to IGF binding proteins. Administration of 278 micrograms/day IGF-I, LR3IGF-I or des(1-3)IGF-I following 70% jejuno-ileal resection significantly attenuated malabsorption of fat and nitrogen. Responses in rats with 80% resection were less substantial, but a dose-responsive reduction in malabsorption was apparent with LR3IGF-I. Both IGF-I and LR3IGF-I were shown to increase body weight gain and food conversion efficiency in a dose-dependent manner following 80% jejuno-ileal resection. Total gut weight was increased by up to 21%, due predominantly to increased weight of the stomach and proximal small bowel, with the latter effect attributable at least in part to an increased bowel length. LR3IGF-I was more potent than IGF-I at stimulating body weight gain and food conversion efficiency, but its potency advantage on gut absorptive function and small intestinal re-growth was less marked. We conclude that administration of IGF-I peptides improves gastro-intestinal absorptive function following partial gut resection, most likely reflecting, at least in part, an increase in gut absorptive surface area.

Selection of optimal lipid sources in enteral and parenteral nutrition

The manipulation of dietary fat intake can affect the response to disease, injury, and infection. These effects include enhancement or inhibition of immune function, altered susceptibility to cardiovascular disease, promotion or maintenance of gut integrity, and prevention of total parenteral nutrition-induced hepatic dysfunction. These effects may occur as a result of changes in the fatty acid composition of biomembranes or changes in concentrations of lipid moieties such as prostaglandins or leukotrienes. Those fats that have been shown to affect physiologic function include long-chain, medium-chain, and short-chain fatty acids and omega-3 and omega-6 fatty acids. Currently available enteral and parenteral products used for nutrition support contain widely varied amounts of these different fatty acids. Therefore, the selection of the most appropriate product or nutrition support regimen for an individual patient requires an understanding of the metabolism of these different fat substrates, their therapeutic indications, and the contraindications and controversies that surround their use. This article reviews these issues and also focuses on several alternate lipid sources such as short-chain fatty acids, medium-chain fatty acids, omega-3 fatty acids, and blended and structured lipids.

Effects of enteral fat emulsion on fat absorption in obstructive jaundiced rats

The effects of fat emulsion given enterally on fat absorption were studied with obstructive jaundiced rats (J group) as compared with jaundice-free rats (C group). The J and C groups were subdivided into JE and CE groups using emulsified fat for the fat absorption test, and JU and CU groups using unemulsified fat. Rats in all groups were fed for 7 days with regular rat chow. After fasting for 12 hours, 14C-labeled fat emulsion was infused to the JE and CE, and 14C-labeled unemulsified fat to the JU and CU groups through a gastrostomy for the absorption test. The hourly and cumulative output of 14CO2 by respiration, absorption rate of 14C-labeled fat in the intestine, and metabolic oxidation rate of the absorbed fat were determined during an 8-hour period after the gastroenteral administration of emulsified or unemulsified fat. The peak of hourly output was seen after the first 2 hours in the CE, JE, and CU groups, following which a remarkable decline was seen in the CE and CU groups. However, a more gentle descent in the JE, and fluctuation at a low level in the JU group were observed. The cumulative output in the JE was 61% of that in the CE, while the output in the JU was 16% of that in the CU group. The absorption rate in the JE was 81% of that in the CE group, while the rate in the JU was 22% of that in the Cu group.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of hyperoxia on the lungs of rats deficient in essential fatty acids

Morphological alterations in the lungs of rats deficient in either or both of vitamin E and essential fatty acids were investigated after exposure to hyperoxia for 48 h. In rats deficient in both vitamin E and essential fatty acids, there was damage to type-2 alveolar cells observed as swollen mitochondria and bleb formation in the cytoplasm. None of these changes was found in rats deficient in only one of these substances. Hyperoxia in rats deficient in both substance also caused destruction of the capillary endothelial cells and edema in the interstitium. The lungs of rats deficient in only one of the substances showed some edema in the capillary endothelial cells, but not destruction, and less interstitial edema. These findings suggest that simultaneous deficiency in vitamin E and essential fatty acids facilitates lung damage in rats exposed to hyperoxia.

Effect of emulsions of medium and long chain triglyceride on human adipose tissue prostaglandin production in vitro

Preliminary in vitro studies have been performed to assess the effect of experimental lipid emulsions of varying fatty acid composition on human adipose tissue metabolism. Subcutaneous human adipose tissue was obtained during elective surgery and placed in tissue culture. Physical mixtures of long chain triglyceride (LCT) and/or medium chain triglyceride (MCT) were added to the tissue culture medium so that the final concentration was 400 mg/dl. After a 3-day incubation period the tissue was harvested, placed in buffer and used to determine in vitro production of the prostaglandins prostacyclin I2 (measured as its stable endproduct 6-keto PGF1 alpha), thromboxane A2 (measured as TXB2), and prostaglandin E2. Measurements of the fatty acid profile found in the neutral- and phospholipid fraction of the adipose tissue and fat cell size were also made. The results demonstrate that samples incubated in 100% MCT had the most significant increase in prostaglandin production whereas those incubated in 100% LCT had the most significant decrease in activity of the three prostaglandins assayed, when compared to controls. The addition of LCT to MCT caused a dose-related decrease in adipose tissue prostaglandin production. There were no significant changes in the profile of fatty acids found in the neutral- or phospholipid fraction of adipose tissue. The results indicate that the relative level of MCT/LCT incubated with human adipose tissue has a significant effect on prostaglandin production.

Essential fatty acid deficiency and postresection mucosal adaptation in the rat

The effect of short-term (biochemical) and long-term (clinical) essential fatty acid (EFA) deficiency on mucosal adaptation was studied in a surgical model of short bowel syndrome. Rats fed an EFA-deficient diet for 4 wk had biochemical evidence of EFA deficiency (hepatic and red blood cell triene to tetraene ratios greater than 0.4). Resected animals (70% proximal jejunoileal resection) receiving an EFA-deficient diet had a significantly impaired intestinal mucosal hyperplasia response in all remaining small bowel segments compared with resected controls. The effect of refeeding a control diet to clinically EFA-deficient resected rats was also evaluated. Short-term refeeding (2 wk) of a control diet resulted in a significant return toward normal tissue triene to tetraene ratios. Concomitantly, refed animals had significantly greater mucosal adaptation in the remaining duodenal/jejunal segment compared with resected animals maintained on an EFA-deficient diet postoperatively. These experiments underscore the dynamic nature of tissue EFA status and the importance of fatty acids in the normal compensatory mechanisms of mucosal adaptation after resection.

Plasma phospholipid fatty acids and urinary excretion of prostaglandins PGE1 and PGE2 in infants during total parenteral nutrition, with continuous or sequential administration of fat emulsion

During total parenteral nutrition, using an identical supply of fat emulsion (350 mg/kg/24 hr) to correct essential fatty acid deficiency in children, the efficacy of two methods of administration was studied: continuous over 24 hr, or discontinuous 3 hr/day. At the beginning of the study, all the infants (1-4 months old) had proven essential fatty acid deficiency. After at least 1 month of one of the two nutritional protocols (continuous or discontinuous), plasma phospholipid fatty acid composition and PGE1 and PGE2 urinary excretion were measured. The results obtained indicate better utilization of the fat emulsion when it is administered almost every day, in continuous infusion over 24 hr (1 g/kg/24 hr of Intralipid 20%).

Serum fatty acid concentrations in patients on postoperative parenteral nutrition with and without fat

To examine changes in fatty acid composition of serum lipids, sixteen patients with gastric cancer were maintained on total parenteral nutrition (TPN) or intravenous feeding immediately after total gastrectomy. Subjects receiving no fat showed decreases in linoleic acid, linolenic acid and arachidonic acid and increases in palmitoleic acid and oleic acid, whereas those receiving fat emulsion showed no detectable changes. Decrease in the linoleic acid content was greater in subjects on a higher carbohydrate intake, but less in those on a higher fat intake. Multiple regression analysis of the relationships among carbohydrate intake (X1) and fat intake (X2) and changes in the linoleic acid percentage of total serum fatty acids (Y) in each case yielded an equation: Y =-4.75 X1 + 69.0 X2 - 27.9 (R = 0.885, p less than 0.05). Approximately 1 g/kg/day of fat provided in 40-50 kcal/kg/day of nonprotein energy intake was estimated to prevent decrease in the linoleic acid content in the serum fatty acid pattern during the postoperative catabolic stage.