Biological effects and safety issues related to long-chain polyunsaturated fatty acids in infants

HPLC/HRMS and GC/MS for Triacylglycerols Characterization of Tuna Fish Oils Obtained from Green Extraction

Background: Fish oil is one of the most common lipidic substances that is consumed as a dietary supplement. The high omega-3 fatty acid content in fish oil is responsible for its numerous health benefits. Fish species such as mackerel, herring, tuna, and salmon are particularly rich in these lipids, which contain two essential omega-3 fatty acids, known as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Objectives: Due to the scarcity of information in the literature, this study aimed to conduct a qualitative and quantitative characterization of triglycerides (TAGs) in crude tuna fish oil using HPLC/HRMS. Fatty acid (FA) determination was also performed using GC/MS. The tuna fish oils analyzed were produced using a green, low-temperature process from the remnants of fish production, avoiding the use of any extraction solvents. Results: The analyses led to the tentative identification and semi-quantitation of 81 TAGs. In silico saponification and comparison with fatty acid methyl ester results helped to confirm the identified TAGs and their quantities. The study found that the produced oil is rich in EPA, DHA, and erucic acid, while the negligible isomerization of fatty acids to trans-derivatives was observed.

Comparison of Molecular Species Distribution of DHA-Containing Triacylglycerols in Milk and Different Infant Formulas by Liquid Chromatography-Mass Spectrometry

Long-chain polyunsaturated fatty acids (LC-PUFA) are an important nutritional lipid and have potential in being able to promote human health. Docosahexaenoic acid (DHA, C22:6ω3) is often added in infant formulas to meet the nutritional requirement of formula-fed infants. A comprehensive survey on DHA-containing triacylglycerol (DHA-TAG) molecular species has been conducted for seven infant formulas (IFs) sourced from Australia, Europe, and the USA as well as bovine milk and human milk. Using LC-triple quadrupole MS and LC-LTQ-orbitrap MS we were able to identify and quantify 56 DHA-TAG species in these samples; the fatty acid structure of these species was assigned using their MS(2) spectra. The species composition of DHA-TAG was found to be different between bovine milk, human milk, and IFs and also between different brands of IFs. Bovine milk and human milk contain DHA-TAG of smaller molecular size (728-952 Da), whereas five out of the seven IF samples contain species of broader mass range (from 728 to 1035 Da). Our study indicates that two types of DHA were used in the seven IF products surveyed and that there is very large difference in molecular species distribution in different IF products that may influence the fine nutritional profile and biological functions of IF products.

Parenteral lipid emulsions based on olive oil compared with soybean oil in preterm (<28 weeks' gestation) neonates: a randomised controlled trial

BACKGROUND

: New olive oil-based (OL) lipid emulsions (olive:soy oil = 4:1) have lower polyunsaturated fatty acid (PUFA) (20% vs 60%) and higher vitamin E content (an antioxidant) compared with traditional soybean oil (SO) emulsions.

OBJECTIVE

: Compare efficacy and safety of OL with SO emulsions in preterm neonates (<28 weeks) at high risk for oxidative stress.

PATIENTS AND METHODS

: Preterm neonates (gestation 23-<28 weeks) were randomised to receive OL or SO emulsion for 5 days using a standard protocol in a tertiary perinatal centre (King Edward Memorial Hospital for Women, Perth, Western Australia). Investigators and outcome assessors were masked to allocation. Plasma F2-isoprostanes (lipid peroxidation marker), plasma, and red blood cell fatty acids were measured before and after the study. Safety was monitored by liver function tests.

RESULTS

: Forty-four of 50 participants (OL-23, SO-21) completed the study. Both emulsions were well tolerated with no significant adverse events. F2-isoprostane levels were comparable at baseline and study end. Oleic and linoleic acid levels were significantly high on day 6 in OL and SO groups, respectively. Long-chain PUFA levels were similar between groups despite the lower PUFA content of OL. The olive oil-based group had significantly higher levels of C18:4n-3, suggesting Delta6-desaturase enzyme inhibition in the SO group.

CONCLUSIONS

: Olive oil-based emulsion was safe and well tolerated by preterm neonates. Similar long-chain PUFA levels were achieved in the OL group despite significantly lower amount of PUFA content; however, there was no difference in lipid peroxidation (F2-isoprostane levels). Large trials are needed to confirm these benefits.

Growth and development of preterm infants fed infant formulas containing docosahexaenoic acid and arachidonic acid

OBJECTIVES

To evaluate safety and benefits of feeding preterm infants formulas containing docosahexaenoic acid (DHA) and arachidonic acid (ARA) until 92 weeks postmenstrual age (PMA), with follow-up to 118 weeks PMA.

STUDY DESIGN

This double-blinded study of 361 preterm infants randomized across three formula groups: (1) control, no supplementation; (2) algal-DHA (DHA from algal oil, ARA from fungal oil); and (3) fish-DHA (DHA from fish oil, ARA from fungal oil). Term infants breast-fed > or =4 months (n = 105) were a reference group. Outcomes included growth, tolerance, adverse events, and Bayley development scores.

RESULTS

Weight of the algal-DHA group was significantly greater than the control group from 66 to 118 weeks PMA and the fish-DHA group at 118 weeks PMA but did not differ from term infants at 118 weeks PMA. The algal-DHA group was significantly longer than the control group at 48, 79, and 92 weeks PMA and the fish-DHA group at 57, 79, and 92 weeks PMA but did not differ from term infants from 79 to 118 weeks PMA. Supplemented groups had higher Bayley mental and psychomotor development scores at 118 weeks PMA than did the control group. Supplementation did not increase morbidity or adverse events.

CONCLUSIONS

Feeding formulas with DHA and ARA from algal and fungal oils resulted in enhanced growth. Both supplemented formulas provided better developmental outcomes than unsupplemented formulas.

Dietary long-chain PUFA in the form of TAG or phospholipids influence lymph lipoprotein size and composition in piglets

Several sources of long-chain PUFA (LCP) are currently available for infant formula supplementation. These oils differ in their FA composition, the chemical form of the FA esters [TAG or phospholipids (PL)], and presence of other lipid components. These differences may affect LCP absorption, distribution, and metabolic fate after ingestion. The purpose of this study was to evaluate the influence of different chemical forms of dietary LCP on the composition of lymph lipoproteins. Eighteen pigs (5 d old) were bottle-fed different diets for 2 wk: a control diet (C), a diet containing LCP as TAG from tuna and fungal oils (TF-TAG), or a diet containing LCP as PL from egg yolk (E-PL). We measured lipid and FA composition of lymph, main lymph fractions (TAG or PL), and the particle size of lymph lipoproteins. The average diameter of lymph lipoproteins was significantly lower in the E-PL group compared with the control and TF-TAG groups (C: 3902 +/- 384 A; TF-TAG: 3773 +/- 384 A; E-PL: 2370 +/- 185 A). Arachidonic acid and DHA contents in lymph and lymph-TAG were significantly higher in the TF-TAG group compared to the E-PL group (0.50 +/- 0.03 and 0.24 +/- 0.03 g/100 g vs. 0.29 +/- 0.04 and 0.12 +/- 0.03 g/100 g, respectively). The addition to the diet of LCP in the form of TAG or PL affected the size of intestinal lipoproteins and also led to a different distribution of these FA in lymph lipoproteins.

Lipids with an emphasis on long-chain polyunsaturated fatty acids

In addition to their role as a source of energy, several fatty acids are important components of cell membranes and/or precursors of biologically important eicosanoids. The long-chain polyunsaturated fatty acids, docosahexaenoic acid (DHA) and arachidonic acid (AA), are important for optimal visual function and neurodevelopment. These fatty acids are present in human milk but, until recently, have not been included in formulas marketed in the United States. Although the results of clinical trials assessing the effect of DHA and AA intakes on visual and cognitive development have been inconsistent, some studies suggest benefits. Adequate intake of these fatty acids may be especially important for the preterm infant.

Nutrient requirements for preterm infant formulas

Achieving appropriate growth and nutrient accretion of preterm and low birth weight (LBW) infants is often difficult during hospitalization because of metabolic and gastrointestinal immaturity and other complicating medical conditions. Advances in the care of preterm-LBW infants, including improved nutrition, have reduced mortality rates for these infants from 9.6 to 6.2% from 1983 to 1997. The Food and Drug Administration (FDA) has responsibility for ensuring the safety and nutritional quality of infant formulas based on current scientific knowledge. Consequently, under FDA contract, an ad hoc Expert Panel was convened by the Life Sciences Research Office of the American Society for Nutritional Sciences to make recommendations for the nutrient content of formulas for preterm-LBW infants based on current scientific knowledge and expert opinion. Recommendations were developed from different criteria than that used for recommendations for term infant formula. To ensure nutrient adequacy, the Panel considered intrauterine accretion rate, organ development, factorial estimates of requirements, nutrient interactions and supplemental feeding studies. Consideration was also given to long-term developmental outcome. Some recommendations were based on current use in domestic preterm formula. Included were recommendations for nutrients not required in formula for term infants such as lactose and arginine. Recommendations, examples, and sample calculations were based on a 1000 g preterm infant consuming 120 kcal/kg and 150 mL/d of an 810 kcal/L formula. A summary of recommendations for energy and 45 nutrient components of enteral formulas for preterm-LBW infants are presented. Recommendations for five nutrient:nutrient ratios are also presented. In addition, critical areas for future research on the nutritional requirements specific for preterm-LBW infants are identified.

The role of polyunsaturated fatty acids in term and preterm infants and breastfeeding mothers

DHA and AA, which are components of breast milk but not infant formulas marketed in the United States and some other countries, are important components of the brain, and DHA is a major component of the retina. Also, many studies have demonstrated advantages of breastfeeding versus formula-feeding on subsequent cognitive and visual function; however, available data are insufficient to justify the conclusion that the presence of DHA and AA in breast milk is partially or soley responsible for the apparent advantages of breastfeeding. On the other hand, many studies of DHA (and AA)-supplemented versus unsupplemented formulas have shown clear advantages of the supplemented formulas on visual acuity at 2 and 4 months of age or neurodevelopmental status at 12 to 18 months of age. Although one logically may assume that these early effects may have long-term effects, this assumption is not warranted by the available data. One of the major problems is the difficulty of assessing visual and cognitive function of infants. Scores on standard neurodevelopmental tests at 1 year of age, for example, are only weakly correlated with performance at school age (when more definitive assessments are possible), and little is known about the predictability of later visual function from behavioral or electrophysiologic assessments of visual function early in life. Even prematurely born infants can synthesize DHA and AA and other omega-3 and omega-6 LC-PUFAs from the dietary EFAs, LA and ALA. Nonetheless, plasma, erythrocyte and brain lipid levels of DHA are lower in infants whose diets do not contain DHA. Whether more optimal intakes of ALA result in higher plasma and tissue levels of this FA is unclear. The breast-milk content of LC-PUFAs is not regulated by the mammary gland but, rather, reflects the concentrations of LC-PUFAs in maternal plasma lipids that, in turn, are dependent on maternal diet and, probably, maternal activities of the desaturases and elongases involved in converting dietary LA and ALA to LC-PUFAs. This occurrence suggests that some infants receive sufficient LC-PUFA to support normal rates of deposition, whereas others may not. Also, some infants probably can synthesize additional LC-PUFAs from the LA and ALA contents of human milk. Thus, depending on maternal diet and maternal and infant desaturase and elongase activities, some breastfed infants may receive less than adequate LC-PUFAs to support normal rates of deposition. Clearly, the role of LC-PUFAs in infant development is not a simple issue. Also, no foolproof method exists to ensure an adequate but not excessive intake. Thus, because some evidence shows that dietary LC-PUFA (DHA, AA, or both) as components of breast milk or formula confers at least transient developmental benefits, supplementation of infant formulas with LC-PUFAs is supportable provided that the supplements used are safe. The safety of all available supplements is unknown; however, some trials reveal few reasons for major concerns about the safety of single-cell oils, low-EPA fish oil, or egg-yolk phospholipid or triglyceride fractions.