Long-chain polyunsaturated fatty acids in diets for infants: choices for recommending and regulating bodies and for manufacturers of dietary products

Metabolomics of dietary fatty acid restriction in patients with phenylketonuria

Background

Patients with phenylketonuria (PKU) have to follow a lifelong phenylalanine restricted diet. This type of diet markedly reduces the intake of saturated and unsaturated fatty acids especially long chain polyunsaturated fatty acids (LC-PUFA). Long-chain saturated fatty acids are substrates of mitochondrial fatty acid oxidation for acetyl-CoA production. LC-PUFA are discussed to affect inflammatory and haemostaseological processes in health and disease. The influence of the long term PKU diet on fatty acid metabolism with a special focus on platelet eicosanoid metabolism has been investigated in the study presented here.

Methodology/Principal Findings

12 children with PKU under good metabolic control and 8 healthy controls were included. Activated fatty acids (acylcarnitines C6–C18) in dried blood and the cholesterol metabolism in serum were analyzed by liquid chromatographic tandem mass spectrometry (LC-MS/MS). Fatty acid composition of plasma glycerophospholipids was determined by gas chromatography. LC-PUFA metabolites were analyzed in supernatants by LC-MS/MS before and after platelet activation and aggregation using a standardized protocol. Patients with PKU had significantly lower free carnitine and lower activated fatty acids in dried blood compared to controls. Phytosterols as marker of cholesterol (re-) absorption were not influenced by the dietary fatty acid restriction. Fatty acid composition in glycerophospholipids was comparable to that of healthy controls. However, patients with PKU showed significantly increased concentrations of y-linolenic acid (C18:3n-6) a precursor of arachidonic acid. In the PKU patients significantly higher platelet counts were observed. After activation with collagen platelet aggregation and thromboxane B₂ and thromboxane B₃ release did not differ from that of healthy controls.

Conclusion/Significance

Long-term dietary fatty acid restriction influenced the intermediates of mitochondrial beta-oxidation. No functional influence on unsaturated fatty acid metabolism and platelet aggregation in patients with PKU was detected.

Fatty acid profile of unconventional oilseeds

The continued increase in human population has resulted in the rise in the demand as well as the price of edible oils, leading to the search for alternative unconventional sources of oils, particularly in the developing countries. There are hundreds of un- or underexplored plant seeds rich in oil suitable for edible or industrial purposes. Many of them are rich in polyunsaturated essential fatty acids, which establish their utility as "healthy oils." Some agrowaste products such as rice bran have gained importance as a potential source of edible oil. Genetic modification has paved the way for increasing the oil yields and improving the fatty acid profiles of traditional as well as unconventional oilseeds. Single cell oils are also novel sources of edible oil. Some of these unconventional oils may have excellent potential for medicinal and therapeutic uses, even if their low oil contents do not promote commercial production as edible oils.

Dietary long-chain polyunsaturated fatty acid supplementation in infants with phenylketonuria: a randomized controlled trial

BACKGROUND

Pre- and postnatal tissue accretion of long-chain polyunsaturated fatty acids (LCPUFA) has been related to visual and cognitive development in healthy children in several studies. Children with phenylketonuria (PKU) consume diets with very low contents of preformed LCPUFA. We studied prospectively the LCPUFA status in infants with PKU without or with LCPUFA supplementation during the first year of life.

SUBJECTS AND METHODS

Infants with PKU were enrolled at diagnosis (<4 weeks of age) and randomized double blind to phenylalanine-free amino acid supplements without LCPUFA (n = 11) or with both arachidonic (AA, 0.46 wt%) and docosahexaenoic acids (DHA, 0.27 wt%) (n = 10). At enrolment and again at 1, 2, 3, 4, 6, 9 and 12 months, plasma phospholipid fatty acids were measured and dietary intakes were calculated from dietary protocols.

RESULTS

Unsupplemented patients showed a marked LCPUFA depletion to levels clearly below those observed in healthy breast-fed infants. In contrast, supplemented infants had stable and higher LCPUFA levels than unsupplemented infants, reaching significant differences for AA values at 3, 4 and 6 months, and for DHA values at 1, 3, 4, 6, 9 and 12 months. Plasma phospholipid levels correlated closely with estimated dietary intakes of preformed LCPUFA.

CONCLUSION

Low LCPUFA intakes with PKU diets induce marked depletion of AA and particularly of DHA in the first year of life. Thus endogenous synthesis of LCPUFA from precursors supplied by diet seems unable to compensate for low LCPUFA intakes. LCPUFA supplementation of PKU diets during the first year of life effectively enhances LCPUFA status to levels comparable to those of healthy breast-fed infants.

Tissue accretion and milk content of docosahexaenoic acid in female rats after supplementation with different docosahexaenoic acid sources

BACKGROUND

Docosahexaenoic acid (DHA) is highly concentrated in the mammalian nervous and visual system. The fatty acid, which is required by the fetus and the newborn, is supplied by the mother from their tissue reservoirs. It has been suggested that mother's supplementation with DHA during pregnancy and even before pregnancy. Different sources of DHA are available for supplementation such as: single-cell algae triglycerides (TG), egg's yolk phospholipids (PL), DHA ethyl esther (EE), and sn-2 DHA monoacylglyceride (MG). We evaluated comparatively the effectiveness of these different DHA sources to produce tissue DHA accretion and to increase milk DHA content.

METHODS

Female Wistar rats fed a diet which provided no DHA, were daily supplemented by 40 days before mating (BM) and during the pregnancy with either TG, PL, EE, or MG to an amount which provided 8 mg/kg b.w. of DHA. Samples of blood plasma, erythrocytes, hepatic and adipose tissue were obtained from rats at the BM condition and after the delivery (AD), and milk samples were also obtained from the gastric content of the pups nursed by the rats at day 3, 11 and 20 of suckling. Samples were processed to assess DHA and arachidonic acid (AA) content by gas-chromatography.

RESULTS

TG, PL, EE, and MG supplementation produced a similar intestinal absorption of DHA as estimated from the plasma DHA at the BM condition. However, PL and MG supplementation produced a higher accretion of DHA into erythrocytes, hepatic, and adipose tissue than TG and EE supplementation at the BM condition. AA content was not modified by the different supplementing oils. A reduction of the DHA content of plasma, erythrocytes, hepatic and adipose tissue at the AD condition was observed, and a reduction of AA for the hepatic and adipose tissues was also observed, suggesting the importance of these tissues as DHA and AA reservoirs. Milk secretion from PL and MG supplemented rats showed a higher DHA content than secretion from TG- and EE-supplemented rats.

CONCLUSIONS

We conclude that PL and MG supplementation provides higher tissue DHA accretion and higher milk DHA content than TG and EE supplementation. However, we were not able to visualize the comparative advantages derived from PL vs. MG supplementation.

Is docosahexaenoic acid, an n-3 long-chain polyunsaturated fatty acid, required for development of normal brain function? An overview of evidence from cognitive and behavioral tests in humans and animals

This review is part of a series intended for nonspecialists that will summarize evidence relevant to the question of whether causal relations exist between micronutrient deficiencies and brain function. Here, we focus on experiments that used cognitive or behavioral tests as outcome measures in experimental designs that were known to or were likely to result in altered brain concentrations of the n-3 fatty acid docosahexaenoic acid (DHA) during the perinatal period of "brain growth spurt." Experimental designs reviewed include observational breastfeeding studies and randomized controlled trials in humans and studies in rodents and nonhuman primates. This review is based on a large number of expert reviews and commentaries and on some 50 recent studies in humans and animals that have not yet been included in published reviews. Expert opinion regarding the strengths and weaknesses of the major experimental systems and uncertainties associated with interpreting results is summarized. On the basis of our reading of this literature, we conclude that evidence from several types of studies, particularly studies in animals, suggests that, within the context of specific experimental designs, changes in brain concentrations of DHA are positively associated with changes in cognitive or behavioral performance. Additional experimental information required to conclude that a causal association exists is discussed, as are uncertainties associated with applying results from specific experimental designs to the question of whether infant formula should be supplemented with DHA.

Effect of supplementation with docosahexaenoic acid ethyl ester and sn-2 docosahexaenyl monoacylglyceride on plasma and erythrocyte fatty acids in rats

BACKGROUND/AIMS

Docosahexaenoic acid (C22:6, DHA) is an omega-3 fatty acid required for the normal development of the mammalian nervous and visual system. DHA is provided by the mother during pregnancy and lactating period. Mother's DHA supplementation during pregnancy, and even before pregnancy, has been suggested. DHA can be provided by marine oils, egg's yolk phospholipids, single cell algae oils, the pure fatty acid, or by the ethyl ester derivative (DHA-EE). Another way to provide DHA can be by sn-2 docosahexaenyl monoacylglyceride (DHA-MG), obtained by the treatment of fish oil with stereospecific lipases. sn-2 Fatty acid monoacylglycerides can be more easily absorbed at the intestine than other fatty acid derivatives.

METHODS

Female rats fed with a synthetic, which provided essentially no DHA, received a 40-day supplementation of either DHA-EE or DHA-MG. Plasma and erythrocyte fatty acid composition were assessed by gas chromatography at day 0 and 40 of supplementation.

RESULTS

DHA-EE increased plasma and erythrocyte DHA by 15 and 11.9%, respectively, with no modification of arachidonic acid (AA) content. DHA-MG supplementation increased plasma and erythrocyte DHA by 24 and 23.8%, respectively, but reduced AA by 5.5 and 3%, respectively.

CONCLUSIONS

We conclude that in the rat, DHA-MG supplementation allows a higher plasma and erythrocyte DHA content than DHA-EE with minor modification of AA content.

Fatty acid absorption in preterms on formulas with and without long-chain polyunsaturated fatty acids and in terms on formulas without these added

BACKGROUND/OBJECTIVE

Long chain polyunsaturated fatty acids have beneficial effects in preterm neurophysiological development and are semi-essential. Their levels and variation in plasma and red cells in term and preterms are better known than their intestinal absorption. In this paper the absorption of supplemented arachidonic acid (AA) and docosahexaenoic acid (DHA) is evaluated in a preterm group.

DESIGN

Four newborn randomized groups were studied. Group T comprised 11 terms on regular formula. Preterms: group P (n=9) was on a classic preterm formula.

INTERVENTION

groups PA (n=9) and PB (n=13) were on the same formula but PB contained AA and DHA in similar proportion to breast milk. At 20 days a 3 day metabolic balance was taken for Ca, P(i), Mg, total fat and individual fatty acids (C8-C24, saturated unsaturated).

RESULTS

Calcium absorption was (mean+/-s.d.) 51+/-13% in terms. In preterms it was respectively 45+/-18, 38+/-11 and 37+/-21%. Total fat absorption was 92.0+/-8.0% in terms, and from 95.0+/-2.0 to 91.0+/-8.0% in preterms. Absorption of 8:0, 10:0 and 12:0 showed a very high and constant rate despite significant intake differences (715-33 mg/kg/day). Linoleic acid and alpha-linolenic acid were absorbed in the three groups at around 94% regardless of a greater LA intake in group P. Details of absorption (mg/kg/day) were: for AA, intake 17+/-7, fecal excretion 5+/-4, net retention 12+/-5 (75.0+/-18%); for DHA, intake 10+/-3, fecal excretion 3+/-2, net retention 6+/-4 (62.3+/-30%).

CONCLUSION

Intestinal absorption of fatty acids is high and is comparable in terms and preterms as regards the studied acids. Longer acids were less well absorbed. The supplemented amounts of AA and DHA were less well absorbed and probably not impairing calcium absorption.

SPONSORSHIP

University of Alicante, University of Miguel Hernández.

Influence of formulas with borage oil or borage oil plus fish oil on the arachidonic acid status in premature infants

Several studies have reported that feeding gamma-linolenic acid (GLA) has resulted in no increase in arachidonic acid (AA) in newborns. This result was ascribed to the eicosapentaenoic acid (EPA)-rich fish oil used in these formulas. Docosahexaenoic acid (DHA) sources with only minor amounts of EPA are now available, thus the addition of GLA to infant formulas might be considered an alternative to AA supplementation. Sixty-six premature infants were randomized to feeding one of four formulas [ST: no GLA, no long-chain polyunsaturated fatty acids; BO: 0.6% GLA (borage oil); BO + FOLOW: 0.6% GLA, 0.3% DHA, 0.06% EPA; BO + FOHIGH: 0.6% GLA, 0.3% DHA, 0.2% EPA] or human milk (HM, nonrandomized) for 4 wk. Anthropometric measures and blood samples were obtained at study entry and after 14 and 28 d. There were no significant differences between groups in anthropometric measures, tocopherol, and retinol status at any of the studied time points. The AA content of plasma phospholipids was similar between groups at study start and decreased significantly until day 28 in all formulafed groups, but not in the breast-fed infants [ST: 6.6 +/- 0.2%, BO: 6.9 +/- 0.3%, BO + FOLOW: 6.9 +/- 0.4%, BO + FOHIGH: 6.7 +/- 0.2%, HM: 8.6 +/- 0.5%, where values are reported as mean +/- standard error; all formulas significantly different (P< 0.05) from HM]. There was no significant influence of GLA or fish oil addition to the diet. GLA had only a very limited effect on AA status which was too small to obtain satisfactory concentrations (concentrations similar to breast-fed babies) under the circumstances tested. The effect of GLA on AA is independent of the EPA and DHA content in the diet within the dose ranges studied.

Novel pathway of metabolism of alpha-linolenic acid in the guinea pig

Docosahexaenoic acid (DHA) plays an important role in the nervous system. The capacity of the infant to use the essential fatty acid alpha-linolenic acid (ALA) as a substrate for neural DHA has been the subject of much debate recently. In this study, we explored the metabolic fate of an oral dose of 14C-labeled ALA in guinea pigs fed a defined diet for 3 wk from weaning. Of the 14C-labeled ALA administered, more than 46% was associated with the skin and fur lipids, mostly in the FFA fraction, and less than 0.1% was in brain lipids. About 39% of the label was not recovered in the body lipids and was assumed to be expired as CO2 or unabsorbed. The fur and skin were almost equally labeled; however, because of the very low mass of ALA in the fur, the specific activity of the fur was very high. These data identify a new route of metabolism of ALA in this species, presumably through the sebaceous glands onto fur. If this pathway exists in other species, including humans, it may account for the poor efficiency of conversion of ALA to DHA, because dietary ALA would not be available for anabolic pathways such as DHA synthesis. The relevance of these data to infants is that ALA may play an important hitherto unidentified role in the skin related to barrier function or epidermal integrity. This calls for more research into the importance of ALA as an essential fatty acid in its own right in human infants.