A randomized trial of visual attention of preterm infants fed docosahexaenoic acid until two months

This was a randomized, double-blind trial to determine if a nutrient-enriched (preterm) formula supplemented with 0.2% docosahexaenoic acid (DHA, 22∶6n−3) from a low eicosapentaenoic acid (0.06%) source of marine oil would enhance visual novelty preference and attention of preterm infants. Both the standard and experimental formulas contained 3% of total fatty acids as linolenic acid (18∶3n−3) and were fed from approximately three days of age to two months past term. After two months, both diet groups were fed a commercially-available term formula with linolenic acid as the only source of n−3 fatty acid. At 12 mo visual recognition memory (novelty preference) and visual attention (number and duration of discrete looks) were determined with the Fagan Test of Infant Intelligence. The DHA-supplemented group compared with the control group had more and shorter duration looks in comparisons of familiar and novel stimuli, confirming earlier evidence that DHA can increase information processing speed of preterm infants who otherwise are receiving good intakes of linolenic acid. Because supplementation was stopped at two months and the effects seen at 12 mon, this study demonstrates for the first time that a relatively short period of DHA supplementation can produce significant effects on later visual attention. Based on a presentation at the AOCS Annual Meeting & Expo in San Antonio, Texas, May 7–11, 1995.     

The effect of α-linolenic acid and linoleic acid on the growth and development of formula-fed infants: A systematic review and meta-analysis of randomized controlled trials

This systematic review and meta-analysis aimed to evaluate the effect of modifying 18-carbon PUFA [18-C PUFA: α-linolenic acid (ALA, 18∶3n−3) and linoleic acid (LA, 18∶2n−6)] in the diets of term and preterm infants on DHA (22∶6n−3) status, growth, and developmental outcomes. Only randomized controlled trials (RCT) involving formula-fed term and preterm infants, in which the 18-C PUFA composition of the formula was changed and growth or developmental outcomes were measured, were included. Differences were presented as control (standard formula) and treatment (18-C PUFA-supplemented formula). Primary analyses for term infants were 4 and 12 mon and for preterm infants 37–42 and 57 wk postmenstrual age. Five RCT involving term infants and three RCT involving preterm infants were included in the systematic review. Infants fed ALA-supplemented formula had significantly higher plasma and erythrocyte phospholipid DHA levels than control infants. There was no effect of ALA supplementation on the growth of preterm infants. In term infants, ALA supplementation was associated with increased weight and length at 12 mon, which was at least 4 mon after the end of dietary intervention. Developmental indices of term infants did not differ between groups. There was a transient improvement in the retinal function of preterm infants fed ALA-supplemented diets compared with controls. The findings suggest that ALA-supplemented diets improve the DHA status of infants. Further studies are needed to provide convincing evidence regarding the effects of ALA supplementation of formula on infant growth and development.     

Infant cerebellar gray and white matter fatty acids in relation to age and diet

There is little evidence as to the fatty acid composition of the cerebellum in infancy and it remains uncertain whether milk diet can influence its composition. We therefore examined cerebellar gray and white matter of infants less than 6 mon old who had died unexpectedly. The fatty acid content of 33 gray and 21 white matter specimens from infants born at term and 6 gray and 5 white matter specimens from pretern infants was assessed by gas chromatographic/mass spectrometric analysis. Infants were grouped according to whether they had received human or manufactured formula milk. Whereas cerebellar cortex docosahexaenoic acid (DHA, 22∶6n−3) concentrations were significantly lower (P<0.01) in the formula-fed than breast-fed infants, no differences existed between the term (n=10) and preterm (n=5) Scientific Milk Adaptation (SMA) formula-fed infants. Cerebellar white matter DHA concentrations were similarly lower (P<0.01) in the SMA formula-fed infants (n=8) than in an age-matched breast-fed group. Low concentrations of cerebellar white matter lignoceric (24∶0) and nervonic acid (24∶1n−9) in two 7-wk-old preterm infants appeared to correlated with postgestational rather than chronological age. Dietary long-chain polyunsaturated fatty acids particularly DHA, are probably essential for normal development of the infant cerebellum.     

Visual acuity and blood lipids in term infants fed human milk or formulae

This multicenter, parallel group study determined plasma phospholipid and red blood cell (RBC) phosphatidylcholine and phosphatidylethanolamine fatty acids, plasma cholesterol, apo A-1 and B, growth and visual acuity (using the acuity card procedure) in term infants fed from birth to 90 d of age with formula containing palm-olein, high oleic sunflower, coconut and soy oil (22.2% 16∶0, 36.2% 18∶1, 18% 18∶2n−6, 1.9% 18∶3n−3) (n=59) or coconut and soy oil (10.3% 16∶0 18∶6% 18∶1, 34.2% 18∶2n−6, 4.7% 18∶3n−3) (n=57) or breast-fed (n=56) with no formula supplementation. Different centers in North America were included to overcome potential bias due to differences in n−6 or n−3 fatty acids at birth or in breast-fed infants that might occur in a single-site study. Plasma and RBC phospholipid docosahexaenoic acid (DHA, 22∶6n−3) and arachidonic acid (AA, 20∶4n−6), cholesterol and apo B were significantly lower in the formula- than breast-fed infants. There were no differences in looking acuity or growth among the breast-fed and formula-fed infants. No significant relations were found between DHA and looking acuity, or AA and growth within or among any of the infant groups. This study provides no evidence to suggest the formula provided inadequate n−6 or n−3 fatty acids for growth and looking acuity for the first 3 mon after birth.     

n−3 Fatty acid requirements of the newborn

Whether docosahexaenoic acid (22∶6n−3) is an essential nutrient for term or preterm infants, or if not, the quantity of dietary linolenic acid (18∶3n−3) needed to support sufficient synthesis of 22∶6n−3 for assimilation in the central nervous system is unknown. Infants fed formulas have lower plasma and red blood cell (RBC) levels of 22∶6n−3 than breast fed infants. No relationship between the intake of 18∶3n−3 in formula (0.8 or 4.5% of fatty acids, 18∶2n−6/18∶3n−3 ratio 35∶1 or 7∶1, respectively) and the infant's RBC 22∶6n−3 was found. Premature infants (<33 wk gestation) also showed a decrease in RBC 22∶6n−3 during feeding with formula containing 18∶3n−3 as the only n−3 fatty acid. However, a marked decrease in plasma and RBC 22∶6n−3 occurred between premature birth and the start of full enteral feeding at 1–2 wk of age. This was not reversed by breast milk or formula feeding. Piglets, which are appropriate for studies of infant lipid metabolism, had decreased brain synaptic plasma membrane, retina and liver 22∶6n−3 and increased 22∶5n−6 when fed formula with 0.8% fatty acids (0.3% of kcal) as 18∶3n−3. Formula with 4.0% fatty acids (1.7% of kcal) as 18∶3n−3 resulted in similar accretion of 22∶6n−3 in the organs compared to milk fed animals. The studies suggest the dietary requirement for 18∶3n−3 in term animals in energy balance exceeds 0.3% diet kcal. Studies in the premature infants suggest 18∶3n−3 may be oxidized rather than desaturated to 22∶6n−3 if energy requirements are not met, and that due to early lipid restriction and later rapid growth, premature infants may have higher dietary n−3 requirements than term infants. Based on a paper presented at the Symposium on Milk Lipids held at the AOCS Annual Meeting, Baltimore, MD, April 1990.     

Blood lipid docosahexaenoic and arachidonic acid in term gestation infants fed formulas with high docosahexaenoic acid,low eicosapentaenoic acid fish oil

The effect of fish oil high in docosahexaenoic acid (22∶6n−3) and low in eicosapentaenoic acid (20∶5n−3) in formula on blood lipids and growth of full-term infants was studied. Infants were fed formula with about 15% oleic acid (18∶1), 32% linoleic acid (18∶2n−6), 4.9% linolenic acid (18∶3n−3) and 0, 0.10 or 0.22% 22∶6n−3, or 35% 18∶1, 20% 18∶2n−6, 2.1% 18∶3n−3 and 0, 0.11 or 0.24% 22∶6n−3 from 3 d to 16 wk of age (n=16, 18, 17, 21, 17, 16, respectively). The formulae had <0.1% 20∶5n−3 and no arachidonic acid (20∶4n−6). Breast-fed infants (n=26) were also studied. Plasma phospholipid and red blood cell (RBC) phosphatidylcholine (PC) and phosphatidylethanolamine (PE) fatty acids were determined at 3 d and 4, 8, and 16 wk of age. These longitudinal analyses showed differences in blood lipid 22∶6n−3 between breast-fed and formula-fed infants depending on the feeding duration. At 16 wk, infants fed formula with 0.10, 0.11% 22∶6n−3, or 0.22% 22∶6n−3 had similar 22∶6n−3 levels in the plasma phospholipid and RBC PC and PE compared with breast-fed infants and higher 22∶6n−3 than infants fed formula without 22∶6n−3. Formula with 0.24% 22∶6n−3, however, resulted in higher plasma phospholipid 22∶6n−3 than in breast-fed infants at 16, but not 4 or 8 wk of age. Plasma and RBC phospholipid 20∶4n−6 was lower in formula-fed than breast-fed infants, but no differences in growth were found. Higher blood lipid C₂₀ and C₂₂ n−6 and n−3 fatty acids in infants fed formula with 20% 18∶2n−6 and 2.4% 18∶3n−3 compared with 32% 18∶2n−6 and 4.9% 18∶3n−3 show the increase in blood lipid 22∶6n−3 in response to dietary 22∶6n−3 depending on other fatty acids in the formula.     

Fatty acid profile of buccal cheek cell phospholipids as an index for dietary intake of docosahexaenoic acid in preterm infants

Cheek cells (buccal epithelia) were utilized as a noninvasive index of fatty acid status in a study of the effects of n−3 long chain polyunsaturated fatty acid supplementation on visual function in preterm infants. The fatty acid profile of cheek cell phospholipids was directly correlated with the dietary docosahexenoic acid (DHA) intake of infants receiving: (i) primarily human milk; (ii) n−3 fatty acid-deficient, corn oil-based, commercial formula (CO); (iii) α-linolenic acid-enriched, soy oilbased, commercial formula; or (iv) experimental formula enriched with soy and marine oils providing a DHA level equivalent to that in human milk. In a subset of infants with complete cheek cell fatty acid profiles and visual function assessments, preterm infants at both 36 wk (n=63) and 57 wk (n=45) postconceptional age had significantly (P<0.0005) reduced cheek cell phospholipid DHA levels in the n−3-dificient, CO-fed group compared to the other diet groups. The DHA content in cheek cell phospholipids was highly correlated (P<0.0005) with that of both red blood cell lipids and plasma phospholipids at the 36-and 57-wk time points. The DHA content in cheek cell lipids of infants at 36 wk was significantly correlated with electroretinographic responses (r=−0.29; P<0.03) and visual acuity (r=−0.31; P<0.02) as measured by visual-evoked potentials (VEP). Cheek cell DHA was highly correlated (r=−0.57; P<0.0005) with VEP acuity at the 57-wk time point. These results suggest that the fatty acid profile of cheek cells is a valid index of essential fatty acid status, can be monitored frequently, and is associated with functional parameters in infants.     

Maternal fish oil supplementation in lactation: Effect on visual acuity and n−3 fatty acid content of infant erythrocytes

Studies on formula-fed infants indicate a beneficial effect of dietary DHA on visual acuity. Cross-sectional studies have shown an association between breast-milk DHA levels and visual acuity in breast-fed infants. The objective in this study was to evaluate the biochemical and functional effects of fish oil (FO) supplements in lactating mothers. In this double-blinded randomized trial, Danish mothers with habitual fish intake below the 50th percentile of the Danish National Birth Cohort were randomized to microencapsulated FO [1.3 g/d long-chain n−3 FA (n−3 LCPUFA)] or olive oil (OO). The intervention started within a week after delivery and lasted 4 mon. Mothers with habitual high fish intake and their infants were included as a reference group. Ninety-seven infants completed the trial (44 OO-group, 53 FO-group) and 47 reference infants were followed up. The primary outcome measures were: DHA content of milk samples (0, 2, and 4 mon postnatal) and of infant red blood cell (RBC) membranes (4 mon postnatal), and infant visual acuity (measured by swept visual evoked potential at 2 and 4 mon of age). FO supplementation gave rise to a threefold increase in the DHA content of the 4-mon milk samples (P<0.001). DHA in infant RBC reflected milk contents (r=0.564, P<0.001) and was increased by almost 50% (P<0.001). Infant visual acuity was not significantly different in the randomized groups but was positively associated at 4 mon with infant RBC-DHA (P=0.004, multiple regression). We concluded that maternal FO supplementation during lactation did not enhance visual acuity of the infants who completed the intervention. However, the results showed that infants with higher RBC levels of n−3 LCPUFA had a better visual acuity at 4 mon of age, suggesting that n−3 LCPUFA may influence visual maturation.     

Effect of dietary docosahexaenoic acid on desaturation and uptake in vivo of isotope-labeled oleic, linoleic, and linolenic acids by male subjects

The effect of dietary docosahexaenoic acid (22∶6n−3, DHA) on the metabolism of oleic, linoleic, and linolenic acids was investigated in male subjects (n=6) confined to a metabolic unit and fed diets containing 6.5 or <0.1 g/d of DHA for 90 d. At the end of the diet period, the subjects were fed a mixture of deuterated triglycerides containing 18∶1n−9[d6], 18∶2n−6[d2], and 18∶3n−3[d4]. Blood samples were drawn at 0, 2, 4, 6, 8, 12, 24, 48, and 72 h. Methyl esters of plasma total lipids, triglycerides, phospholipids, and cholesterol esters were analyzed by gas chromatography-mass spectrometry. Chylomicron triglyceride results show that the deuterated fatty acids were equally well absorbed and diet did not influence absorption. Compared to the low-DHA diet (LO-DHA), clearance of the labeled fatty acids from chylomicron triglycerides was modestly higher for subjects fed the high DHA diet (HI-DHA). DHA supplementation significantly reduced the concentrations of most n-6[d2] and n-3[d4] long-chain fatty acid (LCFA) metabolites in plasma lipids. Accumulation of 20∶5n−3[d4] and 22∶6n−3[d4] was depressed by 76 and 88%, respectively. Accumulations of 20∶3n−6[d2] and 20∶4n−6[d2] were both decreased by 72%. No effect of diet was observed on acyltransferase selectivity or on uptake and clearance of 18∶1n−9[d6], 18∶2n−6[d2], and 18∶3n−3[d4]. The results indicate that accumulation of n−3 LCFA metabolites synthesized from 18∶3n−3 in typical U.S. diets would be reduced from about 120 to 30 mg/d by supplementation with 6.5 g/d of DHA. Accumulation of n−6 LCFA metabolites synthesized from 18∶2n−6 in U.S. diets is estimated to be reduced from about 800 to 180 mg/d. This decrease is two to three times the amount of n−6 LCFA in a typical U.S. diet. These results support the hypothesis that health benefits associated with DHA supplementation are the combined result of reduced accretion of n−6 LCFA metabolites and an increase in n−3 LCFA levels in tissue lipids.     

Omega-3 fatty acid and cholesterol content of newly hatched chicks from α-linolenic acid enriched eggs

Egg yolk was enriched with α-linolenic acid (18∶3n−3) by feeding laying hens diets containing flax, canola or soybean seeds. Fertilized eggs were incubated and the fatty acid composition of whole body, liver, plasma, brain and the cholesterol content of plasma and liver tissue of the hatched chicks were studied. Eggs enriched with 18∶2n−6 fatty acids by feeding hens diets containing sunflower seeds were used as the controls. Feeding flax enriched (P<0.05) egg yolk and the developing progeny with 18∶3n−3, 20∶5n−3, 22∶5n−3 and 22∶6n−3. Feeding sunflower seeds resulted in an increase (P<0.05) of 18∶2n−6, 20∶4n−6, 22∶4n−6 and 22∶5n−6. The predominant polyunsaturated fatty acid of the brain was docosahexaenoic acid (22∶6n−3) which was higher (P<0.05) in the flax and canola fed group. The cholesterol content of the liver tissue was lower (P<0.05) in chicks hatched from hens fed flax seeds. This study indicates that 18∶3n−3 and 18∶2n−6 in the maternal diet are potent modulators of long-chain polyunsaturated n−3 or n−6 fatty acid and of cholesterol content in the developing progeny.     

Type 1 diabetes compromises plasma arachidonic and docosahexaenoic acids in newborn babies

The activity of Δ6- and Δ5-desaturase, enzymes required for the synthesis of AA and DHA, are impaired in human and experimental diabetes. We have investigated whether neonates of type 1 diabetic women have compromised plasma AA and DHA at birth. Cord blood was obtained from healthy babies born to mothers with (n=31) and without (n=59) type 1 diabetes. FA composition of plasma choline phosphoglycerides (CPG), TG, and cholesterol esters (CE) was assayed. The neonates of the diabetics had lower levels of AA (20∶4n−6, P<0.0001), adrenic acid (22∶4n−6, P<0.01), Σn−6 metabolites (P<0.0001), docosapentaenoic acid (22∶5n−3, P<0.0001), DHA (22∶6n−3, P<0.0001), Σn−3 (P<0.0001), and Σn−3 metabolites (P<0.0001) in CPG compared with the corresponding babies of the nondiabetic mothers. Similarly, they had lower levels of AA (P<0.05), Σn−6 metabolites (P<0.05), DHA (P<0.0001), and Σn−3 metabolites (P<0.01) in plasma CE. There was also a nonsignificant reduction of AA and DHA in TG in the babies of the diabetic group. The current investigation indicates that healthy neonates born to mothers with type 1 diabetes have highly compromised levels of AA and DHA. These nutrients are of critical importance for neurovisual and vascular system development. In poorly controlled maternal diabetes, it is conceivable that the relative “insufficiency” of AA and DHA may exacerbate speech and reading impairments, behavioral disorders, suboptimal performance on developmental tests, and lower IQ, which have been reported in some children born to mothers with type 1 diabetes mellitus. Further studies are needed to understand the underlying mechanism for this biochemical abnormality and its implications for fetal and infant development.     

Effect of DHA supplementation on DHA status and sperm motility in asthenozoospermic males

The effects of supplementation with docosahexaenoic acid (DHA) on DHA levels in serum, seminal plasma, and sperm of asthenozoospermic men as well as on sperm motility were examined in a randomized, double-blind, placebo-controlled manner. Asthenozoospermic men (n=28; ≤50% motility) were supplemented with 0, 400, or 800 mg DHA/d for 3 mon. Sperm motility and the fatty acid composition of serum, seminal plasma, and sperm phospholipid were determined before and after supplementation. In serum, DHA supplementation resulted in decreases in 22∶4n−6 (−30% in the 800-mg DHA group only) and total n−6 (−6 and −12% in the 400- and 800-mg DHA groups, respectively) fatty acids. Increases were noted in DHA (71 and 131% in the 400- and 800-mg DHA groups, respectively), total n−3 fatty acids (42 and 67% in the 400- and 800-mg DHA groups, respectively), and the n−3/n−6 ratio (50 and 93% in the 400- and 800-mg DHA groups, respectively). In seminal plasma, DHA supplementation resulted in a decrease in 22∶4n−6 (−31% in the 800-mg DHA group only) and an increase in the ratio of n−3 to n−6 (35 and 33% in the 400- and 800-mg DHA groups, respectively). There were insignificant increases in DHA and total n−3 fatty acids. In sperm, decreases were noted in 22∶4n−6 (−37 and −31% in the 400-and 800-mg DHA groups, respectively). There were no other changes. There was no effect of DHA supplementation on sperm motility. The results show that dietary DHA supplementation results in increased serum- and possibly seminal plasma—phospholipid DHA levels, without affecting the incorporation of DHA into the spermatozoa phospholipid in asthenozoospermic men. This inability of DHA to be incorporated into sperm phospholipid is most likely responsible for the observed lack of effect of DHA supplementation on sperm motility.     

Mice raised on milk transgenically enriched with n−3 PUFA have increased brain docosahexaenoic acid

The brain contains high levels of the long-chain n−3 FA DHA(22∶6n−3), mainly in the gray matter and synaptosomes. Adequate intake of DHA is crucial for optimal nervous system function, particularly in infants. Supplementation of infant formulas with DHA at levels similar to human breast milk is recommended for biochemical and functional benefits to neonates. We generated transgenic mice that produce elevated levels of n−3 PUFA in their milk by expressing the Caenorhabditis elegans n−3 FA desaturase under the control of a lactation-induced goat beta-casein promoter. To examine the postnatal effects of consuming the n−3-enriched milk, we compared the growth and brain and plasma FA composition of mouse pups raised on milk from transgenic dams with those observed for pups raised on milk from nontransgenic dams. A significant decrease in arachidonic acid (ARA, 20∶4n−6) and concomitant increases in n−3 PUFA were observed in the phospholipid fraction of transgenic mouse milk. The n−6∶n−3 FA ratios were 4.7 and 34.5 for the transgenic and control milk phospholipid fractions, respectively. DHA and DPA (22∶5n−6) comprised 15.1% and 2.8% of brain FA from weanling mice nursed on transgenic dams, as compared with 6.9% and 9.2% for weanling mice nursed on control dams, respectively. This transgenic mouse model offers a unique approach to disassociate the effects and fetal programming resulting from a high n−6∶n−3 FA ratio gestational environment from the postnatal nutritional effects of providing milk with differing n−6∶n−3 FA ratios.     

Hypothyroidism and thyroxin substitution affect the n−3 fatty acid composition of rat liver mitochondria

The effects of hypothyroidism and of daily treatment for up to 21 days with thyroxin (T4, 0.5 μg/100 g body weight) on the fatty acid composition of total lipid, phosphatidylethanolamine, and phosphatidylcholine of rat liver mitochondria were studied. The fatty acid compositions of hypothyroid and euthyroid (control) rats of similar age were compared. The n−6 and n−3 polyunsaturated fatty acids (PUFA) were affected differently by the hypothyroid state. The levels of linoleic (18∶2n−6), γ-linolenic (18∶3n−6) and dihomo-γ-linolenic acids (20∶3n−6) were higher in hypothyroid rats than in controls, while the level of arachidonic acid (20∶4n−6) was lower, which suggests an impairment of the elongase and desaturase activities. The n−3 polyunsaturated fatty acids, eicosapentaenoic (EPA, 20∶5n−3) and docosapentaenoic (22∶5n−3) acids, were higher in hypothyroid rats, whereas the linolenic acid (18∶3n−3) content remained constant. The level of docosahexaenoic acid (DHA, 22∶6n−3) was dramatically decreased in hypothyroid rats, while the levels of C₂₂ n−6 fatty acids were unchanged. The differences were probably due to the competition between n−3 and n−6 PUFA for desaturases, elongases and acyltransferases. When hypothyroid rats were treated with thyroxin, the changes induced by hypothyroidism in the proportions of n−6 fatty acids were rapidly reversed, while the changes in the n−3 fatty acids were only partially reversed. After 21 days of thyroxin treatments, the DHA content was only half as high in hypothyroid rats than in euthyroid rats. These results suggest that the conversion of 18∶2n−6 to 20∶4n−6 is suppressed in the hypothyroid state which favors the transformation of 18∶3n−3 to 20∶5n−3. The marked decrease in DHA content indicates an impairment of the enzymes involved in the DHA metabolism, possibly the n−3 Δ4 desaturase or the acyltransferases. The increased levels of EPA and 22∶5n−3 is consistent with the inhibition of the n−3 pathway at the Δ4 desaturase step. Observed modifications in the fatty acid composition may significantly alter eicosanoid synthesis and membrane functions in hypothyroidism.     

Fish oil supplementation of lactating mothers affects cytokine production in 2 1/2-year-old children

n−3 PUFA influence immune functioning and may affect the cytokine phenotype during development. To examine whether maternal fish oil supplementation during lactation could modify later immune responses in children, 122 lactating Danish mothers with a fish intake below the population median were randomized to groups supplemented for the first 4 mon of lactation with 4.5 g/d of fish oil (equivalent to 1.5 g/d of n−3 long-chain PUFA) or olive oil. Fifty-three mothers with a fish intake in the highest quartile of the population were also included. The FA composition of erythrocyte membranes was measured at 4 mon and at 2 1/2 yr. Plasma immunoglobulin E (IgE) levels and cytokine production in lipopolysaccharide-stimulated whole-blood cultures were determined at 2 1/2 yr. Erythrocyte n−3 PUFA at 4 mon were higher in infants from the fish oil group compared with the olive oil group (P<0.001) but were no longer different at 2 1/2 yr. The median production of lipopolysaccharide-induced interferon γ(IFN-γ) in the fish oil group was fourfold higher than that in the olive oil group (P=0.034), whereas interleukin-10 (IL-10) production was similar. The IFN-γ/IL-10 ratio was twofold higher in the fish oil group (P=0.019) and was positively correlated with 20∶5n−3/20∶4n−6 in erythrocytes at 4 mon (P=0.050). The percentages of atopic children and plasma IgE were not different in the two groups, but the study was not designed to look at atopy. Cytokine responses and erythrocyte FA composition in children of mothers with a high fish intake were intermediate in comparison with those in the randomized groups. Fish oil supplementation during lactation resulted in increased in vitro IFN-γ production in the children 2 yr after the supplementation was given, which may reflect a faster maturation of the immune system.     

Effects of dietary saturated fat on erucic acid induced myocardial lipidosis in rats

Male Sprague-Dawley rats were fed for one week diets containing 20% by weight fat/oil mixtures with different levels of erucic acid (22∶1n−9) (∼2.5 or 9%) and total saturated fatty acids (∼8 or 35%). Corn oil and high erucic acid rapeseed (HEAR) oil were fed as controls. The same hearts were evaluated histologically using oil red O staining and chemically for cardiac triacylglycerol (TAG) and 22∶1n−9 content in cardiac TAG to compare the three methods for assessing lipid accumulation in rat hearts. Rats fed corn oil showed trace myocardial lipidosis by staining, and a cardiac TAG content of 3.6 mg/g wet weight in the absence of dietary 22∶1n−9. An increase in dietary 22∶1n−9 resulted in significantly increased myocardial lipidosis as assessed histologically and by an accumulation of 22∶1n−9 in heart lipids; there was no increase in cardiac TAG except when HEAR oil was fed. An increase in saturated fatty acids showed no changes in myocardial lipid content assessed histologically, the content of cardiac TAG or the 22∶1n−9 content of TAG at either 2.5 or 9% dietary 22∶1n−9. The histological staining method was more significantly correlated to 22∶1n−9 in cardiac TAG (r=0.49;P<0.001) than to total cardiac TAG (r=0.40;P<0.05). The 22∶1n−9 content was highest in cardiac TAG and free fatty acids. Among the cardiac phospholipids, the highest incorporation was observed into phosphatidylserine, followed by sphingomyelin. With the addition of saturated fat, the fatty acid composition showed decreased accumulation of 22∶1n−9 and increased levels of arachidonic and docosahexaenoic acids in most cardiac phospholipids, despite decreased dietary concentrations of their precursor fatty acids, linoleic and linolenic acids.     

Maternal dietary FA modulate the long-chain n−3 PUFA status of chick cardiac tissue

The effect that egg yolk or maternal n−3 FA have on the cardiac tissue long-chain n−3 FA status of chicks during growth was investigated. Fggs with low, medium, and high levels of n−3 PUFA were obtained by feeding breeder hens a wheat/soybean meal-based diet containing 5% sunflower oil (Low n−3), 2.5% sunflower oil plus 2.5% fish oil (Medium n−3), or 5% fish oil (High n−3). The chicks hatched from Low, Medium, and High n−3 eggs were fed a diet containing 18∶3n−3, but devoid of long-chain n−3 FA. The FA composition of cardiac tissue was determined on days 0, 14, 28, and 42. At day 0, the cardiac FA reflected maternal diet. With time, the level of all the long-chain n−3 FA decreased compared with day 0, and this was true especially by day 14. These data show that dietary 18∶3n−3 fed to the chicks did not sustain high levels of EPA and DHA in cardiac tissue, despite the high content of long-chain n−3 FA in the maternal diet. At days 0 and 14, the chicks hatched from High and Medium n−3 eggs had higher 20∶5n−3, 22∶5n−3, and 22∶6n−3 contents with a concomitant reduction in 20∶4n−6 in the cardiac tissue compared with the Low n−3 egg group. Cardiac tissue of birds hatched from Medium n−3 eggs retained higher levels of 20∶5n−3 up to day 42 of growth when compared with other treatments (P<0.05). None of the treatments was effective in maintaining DHA levels after day 14 of growth.     

Supplementation and delivery of n−3 fatty acids through spray-dried milk reduce serum and liver lipids in rats

Indian diets comprising staples such as cereals, millets, and pulses provide 4.8 energy % from linoleic acid (18∶2n−6) but fail to deliver adequate amounts of n−3 FA. Consumption of long-chain n−3 PUFA such as EPA (20∶5n−3) and DHA (22∶6n−3) is restricted to those who consume fish. The majority of the Indian population, however, are vegetarians needing additional dietary sources of n−3 PUFA. The present work was designed to use n−3 FA-enriched spray-dired milk powder to provide n−3 FA. Whole milk was supplemented with linseed oil to provide α-linolenic acid (LNA, 18∶3n−3), with fish oil to provide EPA and DHA, or with groundnut oil (GNO), which is devoid of n−3 PUFA, and then spray-dired. Male Wistar rats were fed the spray-dired milk formulations for 60 d. The rats given formulations containing n−3 FA showed significant increases (P<0.001) in the levels of LNA or EPA/DHA in the serum and in tissue as compared with those fed the GNO control formulation. Rats fed formulations containing n−3 FA had 30–35% lower levels of serum total cholesterol and 25–30% lower levels of serum TAG than control animals. Total cholesterol and TAG in the livers of rats fed the formulations containing n−3 FA were lower by 18–30% and 11–18%, respectively, compared with control animals. This study showed that spray-dried milk formulations supplemented with n−3 FA are an effective means of improving dietary n−3 FA intake, which may decrease the risk factors associated with cardiovascular disease.     

Dietary phospholipid alters biliary lipid composition in formula-fed piglets

Plasma cholesterol, arachidonic acid (AA, 20∶4n−6), and docosahexaenoic acid (DHA, 22∶6n−3) are higher in breast-fed infants than in infants fed formula without cholesterol, AA, or DHA. This study investigated differences in plasma, hepatic, and bile lipids and phospholipid fatty acids, and expression of hepatic proteins involved in sterol metabolism that result from feeding formula with cholesterol with egg phospholipid to provide AA and DHA. For this study, three groups of piglets were evaluated: piglets fed formula with 0.65 mmol/L cholesterol, the same formula with 0.8% AA and 0.2% DHA from egg phospholipid, and piglets fed sow milk. Piglets fed the formula with phospholipid AA and DHA had higher plasma high density lipoprotein, but not apoprotein (apo) B cholesterol or triglyceride; higher bile acid and phospholipid concentrations in bile; and higher liver and bile phospholipid AA and DHA than piglets fed formula without AA and DHA (P<0.05). Hydroxy methylglutaryl (HMG)-CoA reductase and 7-α-hydroxylase, the rate-limiting enzymes of cholesterol and bile acid synthesis, respectively, and low density lipoprotein receptor mRNA levels were not different between piglets fed formula without and with phospholipid AA and DHA, but HMG-CoA reductase and 7α-hydroxylase mRNA were higher, and plasma apo B containing lipoprotein cholesterol was lower in all piglets fed formula than in piglets fed milk. These studies show that supplementing formula with AA and DHA from egg phospholipid alters bile metabolism by increasing the bile AA and DHA, and bile acid and phospholipid.     

Dietary docosahexaenoic acid affects stearic acid desaturation in spontaneously hypertensive rats

Docosahexaenoic acid (DHA, 22∶6n−3) is an n−3 polyunsaturated fatty acid which attenuates the development of hypertension in spontaneously hypertensive rats (SHR). The effects of DHA on delta-9-desaturase activity in hepatic microsomes and fatty acid composition were examined in young SHR. Two groups of SHR were fed either a DHA-enriched diet or a control diet for 6 wk. Desaturase activity and fatty acid composition were determined in hepatic microsomes following the dietary treatments. Delta-9-desaturase activity was decreased by 53% in DHA-fed SHR and was accompanied by an increase in 16∶0 and a reduction in 16∶1n−7 content in hepatic microsomes. The DHA diet also increased the levels of eicosapentaenoic acid (20∶5n−3) and DHA. The n−6 fatty acid content was also affected in DHA-fed SHR as reflected by a decrease in gamma-linolenic acid (18∶3n−6), arachidonic acid (20∶5n−6), adrenic acid (22∶4n−6), and docosapentaenoic acid (22∶5n−6). A higher proportion of dihomo-gamma-linolenic acid (20∶3n−6) and a lower proportion of 20∶4n−6 is indicative of impaired delta-5-desaturase activity. The alterations in fatty acid composition and metabolism may contribute to the antihypertensive effect of DHA previously reported.