Blood fatty acid composition of pregnant and nonpregnant Korean women: Red cells may act as a reservoir of arachidonic acid and docosahexaenoic acid for utilization by the developing fetus

Relative fatty acid composition of plasma and red blood cell (RBC) choline phosphoglycerides (CPG), and RBC ethanolamine phosphoglycerides (EPG) of pregnant (n=40) and nonpregnant, nonlactating (n=40), healthy Korean women was compared. The two groups were of the same ethnic origin and comparable in age and parity. Levels of arachidonic (AA) and docosahexaenoic (DHA) acids were lower (P<0.05) and palmitic and oleic acids higher (P<0.0001) in plasma CPG of the pregnant women. Similarly, the RBC CPG and EPG of the pregnant women had lower AA and DHA (P<0.05) and higher palmitic and oleic acids (P<0.01). The reduction in DHA and total n−3 fatty acids in plasma CPG of the pregnant women was paralleled by an increase in docosatetraenoic (DTA) and docosapentaenoic (DPA) acids of the n−6 series and in DPA/DTA ratio. In the RBC phospholipids (CPG and EPG) of the pregnant women, DTA and DPA acids of the n−6 series and DPA/DTA ratio did not increase with the decrease of the n−3 metabolites (eicosapentaenoic acid, DPA, and DHA) and total n−3. Since pregnancy was the main identifiable variable between the two groups, the lower levels of AA and DHA in RBC CPG and EPG of the pregnant women suggest that the mothers were mobilizing membrane AA and DHA to meet the high fetal requirement for these nutrients. It may also suggest that RBC play a role as a potential store of AA and DHA and as a vehicle for the transport of these fatty acids from maternal circulation to the placenta to be utilized by the developing fetus.     

Gestational diabetes mellitus enhances arachidonic and docosahexaenoic acids in placental phospholipids

In previous studies, we reported that neonates of women with gestational diabetes mellitus (GDM) have reduced blood levels of arachidonic acid (AA) and docosahexaenoic acid (DHA) that were unrelated to maternal status. Since both AA and DHA are selectively transferred from maternal to fetal circulation by the placenta, we have investigated whether the FA composition of the placenta is altered by GDM. Thirty-six women, 11 with and 25 without GDM, were recruited from Newham General Hospital, London. The women with GDM had higher levels of di-homo-γ-linolenic (P<0.05), docosate-traenoic (n-6 DTA; P<0.0001), docosapentaenoic n-6 (P<0.005), total n-6 (P<0.005), docosapentaenoic (n-3 DPA; P<0.005), and total n-3 (P<0.01) FA, as well as higher levels of AA (P<0.05) and DHA (P<0.01), in placental choline phosphoglycerides (CPG) compared with the healthy women who served as controls. Similarly, the women with GDM had elevated n-6 DTA (P<0.005), AA, total n-6 metabolites (P<0.05), DHA, total n-3 metabolites, and total n-3 FA (P<0.005) in ethanolamine phosphoglycerides (EPG). In contrast to CPG and EPG, the placental TG of the women with GDM had higher linoleic acid (P<0.05) and lower AA, n-6 metabolites, and n-3 DPA (P<0.01). The placenta is devoid of desaturase activity, and it is thought to be reliant on maternal circulation for both AA and DHA. Hence, the enhanced levels of the two FA in the placenta of the GDM group suggests that these FA are taken up from the maternal circulation and retained after esterification into phosphoglycerides instead of being transferred to the fetus. Further study is needed to elucidate the mechanism involved and the effect of the phenomenon on postnatal growth and development of the offspring.     

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

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

The effect of dietary arachidonic acid on plasma lipoprotein distributions, apoproteins, blood lipid levels, and tissue fatty acid composition in humans

Normal healthy male volunteers (n=10) were fed diets (high-AA) containing 1.7 g/d of arachidonic acid (AA) for 50 d. The control (low-AA) diet contained 210 mg/d of AA. Dietary AA had no statistically significant effect on the blood cholesterol levels, lipoprotein distribution, or apoprotein levels. Adipose tissue fatty acid composition was not influenced by AA feeding. The plasma total fatty acid composition was markedly enriched in AA after 50 d (P<0.005). The fatty acid composition of plasma lipid fractions, cholesterol esters, triglycerides, free fatty acids, and phospholipid (PL) showed marked differences in the degree of enrichment in AA. The PL plasma fraction from the subjects consuming the low-AA diet contained 10.3% AA while the subjects who consumed the high-AA diet had plasma PL fractions containing 19.0% AA. The level of 22:4n-6 also was different (0.67 to 1.06%) in the plasma PL fraction after 50 d of AA feeding. After consuming the high-AA diet, the total red blood cell fatty acid composition was significantly enriched in AA which mainly replaced linoleic acid. These results indicate that dietary AA is incorporated into tissue lipids, but selectively into different tissues and lipid classes. Perhaps more importantly, the results demonstrate that dietary AA does not alter blood lipids or lipoprotein levels or have obvious adverse health effects at this level and duration of feeding.     

Incorporation of n-3 fatty acids into plasma lipid fractions, and erythrocyte membranes and platelets during dietary supplementation with fish, fish oil, and docosahexaenoic acid-rich oil among healthy young men

The effects of n-3 fatty acid supplementation in the form of fresh fish, fish oil, and docosahexaenoic acid (DHA) oil on the fatty acid composition of plasma lipid fractions, and platelets and erythrocyte membranes of young healthy male students were examined. Altogether 59 subjects (aged 19–32 yr, body mass index 16.8–31.3 kg/m²) were randomized into the following diet groups: (i) control group; (ii) fish diet group eating fish meals five times per week [0.38±0.04 g eicosapentaenoic acid (EPA) and 0.67±0.09 g DHA per day]; (iii) DHA oil group taking algae-derived DHA oil capsules (1.68 g/d DHA oil group taking algae-derived DHA oil capsules (1.68 g/d DHA in triglyceride form); and (iv) fish oil group (1.33 g EPA and 0.95 g DHA/d as free fatty acids) for 14 wk. The fatty acid composition of plasma lipids, platelets, and erythrocyte membranes was analyzed by gas chromatography. The subjects kept 4-d food records four times during the study to estimate the intake of nutrients. In the fish diet, in DHA oil, and in fish oil groups, the amounts of n-3 fatty acids increased and those of n-6 fatty acids decreased significantly in plasma lipid fractions and in platelets and erythrocyte membranes. A positive relationship was shown between the total n-3 polyunsaturated fatty acids (PUFA) and EPA and DHA intake and the increase in total n-3 PUFA and EPA and DHA in all lipid fractions analyzed. DHA was preferentially incorporated into phospholipid (PL) and triglyceride (TG) and there was very little uptake in cholesterol ester (CE), while EPA was preferentially incorporated into PL and CE. The proportion of EPA in plasma lipids and platelets and erythrocyte membranes increased also by DHA supplementation, and the proportion of linoleic acid increased in platelets and erythrocyte membranes in the DHA oil group as well. These results suggest retroconversion of DHA to EPA and that DHA also interferes with linoleic acid metabolism.     

Platelet and aorta arachidonic and eicosapentaenoic acid levels andin vitro eicosanoid production in rats fed high-fat diets

There is a significant interest in the interrelationship between long-chain n-3, and n-6 fatty acids due to their ability to modulate eicosanoid production. In general, the intake of arachidonic acid (AA) results in enhanced eicosanoid production, whereas n-3 polyunsaturated fatty acids (PUFA) decrease the production of eicosanoids from AA. The purpose of this study was to investigate whether the effects of dietary AA on eicosanoid production in the rat were correlated with the AA and EPA levels in platelets and aorta (eicosanoid-producing tissues). Four groups of male Sprague-Dawley rats were fed a highfat diet enriched with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (approximately 100 mg/day of EPA+DHA) for 24 d. During the last 10 d, the four groups were orally supplemented with 0,30,60, and 90 mg/day of ethyl arachidonate. A further group of rats was fed a control diet (without longchain n-3 PUFA) for 24 d.In vitro aorta prostacyclin (PGI₂) production, serum thromboxane A₂ (TxA₂) production and plasma, and platelet and aorta phospholipid (PL) fatty acids were measured. Enriching the diet with n-3 PUFA resulted in significant reductions in tissue AA levels and an increase in the n-3 PUFA, particularly EPA. On this diet, the AA to EPA ratio was 1:1 in platelet PL, and it was 2:1 in the aorta PL. There were significant decreases in thein vitro PGI₂ and TxA₂ production compared with the control animals. The inclusion of AA in the diet resulted in marked increases in AA levels in the platelet and aorta PL with corresponding decreases in EPA. The lowest dose of AA (30 mg/rat) reversed the effects of 100 mg/day of n-3 PUFA on AA levels in platelet and aortic PL and onin vitro aorta PGI₂ and serum TxA₂ production. The dietary AA caused a differential (twofold) increase in TxA₂ relative to PGI₂ for all three levels of AA supplementation. There were greater changes in the levels of AA and/or EPA in platelet PL compared with the aorta PL, which might have accounted for the differential effects of these PUFA on thromboxane production compared with PGI₂ production in this study.     

Specific modifications of phosphatidylinositol and nonesterified fatty acid fractions in cultured porcine cardiomyocytes supplemented with n-3 polyunsaturated fatty acids

Mechanisms for the antiarrhythmic effect of n−3 polyunsaturated fatty acids (PUFA) are currently being investigated using isolated cardiac myocytes. It is still not known whether the incorporation of n−3 PUFA into membrane phospholipids is a prerequisite for its protective action or if n−3 PUFA exert antiarrhythmic effects in their nonesterified form as demonstrated by recent studies. Adult porcine cardiomyocytes were grown in media supplemented with arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). After 24 h, analysis of total lipids showed that the myocytes were enriched with the respective fatty acids compared to control cells. Large proportions of all three fatty acids supplemented (69% AA, 72% DHA, and 66% EPA) remained unesterified. Fatty acid analysis of total phospholipids (PL) revealed that the incorporation of EPA and DHA, though small, was significantly different (P<0.05) from that of the control cells. The PL fraction was further separated into phosphatidylinositol (Pl), phosphatidylethanolamine, phosphatidylcholine, and phosphatidylserine to study the pattern of incorporation of the fatty acids in these fractions. It became apparent that EPA and DHA were selectively incorporated into the Pl fraction. This study demonstrates that in adult porcine cardiomyocytes, the n−3 PUFA supplementation selectively modulates two important lipid fractions, nonesterified fatty acid and Pl, which were implicated in the mechanisms of prevention of cardiac arrhythmias.     

Autistic Children Exhibit Decreased Levels of Essential Fatty Acids in Red Blood Cells

Omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFA) are essential nutrients for brain development and function. However, whether or not the levels of these fatty acids are altered in individuals with autism remains debatable. In this study, we compared the fatty acid contents between 121 autistic patients and 110 non-autistic, non-developmentally delayed controls, aged 3–17. Analysis of the fatty acid composition of red blood cell (RBC) membrane phospholipids showed that the percentage of total PUFA was lower in autistic patients than in controls; levels of n-6 arachidonic acid (AA) and n-3 docosahexaenoic acid (DHA) were particularly decreased (p < 0.001). In addition, plasma levels of the pro-inflammatory AA metabolite prostaglandin E2 (PGE2) were higher in a subset of the autistic participants (n = 20) compared to controls. Our study demonstrates an alteration in the PUFA profile and increased production of a PUFA-derived metabolite in autistic patients, supporting the hypothesis that abnormal lipid metabolism is implicated in autism.     

Supplemental dietary flaxseed oil affects both neutral and phospholipid fatty acids in cultured tilapia

This work aimed to evaluate the neutral lipid (NL) and phospholipid (PL) classes in tilapia (Oreochromis niloticus) muscle tissue. Tilapias were raised in captivity for a period of 5 months with increasing levels (0, 1.25, 2.50, 3.75, and 5.00%) of flaxseed oil [source of α‐linolenic acid (LNA), 18:3n‐3] in substitution for sunflower oil (control). The NL/PL ratio was 1.9, and 45 fatty acids were determined for both classes of lipid. The class totals of n‐3 acids always increased in all treatments, while the totals for n‐6 acids always decreased (p <0.05). For a given level of flaxseed oil, the LNA contents were consistently higher, including EPA (20:5n‐3) and DHA (22:6n‐3). Arachidonic acid (20:4n‐6) remained high in the PL but was reduced as levels of dietary flaxseed oil were increased. The n‐6/n‐3 ratios decreased significantly with the rise in flaxseed oil content in all treatments, and highly unsaturated fatty acid contents increased with the levels of flaxseed oil. Overall, the influence of flaxseed oil on the fatty acid composition in the contributing NL and PL classes was to increase n‐3 PUFA, thus raising the nutritional value of this freshwater fish meat and, consequently, contributing to the health of consumers.     

Effects of highly purified eicosapentaenoic acid and docosahexaenoic acid on fatty acid absorption, incorporation into serum phospholipids and postprandial triglyceridemia

Fourteen healthy volunteers were randomly allocated to receive 4 g highly purified ethyl esters of eicosapentaenoic acid (EPA) (95% pure, n=7) or docosahexaenoic acid (DHA) (90% pure, n=7) daily for 5 wk in supplement to their ordinary diet. The n−3 fatty acids were given with a standard high-fat meal at the beginning and the end of the supplementation period. EPA and DHA induced a similar incorporation into chylomicrons which peaked 6 h after the meal. The relative uptake of EPA and DHA from the meal was >90% compared with the uptake of oleic acid. During absorption, there was no significant elongation or retroconversion of EPA or DHA in total chylomicron fatty acids. The concentration of EPA decreased by 13% and DHA by 62% (P<0.001) between 6 and 8 h after the meal. During the 5-wk supplementation period, EPA showed a more rapid and comprehensive increase in serum phospholipids than did DHA. DHA was retroconverted to EPA, whereas EPA was elongated to docosapentaenoic acid (DPA). The postprandial triglyceridemia was suppressed by 19 and 49% after prolonged intake of EPA and DHA, respectively, indicating that prolonged intake of DHA is equivalent to or even more efficient than that of EPA in lowering postprandial triglyceridemia. This study indicates that there are metabolic differences between EPA and DHA which may have implications for the use of n−3 fatty acids in preventive and clinical medicine.     

Reduced Maternal Erythrocyte Long Chain Polyunsaturated Fatty Acids Exist in Early Pregnancy in Preeclampsia

The present prospective study examines proportions of maternal erythrocyte fatty acids across gestation and their association with cord erythrocyte fatty acids in normotensive control (NC) and preeclamptic pregnancies. We hypothesize that maternal fatty acid status in early pregnancy influences fetal fatty acid stores in preeclampsia. 137 NC women and 58 women with preeclampsia were included in this study. Maternal blood was collected at 3 time points during pregnancy (16–20th weeks, 26–30th weeks and at delivery). Cord blood was collected at delivery. Fatty acids were analyzed using gas chromatography. The proportions of maternal erythrocyte α‐linolenic acid, docosahexaenoic acid, nervonic acid, and monounsaturated fatty acids (MUFA) (p < 0.05 for all) were lower while total n‐6 fatty acids were higher (p < 0.05) at 16–20th weeks of gestation in preeclampsia as compared with NC. Cord 18:3n‐3, 22:6n‐3, 24:1n‐9, MUFA, and total n‐3 fatty acids (p < 0.05 for all) were also lower in preeclampsia as compared with NC. A positive association was observed between maternal erythrocyte 22:6n‐3 and 24:1n‐9 at 16–20th weeks with the same fatty acids in cord erythrocytes (p < 0.05 for both) in preeclampsia. Our study for the first time indicates alteration in maternal erythrocyte fatty acids at 16th weeks of gestation which is further reflected in cord erythrocytes at delivery in preeclampsia.     

The Percentage of n-3 Highly Unsaturated Fatty Acids in Total HUFA as a Biomarker for Omega-3 Fatty Acid Status in Tissues

A blood biomarker of omega-3 fatty acid intake and tissue status could serve as a modifiable risk factor for cardiovascular disease. The percentage of omega-3 highly unsaturated fatty acid (HUFA ≥ 20 carbons and ≥3 double bonds) in the total HUFA pool (the n-3 HUFA score) was examined as a potential blood biomarker of omega-3 fatty acids in tissues. The fatty acid composition of total lipid extracts (TLE) and phospholipid (PL) fractions were determined for plasma and erythrocytes samples of human subjects (n = 20) and the n-3 HUFA score and the sum of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were compared. Omega-3 fatty acids in blood and tissues of rats (n = 31) and pigs (n = 48) were also determined and the associations were compared. The n-3 HUFA score is more consistent across plasma and erythrocytes, with strong correlations between TLE and PL in plasma (r = 0.93) and erythrocytes (r = 0.94). The n-3 HUFA score was less variable and blood levels correlated strongly with various animal tissues. The n-3 HUFA score is a useful blood biomarker that does not require the isolation of the PL class thereby supporting high throughput analyses. The strength of association between the n-3 HUFA score and disease risk needs to be examined.     

Arachidonic acid to eicosapentaenoic acid ratio in blood correlates positively with clinical symptoms of depression

In this study of 20 moderately to severely depressed patients, diagnosed using current research diagnostic criteria and excluding known bipolar affective disorder and reactive depression, we investigated relationships between severity of depression and levels and ratios of n-3 and n-6 long-chain polyunsaturated fatty acids (PUFA) in plasma and erythrocyte phospholipids (PL). Severity of depression was measured using the 21-item Hamilton depression rating scale (HRS) and a second linear rating scale (LRS) of severity of depressive symptoms that omitted anxiety symptoms. There was a significant correlation between the ratio of erythrocyte PL arachidonic acid (AA) to eicosapentaenoic acid (EPA) and severity of depression as rated by the HRS (P<0.05) and the LRS for depression (P< 0.01). There was also a significant negative correlation between erythrocyte EPA and the LRS (P<0.05). The AA/EPA ratio in plasma PL and the ratio of erythrocyte long-chain (C₂₀ and C₂₂ carbon) n-6 to long-chain n-3 PUFA were also significantly correlated with the LRS (P<0.05). These findings do not appear to be simply explained by differences in dietary intake of EPA. We cannot determine whether the high ratios of AA/EPA in both plasma and erythrocyte PL are the result of depression or whether tissue PUFA change predate the depressive symptoms. We suggest, however, that our findings provide a basis for studying the effect of the nutritional supplementation of depressed subjects, aimed at reducing the AA/EPA ratio in tissues and severity of depression.     

Long-chain polyunsaturated fatty acids in plasma lipids of obese children

Fatty acid composition of plasma phospholipids (PL), triglycerides (TG), and sterol esters (STE) was determined by high-resolution capillary gas-liquid chromatography in 22 obese children (age: 13.7±1.4 y, body weight relative to normal weight for height: 170±24%, mean ±SD) and compared with data obtained in 25 age-matched healthy controls. There were no differences in the levels of linoleic acid (LA, C_18∶2n-6) in any of the plasma fractions from the obese children and the controls. Obese children exhibited significantly higher values of arachidonic acid (AA, C_20∶4n-6) than controls both in PL (12.6 [2.4] vs. 8.3 [1.4], % wt/wt, [median (interquartile range)],P<0.001) and STE (7.3 [1.8] vs. 6.0 [1.1],P<0.05). Similarly, obese children showed higher values than controls for dihomo-γ-linolenic acid (DHGLA, C_20∶3n-6) in PL (4.0 [0.5] vs. 3.0 [0.6],P<0.001), TG (0.4 [0.1] vs. 0.2 [0.1],P<0.001), and STE (0.9 [0.1] vs. 0.7 [0.1],P<0.01), and for γ-linolenic acid (C_18∶3n-6) in STE (1.1 [0.2] vs. 0.8 [0.2],P<0.001). The AA/LA ratios were higher in obese children than in controls in PL (0.68 [0.16] vs. 0.42 [0.09],P<0.0005) and STE (0.16 [0.04] vs. 0.12 [0.02],P<0.05), whereas the AA/DHGLA ratios were lower in TG of obese children than in controls (3.40 [0.64] vs. 5.10 [1.75],P<0.005). Plasma glucose concentrations were inversely related to AA in TG (r=0.53,P<0.05), and plasma TG concentrations were inversely related to AA in PL and STE (r=−0.49,P<0.05 andr=−0.48,P<0.05) and to the AA/DHGLA ratios in PL (r=−0.57,P<0.01),TG (r=−0.56,P<0.01) and STE (r=−0.56,P<0.01). We conclude that the significantly higher values of n-6 long-chain polyunsaturated fatty acids (LCP) in plasma lipids of obese children than in age-matched controls may be caused by an enhanced activity of Δ6-desaturation, and we speculate that elevated fasting immunoreactive insulin seen in obese children (19.4±8.0 μU/mL) may stimulate synthesis of n-6 LCP fatty acids.     

Daily Intake of Cod or Salmon for 2?Weeks Decreases the 18:1n-9/18:0 Ratio and Serum Triacylglycerols in Healthy Subjects

Intake of fish and omega-3 (n-3) fatty acids is associated with a reduced concentration of plasma triacylglycerols (TAG) but the mechanisms are not fully clarified. Stearoyl-CoA desaturase-1 (SCD1) activity, governing TAG synthesis, is affected by n-3 fatty acids. Peripheral blood mononuclear cells (PBMC) display expression of genes involved in lipid metabolism. The aim of the present study was to estimate whether intake of lean and fatty fish would influence n-3 fatty acids composition in plasma phospholipids (PL), serum TAG, 18:1n-9/18:0 ratio in plasma PL, as well as PBMC gene expression of SCD1 and fatty acid synthase (FAS). Healthy males and females (n = 30), aged 20–40, consumed either 150 g of cod, salmon, or potato (control) daily for 15 days. During intervention docosahexaenoic acid (DHA, 22:6n-3) increased in the cod group (P < 0.05), while TAG concentration decreased (P < 0.05). In the salmon group both eicosapentaenoic acid (EPA, 20:5n-3) and DHA increased (P < 0.05) whereas TAG concentration and the 18:1n-9/18:0 ratio decreased (P < 0.05). Reduction of the 18:1n-9/18:0 ratio was associated with a corresponding lowering of TAG (P < 0.05) and an increase in EPA and DHA (P < 0.05). The mRNA levels of SCD1 and FAS in PBMC were not significantly altered after intake of cod or salmon when compared with the control group. In conclusion, both lean and fatty fish may lower TAG, possibly by reducing the 18:1n-9/18:0 ratio related to allosteric inhibition of SCD1 activity, rather than by influencing the synthesis of enzyme protein.     

Differential effects of eicosapentaenoic acid and docosahexaenoic acid on human skin fibroblasts

To better understand the mode of action of ω3 fatty acids in cell membranes, human foreskin fibroblasts were grown in serum-free medium supplemented with 50 μM oleic acid linoleic acid, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), and the effects on membrane composition, fluorescence polarization and enzyme activities were followed. The cells were enriched with EPA and DHA up to 7 and 13% of total lipids, respectively, of which >95% was associated with phospholipids. In addition, the concentration of 22∶5n−3 increased with both EPA and DHA to 7.5, and 2.1% of the total fatty acids, respectively. When compared to controls (oleic acid), cells treated with DHA showed a decrease in cholesterol, phospholipids, arachidonic acid (AA) and free cholesterol/phospholipid ratio (P<0.05). In the presence of EPA, only decreases in AA and cholesterol were significant (P<0.05). Membrane fluidity, assessed by fluorescence anisotropy, was increased 16% in cells enriched with DHA (P<0.05), but showed no change with EPA or linoleic acid. There was an increase in membrane-associated 5′-nucleotidase (+27%) and adenylate cyclase (+19%) activities (P<0.05), in DHA-enriched, but not in EPA-enriched cells, when compared with oleate controls. The studies show that incorporation of DHA, but not EPA, into cell membranes of fibroblasts alters membrane biophysical characteristics and function. We suggest that these two major n−3 fatty acids of fish oils have differential effects on cell membranes, and this may be related to the known differences in their physiological effects.     

Transforming growth factor beta in human milk does not change in response to modest intakes of docosahexaenoic acid

Long-chain polyunsaturated fatty acids have been associated with aspects of immune regulation including cytokine production. The purpose of this study was to investigate the effect of maternal dietary supplementation with tuna oil, rich in docosahexaenoic acid (DHA), on the concentration of transforming growth factor beta 1 (TGFβ1) and TGFβ2 in breast milk. In this randomized, dietary intervention trial, mothers of term infants consumed a daily supplement of 2000 mg oil containing either placebo (n=40), 300 mg DHA (n=40), or 600 mg DHA (n=40). The DHA increase in milk and plasma was proportional to dietary DHA. There was no relationship between milk DHA status and TGFβ1 and TGFβ2 levels.     

Diet,Plasma, Erythrocytes,and Spermatozoa Fatty Acid Composition Changes in Young Vegan Men

There has been increasing interest in vegan diets, but how this dietary pattern regulates tissue fatty acids (FA), especially in men, is unclear. Our aim was to evaluate the effect of a vegan diet on plasma, erythrocyte, and spermatozoa FA composition in young men. Two groups consisting of 67 young (18–25 years old) men were studied. One group following an omnivore diet but did not consume fish, shellfish or other marine foods (control, n = 33), and another group following a vegan diet (vegan, n = 34) for at least 12 months were compared. Dietary intake was assessed via a food frequency questionnaire and a 24-h recall. FA composition was measured in plasma, erythrocyte phospholipids, and spermatozoa by gas–liquid chromatography. Compared to controls, the vegan group had higher reported intakes of carbohydrate, dietary fiber, vitamins (C, E, K, and folate), and minerals (copper, potassium) but lower intakes of cholesterol, trans FA, vitamins B₆, D, and B₁₂, and minerals (calcium, iron, and zinc). Vegan's reported a lower saturated FA and not arachidonic acid intake, both groups did not intake eicosapentaenoic acid and docosahexaenoic acid (DHA), but vegan's showed a higher alpha linolenic acid ALA intake. Vegans had higher plasma, erythrocyte phospholipid, and spermatozoa ALA, but lower levels of other n-3 polyunsaturated fatty acid (PUFA), especially DHA. Vegans were characterized by higher ALA, but lower levels of other n-3 PUFA, especially DHA in plasma, erythrocytes, and spermatozoids. The biological significance of these findings requires further study.     

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.     

Erythrocyte fatty acids of term infants fed either breast milk,standard formula,or formula supplemented with long-chain polyunsaturates

The purpose of our study was to assess whether a supplement of fish oil (FO) and evening primrose oil (EPO) for formula-fed infants was capable of avoiding reductions in erythrocyte docosahexaenoic acid (DHA, 22∶6n−3) and arachidonic acid (AA, 20∶4n−6) associated with standard formula feeding. Healthy, term infants, whose mothers chose to formula feed, were randomized to either a placebo or supplemented formula for their first 30 wk of life. A reference group of beast-fed infants also was enrolled. Erythrocyte fatty acids were measured by capillary gas chromatography on day 5 and in weeks 6, 16, and 30. Supplementation of formula with 0.36% of total fatty acids as DHA resulted in erythrocyte DHA being maintained at or above breast-fed levels for the entire 30-wk study period, and breast feeding (0.21% DHA) resulted in a modest fall in erythrocyte DHA relative to baseline (day 5) values. The level of erythrocyte DHA in placebo formula-fed infants was halved by week 16. AA levels decreased in all infants in the first six weeks, but the levels in breast- and placebo formula-fed infants increased with age and returned to approximate baseline (day 5) values by 16 and 30 wk of age, respectively. Erythrocyte AA in FO+EPO-supplemented infants remained low and below breast- and placebo formula-fed levels. Our data suggest that dietary supplementation with DHA at 0.36% total fatty acids results in erythrocyte DHA levels above those found in breast-fed infants. EPO supplementation was not effective at maintaining erythrocyte AA when given with FO.