A randomized controlled trial of the effect of fish oil supplementation in late pregnancy and early lactation on the n−3 fatty acid content in human breast milk

The aim of this research was to investigate the effect of fish oil supplementation, in the third trimester of pregnancy and early lactation period of healthy pregnant Danish women. Forty-four pregnant women were randomly allocated to fish oil supplementation (1.3 g EPA and 0.9 g DHA per day) from week 30 of gestation (FO-group) or to a control regimen (olive oil or no oil; controls). The FO-group was randomly subdivided into women stopping fish oil supplementation at delivery [FO(pregn)], and women continuing supplementation for an, additional 30 d [FO(pregn/lact)]. Thirty-six women agreed to collect milk samples at days 4, 16, and 30 postpartum. The FA composition of the milk samples was determined by GLC. At days 4, 16, and 30 in lactation, FO(pregn/lact) women (n=12) had, respectively 2.3 (P=0.001), 4.1 (P=0.001), and 3.3 (P=0.001) times higher mean contents of LCPUFA(n−3) in their breast milk compared with controls (n=13), and 1.7 (P=0.005), 2.8 (P=0.001), and 2.8 (P=0.001), times higher LCPUFA(n−3) contents, respectively, at these days compared with FO(pregn) women (n=11). The latter group did not differ significantly from controls with regard to LCPUFA(n−3) content in the breast milk. Similar results were obtained when analyzing separately for effects on the milk content of DHA. Dietary supplementation with 2.7 g LCPUFA(n−3) per day from week 30 of gestation and onward more than tripled the LCPUFA(n−3) content in early breast milk; supplementation limited to pregnancy only was much less effective.     

Hyperphagia modifies FA profiles of plasma phospholipids,plasma FFA,and adipose tissue TAG

Hyperphagia was achieved by continuous intracerebroventricular infusion of a melanocortin receptor antagonist (HS024; Neosystem, Strasbourg, France) in rats. The effects of hyperphagia on FA composition and concentration of plasma phospholipids (PL), plasma FFA, and adipose tissue TAG were studied in rats for 8 d [short-term hyperphagia (STH); n=8], or 28 d [longterm hyperphagia (LTH); n=9]. The control rats were treated with artificial cerebrospinal fluid for 8 d (n=8) or 28 d (n=10). The rats were fed the same regular diet. In STH rats the plasma PL and fasting plasma FFA contained higher concentrations of saturated FA (SFA) and monounsaturated FA (MUFA), and plasma FFA contained lower n−6 PUFA than in the control rats. In LTH rats the plasma PL contained higher concentrations of SFA, MUFA, and n−3 PUFA and higher proportions of 16∶1n−7 and 18∶1n−9 at the expense of 18∶2n−6 than in the control rats. In LTH rats the abundant dietary intake of 18∶2n−6 did not enrich 18∶2n−6 of the plasma PL or adipose tissue TAG. In LTH rats the fasting plasma FFA contained more than twofold higher concentrations of SFA and MUFA, and higher proportions of 16∶1n−7 and 18∶1n−9 at the expense of 18∶2n−6 than in the control rats. This animal obesity model shows that LTH affects the FA composition and concentration of plasma PL, plasma FFA, and adipose tissue TAG, a result consistent with changes associated with increased risk of various diseases in humans. These results also demonstrate that LTH alters the FA composition of plasma PL and adipose tissue TAG in a way that does not reflect the FA composition of dietary fat.     

Fluctuations in human milk long-chain PUFA levels in relation to dietary fish intake

Within the Danish population, milk DHA (22∶6n−3) levels vary by more than a factor of 10. This paper deals with fluctuations in the milk content of 22∶6n−3 and other long-chain PUFA (LCPUFA) and the acute effects of fish meals and fish oil supplements on milk levels of LCPUFA. Twelve fish-eating mothers with 4-mon-old infants provided one blood and one adipose tissue sample, and seven consecutive morning hindmilk samples with dietary records from the previous days. Another 12 lactating women were given fish oil (2–8 g) for breakfast and delivered 6–12 milk samples during the following 24 h. The mean milk 22∶6n−3 content of the fish-eating mothers was 0.57±0.28 FA% (=percentage of total area of FAME peaks in GLC) and the day-to-day variation (SD/mean) within the individual was 35±17%. Mean milk 22∶6n−3 content on mornings with no fish the day before was 0.42±0.15 FA%; this was increased by 82±17% (n=9, P=0.05) if the mother had eaten fatty fish. Fish oil resulted in a twofold increase in milk 22∶6n−3 levels, which peaked after 10 h and lasted for 24 h. The EPA content of milk was also increased by fish meals and fish oil supplements, but these had no effect on the level of arachidonic acid. The study showed that diurnal and day-to-day fluctuations in levels of milk n−3 LCPUFA are large, which makes it difficult to assess the 22∶6n−3 intake of breast-fed infants from a single milk sample. In studies of the functional outcome of dietary 22∶6n−3 in breast-fed infants it is suggested also to use a measure of maternal 22∶6n−3 status.     

Incorporation of n−3 fatty acids into plasma and liver lipids of rats: Importance of background dietary fat

The health benefits of long-chain n−3 PUFA (20∶5n−3 and 22∶6n−3) depend on the extent of incorporation of these FA into plasma and tissue lipids. This study aimed to investigate the effect of the background dietary fat (saturated, monounsaturated, or n−6 polyunsaturated) on the quantitative incorporation of dietary 18∶3n−3 and its elongated and desaturated products into the plasma and the liver lipids of rats. Female weanling Wistar rats (n=54) were randomly assigned to six diet groups (n=9). The fat added to the semipurified diets was tallow (SFA), tallow plus linseed oil (SFA-LNA), sunola oil (MUFA), sunola oil plus linseed oil (MUFA-LNA), sunflower oil (PUFA), or sunflower oil plus linseed oil (PUFA-LNA). At the completion of the 4-wk feeding period, quantitative FA analysis of the liver and plasma was undertaken by GC. The inclusion of linseed oil in the rat diets increased the level of 18∶3n−3, 20∶5n−3, and, to a smaller degree, 22∶6n−3 in plasma and liver lipids regardless of the background dietary fat. The extent of incorporation of 18∶3n−3, 20∶5n−3, and 22∶5n−3 followed the order SFA-LNA>MUFA-LNA>PUFA-LNA. Levels of 22∶6n−3 were increased to a similar extent regardless of the type of major fat in the rat diets. This indicates that the background diet affects the incorporation in liver and plasma FA pools of the n−3 PUFA with the exception of 22∶6n−3 and therefore the background diet has the potential to influence the already established health benefits of long-chain n−3 fatty acids.     

Relationship between platelet phospholipid FA and mean platelet volume in healthy men

Increased mean platelet volume (MPV) has been suggested as an independent risk factor for acute myocardial infarction and the increased reactivity of large platelets. The aim of this study was to investigate the correlation between platelet phospholipid (PL) PUFA composition and MPV in 139 free-living healthy men ages 20–55 yr (vegans, n=18; ovolacto vegetarians, n=43; modrerate meat-eaters, n=60; and high meateaters, n=18). Each subject completed a semiquantitative Food Frequency Questionnaire and gave a blood sample. Platelet PL FA composition and MPV were determined by standard methods. MPV was significantly greater in the vegans than in the ovolacto vegetarian, moderate, or high meat-eater groups (P<0.01). Both vegan and ovolacto vegetarian groups had significantly higher platelet PL 18∶2n−6 and 22∶4n−6, and lower 20∶5n−3 and 22∶6n−3 compared with the moderate and high meat-eater groups. The vegans demonstrated a significant reduction in 20∶4n−6 and 22∶5n−3 compared with the ovolacto vegetarian, high meat-eater, and moderate meat-eater groups. Bivariate analysis results showed that MPV was significanly positively correlated with platelet PL 18∶2n−6 (P=0.048) and negatively correlated with 20∶3n−6 (P=0.02), 20∶5n−3 (P=0.005), and 22∶5n−3 (P<0.0001), respectively. In a multiple linear regression analysis, after controlling for potential confounding factors such as dietary group, age exercise, body mass index, and dietary polyunsaturated and saturated fat, cholesterol, carbohydrate, and fiber intake, the MPV was still strongly negatively correlated with platelet PL 20∶3n−6 (P=0.003) and 22∶5n−3 (P=0.001). The present data suggest that 20∶5n−3 and 20∶3n−6 may play a role in the structural function of the platelet membrane.     

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.     

Dietary nucleotides do not alter erythrocyte long-chain polyunsaturated fatty acids in formula-fed term infants

There have been conflicting reports regarding the effectiveness of dietary nucleotides (NT) to regulate tissue desaturases and hence stimulate accumulation of both n−6 and n−3 long-chain polyunsaturated fatty acids (LCPUFA). The aim of this study was to examine the effect of NT-supplemented cow's milk-based formula on erythrocyte phospholipid FA status in a large randomized controlled trial involving a well-nourished infant population born at term. Formula-fed infants were allocated to control formula with an innate level of NT at 10 mg/L (n=102), or formula fortified with NT at 34 mg/L (n=98). A parallel group of breastfed infants was included as a reference. Peripheral blood samples were collected by venipuncture at 7 mon of age and erythrocyte phospholipid FA determined by capillary GC. Erythrocyte LCPUFA levels did not differe between the NT-supplemented and control formula groups and were reduced in both groups compared with breastfed infants. We conclude that there is no induction of LCPUFa accumulation in erythrocyte phospholipids of term, formula-fed infants following 7 mon of NT supplementation.     

Low-fat, monounsaturate-rich diets reduce susceptibility of low density lipoproteins to peroxidation ex vivo

Oxidative modification of low density lipoprotein (LDL) plays an important role in the process of atherosclerosis. The susceptibility of LDL to oxidation and the amount of peroxidation products formed are influenced by the lipoprotein content of 18∶1 n−9, 18∶2n−6, and the 18∶2n−6/18∶1n−9 ratio, which is dependent in part on dietary fatty acids. The purpose of this study was to determine if changing from a typical American diet to a low-fat, monousaturate-rich diet (LFMR) would result in favorable alterations in the fatty acid composition and oxidative profile of LDL in hypercholesterolemic individuals. Free-living postmennopausal hypercholesterolemic women who routinely consumed a diet moderately high in total fat and total saturates (34 and 11%, respectively) followed an LFMR diet (26% fat, 6% saturated fat, and 14% monounsaturated fat) for 6 mon. Sixteen postmenopausal hypercholesterolemic women already following standard low-fat (LF) diets acted as a control for seasonal variations in serum lipids. LDL from randomly selected subjects (LF n=6, LFMR n=5) was evaluated. LFMR diets resulted in LDL with increased concentrations and percentages of 18∶1n−9, reduced 18∶2n−6/18∶1n−9 ratio, and lower percentages of 18∶2n−6. No significant changes in LDL fatty acids occurred in the LF group. Conjugated diene lag time increased in both groups during copper-induced in vitro oxidation. Only the LFMR group experienced an increase in lipid peroxide lag time and a decrease in lipid peroxide formation. The LFMR diet was well tolerated and may be of therapeutic value in the treatment of hypercholesterolemia. A portion of this material was presented earlier at the annual meeting of the American Oil Chemists' Society and in abstract form [O'Byrne, D.J., Shireman, R.B., Knauft, D. (1993) The effects of a low-fat/high oleic acid diet on lipoproteins in postmenopausal hypercholesterolemic women, INFORM 4:553,#SS7].     

Fatty acid profiles and relative mobilization during fasting in adipose tissue depots of the American marten (Martes americana)

The American marten (Martes americana) is a boreal forest marten with low body adiposity but high metabolic rate. The study describes the FA composition in white adipose tissue depots of the species and the influence of food deprivation on them. American marten (n=8) were fasted for 2 d with 7 control animals. Fasting resulted in a 13.4% weight loss, while the relative fat mass was >25% lower in the fasted animals. The FA composition of the fat depots of the trunk was quite similar to other previously studied mustelids with 14∶0, 16∶0, 18∶0, 16∶1n−7, 18∶1n−9, and 18∶2n−6 as the most abundant FA. In the extremities, there were higher proportions of monounsaturated FA (MUFA) and PUFA. Food deprivation decreased the proportions of 16∶0 and 16∶1n−7, while the proportion of long-chain MUFA increased in the trunk. The mobilization of FA was selective, as 16∶1n−7, 18∶1n−9, and particular n−3 PUFA were preferentially mobilized. Relative mobilization correlated negatively with the carbon chain length in saturated FA (SFA) and n−9 MUFA. The Δ9 desaturation of SFA enhanced the mobilization of the corresponding MUFA, but the positional isomerism of the first double bond did not correlate consistently with relative mobilization in MUFA or PUFA. In the marten, the FA composition of the extremities was highly resistant to fasting, and the tail tip and the paws contained more long-chain PUFA to prevent the solidification of lipids and to maintain cell membrane fluidity during cooling.     

Long-chain polyunsaturated fatty acids and eicosanoids in infants-physiological and pathophysiological aspects and open questions

Eicosanoids are highly active lipid mediators in physiologic and pathologic processes, with their effects ranging from cytoprotection and vasoactivity to modulation of inflammatory and proliferative reactions. Generation of eicosanoids can be affected by changes in the pools of their precursors, the long-chain polyunsaturated fatty acids (LCPUFA). Thus, dietary interventions such as supplementation of infant formula with specific n−3 and n−6 LCPUFA will alter formation as well as activity of the eicosanoids produced. This report summarizes the results and discussion of the workshop on “Eicosanoids and Polyunsaturated Fatty Acids in Infants”. The intention of the workshop organizers was to give an overview of the role of eicosanoids in physiological and pathophysiological processes in infants, to discuss the implications that an increased n−3 and n−6 LCPUFA intake may have on eicosanoid genration, and to point out open questions and controversies for future research.     

Isolated brain capillary endothelia: Influence of various levels of essential fatty acids on the acyl group composition of glycerophospholipids

On day seven of gestation, Wistar rats were assigned to a high essential fatty acid (EFA), low EFA, or a fat free diet. The same diets were continued during lactation. On weaning, the offspring were fed the same diets as their mother. Rats were killed at 222 days, brain capillary endothelia isolated, and total lipids extracted from the purified capillaries. The composition of the constituent fatty acids of ethanolamine glycerophospholipid (EGP), choline glycerophospholipid (CGP), and the alk-1-eny EGP composition from each diet is reported. A decrease in dietary EFA led to reduced proportions of total saturated acyl groups in EGP with no change observed in the total saturated acyl groups from CGP, and an increase in monoenoic fatty acids, particularly 18∶1n−9 for each phospholipid class. The proportions of 20∶4n−6 in alk-1-enyl EGP were reduced in fat-free fed animals. In addition, the relationship between 20∶3n−9 and 20∶4n−6 fatty acids in brain capillary endothelia were markedly increased with a reduction in dietary fat. Low EFA and fat deficient animals showed a tendency to sequester 22∶6n−3.     

Gestational age and birth weight in relation to n−3 fatty acids among inuit (Canada)

Seafood consumption during pregnancy carries both benefits (high n−3 FA intake) and risks (exposure to environmental contaminants) for the developing fetus. We determined the impacts of marine n−3 FA and environmental contaminants on gestational age (GA) of Nunavik women and the anthropometric characteristics of their newborns. FA and contaminant (polychlorinated biphenyls and mercury) concentrations were measured in cord plasma of Nuvavik newborns (n=454) and compared with those of a group of newborns (n=29) from southern Québec. Data were collected from hospital records and birth certificates. In Nunavik newborns, arachidonic acid (AA) was two times lower (P<0.0001), whereas DHA concentration, the Σn−3/Σn−6 ratio, and the percentage of n−3 highly unsaturated FA (HUFA) (of the total HUFA) were three times higher (P<0.0001) compared with southern Québec newborns. After controlling for confounders, GA and birth weight were higher by 5.4 d [95% confidence interval (CI): 0.7–10.1] and 77 g (95% CI: −64 to 217) in the third tertile of percentage of n−3 HUFA (of the total HUFA) as compared with the first tertile. There was no evidence that contaminants had negative effects on GA or birth weight. In this seafood-eating population, an increase in the proportion of n−3 HUFA (of the total HUFA), measured in umbilical cord plasma phospholipids, was associated with a significantly longer GA.     

Replacement of dietary fish oil with increasing levels of linseed oil: Modification of flesh fatty acid compositions in Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis>) using a fish oil finishing diet

Five groups of salmon, of initial mean weight 127±3 g, were fed increasing levels of dietary linseed oil (LO) in a regression design. The control diet contained capelin oil (FO) only, and the same oil was blended with LO to provide the experimental diets. After an initial period of 40 wk, all groups were switched to a finishing diet containing only FO for a further 24 wk. Growth and flesh lipid contents were not affected by dietary treatment. The FA compositions of flesh total lipids were linearly correlated with dietary FA compositions (r ²=0.88–1.00, P<0.0001). LO included at 50% of added dietary lipids reduced flesh DHA and EPA (20∶5n−3) concentrations to 65 and 58%, respectively, of the concentrations in fish fed FO. Feeding 100% LO reduced flesh DHA and EPA concentrations to 38 and 30%, respectively, of the values in fish fed FO. Differences between diet and flesh FA concentrations showed that 16∶0, 18∶1n−9, and especially DHA were preferentially retained in flesh, whereas 18∶2n−6, 18∶3n−3, and 22∶1n−11 were selected against and presumably utilized for energy. In fish previously fed 50 and 100% LO, feeding a finishing diet containing FO for 16 wk restored flesh DHA and EPA concentrations, to ≈80% of the values in fish fed FO throughout. Flesh DHA and EPA concentrations in fish fed up to 50% LO were above recommended intake values for humans for these EFA. This study suggests that LO can be used as a substitute for FO in seawater salmon feeds and that any reductions in DHA and EPA can be largely overcome with a finishing diethigh in FO before harvest.     

A significant inverse relationship between concentrations of plasma homocysteine and phospholipid docosahexaenoic acid in healthy male subjects

The aim of this study was to investigate the possibility of a relationship between plasma homocysteine (Hcy) and phospholipid FA (PUFA) in healthy Australian males. One hundred thirty six healthy male subjects aged 20–55 yr were recruited from the Melbourne metropolitan area. Each volunteer completed a semiquantitative food frequency questionnaire and gave a blood sample. Plasma Hcy concentrations were determined by an established HPLC method; the plasma phospholipid FA were determined by standard methods. Plasma Hcy concentration was significantly negatively correlated with plasma phospholipid concentration of the PUFA 20∶5n−3 (r=−0.226, P=0.009), 22∶5n−3 (r=−0.182, P=0.036), 22∶6n−3 (r=−0.286, P=0.001), total n−3 (r=−0.270, P=0.002) and the ratio n−3/n−6 PUFA (r=−0.265, P=0.002), and significantly positively correlated with 20∶4n−6 (r=0.180, P=0.037). In the partial correlation analysis, after controlling for serum vitamin B₁₂ and folate concentration, plasma Hcy was significantly negatively correlated with the plasma phospholipid concentration of 22∶6n−3 (r=−0.205, P=0.019), total n−3 (r=−0.182, P=0.038) and the ratio n−3/n−6 PUFA (r=−0.174, P=0.048). Evidence indicates that an increased concentration of n−3 PUFA in tissues has a beneficial effect on cardiovascular health. Our findings provide further evidence that increased consumption of dietary n−3 PUFA increases the concentration of n−3 PUFA in plasma phospholipid, which is associated with a protective effect on cardiovascular diseases and lower plasma Hcy levels. The mechanism that might explain the association between plasma 22∶6n−3 and Hcy levels is not clear.     

Modulation of renal injury in pcy mice by dietary fat containing n−3 fatty acids depends on the level and type of fat

Low-fat diets and diets containing n−3 fatty acids (FA) slow the progression of renal injury in the male Han:Sprague-Dawley (SPRD)-cy rat model of polycystic kidney disease. To determine whether these dietary fat effects are similar in females and in another model of renal cystic disease, in this study we used both male and female pcy mice to examine the effects of fat level and type on disease progression. Adult pcy mice were fed 4, 10, or 20 g soybean oil/100 g diet for 130 d in study 1. In study 2, weanling pcy mice were fed high or low levels of fat rich in 18∶2n−6 (corn oil, CO) 18∶3n−3 (flaxseed oil/CO 4∶1 g/g, FO), or 22∶6n−3 (algal oil/CO 4∶1 g/g, DO) for 8 wk. In adult pcy mice, low-compared with high-fat diets lowered kidney weights (2.4±0.2 vs. 3.1±0.2 g/100 g body weight, P=0.006) and serum urea nitrogen (SUN) (9.6±0.6 vs. 11.9±0.6 mmol/L, P=0.009), whereas in young pcy mice it reduced renal fibrosis volumes (0.44±0.04 vs. 0.62±0.04 mL/kg body weight, P<0.0001). FO feeding in young pcy mice mitigated the detrimental effects of high fat on fibrosis while not altering kidney size, function, and oxidative damage when compared with the CO-fed mice. In contrast, DO-compared with CO-fed mice had higher kidney weights (2.64±0.07 vs. 2.24±0.08 g/100 g body weight, P=0.005), SUN (9.4±0.57 vs. 7.0±0.62 nmol/L, P<0.0001), and cyst volumes (7.9±0.28 vs. 6.2±0.30 mL/kg body weight, P<0.0001) and similar levels of oxidative damage and fibrosis. The FA compositions of the diets were reflected in the kidneys: 18∶2n−6, 18∶3n−3, and 22∶6n−3 were the highest in the CO, FO, and DO diets, respectively. Dietary effects on kidney disease progression were similar in males and females. A low-fat diet slows progression of renal injury in male and female pcy mice, consistent with findings in the male Han:SPRD-cy rat. Dietary fat type also influenced renal injury, with flaxseed oil diets rich in 18∶3n−3 slowing early fibrosis progression compared with diets rich in 18∶2n−6 or in 22∶6n−3.     

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.     

Dietary fat and the development of pancreatic cancer

Pancreatic cancer is the fifth most common cause of death due to cancer. Except for an association with cigarette smoking, its etiology is poorly understood. Because of the dearth of epidemiological clues as to causation, studies with experiemntal animal models assume greater importance. Rodent models of pancreatic cancer indicate that while dietary fatper se does not cause pancreatic cancer, it does enhance or promote tumor development. Subsequent to treatment with a pancreatic carcinogen, high intakes of dietary unsaturated fats of the n−6 series, but not saturated fats, enhance or promote tumor development. A requisite level of linoleic acid is needed for this promotion. Fats of the n−3 series (e.g., certain fish oils) are inhibitory to tumor growth. Promotion by dietary fats appears only partly related to the high caloric content of fat. Mechanistically, certain dietary unsaturated fats appear to selectively enhance the growth rate of carcinogeninduced, pre-cancerous lesions. Irrespective of precise understanding of mechanisms of promotion, it, appears possible to intervene in the process of cancer development and reduce the burden of cancer. Experimentally, this may be accomplished by decreasing total fat intake, decreasing caloric intake, increasing exercise or increasing the intake of n−3 fatty acids. Based on a paper presented at the Symposium on Lipids in Cancer held at the AOCS Annual Meeting, Baltimore, MD, April 1990.     

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.     

Dietary fat composition and age affect synaptosomal and retinal phospholipid fatty acid composition in C57BL/6 mice

The purpose of this study was (i) to determine whether dietary fat-induced differences in neural and retinal membranes occur when dietary fat treatment is implemented in aged animals and (ii) to characterize the effect of long-term differences in dietary fat on neural and retinal membrane composition. For the first objective, young (six-week-old) and old (95-week-old) mice were randomly assigned to beef tallow (TAL) or soybean oil (SBO) diets for eight weeks. For the second objective, young (four-week-old) mice consumed either TAL or SBO diets for 99 weeks. Young and old mice challenged with a change in dietary fat for an eight-week period showed both diet and age effects on neural and retinal phospholipid fatty acid composition (P<0.05). In addition, significant diet by age interactions were evident. In mice that consumed TAL and SBO diets throughout their life, only retinal phosphatidylethanolamine (PE) 18∶2n−6 and neural phosphatidylserine 22∶5n−6, PE 18∶2n−6 and phosphatidylcholine 18∶2n−6 differed between dietary treatments (P<0.05). Neither the unsaturation index nor the n−6/n−3 ratio was affected by diet. Neural and retinal phospholipid fatty acid composition were responsive to changes in dietary fat even when the treatment was implemented beyond developmental or post-weanling stages. In contrast, when mice consumed TAL or SBO diets throughout their life, fewer differences in phospholipid fatty acid composition were detected, suggesting that the effect of the dietary treatment was mitigated by aging.     

Fatty acid composition of habitual omnivore and vegetarian diets

High-fat diets are implicated in the onset of cardiovascular disease (CVD), cancer, and obesity. Large intakes of saturated and trans FA, together with low levels of PUFA, particularly long-chain (LC) omega-3 (n−3) PUFA, appear to have the greatest impact on the development of CVD. A high n−6∶n−3 PUFA ratio is also considered a marker of elevated risk of CVD, though little accurate data on dietary intake is available. A new Australian food composition database that reports FA in foods to two decimal places was used to assess intakes of FA in four habitual dietary groups. Analysis using the database found correlations between the dietary intakes of LC n−3 PUFA and the plasma phospholipid LC n−3 PUFA concentrations of omnivore and vegetarian subjects. High meat-eaters (HME), who consumed large amounts of food generally, had significantly higher LC n−3 PUFA intakes (0.29 g/d) than moderate meat-eaters (MME) (0.14 g/d), whose intakes in turn were significantly higher than those of ovolacto-vegetarians or vegans (both 0.01 g/d). The saturated FA intake of MME subjects (typical of adult male Australians) was not different from ovolacto-vegetarian intakes, whereas n−6∶n−3 intake ratios in vegetarians were significantly higher than in omnivores. Thus, accurate dietary and plasma FA analyses suggest that regular moderate consumption of meat and fish maintains a plasma FA profile possibly more conducive to good health.