Dietary Essential Fatty Acids Research Articles

Dietary Essential Fatty Acids in Cystic Fibrosis

Analyses of serum lipids of children with cystic fibrosis (CF) have indicated a deficiency in essential fatty acids (EFA). In view of a report that intravenous administration of soybean oil emulsions normalized sweat sodium values in CF children, we studied the effects of orally administered essential fatty acids (as corn oil) for one year. Some improvement was noted in all patients, but no one consistent factor predominated. However, arachidonic acid, which was found only in trace amounts or was absent in sera of all children with CF before the clinical trial, was increased significantly in the sera after the oral administration of EFA for one year. Other findings included a significant decrease in sweat sodium and T3 in most patients.

Dietary essential fatty acids, brain polyunsaturated fatty acids, and prostaglandin biosynthesis.

The adult brain contains high levels of polyenoic fatty acids deriving from linoleic (18:2 Δ9,12 n — 6) and from linolenic acid (18:3 Δ9,12,15 n — 3). The two major polyunsaturated fatty acids (Pufa) present in brain are arachidonic acid (20:4 Δ5,8,11,14) of the linoleic acid series and especially docosahexaenoic acid (22:6 Δ4,7,10,13,16,19) of the linolenic acid series. The higher levels of 22:6 in brain, in comparison with other tissues, suggest a special function of the n-3 fatty acid family in nervous system. It has been recently found, for instance, that the electrical response of rod outer segments in the retina to illumination is affected by dietary induced changes of 22:6 n-3 levels in this tissue (Wheeler et al., 1970).

Influence of maternal dietary gamma-linolenic acid on the milk and liver lipids of suckling rats.

In lactating rats, the dietary essential fatty acids influence the composition of the milk. Feeding gamma-linolenic acid increased not only the level of this acid but also that of the 20 and 22 carbon polyunsaturated fatty acids derived from it, both in the milk and the liver triglyceride lipids of the suckling pups. Maternal nutrition, therefore, would play an important role in providing these long-chain polyunsaturated fatty acids during the active phase of growth in the rat.

The effect of different dietary levels of essential fatty acids on body composition of the rat.

Three dietary levels of essential fatty acids (EFA) 3.0, 0.75, and 0.07 cal% were studied for their influence on the concentration of lipids, linoleic and arachidonic acids, water, nitrogen, potassium, and ash of the whole body of rats. The animals were sacrificed and examined at 60, 90, and 120 days of age. They were fed the experimental diets and kept under standardized conditions for two generations or more before the actual experiment. The total body concentration of lipids increased and that of water decreased with increasing age independently of the dietary EFA level. In the rats fed 0.75 cal% EFA, the lipid concentration was higher than in those fed 3.0 cal% EFA, while in rats fed 0.07 cal% EFA the lipid concentration was lower than in those fed 0.75 cal% EFA. The concentration of water varied inversely with that of lipids. The differences were most pronounced at the highest age (120 days), and larger in the female rats than in the males. Nitrogen, potassium, and ash did not differ between the groups at any age. The role of EFA for the amount of the adipose tissue is discussed.

Relationship of dietary essential fatty acid consumption to hepatic drug hydroxylation.

Maximal aniline hydroxylase and hexobarbital oxidase activities were evident in rats fed between 1 and 10 µl arachidonate/day whereas cytochrome P-450 was at a maximum between 10 and 30 <i>µ\l </i>day. NADPH cytrochrome C reductase and cytochrome P-450 reductase activities were unaltered in a significant way by this essential fatty acid. Cytochrome P-450 of microsomes from rats fed increasing quantities of menhaden oil tended to increase but aniline hydroxylase was depressed in both fat-free fed rats and those given 100 αl/day and hexobarbital oxidase was depressed only in livers from rats fed the fat-free diet. Neither cytochrome P-450 reductase nor NADPH cytochrome C reductase was affected by menhaden oil ingestion. Glucose-6-phosphate dehydrogenase activity was elevated in nearly all doses of arachidonate and menhaden oil below 100/4/day. It appears that dietary fatty acids such as arachidonate and docosahexaenoate (menhaden oil) are involved in the synthesis or maintenance of hepatic drug metabolizing enzymes.

The effect of dietary essential fatty acids on the concentration of serum and liver lipids in the rat.

1. By feeding safflower-seed oil to rats deficient in the essential fatty acids it was found that major changes in the liver and serum triglycerides had occurred in 4 d although the fatty acid composition had not fully returned to normal.2. Rats which had been on a saturated-fat diet for 18 weeks were given for 4 d, a diet supplemented with safflower-seed oil, methyl linolenate or ethyl arachidonate. Linoleic and linolenic acids failed to reduce the liver triglycerides but had some effect in raising the serum triglycerides to normal. Arachidonic acid reduced liver triglycerides but had no effect on serum lipids. There were marked changes in the fatty acid composition of the phospholipids but little change in the triglycerides.3. There was good correlation between the concentrations of the phospholipids and the triglycerides in the serum. The concentration of serum phospholipids was positively correlated with the percentage of linoleic and arachidonic acids but negatively correlated with the percentage of palmitoleic, oleic and 5, 8, 11-eicosatrienoic acids.4. In a further 4 d feeding experiment in which the lipoprotein fraction of very low density from the serum was measured, it was found that safflower-seed oil led to an increase but methyl arachidonate resulted in a decrease in the concentration of the lipids.5. Extraction of the lipoprotein fraction of very low density from normal and deficient rats with n-heptane at – 18° indicated that phosphatidyl cholines containing stearic acid and either arachidonic or 5, 8, 1 1-eicosatrienoic acid were the most firmly bound.6. It was concluded that linoleic acid and arachidonic acid had different and specific roles in lipid metabolism.

Release of prostaglandin-like material from dog kidney during nerve stimulation

Canine kidneys were autoperfused in situ at constant flow in 28 experiments. Renal venous effluent was examined for (PLM) prostaglandin-like material following acidic lipid extraction and thin layer chromatography or by continuous bioassay utilizing the bloodbathed organ technique. There was a low basal efflux of PLM from the kidney which was markedly enhanced during the renal vascular constriction elicited by renal nerve stimulation at 2-10 cycles/second or by infusion of norepinephrine. The PLM was tentatively identified as an E-type prostaglandin based on chromatographic behavior and bioassay. The present study indicates that PLM is released from the dog kidney during an increase in renal vascular resistance. Release is not necessarily dependent upon changes in total renal blood flow although alterations in the distribution of intrarenal blood flow might be involved. (authors)

Essential fatty acids, plasma protein bound iodine, and the thyroid gland.

SummaryPlasma protein bound iodine (PBI) of female rats fed an essential fatty acid (EFA) deficient diet for 15 weeks was higher than that of controls receiving dietary EFA, even though weight of the thyroid gland was less in deficient rats. After refeeding EFA to the deficient rats either as soybean oil or the colony stock diet for 3 weeks, the PBI concentration was decreased to the control values and the weights of the thyroid gland increased. Thiouracil added to the EFA-deficient diet lowered the PBI concentration in plasma and increased the weight of the thyroid gland. These data suggest that the increase in plasma PBI in EFA-deficiency is not dependent on TSH but the control mechanism that regulates the secretion of thyroidal iodine is dependent on essential fatty acids

The effect of dietary essential fatty acids upon composition of polyunsaturated fatty acids in depot fat and erythrocytes of the rat

The fatty acid Composition of lipids from erythrocytes and depot fat of rats whose diet was supplemented with various levels of linoleate, arachidonate, or linolenate has been investigated. Dietary linoleate and linolenate are incorporated into the depot fat. The ratio of eicosatrienoic acid to eicosatetraenoic acid, derived from the analysis of depot fat, decreases with increasing amounts of all three dietary essential fatty acids (EFA) in the same manner as observed in organ lipids. The composition of the unsaturated fatty acids of erythrocyte lipids is altered readily by increasing amounts of dietary EFA. The concentration of 20: 3 is lowered extensively by all three EFA. The synthesis of arachidonate is inhibited by dietary linolenate and 20:5 and 22:5ω3 (double bond between third and fourth carbow from ω end) can be detected only in animals given linolenate.