The development of essential fatty acid deficiency in healthy men fed fat-free diets intravenously and orally.

The hypothesis that clinical and biochemical essential fatty acid deficiency (EFA) might occur from the feeding of eucaloric, fat-free diets was tested in two experiments in healthy men. In Study I, eight men were given fat-free, eucaloric diets containing 80% of calories as glucose and 20% as amino acid hydrolysates by a constant drip over a 24-h period. The diets were fed in succession for periods of 2 wk each, either through a superior vena cava catheter or via a nasogastric tube. EFA deficiency was detected by decreases in linoleic acid and by the appearance of 5, 8, 11-eicosatrienoic acid in lipid fractions of plasma. Linoleic acid decreased significantly during 2 wk of the fat-free diet given intravenously from 48.8 to 9.8% (percent of total fatty acids) in cholesterol esters, from 21.2 to 3.2% in phospholipids, from 9.6 to 2.0% in free fatty acids, and from 14.1 to 2.6% in triglycerides. Eicosatrienoic acid, normally undetectable, appeared 0.6% in cholesterol esters, 2.5% in phospholipids, 0.2% in free fatty acids, and 2.3% in triglycerides. EFA deficiency occurred similarly during the nasogastric feeding. In Study II a subject received the same diet continuously by the nasogastric route for 10 days followed by a 24-h fast. He was then given the fat-free diet intermittently in three meals per day for 3 days. Finally, he was repleted with a diet containing 2.6% linoleic acid. By the 3rd day of the continuous nasogastric feeding, linoleic acid had fallen significantly and eicosatrienoic acid had appeared in plasma lipid fractions as in Study I. These findings were accentuated by day 10. Adipose tissue fatty acid composition did not change. Free fatty acid outflow from adipose tissue was presumably suppressed during the 10 days of continuous feeding. With increased free fatty acid outflow during fasting and intermittent feeding, linoleic acid rose and eicosatrienoic acid decreased. After 13 days of repletion with dietary linoleic acid, the EFA deficiency readily develops when fat-free diets containing glucose are given intravenously or orally as constant 24-h infusions. These diets are similar to the hyperalimentation formulas now being used clinically.

Effects of essential fatty acid deficiency on epidermal O-acylsphingolipids and transepidermal water loss in young pigs.

Linoleate-rich O-acylglucosylceramides and acylceramides are thought to be of major significance for the physical structure and function of the epidermal permeability barrier. In the present investigation, the effects of a linoleate-free diet on O-acylsphingolipids and their associated functions were investigated. Starting at 5 days of age, male pigs were fed diets containing 12% of either lard or hydrogenated coconut oil. Transepidermal water loss was measured with an electrolytic water analyzer at weekly intervals. Pigs were killed at intervals, and epidermal lipids were isolated and analyzed. Fatty acid compositions were determined by gas-liquid chromatography (GLC). Within 2-3 weeks, pigs on the diet containing coconut oil began to display biochemical and physiological symptoms of essential fatty acid deficiency. Within 2 months, this group had extremely scaly skin and transepidermal water loss was elevated to five times that of controls. The progressive increase in transepidermal water loss correlated with replacement of linoleate by oleate in both acylceramide and acylglucosylceramide. The formation of lamellar granules and intercellular lipid sheets in the stratum corneum was not impaired in essential fatty acid deficiency as judged by electron microscopy. These results suggest that the linoleic acid normally found in the O-acylsphingolipids is not essential for formation of the epidermal membrane system. Rather, it appears that the nature of the ester-linked fatty acid in the O-acylsphingolipids regulates the permeability of this membrane system.

Modulation of human erythrocyte shape and fatty acids by diet.

A semi-synthetic diet (Vivonex) was administered via nasogastric tube to three cystic fibrosis patients with pancreatic exocrine deficiency for 14 days to gain weight. Dietary essential fatty acids were provided as safflower oil, which constituted 1.3% of total calories. Plasma and red blood cells were analyzed for the content and composition of lipids at the start of the diet and at days 7 and 14 of the dietary period, and the results were correlated with the morphology of the cells. Feeding Vivonex to the patients led to an essential fatty acid deficiency, which was manifested in a 50% decrease in the linoleic acid content of the phosphatidylcholine of plasma and red blood cells at days 7 and 14 and in a 20% decrease in the linoleic acid content of red cell phosphatidylethanolamine at day 14. There was no significant alteration in the levels or composition of the other phospholipid classes and in the free cholesterol/phospholipid ratio. The decrease in the linoleic acid content of the erythrocytes was accompanied by a dramatic increase in the proportion of cells as echinocytes. We conclude that restricted linoleic acid availability in cystic fibrosis patients causes a change in red blood cell shape either directly by decreasing the linoleoylphosphatidylcholine content of the membrane or indirectly by affecting enzyme activity.

Membrane structures in normal and essential fatty acid-deficient stratum corneum: characterization by ruthenium tetroxide staining and x-ray diffraction.

Despite the importance of intercellular lamellar bilayers for stratum corneum (SC) barrier function, knowledge about the structure of these bilayers is limited due to their poor visualization and/or retention. Whereas substitution of ruthenium tetroxide (RuO4) for osmium tetroxide fixation provides clear images of these bilayers, the usefulness of RuO4 has been limited by its slow penetration and cytotoxicity. Utilizing a new fixation protocol for RuO4, we obtained clear images of lamellar domains at all levels of murine SC. Computer-aided image reconstructions demonstrated a lamellar spacing of 129 +/- 2 A, which agreed with x-ray diffraction data from parallel, unfixed samples (131 +/- 2 A), a spacing not affected by hydration. Furthermore, novel structures were seen in the intercellular spaces of normal SC. Finally, in murine essential fatty acid deficiency (EFAD), the overall lamellar spacing is comparable to normal [127 +/- 7 A by computer transform vs. 131.9 +/- 2 A (hydrated) and 129.6 +/- 2.2 A (dry) by x-ray diffraction]. Yet, these domains are structurally abnormal, displaying regions with either an excess or absence of lamellae. The new RuO4 protocol provides quantitative information about SC lamellar dimensions and morphologic abnormalities in bilayer distribution and substructure in EFAD stratum corneum that are not detected by either x-ray diffraction or computer-aided image reconstruction. Thus, the barrier abnormality in EFAD stratum corneum can be ascribed either to focal depletion of lamellae or abnormalities in lamellar substructure.

Inhibition of cholesterol and sphingolipid synthesis causes paradoxical effects on permeability barrier homeostasis.

Cholesterol, fatty acid, and sphingolipid synthesis are required for barrier homeostasis, as demonstrated by studies where synthesis of these species is stimulated in parallel with barrier repair. Moreover, blockade of synthesis of these lipids with inhibitors of two of the rate-limiting enzymes, HMGCoA reductase (lovastatin, fluvastatin) and serine palmitoyl transferase (beta-chloroalanine), alters the kinetics of barrier repair. Whereas these studies demonstrated a requirement for these lipids individually, we asked here whether these lipids are required in either an additive or cooperative fashion. We applied each class of inhibitor alone or the two classes of inhibitors together to acetone-treated skin, or each class separately to essential fatty acid deficient murine skin. When fluvastatin or beta-chloroalanine was applied individually to acetone-treated skin, each caused a delay in the early or late stages of barrier recovery, respectively (assessed as transepidermal water loss). However, when applied together they caused no further worsening at the early time point and a paradoxical improvement at the later time points. This improvement correlated with an accelerated return of sphingolipids, which was perhaps due to a global stimulation of lipid synthesis induced by HMGCoA reductase inhibitors. In essential fatty acid deficient animals, inhibition of HMGCoA reductase caused drastic worsening of both clinical appearance and barrier function, but beta-chloroalanine caused a paradoxical improvement, which correlated with a significant reduction in epidermal sphingolipids. These results are consistent with a requirement for both cholesterol and sphingolipids for barrier homeostasis, and also with the suggestion that both of these lipids must be present (with free fatty acids) for optimal barrier function.

Impaired catecholamine inactivation. A prohypertensive stimulus after dietary linoleate deficiency in salt-loaded rats?

Experiments were carried out on salt-loaded rats (1.5% NaCl as drinking fluid) to further explore the mechanisms by which blood pressure increases after a linoleic acid-deficient (LAd) diet. In 4-week-old LAd rats (0.5 cal% LA, hydrogenated palm kernel fat) compared to linoleic acid-rich rats (LAr, 13.3 cal% LA, sunflower oil), we observed, from the base of a reduced content of omega-6-polyunsaturated fatty acids in the tissues, an increase in blood pressure by 12 mm Hg (p less than 0.001), a diminished formation of prostaglandin E (PGE), and an unchanged formation of PGF in the aorta as well as a reduction in the in vitro uptake of 14C-norepinephrine into cardiac, aortic, and renal tissues, and a reduced degradation rate of 14C-norepinephrine in cardiac tissue. These differences in LAr vs LAd rats were not exaggerated. With respect to aortic PGE formation, 14C-norepinephrine uptake into aortic and renal tissues and 14C-norepinephrine degradation even lessened when the diet was begun prenatally, although the reduction of omega 6-polyunsaturated fatty acids in the tissues was aggravated. Our conclusion is that a fault in catecholamine inactivation may be involved in the pathogenesis of increased sympathetic activity and blood pressure elevation in LAd-fed, salt-loaded rats, possibly via alterations of endogenous prostanoid formation.

Alpha-linolenic acid deficiency in man: effect of ethyl linolenate on plasma and erythrocyte fatty acid composition and biosynthesis of prostanoids.

Treatment of human alpha-linolenic acid deficiency (ALAD) with ethyl linolenate is reported. The patient's scaly dermatitis nearly disappeared after 5-d supplementation with 0.1 mL ethyl linolenate. Pretreatment content of various n-3 fatty acids in RBC was 0-15% of healthy controls. After 14 d of supplementation, cholesterol and triglycerides were reduced by 70% of pretreatment values, 22:5n-3 and 22:6n-3 increased three- to fourfold while 18:3n-3 and 20:5n-3 remained low, indicating a rapid elongation and desaturation of 18:3n-3 in ALAD. Urinary excretion of PGI2-M was approximately 10 times higher than in healthy control subjects, while PGI3-M excretion was low. Linolenate supplementation increased PGI2-M excretion twofold, while PGI3-M remained near detection limit. Platelet capacity to synthesize TXA2, and urinary excretion of TXB2+3-M were nearly unaffected by supplementation. The results confirm that the minimal daily requirement of alpha-linolenic acid is 0.2-0.3% of total energy.

Fatty acid composition of serum lipids of mothers and their babies after normal and hypertensive pregnancies.

The biochemical essential fatty acid (EFA) status of neonates born after normal and hypertensive pregnancies (PIH) and that of their mothers was assessed by measuring the fatty acid composition of phospholipids (PL), triglycerides (TG) and cholesterol esters (CE) of umbilical cord serum and maternal serum, respectively. Relative contents of linoleic acid of serum PL and CE were significantly lower in mothers with PIH compared to normal pregnancies. Most other (n-6) polyenes in PL tended to be higher under hypertensive conditions. Total maternal (n-3) polyenes of serum PL were significantly higher in PIH, mainly due to clupanodonic acid, 22:5 (n-3), and cervonic acid, 22:6 (n-3). Total maternal (n-7) and (n-9) fatty acids were also significantly higher in PIH (PL and CE). The results indicate that PIH is associated with a relative increased unsaturation of maternal serum PL, which might facilitate the placental transfer of long-chain, polyunsaturated fatty acids. As a result, the neonatal EFA status after PIH only slightly differs from normal.

Chemical sympathectomy abolishes the increase in blood pressure of linoleic acid deficient fed rats induced by salt loading.

In previous experiments an altered PG biosynthesis as well as an increase in blood pressure, heart rate and plasma epinephrine could be found after a linoleic acid deficient diet compared with a linoleic acid rich diet in rats with a high salt intake. We injected rats with 200 micrograms 6-hydroxydopamine into the right and left cerebral ventricles 17 days before a four-week linoleic acid deficient diet (0.5 J% linoleic acid) and salt loading (1.5% NaCl). In these rats the elevation of blood pressure and plasma epinephrine compared with linoleic acid rich fed rats (13.3 J+ linoleic acid) was abolished and heart rate was reduced. PG biosynthesis in aorta and kidney medulla homogenate (PGE and PGF) and stomach fundus homogenate (6-Keto-PGF1 alpha) was not influenced by chemical sympathectomy, neither were the food and fluid intakes. We conclude that an enhanced adrenergic activity (via alterations in PG metabolism?) is involved in the blood pressure increase after a linoleic acid deficient diet under high salt intake.

Aspirin toxicity in chicks given diets deficient in linoleic acid.

The toxicity of dietary aspirin on growth rate and lipid metabolism was investigated under linoleic acid (LA; 18: 2n-6) deficient conditions. One-week-old chicks were given diets containing 0 or 2% LA with or without 0.4% aspirin, until 4 weeks of age. Growth was severely depressed by dietary aspirin when chicks were given the LA-free diet. The liver was enlarged by both the aspirin and LA deficiency. The aspirin treatment induced a significant increase of 18:0 and arachidonic acid (20: 4n-6) and a decrease of 18: 1n-9 in the liver. In chicks fed LA-free diets, the ratio of 20:3n-9/20: 4n-6, which was used as an indicator of LA deficiency, was suppressed by aspirin treatment. In conclusion, the present results suggest that aspirin toxicity is altered by dietary LA concentrations.

Friedreich's disease 1982: etiologic hypotheses a personal analysis.

The author reviews the arguments for and against the four etiologic hypotheses in Friedreich's disease that have been proposed since 1974: the "pyruvate hypothesis", the "lipid-membrane hypothesis", the "energy-defect hypothesis" and finally the "taurine hypothesis". While none of these hypotheses are mutually exclusive, the author shows that all of these mechanisms play some role in the pathophysiology of the symptoms, but that only the "taurine hypothesis" appears to be compatible with all the known facts and the biochemical abnormalities reported. The author proposed that the taurine retention defect (possibly due to a block in the high affinity-low capacity transport of taurine - The TH System) is a primary event in Friedreich's disease. Whether it is the primary genetic event still has to be determined.

Linolenic acid deficiency: changes in fatty acid patterns in female and male rats raised on a linolenic acid-deficient diet for two generations.

Rats were fed for two generations a purified, linolenic acid-deficient diet in which the only source of lipid was purified methyl linoleate. This diet contained about 38 mg linolenic acid/kg diet. Control rats were given the same diet supplemented with methyl linolenate (2,500 mg/kg diet). Male and female rats ranged in age from weaning pups to adults. Lipids were extracted from liver, brain, kidney, spleen, heart, muscle, gastrointestinal tract, lung, ovary, testis, adrenal, plasma, erythrocytes, retina, and adipose tissue. Fatty acids of major phospholipid classes (choline phosphoglycerides, ethanolamine phosphoglycerides, and mixed serine phosphoglycerides plus inositol phosphoglycerides) or of total lipid extracts were measured by gas liquid chromatography. Growth rates and organ weights were similar in control and linolenic acid-deficient rats. The major effect of the deficiency was to lower the proportions of n-3 fatty acids, especially 22:6 n-3, in all the organs analyzed. Docosahexaenoic acid (22:6 n-3) was mainly replaced by 22:5 n-6 in deficient rats. The greatest changes in composition were found in brain, heart, muscle, retina, and liver.

Essential fatty acid status in southern Thai preschool children.

Essential fatty acid (EFA) status was assessed in 15 Southern Thai preschool children. The mean (+/- SD) serum linoleate (18:2 n-6), arachidonate (20:4 n-6), linolenate (18:3 n-3), eicosapentaenoate (20:5 n-3), and docosahexaenoate (22:6 n-3) percentages in the preschool children were 21.7 +/- 4.0, 6.0 +/- 1.2, 0.4 +/- 0.1, 1.2 +/- 0.8, and 4.4 +/- 1.3, respectively. Since EFA composition of total serum lipids in healthy children are not available and age and sex do not largely influence these parameters, the results of the preschool children were compared with those of 10 healthy Bangkok adults. The corresponding figures of the aforementioned fatty acids in adults were 34.9 +/- 8.5, 4.6 +/- 1.5, 0.8 +/- 0.4, 0.5 +/- 0.4, and 1.6 +/- 0.8, respectively. The data indicate linoleate and linolenate depletion in the preschool children. This was due to their low fat intake and lack of consumption of vegetable oil rich in linoleic and linolenic acids. Their high serum arachidonate percentage was probably due to the increased conversion of 18:2 n-6 to 20:4 n-6 in the presence of linolenate depletion. The significantly higher serum 20:5 n-3 and 22:6 n-3 percentages in the preschool children should be due to direct consumption of these two n-3 fatty acids from fish intake.

Zinc deficiency and the desaturation of linoleic acid in rats force-fed fat-free diets.

Recent studies with rats force-fed zinc-deficient diets containing various types of fat failed to demonstrate a role of zinc in desaturation of linoleic acid. The present study was conducted to investigate the effect of zinc deficiency on desaturation of linoleic acid in rats that were initially force-fed fat-free diets to stimulate activity of desaturases. Therefore, rats were fed zinc-adequate and zinc-deficient fat-free diets for 6 d. After that period, the groups were divided and half of the rats continued feeding the fat-free diet for another 3.5 d whereas the other half was switched to a fat diet by supplementing the fat-free diet with 5% safflower oil. In order to assess desaturation of linoleic acid, fatty acid compositions of liver phosphatidylcholine, -ethanolamine, and -serine were considered, particularly levels of individual (n-6) polyunsaturated fatty acids (PUFA). Levels of total and individual (n-6) PUFA were similar in zinc-adequate and zinc-deficient rats fed the fat-free diet throughout the experiment. Addition of 5% safflower oil increased levels of total and individual (n-6) PUFA in both zinc-adequate and zinc-deficient rats. However, total (n-6) PUFA in all types of phospholipids were higher in zinc-adequate rats than in zinc-deficient rats. Additionally, in zinc-deficient rats there were changes of (n-6) PUFA levels typical for impaired delta 5 and delta 6 desaturation: linoleic acid and dihomo-gamma-linolenic acid were elevated; arachidonic acid, docosatetraenoic acid, and docosapentaenoic were lowered by zinc deficiency. Therefore, the study shows that zinc deficiency impairs desaturation of linoleic acid in rats force-fed fat-free diets and therefore supports results from former convential zinc deficiency experiments suggesting a role of zinc for desaturation of linoleic acid.

Physiological impairment in linoleic acid deficiency of rats and the effect of n-3 polyunsaturated fatty acids.

Some impairments related to membrane function were found in linoleic acid-deficient rats and the effects of fish oil feeding were investigated. In linoleic acid-deficient rats, glucose transport into erythrocytes was decreased. The concentrations of plasma free fatty acids were significantly reduced in the animals. Further, epinephrine-stimulated lipase was remarkably less sensitive to epinephrine in the deficient rat than in the corn oil-fed control rat. However, these impairments were relieved by fish oil feeding. Therefore, the impairments may be ascribed to the decrease of arachidonic acid as a polyunsaturated fatty acid in membrane phospholipids, since n-3 polyunsaturated fatty acids appear to take the place of arachidonic acid.

[Effect of linoleic acid administration on plasma- and liver lipids. Determination of linoleic acid requirements]. / Einfluss der Linolsäurezufuhr auf Plasma- und Leberlipide. Ein Beitrag zur Ermittlung des Linolsäurebedarfs.

In order to estimate the linoleic acid requirement of the rat, four groups of weanling male Wistar-Rats, 18 animals each, were fed isoenergetic semi-synthetic diets containing 14 cal% fat. The linoleic acid content (as linoleic acid methyl ester) amounted to 0; 0.5; 1.3 and 4.0% of total energy intake. The experiment lasted 14 weeks. The parameters analysed were the concentrations of total lipids (TL), free cholesterol (Ch), cholesterol esters (ChE), triglycerides (TG) and phospholipids (PL) in plasma and liver. - Clinical signs of linoleic acid deficiency were only found in the rats fed the linoleic acid free diet. With 0.5 cal% linoleic acid in the diet no deficiency symptoms were observed. - In plasma of the linoleic acid deficient animals the concentrations of TL, Ch, ChE and TG were decreased. Plasma PL contents were insignificantly altered. - While the contents of TL, TG and ChE in the liver of the deficient rats increased significantly, those of PL and Ch were hardly affected. The results show that a linoleic acid supply of 0.5 cal% prevents nearly all alterations of plasma and liver lipid concentrations noticed in linoleic acid deficiency. The effect of this dose was as good as that of 1.3 cal% linoleic acid. Therefore we assume that the minimum requirement of male young rats for linoleic acid is markedly less than 1,3% of total energy intake.

[Essential fatty acid deficiency in enteral nutrition]. / Déficit de ácidos grasos esenciales durante nutrición enteral.

A case is presented of a 57-year-old patient who developed a clinical picture compatible with linoleic acid deficit while on a diet with 6.4 g of this fatty acid (2.8% of total calories). The factors involved in essential fatty acid requirements, and the need of some patients for up to 50 g of linoleic acid in order to reach normal serum levels are discussed. It was concluded that some commercial diets should be supplemented with additional linoleic acid.

[Effect of short-term administration of sunflower oil on the blood serum level of linoleic and arachidonic acids and lipids in multiple sclerosis]. / Wplyw krótkotrwalego podawania oleju slonecznikowego na poziom kwasów linolowego i arachidonowego oraz lipidów w surowicy krwi chorych ze stwardnieniem rozsianym.

Patients with multiple sclerosis had an oral load of sunflower seed oil in daily doses of 40 g during five days. This daily doses contained 27 g of linoleic acid (LA). Prior and after diet supplementation with sunflower seed oil the levels of linoleic and arachidonic acids were determined in the serum of patients. The values were expressed as relative percentages of total fatty acids. Before addition of sunflower oil to the diet the serum levels of linoleic acid (LA) and arachidonic acid (AA) were in these patients significantly lower than in controls amounting to 17.0% and 1.05% (p less than 0.001). After addition of sunflower oil the levels of LA and AA rose to 32.7% and 3.02%. The concentration of total lipids and non-esterified fatty acids in the serum increased also significantly after addition of sunflower oil. Determinations of LA and AA 10 days after withdrawal of sunflower oil showed that their levels were 23.7% and 1.95% respectively. In 2 patients addition of sunflower oil only slightly changed the very low serum LA level. These results indicate that LA and AA deficiency in patients with multiple sclerosis has the character of a non-specific dietary deficiency mainly, although the role of genetic factors controlling the levels of polyunsaturated fatty acids cannot be ruled out.

[Essential fatty acids: its transformations and functions]. / Los ácidos grasos esenciales: sus transformaciones y funciones.

Essential fatty acids, in animals, pertain to two different fatty acid families: the linoleic and the linolenic. These, and the non-essential families of oleic and palmitoleic are produced by action of the enzymes proper. The lack of essential fatty acids produces typical symptoms that are accompanied by fatty acid compositions, also typical, utilized with diagnostic value. The biological effects of essential fatty acids can be specific and nonspecific. The latter manifest themselves particularly in the phospholipid composition and, therefore, in the structure and fluency of the membranes. In contrast, specific essential fatty acids act in the formation of prostaglandins, prostacyclins, tromboxans and leucotriens. Each essential fatty acid produces specific effects, depending on the prostanoids formed and the tissue in question.

[Characteristics of early disorders of fatty-acid composition of kidney lipids in spontaneous (hereditary) arterial hypertension]. / Kharakteristika rannikh narushenii zhirnokislotnogo sostava lipidov pochek pri spontannoi (nasledstvenno obuslovlennoi) arterial'noi gipertenzii.

Fatty acid composition of kidney lipids from spontaneously hypertensive Okamoto-Aoki rats (SHR) and normotensive Wistar rats (NR) was investigated two days after birth by gas-liquid chromatography. In SHR kidney phospholipids, as compared to the respective NR values, the content of arachidonic acid (20:4n6) was decreased and the levels of oleic (18:1n9) and docosahexaenoic (22:6n3) acids were increased; in kidney triglycerides, the content of eicosatrionoic acid (20:3n9) and all fatty acids of the linoleic acid series was decreased, except the content of a polyunsaturated long-chain product of linoleic acid metabolism, docosapentaenoic acid (22:5n6) that was increased. These changes may have developed prenatally as a result of genetic peculiarities of SHR.