A heretical view of the American Heart Association's nutritional dogma [abstract]

The dogma is as follows: no more than 33 percent of the calories in the diet should come from fat, and of those no more than 33 percent should come from saturated fat. Because of the saturated fats in eggs and butter, both of these foods are unsuitable. Diets that do not conform to these standards raise serum cholesterol levels and thereby promote coronary heart disease (CHD). However, serum cholesterol is not correlated with dietary cholestorol. diet or drug regimes that reduce serum cholesterol do not reduce mortality. Blood lipoprotein a, the best single predictor of CHD, correlates not at all with fat in the diet but inversely with ascorbic acid. Low-fat diets do not protect against CHD type 2. In practice, they are almost always high-carbohydrate, and often high-sucrose diets. Such diets promote obesity, Type-2 diabetes mellitus, and the production of advanced glycosylation end-products, which in turn promote hypertension and CHD. Because of the need for essential fatty acids, all diets should include unsaturated fatty acids. However, as quantities rise above optimum the unsaturated acids promote greater free radical damage and require increasing amounts of oil-soluble anti-oxidants to counteract this effect. Eggs are excellent food, containing, in addition to protein, carbohydrate, fat and all the vitamins, minerals and essential fatty acids needed to produce a chicken. They do not promot CHD. Nutritionally, butter is much better than margarine which contains large amounts of trans fatty acids, that interfere with the metabolism of essential fatty acids, raise low density lipoprotein and triglycerides and lower high density lipoprotein. The best is a low-carbohydrate diet with little sucrose and adequate levels of vitamins, minerals and essential fatty acids. (AU)

Fatty acid composition and possible health care effects of coconut constituents

The link between excessive composition of dietary saturated fats and coronary heart disease (CHD) is now well established. Because of its high content of saturated fatty acids, the composition of foods containing coconut oil may therefore be a risk factor for CHD. While the fatty acid composition of coconut oil is well established, relatively little is known about the other constituents of coconut: the milk, water, cream and meat fractions. In this study, we show that while the water fraction is low in lipid content, the milk contains about 24 percent of the fat content of oil and the cream and meat fractions about 34 percent. The other coconut constituents contain significant amounts of medium-chain triglycerides that are formed from fatty acids of chain length 8:0 to 14:0. It is these fatty acids, primarily 14:0, that are thought to be atherogenic. On the other hand, medium-chain triglycerides provide a ready source of energy and may be useful in baby foods or in diet therapy. Nevertheless, the possible negative effects of the saturated acids and the absence of the essential fatty acid linolenic acid from all coconut constituents suggest that the coconut milk, oil and cream should not be used on a regular basis in adults. (AU)

Metabolic handling of different fatty acids during rehabilitation from childhood malnutrition

The gastrointestinal handling and post absorptive metabolism of [1, 1, 1-13 C] triolein (TO) and [1, 1, 13 C] tripalmitin (TP) were studied in two groups of eight severely malnourished children (5-0 months): on admission (Phase 1), during rapid-catch up growth (Phase 2) and when weight for height had reached 90 percent of the reference (Phase 3). Total excretion of 13 C label in stool (over 3 days) and breath as 13 CO 2 (over 24 hours) were analysed by isotope radio mass spectrometry. Stool 13 C excretion at admission was approximately 10 percent of the administered dose for both trials but varied markedly between subjects, was significantly reduced during rehabilitation in the TO trial (Phase 2:0.5 +or- 1.0; Phase 3: 1.3 +or- 0.9; p<0.05) and tended to decline on the P trial. ANOVA analysis of the magnitude and time course of 13 C excretion in breath (from area under the curve), excretion tended to decrease during rehabilitation in the TO trial but remained unchanged on the TP trial. These results suggest that the efficiency with which dietary triacylglycerol is handled within the gastrointestinal tract is generally impaired in severely malnourished children at admission but improves during rehabilitation.(Au)

Acidovorax anthurii sp. nov., a new phytopathogenic bacterium which causes bacterial leaf-spot of anthurium

The bacterial leaf-spot of anthurium emerged during the 1980s, in the French West Indies and Trinidad. This new bacterial disease is presently wide spread and constitutes a serious limiting factor for commercial anthurium production. Twenty-nine strains isolated from leaf-spots of naturally infected anthurium were characterized and compared with reference strains belonging to the Comamonadaceae family, the genera Ralstonia and Burkholderia, and representative fluorescent pseudomonads. From artificial inoculations 25 out of 29 strains were pathogenic on anthurium. Biochemical and physiological tests, fatty acid analysis, DNA-DNA hybridization, 16S rRNA gene sequence analysis, DNA-16S RNA hybridization were performed. The 25 pathogenic strains on anthurium were clustered in one phenon closely related to phytopathogenic strains of the genus Acidovorax. Anthurium strains were 79-99% (deltaTm range 0.2-1.6) related to the strain CFBP 3232 and constituted a discrete DNA homology group indicating that they belong to the same species. DNA-rRNA hybridization, 16S rRNA sequence and fatty acid analysis confirmed that this new species belongs to the beta-subclass of Proteobacteria and to rRNA superfamily III, to the family of Comamonadaceae and to the genus Acidovorax. The name Acidovorax anthurii is proposed for this new phytopathogenic bacterium. The type strain has been deposited in the Collection Fran‡aise des Bact‚ries PhytopathogŠnes as CFBP 3232T.

Ethnic differences in glucose tolerance: the diet (fatty acid) rather than genetic variation

This study examined the possible role of plasma fatty acids (FA) and serum lipid composition in ethnic differences in glucose tolerance (GT). In carefully taken population samples (77 percent response) aged 45-74 years, 75 g GT test results were compared between 100 African-Caribbeans (AfC) [53 women (w)], 188 white Europeans (60w) and 113 Gujratis (55w), excluding known diabetics. 2 hr normoglycaemic (ng) AfC (n=70) had considerably lower age and sex adjusted fasting non-esterified (NE) FA at 0.42 (mean, 95 percent CI 0.36-0.48) mmol/l vs 0.58 (0.52-0.64) mmol/l in Europeans and 0.58 (0.51-0.65) mmol/l in Gujratis (F=8.2, p=0.0004). NEfA were significantly (26-52 percent) greater in, with no ethnic difference between, glucose intolerants (GIT). Gujratis had higher proportion of serum linoleate (18.2n-6) at 35.3 (34-36.6 percent) than AfC (27.4, 26-29 percent) or whites (24, 23-26 percent) but half or less of docosahexanoate (22:6n-3) - 1.2(0.8-15)percent vs 2.7(2.3-3) percent and 2.4(2-2.8) percent in both ng and GIT groups. With BMI and insulin, NEFA were independently associated with 2 hr glucose accounting for much of the ethnic difference.(AU)

Hyperlipidaemia and insulin resistance

There is reason to believe that increased plasma fatty acid (FFA) levels may be a cause for the strong association between fat ingestion and obesity. It has been recently shown in offspring of parents with non-insulin dependent diabetes mellitus (NIDDM), known to be at high risk to develop the disease, that elevated FFA levels were associated with insulin resistance. Moreover, 80-85 percent of patients with NIDDM are obese, are insulin-resistant, and many have elevated FFA levels which correlate with glucose tolerance. In support of the notion that plasma FFA are responsible for the insulin resistance observed in obesity, it was demonstrated more than 30 years ago that increased availability of FFA decreased CHO oxidation and glucose uptake in perfused rat heart and to a lesser extent in rat diaphragm. Based on these findings, the researchers proposeda glucose-fatty acid cycle presumed to be of fundamental importance for the control of blood glucose and insulin sensitivity both in normal and in diabetic subjects. This intriguing concept has remained controversial mainly because many investigators were unable to reproduce the fatty acid-mediated inhibition of glucose uptake in striated muscle that had been observed in perfused rat hearts. We have recently reinvestigated that onset and duration of the inhibitory effect of intravascular lipolysis, produced by intravenous infusion of triglycerides and heparin, on total body CHO oxidation and glucose disappearance in normal men during euglycaemic-hyperinsulinaemia. These studies demonstrated that the fatty acid-mediated inhibition of insulin-stimulated CHO oxidation occurred early, i.e., within the first 20 minutes while the inhibition of glucose uptake developed after only 3-4 hours of fat infusion. Thus, insufficient time of fat infusion (2 hours in most studies) was the most likely reason why the inhibitory effect of FFA on glucose uptake was not found in many studies. In subsequent studies, we have examined the dose dependency of the fatty acid effect on insulin-stimulated glucose uptake. The results showed that FFA inhibited glucose uptake in a dose-dependent fashion throughout the physiological range of plasma FFA concentration (AU)

Intake of medium chain fatty acids (notably 12:0 and 14:0) from human milk in Antigua is not related to growth and does not cause energy wasting due to excessive beta-oxidation - abstract

The effect of postnatal intake of medium chain fatty acids (MCFA; C6-C14) from human milk on excessive beta-oxidation and growth was studied in Antigua. On day 23-28 a mean estimated intake of 8.9 g(range:3.8-16.6) of MCFA (notably 12:0 and 14:0) per litre did not cause excessive beta-oxidation, as derived from urinary excretion of ketone bodies and beta-hudroxybutyric acid. MCFA intake was not related to growth in the first 23-28 days. Intakes of as low as 2.7 g MCFA (notably 8:0 and 10:0) per litre from semisynthetic medium chain triglycerides are known to produce excessive beta-oxidation and urinary excretion of dicarboxylic acids (Rebouche et al, Am J. Clin. Nutri. 1990;52:820-824). It is concluded that, from a metabolic point of view, 12:0 and 14:0 from human milk belong to an intermediate subclass of MCFA that resembles long chain fatty acids greater than or equal to 16). Their uptake into adipose tissue may prevent hepatic oxidation, despite conceivable transportation of free 12:0 via the portal vein (AU)

Vitamin E, lipid fractions, and fatty acid composition of colostrum, transitional milk, and mature milk: an international comparative study

Triglycerides, cholesterol, fatty acid composition, and tocopherols were determined in colustrum, transitional milk, and mature milk in St. Lucia. With progress of lactation, triglycerides and percentage medium-chain fatty acids increased whereas tocopherols, cholesterol and percentage long-chain polyunsaturated fatty acids decreased. These changes reflect augmented de novo synthesis of fatty acids (8:0, 10:0, 12:0, and 14:0) in the mammary gland and a tendency of increasing fat-globule size as milk matures. Transitional and mature milks, but particularly colustrum, contained higher concentrations of components considered to be derived from the fat-globule membrane (cholesterol, tocopherols, percentage long-chain polyunsaturated fatty acids) compared with those reported for Western countries. Percentage medium-chain fatty acids in mature milk was two to three times higher than in developed countries. Differences from data from studies in Western countries are discussed in relation to analytical methods and possible consequences for lipid digestion, lipid absorption, growth, and brain development.(AU)

Adipose tissue in foetuses, infants, children and adolescents in Curacao (Netherlands Antilles), its fatty acid content and composition: the fatty acid disappearance rate in childhood - abstract

There are uncertainties about the fatty acid (FA) disappearance rate in adipose tissue of infants. We therefore studied the adipose tissue FA content and composition in the foetal period in relation to samples obtained in infancy, childhood and adolescence. Adipose tissue samples were obtained in Curacao from Black foetuses and newborns (n = 42, gestation ages 22-43 weeks), and from infants, children and adolescents (n = 62, ages 0-19 years). FA was analysed by capillary gas chromatography. It was assumed that feeds of human milk or formula in the first ñ6 months accomplished 'pulse labelling' of newborn adipose tissue FA with medium chain saturated fatty acid (MC-SAFA), and that feeding of a "mixed" diet after 6 months of age constituted a 'wash-out' or 'chase' of the marker FAs. FA half-life was calculated from the disappearance rate of MC-SAFAs (AU)

A carbohydrate-rich diet not only leads to incorporation of medium-chain fatty acids (6:0-14:0) in milk triglycerides but also in each milk-phospholipid subclass

We isolated phospholipid (PL) subclasses from milk of women in Dominica and Belize. Fatty acid (FA) compositions of PLs and total lipids were determined. In the total-lipid fraction Dominican milk showed higher relative amounts of medium-chain saturated fatty acids (MC-SAFAs; 6:0-14:0) and 22:6n-3 and lower amounts of long-chain saturated fatty acids (LC-SAFAs) and monounsaturated fatty acids (MUFAs). There was a positive relationship between the MC-SAFA content in total lipids and total PLs. Incorporation of MC-SAFAs in PLs occurred at the expense of LC-SAFAs, MUFAs, polyunsaturated fatty acids (PUFAs), and long-chain PUFAs with o20 carbon atoms (LC-PUFAs oC20). Previous studies from western countries revealed low amounts of MC-SAFAs and high amounts of PUFAs and LC-PUFAs oC20 in milk PLs. Our data show that carbohydrate-rich diets give rise to incorporation of MC-SAFAs in PLs at the expense of PUFAs and LC-PUFAs oC20. The data are discussed in relation to the presumed origin of fat-globule membrane phospholipids. (AU)

Foetal adipose tissue fatty acid accretion - abstract

There are still uncertainties about the origin of the fatty acids (FA) deposited in the foetus, notably the percentage derived from the maternal circulation. This study describes a method to determine the amount of FA synthesized de novo in the foetus and the amount derived from the maternal circulation. Autopsy samples of subcutaeneous adipose tissue were obtained from 42 black foetuses and newborn infants. Samples of similar tissue were obtained from 50 pregnant women and 13 non-pregnant black women during surgery. FA analysis was done by gas chromatography. The accretion rate of FA in foetal adipose tissue was calculated by linear regression analysis of the FA data obtained from foetal/infant samples from the 22nd to 43rd week of gestation. The rate of foetal FA synthesized de novo in adipose tissue was calculated as the difference between the total foetal FA accretion rate and an estimate of the maternally derived FA. The latter was estimated from the values for accretion rates of saturated FA (SAFA), mono-unsaturated FA (MUFA), and polyunsaturated FA (PUFA) and total FA in foetal tissue, and the SAFA, MUFA and PUFA composition of adipose tissue in women (Table). Results show that of the total FA increment in foetal adipose tissue (22.7mg/g wet wt./week), 86.6 per cent was synthesized de novo by the foetus and the rest (13.2 per cent) was maternally derived (AU)

Human milk in mothers in Belize, Curacao, Dominica, St. Lucia and Suriname, the fatty acid composition and the relevance of medium chain fatty acids containing triglycerides - abstract

Fatty acid composition of mature milk from Belize, Curacao, Dominica and Suriname and of colostrum, transitional and mature milk from women in St. Lucia was analyzed by capillary gas chromatography. Remarkable differences and striking similarities were found in fatty acid compositions. The levels of 6:0-12:0, the medium chain fatty acids (MCFA), and 14:0 were high (12:0-16:9 and 9.6-15.0 gm percent respectively) in all 5 countries as compared to reports from European countries. Palmitic acid (16:) levels (20.2-23.6 gm percent were similar to reported levels from other societies. The levels of 22.+c, W3 (docosahexaenoic acid or DHA) were extremely high in Dominica (average 1.15 gm percent) and relatively high (0.25-0.56 gm percent) in other Caribbean countries as compared to reported levels of 0.05-0.23 gm percent in studies from the USA. When a mother is in energy equilibrium or positive energy balance, the fatty acid composition of her breast milk is related to that of her diet, whereas in negative energy balance, it resembles that of her adipose tissue. High levels of DHA in breast milk may be explained by consumption of fish rich in DHA. A high carbohydrate intake leads to a high MCFA content of breast milk, such as seen in all 5 Caribbean countries but especially in Dominica. The levels of MCFAs and 14:0 in breast milk from St. Lucia increased substantially from colostrum to mature milk at the expense of the longer chain fatty acids (AU)

Fatty acids generate dicarboxylic acids in hypoglycin poisoning - abstract

We investigated the metabolic origin of certain dicarboxylic acids which appears in urine of hypoglycin poisoned subjects (Jamaican vomiting sickness). These include hexanedioic (adipic), octanedioic (suberic) and decanedioic (sebacic) acids which, with unsaturated variants, are also excreted in some rare congenital diseases (glutaric acidaemia Type II, generalized dicarboxlic acidaemias), and in ketosis. Long-chain fatty acids have been established as precursors only in the case of diabetic, ketotic rats. In one report, evidence for this origin was negative for the case of hypoglycin poisoning, but no alternative precursors appear likely and the problem has remained unresolved since 1972. The present work utilized palmitic acid labelled either with Tritium, or with 14c at various atoms of the molecule as a tracer in hypoglycin-treated rats. Suberate and sebacate, isolated from urines by gas liquid chromatography, were found to be radioactively labelled, and hence, significant conversion of fatty acid to dicarboxylic acid was demonstrated. A further conclusion emerged from the relative labelling yielded by [1-14C] - and [16-14C] palmitic acid. After chain shortening by 3 -4 cycles of fatty acid á-oxidation, w-oxidation appears to intervene as a consequence of inhibition of the former process by the hypoglycin metabolite methylenecyclopropylacetyl-CoA. This sequence is in contrast to the ketotic animal, in which initial w-oxidation of fatty acid apparently precedes bilateral á-oxidation. In fasted hypoglycin-poisoned rats, excretion of each of these compounds is not insignificant, being about 7 - 33 mg/24 hr(1 - 4 mg/mg creatinine) (AU)

Biochemical aspects of ketogenesis, a review

Ketogenesis occurs only under certain physiological conditions, the physiological substrate for the process being long chain fatty acids. The condition for ketogenesis arises if the long chain fatty acid levels are high enough to render the liver incapable of metabolising all the acetyl CoA, formed as a result of hepatic oxidation of long chain fatty acids, via the tricarboxylic acid cycle to yield water and carbon dioxide. The state in which unesterified fatty acid levels are high enough to cause ketogenesis can be arrived at if there is a lack of insulin or a condition of starvation. Biochemical regulation, pathological condition and relative levels of ketone bodies are also reviewed. It was found that maximum ketonemia reflects not only increased production but also decreased use. The determination of urine or plasma 3-hydroxybutyrate may be of more importance than a simple urinary test upon ketone bodies in diabetic persons