W. O. Lundberg

Comparative Curative Values of Unsaturated Fatty Acids in Fat Deficiency.

Conclusions Unsaturated fatty acids (linoleic, linolenic, arachidonic and cod liver oil acids) show differences in growth and skin effects. They should no longer be treated as an interchangeable group but should be used individually in nutrition studies.

The antioxidant properties of nordihydroguaiaretic acid

SummaryA description is given of the antioxidant properties of nordihydroguaiaretic acid. This substance is readily obtained in substantial yields from a common plant(Larrea divaricata) and compares favorably with other highly effective inhibitors of the phenolic type.It is more soluble in fats than hydroquinone but not as soluble as the tocopherols. Within the limits of these experiments, and at optimal concentrations, it appears to have no deleterious effects on the qualities of lards.Its effectiveness in stabilizing fats is to some extent carried over into baked products.Ascorbic acid enhances its effectiveness.

Effects of Saturated and Unsaturated Fatty Acids on Blood Platelet Aggregation in vitro.

There is now much evidence that platelets are involved in intravascular clotting of blood. The “white head” of a thrombus is an aggregation of platelets that normally would not adhere to each other in the blood stream. Platelet adhesiveness and aggregation are therefore receiving increasing attention, and many studies have been conducted under in vitro conditions using a wide variety of agents (1–4). Dietary fats have been implicated in the development of atherosclerosis and thrombosis in both animals and man. It has been well established that the composition and quantities of blood lipids in man are markedly influenced by dietary fat. Thus increasing attention is being given to relationships between dietary fats as well as blood lipids and such phenomena as platelet aggregation and thrombus formation. Among the plasma lipids that may be altered by changes in dietary fat are the unesterified fatty acids. Long chain fatty acids have been shown to promote thrombus formation in an in vitro system of flowing blood(5) and also when injected intravenously in dogs(6,7). It is important therefore to study the effects of various dietary fats and individual fatty acids on factors involved in platelet aggregation. Using a turbidimetric method, Haslam found in vitro that a saturated fatty acid, behenic, brought about rapid aggregation of washed human platelets under suitable conditions(8). Owren et al(9) have reported that the abnormal platelet adhesiveness in humans with known histories of cardiovascular disease is reduced to normal by oral administration of linseed oil or purified linolenic acid, and have presumed that the tendency toward thrombus formation in such subjects is thereby reduced also. In view of such findings, the effects of various saturated and unsaturated fatty acids, as well as their glyceryl esters, on platelet adhesiveness and aggregation in man and miniature pigs, is being studied in this laboratory.

The kinetics of the oxidation of several antioxidants in oxidizing fats

SummaryThe deterioration of hydroquinone, catechol, NDGA (nordihydroguaiaretic acid), and gallic acid in lard oxidizing at 100° C. has been quantitatively studied. Initial concentrations of 0.02, 0.1, and 0.5% were used.The results indicate that, in general, the deterioration of phenolic antioxidants in oxidizing fats does not occur as a single low order reaction but is complicated by products formed in the oxidation of the fat and possibly also of the antioxidant.The deterioration curves for gallic acid are quite different from those of the other three antioxidants. This is tentatively explained on the basis of the synergistic action of gallic acid upon itself.There is an increasing catalytic effect with increasing initial concentrations of all of these antioxidants on the formation of peroxides during the early stages of the autoxidation of lard.

The linoleic acid content of seed fats and the isomerism of linoleic acid

The linoleic acid content of a series of seed fats was determined by the thiocyanometric and the tetrabromide-precipitation methods in a search for isomeric linoleic acids. The results indicated the presence of only one form of linoleic acid. The tetrabromide number was shown to be affected by the pronounced solubility of alpha tetrabromostearic acid in the other bromides and in the solid acids, its determination therefore being of only limited value. The thiocyanogen numbers of pure linoleic and linolenic acids were found to be empirical values differing markedly from the theoretical constants, requiring a revision of the accepted equations for the calculation of the per cent concentration of the unsaturated acids in oils and mixed fatty acids.

Influence of Dietary Saturated and Unsaturated Fats on Blood Coagulation In Miniature Pigs.

Summary Miniature pigs maintained for one year on diets containing 15% of either beef tallow or safflower oil did not exhibit lipemia in the fasting state, yet the clotting time was much shorter in the tallow group than in the safflower group. The clotting time was shortened 3 hours after ingestion of either fat, but the effect produced by the saturated fat was much more pronounced than that produced by the unsaturated fat. The recalcified plasma clotting time was also a satisfactory measure of the increase in coagulability brought about by dietary fats, and served to detect differences in coagulability brought about by saturated and unsaturated fats.

The fluorescence of chlorophyll in fats in relation to rancidity

Summary1.) Difficulties in applying the “chlorophyll value” test to fat samples has led us to investigate the apparent “quenching” of chlorophyll fluorescence in mineral oil solution when cottonseed oil or lard is added to it. The disappearance of chlorophyll fluorescence in ultraviolet light caused by the addition of cottonseed oil appears to be due to the absorption of the light by the cottonseed oil and to the intense white fluorescence of the oil itself rather than to a chemical reaction of some constituent of the oil with the excited chlorophyll.2.) There was no evidence of a stoichiometric quenching reaction between chlorophyll and acceptor substances in the fats used in this study and, in consequence, no “endpoint” was observed in any of the titrations.3.) A lack of correlation between either the peroxide value or the stabilities measured in conventional ways and the amount of chlorophyll fluorescence of several fats makes the “chlorophyll value” test appear to have doubtful value as a generally applicable test for fat rancidity or stability.4.) The crude absorption curves here presented suggest that the greater absorption of near ultraviolet light by oxidized fats may be related to their content of fat peroxides.

HYPERCHOLESTEROLEMIC EFFECT OF MENHADEN OIL IN THE PRESENCE OF DIETARY CHOLESTEROL IN SWINE.

Summary Thirty male miniature swine were fed a beef tallow basal ration supplemented with crude soybean phosphatides and menhaden oil with and without 0.5% cholesterol for a period of 48 weeks. The animals that received no cholesterol supplement all maintained normal plasma cholesterol values (75–85 mg %). The swine fed soybean phosphatides plus cholesterol showed no change in plasma cholesterol values. The swine fed beef tallow showed on cholesterol supplementation a rise in plasma cholesterol, but returned to normal in 12 weeks. The swine fed menhaden oil showed a 100% increase in plasma cholesterol when supplemented with 0.5% cholesterol and, although this level decreased, it remained substantially above the remaining groups throughout the experiment. Fecal analyses of cholesterol showed much less cholesterol in the feces of fish oil-fed pigs supplemented with cholesterol, indicating that the fish oil (or the highly unsaturated fatty acids in fish oil) may have facilitated the absorption of the dietary cholesterol. The heart and liver analyses showed much lower levels of cholesterol than the other groups, suggesting that the polyunsaturated fatty acids of the fish oil may have aided in transport of the cholesterol to prevent an accumulation in these tissue sites.