F. J. Mataix

Effects of adaptation to diets enriched with saturated, monounsaturated and polyunsaturated fats on lipid and serum fatty acid levels in miniature swine (Sus scrofa).

A total of 37 miniature swine (Sus scrofa) was fed with three diets of 9% fat content, differing only in the quality of the fat source (sunflower oil, olive oil and lard fat). Three groups of animals were fed for a 3 month period, and three other groups were fed for a 12 month period. After the two experimental periods, the influence of the diet on serum lipids and serum fatty acids was studied. In the short term, the serum cholesterol level was higher in the lard group, but with time, it undergoes a significant increase in the sunflower group, due to increases both in HDL-C and in LDL-C. In the olive oil group, LDL-C hardly varies with time, while HDL-C tends to decrease. In the lard group, LDL-C increases and HDL-C decreases. The atherogenic index is, in the long term, lower in the lard group and higher in the polyunsaturated fat group. The fatty acid composition of serum lipids in the long term shows a greater saturation index (SI) for the sunflower group and lard group, an increase in monounsaturated fatty acids in the olive oil group, and a higher percentage of linoleic acid in the sunflower group.

Influence of Dietary Supplementation with Fish on Plasma Fatty Acid Composition in Coronary Heart Disease Patients

The effects of dietary supplementation with fish on plasma fatty acid levels were studied in 20 coronary heart disease patients who had suffered acute myocardial infarction. The study was divided into three periods: hospital admission, after 8 weeks on a heart-healthy diet designed for patients with ischemic heart disease, and after 4 weeks on an n-3 fatty acid-supplemented diet in which red meat was replaced with lean and fatty fish. At the end of each period, the subjects responded to a 48-hour recall questionnaire, so that we could assess their compliance with the diet, and blood samples were collected for the determination of plasma fatty acids. Stearic fatty acid was significantly decreased after the fish diet. n-7 and n-9 fatty acids showed no significant changes throughout the study. At the end of the 4-week period when the fish diet was consumed, linoleic acid and its long-chain derivative docosapentaenoic acid (22:5 n-6) were significantly increased. The most notable changes in n-3 series fatty acids at the end of the third period were the significant decrease in linolenic acid and the significant increase in its long-chain derivatives eicosapentaenoic (20:5 n-3) and docosahexaneoic acid (22:6 n-3). These changes in plasma fatty acid levels may have beneficial effects on coronary heart disease.

Late postprandial pancreatic secretion periods in conscious dogs. Effect of vagotomy.

It is well established that, in the dog, the exocrine pancreatic secretion in response to food intake is a two-phased mechanism with a first phase during 0-4 h period and a second one during 8-12 h period. In the present study we have investigated the role played by the vagus nerve in the genesis of this late pancreatic hypersecretion (second phase) in dogs with truncal vagotomy and pyloroplasty. Truncal vagotomy totally suppressed the first phase of the pancreatic secretion; it did not abolish the second postprandial phase but it increased its latency by delay of 4 hours. In fact, during the 12-18 h period a pancreatic hypersecretory response was evidenced after vagotomy which appeared to be statistically significant as compared to basal values (P less than 0.001). Our results indicate that the vagus nerve does not play a role in the genesis of the late hypersecretory second phase.

Distal ileum resection totally suppresses the late pancreatic postprandial hypersecretion in conscious dogs.

Exocrine pancreatic secretion and serum levels of secretin, vasoactive intestinal peptide (VIP) and gastrin within postprandial 12 hours have been studied in dogs that have undergone a partial ileum resection (last 25 cm) 4 weeks before. In these conditions the following effects were observed: 1) the flow of pancreatic juice secreted after the food intake (1-4h period) was strictly similar to the flow described in intact dogs which did not suffer that surgical manipulation but it came back to its basal value more rapidly; 2) there were no effects regarding the postprandial hormonal pattern; 3) the late pancreatic hypersecretion period that is usually observed in intact dogs within the postprandial 8-12 h period, completely disappeared. These results allow to conclude that the mechanisms inducing the late hypersecretion process that usually takes place within the postprandial 8-12 h in dogs are generated in the distal ileum.

Recovery Study in Mg-Deficient Rats Given an Organic Source of Mg

Recovery from Mg deficiency was studied in rats given an organic source of Mg derived from yeast (Saccharomyces cerevisiae) cultured in an Mg gluconate-enriched medium, as the only source of Mg. Magnesium was given either at a rate above the RDA or as a supplement to the regular laboratory diet at the rate of 70 mg Mg/100 g food, of which 40 mg Mg was in the form of MgCO3 and the remaining 30 mg Mg was in the form of the organic product under study. The results showed a good degree of digestive and metabolic utilization of the organic compound, which led to the recovery of normal Mg levels in blood and bone by the end of the 1st week of treatment, and in muscle by the 3rd week of treatment. Muscle Mg content appears to be a good indicator of deficiency. Supplementation above the RDA failed to improve recovery rates in deficient animals.

Influence of dietary fat on plasma fatty acid composition in rats

We studied the influence of dietary fat on the plasma fatty acid composition in male Wistar rats fed four experimental semisynthetic, isocaloric diets containing different qualities of fat (olive oil, butter, medium chain triglycerides + corn oil 1:1 olive oil + butter + corn oil + medium chain triglycerides 1:1:1:1). The animals were studied from 21 days of age until a body weight of approximately 180 g (60 days) was reached. Under our experimental conditions, feeding with the different diets failed to modify the saturation index, calculated as the sum of the percentages of saturated fatty acids. In contrast, plasma levels of mono- and ω6 polyunsaturated fatty acids (sum of linoleic acid and its derivatives) were clearly influenced by the dietary content of these compounds. However, the relationship between percentage dietary plasma linoleic acid and percentage plasma ω6 polyunsaturated fatty acids was not directly proportional. Diets containing lower proportions of linoleic acid (butter and olive oil) led to significantly higher values (p<0.05 and p<0.02 respectively) of ω3 polyunsaturated acids (sum of linolenic acid and its derivatives) than diets with a larger proportion of this compound (medium chain triglycerides + corn oil, and olive oil + butter + corn oil + medium chain triglycerides).

Effects of Adaptation to Dietary Fat on Fatty Acid Composition of Serum and Serum Lipids in Miniature Swine

The influence of dietary fat on the serum fatty acid composition and distribution in different serum lipids was studied in 24 miniature swine (Sus scrofa) divided into 4 groups. Three groups were fed a low-fat chow with different kind of fats added (sunflower oil, olive oil and bovine lard) and the other group was fed a control diet with no fat added. The animals were fed the four diets for an experimental period of 12 weeks. Afterwards blood samples were taken to obtain serum, and the serum lipids were separated into the following fractions: phospholipids, triglycerides, and esterified cholesterol. The fatty acid composition of the serum and fractions was analyzed by gas chromatography. Under our experimental conditions, the fatty acid composition of the diets was reflected in serum, but not in all cases. In the triglyceride fraction the fatty acid composition was more evident. Our results show the interaction of the fatty acids in the different series and even within a single series, along with the endogenous synthesis processes.