linoleic-acid and tetranorprostanedioic-acid

N-6 fatty acids are considered to promote diseases prevalent in industrialized countries and characterized by an increased eicosanoid biosynthesis from arachidonic acid (AA). We investigated the impact of the linoleic acid (LA) intake on AA levels in humans.. Six healthy female volunteers (age range 23-34 years) were given liquid formula diets (LFD) devoid of AA for 6 weeks, providing a constant intake of zero energy% (LFD 0: protein 15%, carbohydrates 85%) or 20 energy% (LFD 20: protein 15%, carbohydrates 55%, fat 30%) LA, for 3 weeks each. Fatty acids of plasma cholesteryl esters and platelet lipids were determined each week, and the prostaglandin biosynthesis was measured in 24-hour urine samples.. LFD 0 increased (+31% of initial value) and LFD 20 lowered (-30% of initial value) the percentage of AA in plasma cholesteryl esters and platelet lipids. Moreover, absence of dietary AA lowered the percentages of AA in plasma (-31% week 0 vs. week 6) and platelet (-11%) lipids, indicating a low transformation of LA. LFD 0 reduced urinary metabolite levels of prostaglandins D, E, and F in 24-hour urine samples (-48%, p < 0.001) within 24 h, but did not significantly affect platelet aggregation (-10%) and thromboxane formation (-25%). LFD 20 significantly lowered platelet aggregation (-25%) and thromboxane formation (-43%). The prostaglandin metabolite levels increased during the first 10 days, declined thereafter, and were lower than the preexperimental values at the end of the 3-week period.. The results show that dietary LA does not increase the AA levels in plasma or platelet lipids and does not persistently contribute to prostaglandin biosynthesis which is increased by AA intake with Western diets.

Topics: Adult; Arachidonic Acid; Blood Platelets; Dietary Fats, Unsaturated; Eicosanoids; Female; Humans; Linoleic Acid; Phospholipids; Platelet Aggregation; Prostaglandins; Prostanoic Acids; Reference Values; Statistics, Nonparametric; Thromboxanes; Time Factors

Prostaglandin formation, estimated by the determination of tetranorprostanedioic acid (TNPDA) in the urine, and platelet aggregation were investigated in seven healthy volunteers each day during fasting, and in three of them additionally during intake of carbohydrates (328kcal/day) or safflor oil (328 kcal, 20 g linoleic acid). Monitoring TNPDA in 8-h fractions of the urine showed a reduction during the night (23.00-07.00) by 70% on the average. During Days 1 and 2 of fasting the amount of TNPDA in 24-h urine was the same as under a conventional diet. On Day 3, TNPDA decreased in all experimental subjects to 162 micrograms/day on the average and was not changed by carbohydrate intake. A linoleic acid intake of 20 g/day increased TNPDA in 24-h urine to pre-experimental levels measured under free diet. Platelet aggregation did not change during the experiment. No relationship between prostaglandin formation and lipolysis in man was found.

Topics: Adult; Dietary Carbohydrates; Fasting; Female; Humans; Linoleic Acid; Linoleic Acids; Lipolysis; Male; Platelet Aggregation; Prostaglandins; Prostanoic Acids

Prostaglandin formation in healthy female volunteers was investigated during intake of different amounts of linoleic acid in liquid formula diets (LFD). The average amounts of the metabolites convertible to tetranorprostanedioic acid (TNPDA) were 123 +/- 5.2 (x +/- SEM), 175 +/- 7.0 and 352 +/- 10.8 microgram/day, during 2-week periods with a linoleic acid supply of 0, 4 or 20% of energy, respectively. The day-by-day variations in prostaglandin formation were less than the changes observed due to different amounts of linoleic acid. High linoleic acid intake was followed by an increase of TNPDA in the urine after 3-4 days, which was more pronounced when the linoleic acid intake during the period before had been low. In all persons, the highest amount of TNPDA, 411 +/- 13.2 microgram/day, was found between days 5 and 10 of high linoleic acid intake. From day 11 through day 14 an average of 372 +/- 14.3 microgram/day was found and the values were lower in 5 of 6 persons as compared to the values found between days 5 and 10. At the end of the experiment with LFD providing a linoleic acid supply of 0, 4 or 20% of energy, the percentage of cholesteryl linoleate in plasma increased (35 +/- 1.8, 48 +/- 1.0, 63 +/- 0.6) while those of cholesterylarachidonate decreased (14 +/- 1.0, 10 +/- 0.6, 8 +/- 0.6). During the periods without linoleic acid intake the TNPDA excretion was lowest in all persons. A reduction in linoleic acid supply resulted in a decrease of urinary TNPDA within 1 day.

Topics: Adult; Diet; Fatty Acids; Female; Humans; Linoleic Acid; Linoleic Acids; Prostaglandins; Prostanoic Acids