Effect of synthetic triglycerides of myristic, palmitic, and stearic acid on serum lipoprotein metabolism

Abstract

Objectives: To determine relative effects of diets high in synthetic sources of myristic (14:0), palmitic (16:0) or stearic (18:0) acid on concentrations and metabolism of serum lipoproteins. Design: Eighteen healthy women participated in a three-way cross-over study for ®ve week periods separated by seven week washout periods, diets were assigned in random order. Subjects: Premenopausal women, not on medication, were from three races (Caucasian, African-American, Asian) and four apolipoprotein E phenotype groups (3a3, 3a2, 4a3, and 4a2). Intervention: During the ®rst week the subjects consumed a baseline diet providing 11 energy (en)% saturated fat, 10 en% polyunsaturated fat and 14 en% monounsaturated fat. Followed by test diets with 19 en% saturated fat (including 14 en% test saturated fatty acid), 3 en% polyunsaturated fat, and 14 en% monounsaturated fat for four weeks. Synthetic fats (trimyristin, tripalmitin, and tristearin) were used in blends with natural fats and oils. Results: Mean concentrations of serum total, esteri®ed and LDL cholesterol were signi®cantly lower after 18:0 than after 16:0 (n 16 ± 18, P`0.01 for treatment effect). Myristic acid (14:0) had an intermediate effect.Receptor-mediated degradation of 125 I-LDL in mononuclear cells obtained from the subjects was lower after 16:0 than after 14:0 and 18:0 (n 16 ± 18, P 0.05 for treatment effect). Differences in the digestibilities of the fats were not a major factor in the results. Strong cholesterolemic responses to the 16:0 diet were partly explained by apoE phenotype. Conclusions: As noted previously, stearic acid was neutral compared to 14:0 and 16:0. In contrast to studies involving natural fats, 14:0, fed as a synthetic triglyceride, was less cholesterolemic than 16:0 in a majority of subjects. ApoE phenotype in¯uenced the cholesterolemic response particularly when diets high in 16:0 were eaten.

Stearic acid is well absorbed from short- and long-acyl-chain triacylglycerol in an acute test meal

“…The proportion of fatty acids (free, soaps or derived from acylglycerols) of the total lipids has rarely been reported, but the fatty acid concentration in feces has been between 0.2 and 6 g/day (Bonanome and Grundy, 1988;Denke et al, 1993), typically 2-4 g/day (see e.g. Denke and Grundy, 1991;Dougherty et al, 1995;Snook et al, 1999). In the present study, crude fat excretion was at the expected level.…”

Triacylglycerol structure and interesterification of palmitic and stearic acid-rich fats: an overview and implications for cardiovascular disease

“…Others have also reported stearic acid to be well digested whether distributed in the sn-1 and sn-3 positions of the dietary TAG (49) or as a randomly interesterified stearic acid-rich fat (46,50 -52) . Human studies have also shown that the digestibility of palmitic acid is high in human subjects when in the outer positions (47,48) , or randomly distributed on all three positions of the glycerol (51) .…”

“…Furthermore, Grande et al (3) found that native cocoa butter and an artificial interesterified TAG mixture with the same fatty acid composition as native cocoa butter produced similar serum cholesterol concentrations (3) , suggesting no effect of positional composition on lipids in humans. Others have reported that randomly interesterified fats rich in stearic acid lower cholesterol concentrations (mainly from LDL) compared with baseline diets (46,51,73,74) in human subjects. Forsythe et al (75) recently reported a lower total cholesterol concentration (by 0·2 mmol/l; P ¼ 0·02) following palmitic acid-rich diets (8 % energy from palmitic acid) with palmitic acid in the sn-2 position (65 % palmitic acid in the sn-2 position; lard) compared with palmitic acid in the sn-1 and sn-3 positions (23 % palmitic acid in the sn-2 position; palm-stearin), but no differences in HDL-and LDL-cholesterol or TAG concentrations (75) .…”

Influence of triacylglycerol structure of stearic acid-rich fats on postprandial lipaemia

“…However, the synthetic randomised 18: 0-rich fat SALATRIM (34 g 18 : 0/d) has been found to result in a low fat digestibility and a high 18: 0 excretion of 7-12 g/d (Finley et al 1994). Snook et al (1999) have reported increased faecal (1995) have reported lower fat digestibility following consumption of a diet high in native shea butter (25 g 18: 0/d) compared with a low-18 : 0 diet. In contrast, the digestibility of liquid oils is >95%.…”