Comparison of diets enriched in stearic, oleic, and palmitic acids on inflammation, immune response, cardiometabolic risk factors, and fecal bile acid concentrations in mildly hypercholesterolemic postmenopausal women—randomized crossover trial

Abstract

Background Direct comparisons between SFAs varying in chain length, specifically palmitic acid (16:0) and stearic acid (18:0), relative to the latter's metabolic product, oleic acid (18:1), on cardiometabolic risk factors are limited. Objective The aim of this study was to determine the relative comparability of diets enriched in palmitic acid, stearic acid, and oleic acid on inflammation and coagulation markers, T lymphocyte proliferation/ex-vivo cytokine secretion, plasma cardiometabolic risk factors, and fecal bile acid concentrations. Methods Hypercholesterolemic postmenopausal women (n = 20, mean ± SD age 64 ± 7 y, BMI 26.4 ± 3.4 kg/m2, LDL cholesterol ≥ 2.8 mmol/L) were provided with each of 3 diets [55% energy (%E) carbohydrate, 15%E protein, 30%E fat, with ∼50% fat contributed by palmitic acid, stearic acid, or oleic acid in each diet; 5 wk/diet phase] using a randomized crossover design with 2-wk washouts between phases. Outcome measures were assessed at the end of each phase. Results Fasting LDL-cholesterol and non–HDL-cholesterol concentrations were lower after the stearic acid and oleic acid diets than the palmitic acid diet (all P < 0.01). Fasting HDL-cholesterol concentrations were lower after the stearic acid diet than the palmitic acid and oleic acid diets (P < 0.01). The stearic acid diet resulted in lower lithocholic acid (P = 0.01) and total secondary bile acid (SBA) concentrations (P = 0.04) than the oleic acid diet. All other outcome measures were similar between diets. Lithocholic acid concentrations were positively correlated with fasting LDL-cholesterol concentrations (r = 0.33; P = 0.011). Total SBA, lithocholic acid, and deoxycholic acid concentrations were negatively correlated with fasting HDL cholesterol (r = −0.51 to −0.44; P < 0.01) concentrations and positively correlated with LDL cholesterol:HDL cholesterol (r = 0.37–0.54; P < 0.01) ratios. Conclusions Dietary stearic acid and oleic acid had similar effects on fasting LDL-cholesterol and non–HDL-cholesterol concentrations and more favorable ones than palmitic acid. Unlike oleic acid, the hypocholesterolemic effect of stearic acid may be mediated by inhibition of intestinal hydrophobic SBA synthesis. These findings add to the data suggesting there should be a reassessment of current SFA dietary guidance and Nutrient Facts panel labeling. This trial was registered at clinicaltrials.gov as NCT02145936.

Palmitic Acid Versus Stearic Acid: Effects of Interesterification and Intakes on Cardiometabolic Risk Markers—A Systematic Review

“…The concentrations of TAG did not differ between the diets [15][16][17][18][19][20][21][22][23][24], except in one study, where the TAG concentrations were lower after an interesterified stearic acid-rich diet [12]. However, the majority of studies found lower TC concentrations on the stearic acid-rich diet as compared with palmitic acid [15][16][17][18][19][20]23]. In five of these studies, LDL-C concentrations were also decreased [16][17][18]20,23], and in two studies the concentration of LDL-C tended to be lower on stearic acid [12,19].…”

“…In five of these studies, LDL-C concentrations were also decreased [16][17][18]20,23], and in two studies the concentration of LDL-C tended to be lower on stearic acid [12,19]. Lower HDL-C concentrations on the stearic acid-rich diet were found in three studies [17,19,20], while in seven other studies, no significant differences were found [12,16,18,[21][22][23][24]. No changes in concentrations of very-low density lipoprotein (VLDL)-C were reported [17,19,20].…”

“…Lower HDL-C concentrations on the stearic acid-rich diet were found in three studies [17,19,20], while in seven other studies, no significant differences were found [12,16,18,[21][22][23][24]. No changes in concentrations of very-low density lipoprotein (VLDL)-C were reported [17,19,20]. Of the studies that measured apoB and apoA1 [12,17,19,23], one observed decreased concentrations of apoB [17] and two of apoA1 [17,19] on the stearic acid-rich diet.…”

“…Eleven studies have compared side-by-side the effects of diets that are rich in palmitic acid with those of diets rich in stearic acid on fasting cardiometabolic risk markers (Tables 2 and A3). The palmitic acid sources used were palm oil [15][16][17][18][19][20], (interesterified) palm olein [21,22], a blend containing tripalmitin [23], and palm stearin [22]. For stearic acid-rich diets, cocoa butter [15,19,20,24], hydrogenated soybean oil [16,21], shea butter [17,18], hydrogenated canola [22], a blend containing tristearin [23], and an interesterified blend containing fully hydrogenated soybean oil [12] were used.…”

“…However, the majority of studies found lower TC concentrations on the stearic acid-rich diet as compared with palmitic acid [15][16][17][18][19][20]23]. In five of these studies, LDL-C concentrations were also decreased [16][17][18]20,23], and in two studies the concentration of LDL-C tended to be lower on stearic acid [12,19]. Lower HDL-C concentrations on the stearic acid-rich diet were found in three studies [17,19,20], while in seven other studies, no significant differences were found [12,16,18,[21][22][23][24].…”