Ruminant-Produced trans-Fatty Acids Raise Plasma Total and Small HDL Particle Concentrations in Male Hartley Guinea Pigs ,

Abstract

Although trans-fatty acid (tFA) intake has been positively associated with coronary heart disease (CHD), the relative effect of consuming industrially produced (IP)- compared with ruminant-produced (RP)-tFA on CHD risk factors is unclear. This study was designed to examine the effects of feeding partially hydrogenated vegetable oil (PHVO), IP-tFA source, and butter oil (BO), RP-tFA source, on the development of atherosclerosis and risk factors associated with CHD. Forty-eight male Hartley guinea pigs were fed a hypercholesterolemic diet containing (9% by weight) PHVO, BO, coconut oil (CO; positive control), or soybean oil (SO; negative control) for 8 or 12 wk (n = 6/group). Morphological analysis revealed that none of the groups developed atherosclerosis. Plasma and hepatic lipids did not differ between the tFA groups, but total and small HDL particles were significantly higher in the BO group than in the PHVO group and mean HDL particle size was significantly smaller in the BO group than in the PHVO group. Compared with the other treatment groups, the SO treatment resulted in significantly lower total cholesterol (TC) and LDL cholesterol in plasma, whereas hepatic TC was significantly higher in the SO group than in the other treatment groups. Plasma and hepatic cholesterol concentrations did not differ between the tFA and CO treatments. These results demonstrate that when fed at a high dose, IP- and RP-tFA had the same effect on established CHD risk factors in male Hartley guinea pigs. The effects of RP-tFA on HDL particle sizes and concentrations warrant further investigation.

Ruminant-Produced trans-Fatty Acids Raise Plasma HDL Particle Concentrations in Intact and Ovariectomized Female Hartley Guinea Pigs

“…Using these same test fats, we showed that when fed at a high level, IP-and RP-tFA had similar effects on traditional plasma cholesterol risk factors for CVD in male Hartley guinea pigs (14). In the guinea pig, however, RP-tFA, but not IP-tFA, resulted in increased levels of plasma total and small HDL particles, a particle profile that has been hypothesized to be associated with a decreased risk of CVD (14). Guinea pigs are an appropriate and often-used model for testing the effects of dietary interventions on established CVD risk factors because they have reverse cholesterol transport and metabolize lipoproteins similarly to humans (15).…”

“…Results also indicated that gender might play a role in the effects of IP-and RP-tFA intake on risk factors for CVD; RP-tFA raised plasma HDL-and LDL-cholesterol and large HDL and LDL particles in women, but not men, compared with IP-tFA. Using these same test fats, we showed that when fed at a high level, IP-and RP-tFA had similar effects on traditional plasma cholesterol risk factors for CVD in male Hartley guinea pigs (14). In the guinea pig, however, RP-tFA, but not IP-tFA, resulted in increased levels of plasma total and small HDL particles, a particle profile that has been hypothesized to be associated with a decreased risk of CVD (14).…”

“…Both the PHVO and BO test fats were previously used in the TRANSFACT clinical study (13) and in our prior investigation of tFA sources and CVD risk factors in male guinea pigs (14). The manufacture of the test diets has been described in detail elsewhere (18).…”

“…The composition of experimental guinea pig diets is shown in Supplemental Table 1 and was previously reported (14). Diets were prepared and pelleted by Teklad Custom Research Diets (Harlan Laboratories).…”

“…Thus, the equality in total trans-18:1 fatty acid amount allowed Plasma lipid and lipoprotein particle analysis. Plasma was isolated and the concentrations of total cholesterol (TC), TG, LDL-cholesterol, and HDL-cholesterol were determined using enzymatic assays (WAKO Diagnostics) as previously described (14). HDL, IDL, LDL, and VLDL particle sizes and concentrations were measured by H + NMR spectroscopy (Liposcience) as previously described (14).…”