Measurement of apolipoprotein B-48 in the Svedberg flotation rate (S(f))>400, S(f) 60-400 and S(f) 20-60 lipoprotein fractions reveals novel findings with respect to the effects of dietary fatty acids on triacylglycerol-rich lipoproteins in postmenopausal women

Abstract

The present study was designed to examine whether the type of fat ingested in an initial test meal influences the response and density distribution of dietary-derived lipoproteins in the Svedberg flotation rate (S(f))>400, S(f) 60-400 and S(f) 20-60 lipoprotein fractions. A single-blind randomized within-subject crossover design was used to study the effects of palm oil, safflower oil, a mixture of fish and safflower oil, and olive oil on postprandial apolipoprotein (apo) B-48, retinyl ester and triacylglycerol responses in each lipoprotein fraction following an initial test meal containing one of the oils and a second standardized test meal. For all dietary oils, late postprandial (300 min) concentrations of triacylglycerol and apo B-48 were significantly higher in the S(f) 60-400 fraction than in the S(f)>400 fraction (P<0.02). Significantly greater apo B-48 incremental areas under the curve (IAUCs) were also observed in the S(f) 60-400 fraction than in the S(f)>400 fraction following palm oil, safflower oil and olive oil (P<0.04), with a similar non-significant trend for fish/safflower oil. Olive oil resulted in a significantly greater apo B-48 IAUC in the S(f)>400 fraction (P<0.02) than did any of the other dietary oils, as well as a tendency for a higher IAUC in the S(f) 60-400 fraction compared with the palm, safflower and fish/safflower oils. In conclusion, we have found that the majority of intestinally derived lipoproteins present in the circulation following meals enriched with saturated, polyunsaturated or monounsaturated fatty acids are of the density and size of small chylomicrons and chylomicron remnants. Olive oil resulted in a greater apo B-48 response compared with the other dietary oils following sequential test meals, suggesting the formation of a greater number of small (S(f) 60-400) and large (S(f)>400) apo B-48-containing lipoproteins in response to this dietary oil.