Serum nefa following fat, carbohydrate and protein ingestion, and during fasting as related to intracellular lipid deposition

Abstract

Summary The design of this controlled clinical trial permits direct quantitative comparison of changes in the concentrations of non-esterified fatty acids, triglycerides, total cholesterol and phospholipids following fat, carbohydrate and protein test meals and during the prolonged fasting state. Direct comparison can also be made, after carbohydrate ingestion and during the prolonged fasting state, between the concentration of these serum lipid constituents and previous serum measurements of intracel-lular lipid deposition in human aortic cells and MAF cells in tissue culture. The data collected in this controlled randomized clinical trial permitting a direct comparison of changes in serum lipid concentration demonstrate that: (1) Fat ingestion was folio wed in postprandial serum specimens (3–9 hours) by a marked increase in NEFA, a moderate increase in triglycerides, a slight increase in phospholipids and no change in total cholesterol concentration. (2) Carbohydrate ingestion was followed by a sharp decrease and then an over-shoot of serum NEFA concentration. Other lipid measurements were unchanged. (3) Protein ingestion was followed by a moderate decrease and then a gradual rise to just above the initial fasting level of serum NEFA concentration. Other lipid measurements were unchanged. (4) During the prolonged fasting state there was a continuous increase in the serum NEFA concentration with no change in the other lipid measurements. There was a remarkable parallelism between the sharp dip after carbohydrate ingestion and the continuous rise during the prolonged fasting state of serum non-esterified fatty acid levels, and the changes in intracellular lipid deposition in tissue culture cells from serum specimens collected under similar experimental conditions.