Insulin response and changes in composition of non-esterified fatty acids in blood plasma of middle-aged men following isoenergetic fatty and carbohydrate breakfasts.
It was previously shown that a high plasma concentration of non-esterified fatty acids (NEFA) persisted after a fatty breakfast, but not after an isoenergetic carbohydrate breakfast, adversely affecting glucose tolerance. The higher concentration after the fatty breakfast may in part have been a result of different mobilization rates of fatty acids. This factor can be investigated as NEFA mobilized from tissues are monounsaturated to a greater extent than those deposited from a typical meal. Twenty-four middle-aged healthy Caucasian men were given oral glucose tolerance tests (OGTT), and for 28 d isoenergetic breakfasts of similar fat composition but of low (L) or moderate (M) fat content. The composition of NEFA in fasting and postprandial plasma was determined on days 1 and 29. No significant treatment differences in fasting NEFA composition occurred on day 29. During the OGTT and 0-1 h following breakfast there was an increase in plasma long-chain saturated NEFA but a decrease in monounsaturated NEFA (microg/100 microg total NEFA; P<0.001). Between 1 and 3 h following breakfast treatment differences occurred for total saturated and total monounsaturated fatty acids (microg/100 microg total NEFA; P<0.05), expressed as an increase in 18 : 1 and decreases in 16 : 0 and 17 : 0 in treatment M relative to treatment L (P<0.05). Serum insulin attained 35 and 65 mU/l in treatments M and L respectively during this period. Negative correlations were found between 16 : 0 in fasting plasma and both waist:hip circumference (P=0.0009) and insulin response curve area during OGTT (within treatment M, P=0.0001). It is concluded that a normal postprandial insulin response is associated with a rapid change in plasma saturated:monounsaturated NEFA. It is proposed that this change is the result of a variable suppression of fat mobilization, which may partly account for a large difference in postprandial total plasma NEFA between fatty and carbohydrate meals.
Frape
D L
DL
NS Research, The Priory, Churchyard, Mildenhall, Suffolk IP28 7EE, UK. david.l.frape@btinternet.com
Williams
N R
NR
Carpenter
K L
KL
Freeman
M A
MA
Palmer
C R
CR
Fletcher
R J
RJ
D000328:Adult; D000368:Aged; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000494:pharmacology*; D004041:Dietary Fats / Q000008:administration & dosage / Q000494:pharmacology*; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood*; D008297:Male; D008875:Middle Aged; D019518:Postprandial Period
D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified; D007328:Insulin