Habitual Dietary Fat Intake Research Articles

Dietary fat and insulin sensitivity in a triethnic population: the role of obesity. The Insulin Resistance Atherosclerosis Study (IRAS)

From the Insulin Resistance Atherosclerosis Study (IRAS), 1173 men and women of African-American, non-Hispanic white, and Hispanic ethnicity with no history of diabetes were included in an evaluation of the cross-sectional relation of habitual dietary fat intake with insulin sensitivity (SI) as assessed by minimal-model analysis of a 12-sample, insulin-modified frequently sampled intravenous-glucose-tolerance test. Dietary intake was measured by a food-frequency interview modified to enhance sensitivity to food choices within the three ethnic groups. Percentage of energy from total fat was associated with rank of SI (SI(rank); r = -0.06, P = 0.03), with log fasting insulin (r = 0.10, P < 0.001), and with BMI (r = 0.10, P < 0.001). Multiple-linear-regression models included SI(rank) as the dependent variable, dietary fat (g/d) as the primary independent variable adjusted sequentially for total energy, other covariates, body mass index, and waist-hip circumference ratio (WHR). For all subjects combined, total fat intake was inversely related to SI(rank), but this association was not significant (P = 0.14) and was attenuated by adjustment for body mass index and WHR (P = 0.44). The association of total fat (g/d) with SI(rank) differed significantly (P < 0.01) for obese compared with nonobese individuals. Higher fat intake was associated with lower SI(rank) among obese (beta = -1.40, P = 0.03) but not among nonobese persons (beta = 0.16, P = 0.80). Among the obese (body mass index < or = 63), adjustment for body mass index largely accounted for the observed association of dietary fat with SI(rank). These findings were generally consistent for monounsaturated, polyunsaturated, and saturated fats. Among individuals already at increased risk for non-insulin-dependent diabetes mellitus because of obesity, high intake of dietary fat may worsen insulin sensitivity. This effect may be mediated by the relation of dietary fat to obesity.

Plasma factor VII and its relation to adipose tissue fatty acids and other atherogenic risk factors in healthy men.

In this study the authors examined the relationships of plasma factor VII (F-VII) to adipose tissue fatty acid composition, as an objective index of the habitual dietary fat intake, as well as to a number of other atherogenic risk factors in 60 healthy male volunteers (aged 38 years). Significant positive correlations were found between plasma F-VII [measured as antigen (F-VIIAg) and coagulant activity, using bovine thromboplastin (F-VIIbt)] and body mass index (BMI), waist-thigh girth ratio (WTR), cigarette smoking and plasma triglyceride concentration. After adjustment for BMI, only plasma triglycerides remained positively correlated with F-VII (r = 0 center dot 27, P = 0 center dot 03, and r = 0 center dot 29, P < 0 center dot 01, for F-VIIbt and F-VIIAg respectively). A significant positive relation was found between F-VII and the total proportion of fatty acid as monounsaturated fatty acid (r = 0 center dot 26, P < 0 center dot 05, for F-VIIAg), whereas inverse relations were found between F-VII, the total proportion of fatty acid as polyunsaturated fatty acid (r = -0 center dot 26 and r = -0 center dot 25, P < 0 center dot 05, for F-VIIbt and F-VIIAg respectively), polyunsaturated-saturated fat ratio (r = -0 center dot 25, P < 0 center dot 05, for F-VIIbt) and, more significantly, between F-VII and adipose-tissue alpha-linolenic acid (r = -0 center dot 29, P < 0 center dot 01, for F-VIIbt and r = -0 center dot 49, P < 0 center dot 001, for F-VIIAg). All these correlations remained significant after matching for BMI. In a multiple linear regression analysis, only adipose tissue alpha-linolenic acid was a negative and independent predictor of F-VIIAg (P = 0 center dot 004) and, at borderline significance, of F-VIIbt (P = 0 center dot 061) when allowance was made for BMI, WTR, smoking and plasma triglycerides. In conclusion, this study shows significant relations between F-VII and adipose tissue fatty acid composition in healthy male individuals; it supports the possibility that adipose tissue poly-unsaturated fatty acids, derived from dietary intake, play a role in the relation between F-VII and coronary heart disease (CHD), thus suggesting that high dietary polyunsaturated fatty acid intake (especially alpha-linolenic acid) may reduce the risk for CHD by an improvement of a number of risk factors, including a lowering of plasma F-VII (both activity and antigen).

Plasma fatty acid composition as an indicator of habitual dietary fat intake in middle-aged adults. The Atherosclerosis Risk in Communities (ARIC) Study Investigators

We compared the plasma fatty acid (FA) composition of the habitual diet, measured by a 66-item semiquantitative food-frequency questionnaire (FFQ), with the corresponding plasma phospholipid and cholesterol ester (CE) FA composition measured by gas chromatography in 3570 free-living, middle-aged adults. Pearson correlations between dietary and plasma FA (expressed as % of total FAs) for phospholipid and CE, respectively, were as follows: saturated FA (r = 0.15 and 0.23), monounsaturated FA (r = 0.05 and 0.01), polyunsaturated FA (r = 0.25, 0.31), linoleic acid (r = 0.22 and 0.28), linolenic acid (r = 0.15 and 0.21), eicosapentaenoic acid (r = 0.20 and 0.23), and docosahexaenoic acid (r = 0.42 and 0.42). The correlations between diet and plasma FAs held relatively constant regardless of whether participants were overweight, had chronic diseases, were alcohol drinkers, or were cigarette smokers. However, at similar reported dietary intakes, the plasma lipid concentration of saturated FAs was higher and/or that of linoleic acid was lower in people with these characteristics compared with those without these characteristics.

Differences in adipose tissue fatty acid composition between black and white men in New Orleans

We report fatty acid composition in perirenal and buttock adipose tissue in 714 deceased black and white men aged 25–44 yr in New Orleans. Percent saturated fatty acids were higher (p less than 0.001) whereas percent monounsaturated fatty acids were lower (p less than 0.001) in perirenal than in buttock fat. Percent linoleic acid was similar in both races. We conclude that dietary intake of linoleic acid is similar in both races. The trend of decreasing linoleic acid with advancing age suggests that either intake of linoleic acid progressively decreases or its mobilization rate increasingly exceeds deposition rate or both. Percent palmitoleic acid (16:1) is lower (p less than 0.001) and that of stearic acid (18:0) is higher (p less than 0.001) in blacks than in whites. We believe no explanation can rest solely on differences in habitual dietary fat intake.