| Low fat intake is thought to be healthy while high fat intake may compromise health. The effects of dietary fat intake on nutrient intake, cardiovascular risk factors, and inflammatory mediators as related to total body and white blood cell (WBC) fat oxidation (FO) in sedentary healthy individuals were investigated. Five men and 6 women were randomly assigned to 2 diets (19% and 50% calories from fat) for 3 weeks each, with a one-week washout, compared to their habitual diet (30% calories from fat). Food intake and activities were recorded. Subjects were tested before and after each diet. With an overnight fast, body composition was measured and blood was drawn for plasma lipid analysis. On another day, a graded treadmill test was performed to estimate total body FO. Prior to and after exercise, blood samples were collected to determine WBC FO and inflammatory mediators. It was found that the total caloric intake was matched to expenditure on the 30% and 50% fat diets; however, it was decreased on the 19% fat diet and resulted in weight loss. Increased fat intake improved the consumption of vitamin E and zinc, and HDL-C concentration. Decreasing fat intake to 19% of calories lowered apolipoprotein A1 concentration. FO per WBC decreased after exercise, which could be due to the increase in leukocyte count. Total body FO and WBC FO were not influenced by diet. Plasma tumor necrosis factor (TNF)-α, interleukin (IL)-2, and soluble vascular cell adhesion molecule (sVCAM)-1, and in vitro productions of IL-1β and IL-6 by peripheral blood mononuclear cells stimulated with lipopolysaccharide were increased after exercise. Plasma soluble intercellular adhesion molecule (sICAM)-1 was increased after exercise but only on the 19% fat diet. In conclusion, this study demonstrated that the 19% fat diet failed to support calories to maintain body weight, reduced some micronutrient intakes, had adverse effects on lipoprotein profile, and resulted in increased plasma sICAM-1 concentration post-exercise in sedentary subjects. Dietary fat intake had no effect on FO. As WBC FO was not affected by diet and only slightly affected by exercise, it may reflect the genetic predisposition for FO. |
