Development of a reliable and valid nutritional knowledge questionnaire for urban South African adolescents

Objective First, we wanted todispel the myth that avocados are fattening and therefore should beavoided in energy-restricted diets. Second, we examined the effects ofavocados, a rich source of monounsaturated fatty acids, as part of anenergy-restricted diet on weight loss, serum lipids, fibrinogen, andvascular function in overweight and obesesubjects. Methods Sixty-one free-livingvolunteers (13 men and 48 women), with body mass index of 32 ±3.9 kg/m2 (mean ± standard deviation)participated in this randomized, controlled, parallel study. Subjectswere paired and randomly assigned to one of two groups. Theexperimental group consumed 200 g/d of avocado (30.6 g of fat), whichsubstituted for 30 g of other mixed dietary fats such asmargarine or oil, and the control group excluded avocado from theirenergy-restricted diet for 6 wk. Seven-day isoenergetic menus wereplanned according to mean energy requirements of both sexes to providetotal energy intakes consisting of 30% fat, 55%carbohydrates, and 15% protein. Anthropometric measurements,physical activity, blood pressure, and arterial compliance weremeasured with standard methods at the beginning and end of theintervention. Fasting blood samples were drawn at the beginning and endof theintervention. Results Fifty-five subjectscompleted the study. The compliance rate to avocado intake in theexperimental group was 94.6%. The percentage of plasma oleicacid increased significantly with the consumption of avocado in theexperimental group, whereas a decrease was seen in the percentage ofmyristic acid from baseline to the end of the intervention in bothgroups but was significant only in the experimental group.Anthropometric measurements (body mass, body mass index, and percentageof body fat) decreased significantly in both groups during the study(P < 0.001), and the change was similar inboth groups. Serum lipid concentrations (total cholesterol, low-densitylipoprotein cholesterol, high-density lipoprotein cholesterol, andtriacylglycerols), fibrinogen, blood pressure, and arterial compliancedid not change significantly within or betweengroups. Conclusion Theconsumption of 200 g/d of avocado within an energy-restricted diet doesnot compromise weight loss when substituted for 30 g of mixeddietary fat. Serum lipid concentrations, plasma fibrinogen, arterialcompliance, and systolic and diastolic blood pressures were notaffected by weight loss or avocadointake.