Topical Area: Energy and Macronutrient Metabolism, Obesity
The aim of the study was to examine the role of dietary consumption of different types of fatty acids on metabolic risk factors and regional fat deposition in older men and women. We hypothesized that saturated fatty acid (SFA) intake, ratio of monounsaturated fatty acids (MUFA) to polyunsaturated fatty acids (PUFA), and total fat intake, as well as proportion of energy derived from fat, would be associated with markers of insulin resistance, hyperlipidemia, and ectopic fat.
Sedentary, obese (Body Mass Index: 29-48 kg/m2) adults (N=20) aged 45-78 years underwent two-hour oral glucose tolerance test, blood draw, DXA scan, and CT scan of the abdomen and mid-thigh. Seven-day diet records were analyzed with NutritionistPro software and the USDA Foodapedia feature of the Supertracker program.
Subjects had low fitness levels (VO2 max=23.5 ±2.4 mL/kg/min) and high total body fat (43.5±1.7%) with abdominal obesity (visceral adipose tissue area=192.4±18 cm2, subcutaneous abdominal adipose area=465.4±29 cm2) and intermuscular adipose tissue (IMAT) area in thigh (150.1±17 cm2). The average macronutrient composition of the diet was high in fat (fat as a percent of total kcal=35.5) with SFA, MUFA, and PUFA were respectively represented as 33.0, 34.8, and 22.1 percent of total fat intake. The average MUFA to PUFA ratio was 1.66. There were no differences in fatty acid intake between subjects with normal glucose tolerance and impaired glucose tolerance subjects.
The ratio of MUFA to PUFA was positively correlated with higher fasting glucose (r=0.42, P=0.06), glucose intolerance (r=0.43, P=0.06), and serum cholesterol (r=0.48, P=0.03). PUFA intake as a percentage of fat intake was associated with lower serum cholesterol (r=-0.44, P=0.05). Associations between diet composition with body composition (abdominal fat, IMAT) were not found to be uniformly significant among a homogenous sample of obese, sedentary subjects with diets high in proportion of lipid.
Dietary fatty acid intake, specifically MUFA unbalanced by PUFA, was associated with glucose intolerance and increased serum cholesterol, and therefore may confer increased risk for diabetes among obese, sedentary individuals. Future investigation of food sources, or context of dietary lipids, could lead to individualized dietary recommendations to promote healthy eating habits and potentially alter metabolic risk.
Funding Sources :
Supported by grant awards from the Department of Veteran’s Affairs and the National Institute of Health