A randomized controlled-feeding trial based on the Dietary Guidelines for Americans on cardiometabolic health indexes

The 2010 Dietary Guidelines for Americans (DGA) recommend nutrient needs be met by increasing fruit, vegetable, and whole-grain intake with the use of low-fat or fat-free dairy products and by reducing sodium, solid fats, and added sugars. However, the DGA, as a dietary pattern, have not been tested in an intervention trial.

The aim of this study was to evaluate the impact of a DGA-based diet compared with a representative typical American diet (TAD) on glucose homeostasis and fasting lipids in individuals at risk of cardiometabolic disease.

A randomized, double-blind, controlled 8-wk intervention was conducted in overweight and obese women selected according to indexes of insulin resistance or dyslipidemia. Women were randomly assigned to the DGA or TAD group (n = 28 DGA and 24 TAD). The TAD diet was based on average adult intake from the NHANES 2009-2010. The DGA and TAD diets had respective Healthy Eating Index scores of 98 and 62. All foods and beverages were provided during the intervention. Oral-glucose tolerance and fasting lipids were evaluated at 0, 2, and 8 wk of the intervention. Insulin resistance and sensitivity were estimated with the use of surrogates (e.g., homeostasis model assessment of insulin resistance).

By design, volunteers maintained their weight during the intervention. Fasting insulin, glucose, triglycerides, oral-glucose tolerance, and indexes of insulin resistance were not affected by either of the diets. Systolic blood pressure decreased in the DGA group (∼-9 mm Hg; P < 0.05). Total and HDL cholesterol also decreased in both groups (P < 0.05). Exploratory analysis comparing volunteers entering the study with insulin resistance and dyslipidemia with those with only dyslipidemia did not show an effect of pre-existing conditions on glucose tolerance or fasting lipid outcomes.

The consumption of a DGA dietary pattern for 8 wk without weight loss reduced systolic blood pressure. There were no differences between the DGA and TAD diets in fasting insulin, glucose, indexes of insulin resistance, or fasting lipids. This trial was registered at www.clinicaltrials.gov as NCT02298725.