Challenges in Designing and Delivering Diets and Assessing Adherence: A Randomized Controlled Trial Evaluating the 2010 Dietary Guidelines for Americans

Abstract

Background Controlled-feeding trials are challenging to design and administer in a free-living setting. There is a need to share methods and best practices for diet design, delivery, and standard adherence metrics. Objectives This report describes menu planning, implementing, and monitoring of controlled diets for an 8-wk free-living trial comparing a diet pattern based on the Dietary Guidelines for Americans (DGA) and a more typical American diet (TAD) pattern based on NHANES 2009–2010. The objectives were to 1) provide meals that were acceptable, portable, and simple to assemble at home; 2) blind the intervention diets to the greatest extent possible; and 3) use tools measuring adherence to determine the success of the planned and implemented menu. Methods Menus were blinded by placing similar dishes on the 2 intervention diets but changing recipes. Adherence was monitored using daily food checklists, a real-time dashboard of scores from daily checklists, weigh-backs of containers returned, and 24-h urinary nitrogen recoveries. Proximate analyses of diet composites were used to compare the macronutrient composition of the composite and planned menu. Results Meeting nutrient intake recommendations while scaling menus for individual energy intake amounts and food portions was most challenging for vitamins D and E, the sodium-to-potassium ratio, dietary fiber, and fatty acid composition. Dietary adherence for provided foods was >95%, with no differences between groups. Urinary nitrogen recoveries were ∼80% relative to nitrogen intake and not different between groups. Composite proximate analysis matched the plan for dietary fat, protein, and carbohydrates. Dietary fiber was ∼2.5 g higher in the TAD composite compared with the planned menu, but ∼7.4 g lower than the DGA composite. Conclusions Both DGA and TAD diets were acceptable to most participants. This conclusion was supported by self-reported consumption, quantitative weigh-backs of provided food, and urinary nitrogen recovery. Dietary adherence measures in controlled-feeding trials would benefit from standard protocols to promote uniformity across studies. The trial is registered at clinicaltrials.gov as NCT02298725.

Diet affects glycosylation of serum proteins in women at risk for cardiometabolic disease

“…In-depth information about the diet intervention including individual day menus are published in a methods manuscript outlining the process of designing, blinding the intervention from participants, and delivering the diets in this randomized controlled intervention [ 24 ]. Briefly, the energy balanced diets were designed to fit into one that matches the DGA pattern (2.3 cups fruits, 3.5cups of vegetables, 2.8 oz of whole grains, 2.4 oz of refined grains, 1.1 oz of seafood, 3.4 oz of meat, poultry and eggs, 0.8 oz of nuts and seeds, 3.3 cups of dairy and 15% total energy intake from solid fats and added sugars), and another that matches a TAD pattern (1 cup of fruits, 1.5 cups of vegetables, 1.1 oz of whole grains, 5.7 oz of refined grain, 0.6 oz of seafood, 5.4 oz of meat, poultry and eggs, 0.5 oz of nuts and seeds, 1.5 cups of dairy and 33% of total daily energy intake from solid fats and added sugars).…”

“…They were also instructed not to clean their dishes once they consumed each food or drink, and were asked to return containers as is, which were weighed at the WHNRC metabolic kitchen, to evaluate adherence to protocol. Based on both self-reported checklists, weigh backs, as well as 24-h urinary nitrogen measurements (measures taken at week 1, week 4, and week 7 of the intervention), adherence to the provided diet was between 80 and 95%, as reported in depth in the methods manuscript, along with more details about the menu and foods included as well [ 24 ].…”

An 8 week randomized Dietary Guidelines for Americans -based diet intervention improves the omega-3 index of healthy women

“…Study design. The present study used a randomized, double-blind, 8-week dietary intervention in 59 overweight and obese pre-and postmenopausal females registered at www.clinicaltrials.gov as 60 NCT02298725 conducted between Dec 2014 and Mar 2017.A detailed description of the study design has already been published [32,33]. All procedures were approved by the University of California, Davis (UC Davis), Institutional Review Board.…”

“…Pre-and postmenopausal females (n = 44) aged 20-65 years with a BMI (kg/m 2 ) of 25-39.9 were recruited for this intervention. Sample size was based on the study primary outcome investigating the impact of diet quality on glucose homeostasis in women with at least one risk factor for the metabolic syndrome [33].Sententary women or those with low physical activity 91 levels were recruited with inclusion criteria below the physical activity guidelines of moderate activity of 150 min/week, a resting blood pressure of <140/90 mmHg, and if they had 1 or more of the following clinical measures of glucose homeostasis or lipid metabolism: 100-126 mg/dL fasting glucose; 140-199mg/dL oral glucose tolerance test 2-h glucose; Quantitative Insulin Sensitivity Check Index score <0.315 [34]; homeostasis model assessment of insulin resistance (HOMA-IR) >3.67; HbA1c between 5.7-6.5, fasting triglycerides >150mg/dL; high density lipoprotein cholesterol <50mg/dL. Exclusion criteria included: resting blood pressure >140/90mmHg; hemoglobin <11.5g/dL; total cholesterol >300mg/dL; low density lipoprotein cholesterol >189mg/dL; triglycerides >400mg/dL; clinically diagnosed abnormal thyroid or liver function; the presence of any metabolic disease, gastrointestinal disorders, cancer or other serious chronic diseases; pregnancy or lactation; use of tobacco; use of medications for elevated lipids or glucose; regular use of prescription or over-the-counter medications in the 6mo before enrolling into the study; moderate or strenuous physical activity >30 min/d on >5 d/wk; weight change of >5% of body weight in the 6mo before enrolling into the study; working "graveyard" shifts or forced regular all-night wake cycles; dietary restrictions interfering with the intervention foods.…”

A Critical Review of the Study of Neuroprotective Diets to Reduce Cognitive Decline

“…Establish measures to achieve and assess adherence. Most RCTs have questionable long-term adherence to the dietary intervention selected [ 106 ]. To address this, there are two separate components to consider: achieving adherence and assessing adherence.…”