Randomized Trial Comparing Consumption of Military Rations to Usual Intake for 21 Consecutive Days: Nutrient Adequacy and Indicators of Health Status.

BACKGROUND: The US military Meal, Ready-to-Eat food ration is approved as a nutritionally adequate sole source of nutrition for ≤21 days. However, the ration continuously evolves, requiring periodic reassessment of its influence on nutritional status and health. OBJECTIVE: To determine the effects of consuming the US Armed Services Meal, Ready-to-Eat ration for 21 days, relative to usual diets, on nutrient intake, and indicators of nutritional status and cardiometabolic health. DESIGN: Parallel-arm, randomized, controlled trial, secondary analysis. PARTICIPANTS: Sixty healthy, weight stable, free-living adults from the Natick, MA, area participated between June 2015 and March 2017. INTERVENTION: Participants were randomized to consume their usual diet for 31days (CON), or a strictly controlled Meal, Ready-to-Eat-only diet for 21 days followed by their usual diet for 10 days (MRE). MAIN OUTCOME MEASURES: Nutrient intake (absolute and adjusted) throughout the study period, and indicators of nutrition status (vitamins B, D, folate, homocysteine, iron, magnesium, and zinc) and cardiometabolic health (glucose, insulin, and blood lipid levels) before (Day 0), during (Day 10 through Day 21), and after (Day 31) the intervention period. STATISTICAL ANALYSIS PERFORMED: Between-group differences over time were assessed using marginal models. Models for nutritional status and cardiometabolic health indicators were adjusted for age, initial body mass index, and baseline value of the dependent variable. RESULTS: Energy-adjusted fiber; polyunsaturated fatty acids; vitamins A, thiamin, riboflavin, B-6, C, D, and E; and magnesium and zinc intakes all increased in MRE during the intervention and were higher compared with CON (P<0.05), whereas relative protein intake decreased and was lower (P<0.05). Serum triglyceride concentrations averaged 19% (95% CI 0% to 41%) higher in MRE relative to CON during Days 10 to 31 (P=0.05). No statistically significant effects of diet on any other nutritional status or cardiometabolic health indicators were observed. CONCLUSIONS: Findings demonstrate that a Meal, Ready-to-Eat ration diet can provide a more micronutrient-dense diet than usual dietary intake aiding in maintenance of nutritional status over 21 days.