Impact of sustainable diets on micronutrient intakes and status: outcomes of the MyPlanetDiet randomized controlled trial

Background: Data from dietary intervention studies to test the ability of sustainable diets to meet micronutrient (MN) requirements is required. Objectives: To compare MN intakes and status among adults who received dietary counseling to follow a sustainable diet or a standard healthy diet. Methods: We conducted a single-blind, randomized controlled trial among 355 healthy adults aged 18‒64 y in 3 centers over 12-wk. Participants received personalized dietary counseling; the intervention arm for a sustainable healthy diet, and the control arm for a healthy diet. Greenhouse gas emissions (GHGEs), MNs, and biomarkers of nutritional status were assessed, and the prevalence of inadequate intakes was defined by the proportion of participants with usual intakes below harmonized average requirements. Data were analyzed using a 2-way mixed analysis of covariance (time and treatment) on complete cases. Results: There were differential changes in intakes in the intervention arm compared to controls for GHGE (‒22%), energy (‒8%), retinol (‒25%), thiamin (‒11%), riboflavin (‒16%), niacin (‒16%), calcium (‒16%), zinc (‒13%), potassium (‒10%), selenium (‒15%), and iodine (‒26%), vitamins B₆ (‒12%), vitamin B₁₂ (‒36%), vitamin C (‒23%), vitamin D (‒28%) and vitamin K₁ (30%) (P-_interaction < 0.05). These were consistent following energy adjustment for retinol, riboflavin, niacin, calcium, iodine, and vitamins B₁₂ and K_1. The prevalence of inadequate intakes of riboflavin, vitamins B₆ and B₁₂, calcium, and zinc increased considerably, and at the endpoint, there was a higher prevalence of inadequate intakes in the intervention arm for riboflavin, vitamins B₆, B₁₂, and C, calcium, zinc, and selenium than in controls. Iron, iodine, vitamins A, D, E, C, and K₁ status did not change. Conclusions: A diet based on sustainable dietary principles lowered dietary GHGE and several MNs, despite the provision of daily servings of dairy, 3 weekly servings of animal protein, and 2 servings of fish. These findings show that MNs should be considered in developing environmentally protective diets. This trial was registered at clinicaltrials.gov as NCT05253547.