Greenhouse gas emissions in relation to micronutrient intake and implications of energy intake: A comparative analysis of different modelling approaches.

Background: Human diets account for 30% of greenhouse gas emissions (GHGE). Reporting dietary GHGE with or without energy standardization yields different outcomes, often resulting in conflicting conclusions regarding associations with micronutrient intake.

Objectives: To compare methods of reporting dietary GHGE, with and without consideration of energy intake, and their respective associations with micronutrient intake.

Methods: Data were sourced from the Malmö Diet and Cancer Study, a cohort involving 25,970 participants. GHGE were estimated based on life cycle assessment data. The study explores different methods of reporting dietary climate impact: GHGE per day, GHGE per 1000 kcal, and with different energy adjustments. Association with micronutrient intake was modelled as daily intake and per 1000 kcal using linear regression models.

Results: Diets with higher GHGE per day were associated with a higher daily intake of all 17 examined micronutrients. When energy was included in the model, the results for GHGE per 1000 kcal aligned well with those for GHGE per day. However, using GHGE per 1000 kcal generally showed that higher GHGE were linked to lower daily micronutrient intake. Different methods of adjusting for energy intake yielded estimates with varying directions and magnitudes of associations.

Conclusion: This study highlights implications of energy intake when assessing the impact of dietary GHGE and demonstrates that the choice of GHGE modelling approach might have important consequences for the results and interpretation. The method of choice for modeling dietary GHGE in relation to micronutrient intake needs to be carefully considered in future studies.