Thailand – how far are we from achieving a healthy and sustainable diet? A longitudinal ecological study

Background: Newly industrialized countries like Thailand have been influenced by globalization, westernization, and urbanization over the last decades, leading to changes in dietary habits as well as food production. Consequences of these changes include rising non-communicable diseases (NCDs) and environmental degradation, which are defined as the leading global challenges today. The objectives of this study are to identify Thailand's dietary changes, considering health and sustainability aspects, and to determine correlations between these changes and NCD cases as well as environmental impacts (GHG emissions, land-, nitrogen-, phosphorus-use). In this way, diet-related adjustments can be identified to promote planetary and human health. Methods: In this longitudinal ecological study, relative differences between the average food consumption in Thailand and the reference values of a healthy and sustainable diet, the Planetary Health Diet (PHD), were calculated. Furthermore, a bivariate correlation analysis was conducted, using data, based on Food and Agriculture Organization's (FAO's) data, results from the Global Burden of Disease Study (GBD), and PHD's reference values. Findings: The consumption quantities of meat, eggs, saturated oils, and sugar increased significantly since 1961. The food groups, that have exceeded PHD's upper reference values, include sugar (+452%), red meat (+220%), grains (+143%), saturated oils (+20%) and eggs (+19%), while vegetables (–63%), and unsaturated oils (–61%) have fallen below PHD's lower limits. Concerning the bivariate correlation analyses, all investigated variables show significant correlations. The most significant correlations were found in NCD cases (r = 0.903, 95% CI 0.804–0.953), nitrogen use (r = 0.872, 95% CI 0.794–0.922), and land use (r = 0.870, 95% CI 0.791–0.921), followed by phosphorus use (r = 0.832, 95% CI 0.733–0.897), and green-house gas (GHG) emissions (r = 0.479, 95% CI 0.15–0.712). Interpretation: The results show, that the determined differences of unhealthy or unsustainable food groups have increased concurrently with NCD cases and environmental impacts over the last decades in Thailand. A shift towards a reduced intake of sugar, red meat, grains, saturated oils and eggs along with an increase in vegetables and unsaturated oils, might support environmental and human health. Funding: None.