Adherence to the Planetary Health Diet and Cognitive Decline: Findings from the ELSA-Brasil Study
In the global context, the Planetary Health Diet has been proposed as a way to improve human health while protecting the Earth. However, studies on the relationship between the Planetary Health Diet and cognitive decline are very limited. To fill this research gap, researchers Natalia Gomes Gonçalves, Leandro Teixeira Cacau, Naomi Vidal Ferreira, Paulo Andrade Lotufo, Alessandra Carvalho Goulart, Maria Carmen Viana, Sandhi Maria Barreto, Isabela Martins Bensenor, Dirce Maria Marchioni, and Claudia Kimie Suemoto conducted a study to reveal the relationship between the Planetary Health Diet and cognitive decline.
The researchers are from different academic and medical institutions in Brazil, and their findings were published in the journal Nature Aging. The study involved three waves of data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) and aimed to evaluate the association between the Planetary Health Diet and cognitive decline.
The study analyzed data from 11,737 participants (average age 51.6 years, 54% female, 53% white). Using linear mixed-effects models, the study found that a higher degree of adherence to the Planetary Health Diet was associated with a slower rate of memory decline (P = 0.046), and income was a modifier of this association (P < 0.001). In the high-income group, adherence to the Planetary Health Diet was associated with slower decline in memory (P = 0.040) and overall cognition (P = 0.009), whereas no such association was found in the low-income group. This suggests that promoting healthy eating patterns should consider income barriers and dietary habit differences to achieve high adherence.
The global process of urbanization has influenced dietary patterns, leading to increased consumption of ultra-processed, high-calorie, and animal-based foods. Unhealthy dietary patterns characterized by high sugar, red meat, and refined foods are associated not only with faster cognitive decline and higher dementia risk but also with environmental degradation. The EAT-Lancet Commission has set a series of global targets aimed at reducing the challenges associated with unhealthy diets and their related environmental threats through transitions toward healthy diets and environmentally safe food production, such as high fuel use, freshwater misuse, and biodiversity loss due to habitat destruction.
The Planetary Health Diet Index (PHDI) is developed based on the EAT-Lancet dietary recommendations, with scoring based on recommended intake of fruits, vegetables, nuts, legumes, whole grains, etc., to assess adherence to the EAT-Lancet diet.
The study results highlight multiple factors to be considered when promoting the Planetary Health Diet. Although this diet is associated with a lower risk of cardiovascular disease and stroke, achieving the EAT-Lancet diet goals may be unaffordable for more than 1 billion people globally due to cost. For low-income groups, implementing effective strategies to prevent dementia is even more crucial. Therefore, future research needs to explore the specific mechanisms by which income modifies the relationship between diet and health outcomes, to better understand the accessibility, costs, and behaviors determined by socioeconomic status in adhering to a sustainable diet.