Can the planetary health eating regimen save your life and the planet? Study finds mixed results

In a recent study published in JAMA Network Open, researchers evaluate the impact of planetary health eating regimen (PHD) adherence on environmental and human health.

Study: Adherence to a Planetary Health Food plan, Environmental Impacts, and Mortality in Chinese Adults. Image Credit: Created with the help of DALL·E 3

Background

PHD is characterised by an increased consumption of plant-based foods and reduced intake of animal food products. The influence of PHD on environmental and mortality outcomes amongst Asians is unknown.

Previous studies have proposed grading techniques to quantify PHD adherence; nevertheless, no agreement has been reached. Moreover, these trials were exclusively performed amongst Western individuals without considering individual-level calorie consumption and varied levels of PHD adherence.

To this point, few studies have evaluated the link between PHD, environmental variables, and mortality using individual-level data.

Concerning the study

In the current study, researchers investigate whether PHD scores were related to environmental effects and fatalities amongst Chinese Singaporeans. To this end, a grading system was devised to guage PHD adherence and study the associated benefits to environmental and human health.

The researchers examined the Singapore Chinese Health Study (SCHS) participants’ data. Individuals with out a history of heart problems or cancer and everlasting residents of Singapore speaking Cantonese or Hokkien dialects were enlisted from 1993 to 1998 and followed up on utilizing record linkage data until 2020. Data were analyzed between September 2022 and April 2023.

PHD scores were determined using standardized food frequency questionnaires recording the consumption of 14 dietary elements in PHD and individual calorie intake. These surveys were also used to quantify the environmental implications of the eating regimen. Death outcomes, including all-cause mortality, respiratory disease, heart problems, and cancer, were ascertained using national registry data.

The entire water footprint (TWF), land utilization, and greenhouse gas (GHG) release were estimated using the China Health and Nutrition Survey database. These data were used to find out dietary impacts on the environment based on the mean effects determined by dividing the environmental effects by each gram of a food item consumed by the amount consumed. The quantity of GHG emitted was calculated from the period between food production and consumption.

TWF was calculated using the WF Network database for non-aquatic foods, whereas for aquatic food items, TWF was determined using a previous study’s technique. The Food and Agriculture Organization (FAO) database was used to estimate land utilization.

Skilled interviewers performed offline interviews utilizing standardized inquiries to obtain data. The International Classification of Diseases, Ninth and Tenth Revisions (ICD-9 and 10) codes were used to categorize deaths.

Linear regression modeling was performed to find out the relationships between PHD scores and environmental effects, adjusting for age, gender, body mass index (BMI), educational attainment, physical activity, smoking status, alcohol intake, sleep duration, total calorie intake, diabetes, and hypertension. Cox proportional regression modeling was performed to find out the hazard ratio (HR) values for the relationships between PHD scores and mortality risks.

Sensitivity analyses were conducted by excluding participants with diabetes or hypertension, in addition to those that died inside five years after enrollment, and utilizing PHD-S computed using various methodologies. The researchers eliminated 1,060 individuals with an implausible calorie intake of lower than 600 or over 3,000 kcal per day for girls and lower than 700 or over 3,700 kcal per day for males.

Study findings

A complete of 57,078 individuals were included within the study, with a mean age of 56 years, 56% of whom were female. During a median follow-up of 23 years, 22,599 deaths were reported.

The median PHD rating was 55 points and ranged from 13 to 95 points. PHD adherence was low among the many participants, with over 80% reporting good compliance with unsaturated fats, fish, and fruits.

The median values of land utilization, TWF, and GHG releases from each day dietary intake were 3.1 m², 2.5 m³, and a couple of.7 kg carbon dioxide (CO₂) equivalents, respectively. Higher PHD scores reduced GHG emissions by 7% but elevated land usage by 10% and TWF by 8%.

Individuals within the topmost quintile of the PHD rating had a decreased risk of all-cause fatalities, heart problems mortality, cancer mortality, and respiratory disease mortality in comparison with the lowermost quintile. Individuals with higher PHD adherence were more prone to be younger at a median of 54 years as in comparison with 57 years, female, more educated, non-smokers, non-alcoholic consumers, and physically fit.

Total grains, fish, and pork contributed essentially the most to GHG emissions at 55%, 11%, and 9%, respectively. Grains primarily contributed to land utilization at 34% and TWF at 37%. The corresponding contributions by fruits were 10% and eight.6%, respectively.

Pork, dairy, chicken, and fish contributed 11%, 10%, 8.4%, and 5.9% of land use, respectively. Sensitivity analyses produced comparable results, thus indicating the robustness of the first findings.  

Conclusions

Increased PHD adherence was attributed to a reduced risk of death from chronic diseases. Nonetheless, environmental impacts were unknown, as improved abidance to PHD was related to reduced GHG emissions but greater land utilization and water footprints.