Planetary Health Diet Index and risk of total and cause-specific mortality in three prospective cohorts
Original research article
Quick summary
Planetary Health Diet Index (PHDI) addresses alcohol consumption. The PHDI aligns with the recommendations from the EAT-Lancet Commission, which advises limiting alcohol intake. Specifically, it suggests that alcohol should be consumed in small amounts, or not at all.
Due to alcohol’s negative effects on human health and the negative effects of alcohol production on planetary health, the Planetary Health Diet Index provides guidance on alcohol. This guidance is part of the broader goal of the planetary health diet to promote optimal health and sustainability.
The scientific study highlights the importance of limiting alcohol intake to promote better health outcomes and reduce the environmental footprint associated with alcohol production (Nature). For more detailed information, you can read the full article here.
Background
Our current food systems and climate change are inextricably linked. The environmental costs of producing the food we consume (and waste) include greenhouse gas emissions from carbon dioxide, methane, and nitrous oxide, deforestation to use land for crop and production purposes, eutrophication of fresh and seawater due to nutrient runoff from agricultural land, use of vast amounts of freshwater for irrigation, and losses to biodiversity,” writes Christina C Dahm, in an editorial of the The American Journal of Clinical Nutrition.
These costs are high. For example, the greenhouse gas emissions from our food systems alone have been estimated to be of a magnitude to push global warming by the end of the century above the Paris Agreement of 1.5°C. To mitigate climate change, something has to change.”
Christina C. Dahm, Associate Professor, Department of Public Health – Department of Epidemiology, Aarhus University
People who reduce their alcohol intake or do not consume alcohol at all cut their mortality, while simultaneously reducing their climate impact. These results come from the largest study ever to analyze the health and environmental impacts of the widely-publicized EAT-Lancet Planetary Health Diet.
Launched in 2019, the EAT-Lancet Commission brought together state-of-the-art world class research to determine what would be the best way for humans to eat on a global scale, to limit the environmental impacts of farming and food, and alcohol production and consumption.
The Commission came up with a diet rich in fruits, vegetables, whole grain and plant-sourced proteins, and lower in – but crucially not excluding – animal-sourced products like meat and dairy milk. That became known as the Planetary Health Diet.
Until now, however, the benefits of this diet have been explored mainly on a small scale. The new study investigated the human and planetary health benefits of the Planetary Health Diet at a large scale..
This is by far the longest term, large study in actual people to look at both the human and planetary health benefits of the Planetary Health Diet,” says Walter Willett, the Fredrick John Stare professor of epidemiology and nutrition at the Harvard School of Public Health, and lead author on the research, as per Anthropocene Magazine.
Walter Willett, the Fredrick John Stare professor of epidemiology and nutrition at the Harvard School of Public Health
What the researchers studied
In the study, published in The American Journal of Clinical Nutrition, researcher used three pre-existing datasets that drew dietary information from over 200,000 U.S. American nurses over a 34-year period between 1986 to 2019. All participants were disease-free when the surveying started, and were required to complete a questionnaire every four years on the makeup of their diets.
To evaluate this vast trove of data, the researchers first selected 15 indicator foods that captured the span of dietary impacts, including whole fruits, vegetables, and nuts on the lower-impact end; and red meat, processed meat, and dairy on the higher-impact end. Then, they used these foods to develop an index that allowed them to score the nurses’ dietary surveys by how closely they aligned with the EAT-Lancet suggested Planetary Health Diet. Using a lifecycle-analysis, they estimated the environmental impacts of each reported diet according to those 15 indicator foods.
Analyzing alcohol
The researchers conducted subgroup analysis by potential effect modifiers of the association between the PHDI score and disease risk such as age, race, neighborhood socioeconomic status, smoking status, physical activity, alcohol intake, baseline hypercholesterolemia, baseline hypertension, family history of diseases, and BMI.
Regarding alcohol, the researchers assessed alcohol intake as never, between 0–9.9 grams per day, or above 10 grams per day.
The study recorded a varied set of health outcomes for the participants – everything ranging from cancer to diabetes, heart disease, lung disease, and neurodegenerative problems. Therefore, the researchers could correlate participants’ dietary behaviours with their health over the 34-year period.
What the researchers found
The study showed that people who eat diets richer in plants are also healthier, as well as having a lower environmental footprint.
The study also showed that people who consumed smaller or no amounts of alcohol are healthier and had smaller impact on the environment.
The study only showed a correlation, not a causation.
The study findings support a connection that Movendi International analysis has revealed: how alcohol impedes sustainable development because of the negative impact of alcohol consumption, production, transportation, marketing, and retail on human and planetary health.
Through its multiple health, social, environmental, and economic harms, alcohol is a massive obstacle to sustainable human development, adversely affecting all three dimensions of development, the social, environmental, and economic dimensions, and reaching into all aspects of society.
It is jeopardizing human capital, undermining economic productivity, destroying the social fabric and burdening health systems.
Alcohol adversely affects 14 out of 17 SDGs and a total of 54 targets.
Overall, the new research supports dietary guidelines from Northern Europe and Mexico.
The Mexican dietary guidelines, adopted in 2023, contain 10 recommendations for a health and environmentally friendly nutrition approach. One of the recommendations is for people in Mexico to “avoid alcohol consumption for the well-being of our physical and mental health and of our families.”
And also the Nordic Nutrition Recommendations from 2023 stresses the absence of a safe lower limit for alcohol, aligning with a growing body of scientific evidence. These guidelines not only impact health but also address environmental sustainability.
The researchers noted that land use reduction is particularly important as a facilitator of re-forestation, which is seen as an effective way to further reduce levels of greenhouse gases that are driving climate change.
A 2019 study showed that lowering consumption of more discretionary products (oils, sugar, alcohol, and stimulants) by 20% by avoiding production with the highest land use reduces the land use of these products by 39% on average.
And in a 2022 analysis, Movendi International revealed how alcohol affects the three planetary crisis of climate change, biodiversity loss and pollution. And in a Special Alcohol Issues Feature, Movendi International documented the different ways in which Big Alcohol is fueling the climate crisis. Water and food insecurity, environmental degradation, pollution, greenhouse gas emissions, and green-washing are part of the alcohol industry’s harms against planetary health.
Our results support reductions in death from a variety of diseases with increasing adherence to a health and environmentally sustainable dietary pattern described in the EAT-Lancet Commission,” the researchers said, according to Elana Gotkine, reporting for Health Day.
Study authors
Abstract
Background
In 2019, the EAT-Lancet Commission proposed a healthy dietary pattern that, along with reductions in food waste and improved agricultural practices, could feed the increasing global population sustainably. We developed a Planetary Health Diet Index (PHDI) to quantify adherence to the EAT-Lancet reference diet.
Objectives
The researchers aimed to assess associations between PHDI and total and cause-specific mortality in 3 prospective cohorts of males and females in the United States.
Methods
The researchers followed 66,692 females from the Nurses’ Health Study (1986–2019), 92,438 females from the Nurses’ Health Study II (1989–2019), and 47,274 males from the Health Professionals Follow-up Study (1986–2018) who were free of cancer, diabetes, and major cardiovascular diseases at baseline. The PHDI was calculated every 4 y using a semiquantitative food frequency questionnaire. Hazard ratios (HRs) were calculated using multivariable proportional-hazards models.
Results
During follow-up, the researchers documented 31,330 deaths among females and 23,206 among males.
When comparing the highest with the lowest quintile of PHDI, the pooled multivariable-adjusted HRs were 0.77 for all-cause mortality. The PHDI was associated with lower risk of deaths from cardiovascular diseases, cancer, respiratory diseases, and neurodegenerative diseases.
In females, but not males, the PHDI was also significantly associated with a lower risk of deaths from infectious diseases.
PHDI scores were also associated inversely with greenhouse gas emissions and other environmental impacts.
Conclusions
In 3 large United States-based prospective cohorts of males and females with up to 34 y of follow-up, a higher PHDI was associated with lower risk of total and cause-specific mortality and environment impacts.