A large-scale study reinforces the link between following an environmentally friendly diet and lower mortality rates

This study presents a robust methodological design for observational studies. It is based on two large prospective cohorts, NHANES in the US and UK Biobank in the UK, which include a large sample size of more than 168,000 people. In addition, they have supplemented the study with a meta-analysis of 37 previous studies involving more than 3 million participants. They have taken into account the main confounding variables, i.e., those that could distort the actual association, and have performed sensitivity analyses to confirm the consistency of the findings. In addition, an assessment of the environmental impact of the diet has been incorporated, adding an interesting dimension in the current context.

It confirms previous results carried out in various population cohorts on the benefits of a planetary health diet. This diet is characterized by being based on high-quality plant-based foods and taking into account consumption limits for foods that are related to human health and the health of the planet. The results are consistent with previous research in different countries, including two studies carried out by our research group, one of them in Spain, where we have also studied how this diet compares to the Mediterranean diet in terms of health and environmental impact (both share similar characteristics in that they are based mainly on the consumption of whole plant foods).

Like any observational study, this work has some limitations. For example, UK Biobank participants tend to have healthier lifestyles than the general population, which may limit the generalizability of the results. It is also important to note that diet was assessed at a single point in time, without taking into account possible changes over time. Furthermore, although many factors were adjusted for, there is always the possibility of residual confounding. Although they assess environmental impact by carbon footprint, there are also other indicators. Finally, some heterogeneity was observed in the meta-analysis, especially in total mortality, due to differences in how diet was measured and adherence indices were calculated.

We know that the implications of following diets based on high-quality plant-based foods are important for disease prevention and can help reduce the burden of chronic diseases and premature mortality. In addition, by adopting this pattern, we are helping planetary health by reducing greenhouse gas emissions associated with food production.

In Spain, where the Mediterranean diet is already part of the food culture, the transition to this pattern could be easier and/or complementary. In fact, in our study, in a representative Spanish population, we saw that the planetary health diet had similar benefits to those of the Mediterranean diet, both in terms of health and sustainability, which helps people choose one pattern or the other based on their preferences. This helps to continue promoting food policies that integrate health and environmental criteria, including the consumption of plant-based foods, the reduction of red and processed meats, ultra-processed foods, and sugary drinks, and the increase of legumes, fruits, vegetables, nuts, and whole grains.

The results of this interesting study are in line with other publications, although some studies have reported conflicting results. The observations show that people who follow more sustainable diets (according to the standard and measurement method proposed by the EAT-Lancet Commission, initially formed by 37 scientists from 16 countries, leaders in various disciplines) also benefit from a lower risk of all-cause mortality overall.

The greatest strength is that the authors have analyzed information from two databases that include many individuals, using a careful methodology. With regard to the US study, the NHANES study is a cross-sectional study that collects information in two-year cycles from a random sample representative of the US population. Each cycle, therefore, analyzes different people and shows a snapshot of the moment. The authors jointly analyzed data from people who participated in this study between 1999 and 2018 (aged 20 and over). The study data is linked to information from the National Death Index (NDI), so they were able to analyze which people had died, when, and the cause of death. In this case, they considered information up to 2019.

The British study (UKBiobank) is a longitudinal study in which more than 500,000 people (aged 40 to 69) were recruited between 2006 and 2010 and measured at three different times. The information is linked to data from the National Health Service (NHS), including the date and causes of death, where applicable.

In addition, they have supplemented the information with a meta-analysis, i.e., a systematic review and summary analysis of data from epidemiological studies in which the authors asked similar research questions.

However, some limitations need to be taken into account. What information about the participants' eating habits was used as a basis? With regard to the NHANES study, the authors considered information about what participants consumed on one day when they participated in the study, which means that the estimates are not very accurate (they do not describe making adjustments to take into account that food intake varies greatly between individuals and also within each individual from day to day). In addition, they describe that the median follow-up period in this group was 9.3 years (meaning that for half of the participants this period was shorter, but for the other half the time elapsed was greater than 9.3 years, even up to 18 years). The analysis did not take into account whether these eating habits changed during the follow-up period.

As for the British study, they only considered participants for whom there was data on more than one day of intake and considered the average of the days of intake available. Participants completed measurements and questionnaires on three different occasions over time.

Another limitation to be taken into account when interpreting the results is related to how the environmental impact of estimated food consumption was measured, as it was based only on the estimated greenhouse gas emissions (GHGe), but the authors did not consider other dimensions of environmental impact.

There is growing scientific evidence supporting the role of diet as a possible risk factor or protective element for health. On this scientific basis, it can be said that a healthy diet should be based on the daily consumption of plant-based foods, mainly fruits and vegetables, as well as legumes and cereals, especially whole grains, along with varying amounts of foods from other groups (eggs, dairy products, fish, meat), alternating between them. This dietary profile coincides with a consumption pattern that is also associated with a lower environmental impact in terms of GHG emissions and other dimensions of environmental impact. Furthermore, it is consistent with the Mediterranean diet pattern, whose favorable effects on health are supported by scientific evidence, and various studies have also observed a more favorable environmental impact compared to other dietary patterns.

This is a high-quality study, as it combines two of the largest available cohorts —NHANES in the U.S. and the UK Biobank— with a meta-analysis of more than three million participants, providing unusual robustness for nutrition research. Its conclusions —that higher adherence to the Planetary Health Diet is associated with lower mortality and reduced chronic-disease risk— are consistent with previous evidence and reinforce the idea that what is good for human health is also good for the planet. Limitations include the observational nature (no proof of causality) and limited generalizability across all social and cultural contexts. In Spain, where the Mediterranean pattern still has a footprint, the findings support lower red/processed meats and more fruits, vegetables, legumes, and whole grains. The key takeaway is that these shifts improve health and help mitigate climate change.

This large study shows that following the Planetary Health Diet is linked to lower premature mortality and fewer chronic diseases — and strikingly, it benefits both people and the planet.  

This research analyzes the relationship between the planetary diet, a dietary pattern proposed by the EAT-Lancet Commission that prioritizes plant-based foods and limits the consumption of red meat and dairy products to promote health and sustainability, and the risk of mortality and chronic diseases. To do this, the authors use two large prospective cohorts, with more than 160,000 participants, and supplement the findings with a comprehensive meta-analysis of 37 studies.

The results show that greater adherence to the planetary diet is associated with a lower risk of all-cause mortality and a reduction in the incidence of cancer, cardiovascular disease, diabetes, and respiratory disease. These findings reinforce previous evidence on the benefits of this dietary pattern, which combines individual health with environmental sustainability.

The study has a very large sample size, although, as with all observational studies, it does not allow causal relationships to be established.

Overall, the research provides solid evidence supporting the need to move toward more sustainable dietary patterns, in which plant-based foods predominate, with clear positive implications for health and the environment.

There is growing interest among the population in following diets and eating healthy foods that are compatible with respect for the environment in a scenario of climate change. For this reason, studies evaluating the impact of diets that provide benefits to both health and the planet are very timely. In this regard, the Planetary Health Diet (PHD) is an approach focused on mitigating the production of greenhouse gases associated with diet while promoting human health.

The present study addresses this issue from two perspectives. On the one hand, it studies the association between adherence to the PHD and the risk of mortality and chronic disease based on two large databases, the US National Health and Nutrition Examination Survey (US NHANES) and the UK Biobank. On the other hand, it performs a meta-analysis to jointly evaluate the association between the PHD and all-cause mortality, cancer, and cardiovascular disease.

The result of both approaches to the problem is that people who follow a diet more similar to the PHD have a lower risk of dying from chronic diseases, while reducing greenhouse gas emissions. The authors conclude that this type of diet should be promoted to improve public health and combat climate change.

The approach using official surveys has the advantage of providing access to a considerably large sample size. In fact, between the two databases used in the study, information from almost 170,000 people was accessed. However, it also has its limitations. First, the questions asked of respondents do not always have to be focused on the problem or hypothesis being addressed. In this study, for example, there are no direct questions about the PHD, which detracts from the value of the results. In addition, the surveys may not be up to date. For example, data from the US NHANES survey only goes up to 2018. In these surveys, dietary intake is assessed at baseline but may change during the follow-up period, so baseline measurements may not accurately reflect exposure levels throughout the study, which could introduce bias.

On the other hand, the meta-analysis approach allows for even larger sample sizes by combining all the studies included in the review. In this case, there are 37 studies, including more than 3,000,000 participants. The limitation is that the experimental designs are diverse, which may reduce the homogeneity of the results. Furthermore, as both approaches are observational in nature, they do not allow for the establishment of cause-and-effect relationships.

In any case, the combination of both approaches lends strength to the results and underscores the importance of considering the nutritional quality and environmental impact of foods and diets as a whole.

This study analyzed the impact of the Planetary Health Diet (PHD), a dietary pattern that seeks to improve health and achieve greater environmental sustainability, on the risk of overall mortality, cancer, cardiovascular disease, and diabetes using data from two large cohorts, one from the US and one from the UK. To reinforce their findings, the authors also conducted a meta-analysis of all studies published to date on the subject.

The results confirm the importance of nutrition in reducing the risk of chronic disease and mortality and reflect a change in eating habits: younger people tend to consume more red meat and dairy products, with potentially negative consequences for their health, longevity, and the environment.

Beyond the numbers, the PHD is a pattern that seeks to combine harmony and balance. Those who most closely follow this type of diet not only reduce their risk of disease, but also show a more favorable health profile from the outset: lower body mass index, lower prevalence of hypertension and diabetes, and a lifestyle more aligned with prevention and health.

Interestingly, unlike other diets, energy consumption was not reduced in the PHD. Participants with a higher PHD consumed more calories, but from foods with higher nutritional density, such as legumes, whole grains, nuts, and vegetables that promote better nutrition and a more habitable planet.

Among its limitations, it should be noted that dietary data were collected only at the beginning of the studies and that cohorts are not always representative of the general population, which requires some caution in interpreting the results. Even so, this study provides further evidence to emphasize that a balanced, varied diet rich in nutrients and quality foods (not just red meat and dairy products) not only reduces the risk of chronic diseases and mortality, but also protects the health of the planet and, therefore, that of future generations.