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

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.