Studies show that vegetarians tend to have modestly lower mortality rates, but as for all such observations of human populations there is plenty of room to debate why this is the case. All the normal arguments can be deployed: that a vegetarian diet tends to result in a lower calorie intake and thus less excess fat tissue, that it is more often practiced by people who are more health-conscious in the first place, that it is associated with greater wealth and education, that it results in a lower intake of dietary advanced glycation end products, and so forth. But which of those factors are more important? Therein lies the question.
The development of better medical technologies in the future has the goal of making all of this sort of debate over health practices irrelevant. Rejuvenation biotechnology and other forms of new medicine should render it moot as to how you lived your life: the benefits provided to health and longevity will be enormous in comparison to those derived by living well. But we are not there yet, and there are decades yet to get past if we want to benefit from the rejuvenation treatments presently in very early development. These research press materials are an odd mix of environmentalist and health concerns, and I point it out for the latter, not the former:
The mortality rate for non-vegetarians was almost 20 percent higher than that for vegetarians and semi-vegetarians. On top of lower mortality rates, switching from non-vegetarian diets to vegetarian diets or even semi-vegetarian diets also helps reduce greenhouse gas emissions. The vegetarian diets resulted in almost a third less emissions compared to the non-vegetarian diets. Modifying the consumption of animal-based foods can therefore be a feasible and effective tool for climate change mitigation and public health improvements, the study concluded. "The takeaway message is that relatively small reductions in the consumption of animal products result in non-trivial environmental benefits and health benefits."
The study drew data from the Adventist Health Study, which is a large-scale study of the nutritional habits and practices of more than 96,000 Seventh-day Adventists throughout the United States and Canada. The study population is multi-ethnic and geographically diverse. "The study sample is heterogeneous and our data is rich. We analyzed more than 73,000 participants. The level of detail we have on food consumption and health outcomes at the individual level makes these findings unprecedented." The analysis is the first of its kind to use a large, living population, since previous studies relating dietary patterns to greenhouse gas emissions and health effects relied on simulated data or relatively small populations to find similar conclusions. "To our knowledge no studies have yet used a single non-simulated data set to independently assess the climate change mitigation potential and actual health outcomes for the same dietary patterns."