Our ability to live a long life is influenced by the combination of our genes and the environment. In studies with identical twins, scientists have estimated that no more than 30% of this influence controls how long a person lives.
Of the many possible environmental factors, few have been studied or debated as the diet. Caloric restriction, for example, is an area under investigation. So far, studies seem to show that calorie restriction can improve the diet useful, at least in small creatures. But what works for mice does not always work in humans.
What we eat, compared to the amount we eat, is also influential in our life; Often eating meat under the microscope, to assess whether it is really healthy or not. A study that followed 100,000 Americans for five years found that those who did not eat meat were less likely to die for any cause during the study period than those who did. This effect was especially notable in men.
Some meta-analyzes, which combine and re-analyze data from several studies, have also shown that a low-meat diet is associated with increased longevity and that the less time a person has a meat-free diet, the greater will be the benefit; Even so, there are studies that contradict the latter.
What is clear is the evidence that meat-free diets can reduce the risk of developing health problems such as type 2 diabetes, high blood pressure and even cancer.
So, can you firmly say that vegetarian diets increase your life? Not at all.
What is clear is that, compared to most other living things, humans live for a very long time. This makes it very difficult to conduct studies that measure the effect of any element on longevity (it would be difficult to find a scientist willing to wait 90 years for a study to complete). Instead, they look at existing health records or recruit volunteers for shorter-term studies, measuring mortality rates and looking at which group, on average, is more likely to die. From these data, the effect on certain longevity activities, including meat avoidance, is guaranteed.
There are problems with this approach. In the first place, the search for a relationship between the two factors - such as eating meat and premature death - does not necessarily mean that one causes the other. In other words, correlation is not equal to causality. It may seem that vegetarianism and longevity are related, but a different variable may explain the link. It could be that vegetarians exercise more, smoke less or drink less alcohol than those who eat meat, for example.
Nutrition studies also rely on volunteers to accurately and truthfully record food intake. But that can not be taken for granted. Studies have shown that people tend not to report calorie intake and actual consumption of healthy foods. Without really controlling people's diet and measuring how long they live, it is difficult to have absolute confidence in the results.
So, should you avoid meat for a long and healthy life? The key to healthy aging is probably in our interaction with the environment, including what we eat. From the possible evidence that we have present, it is possible that a diet without meat can contribute to it, and that avoiding the meat can certainly increase your chances of avoiding certain diseases as you get older. But there is no doubt, too, that this is related to other facts that are known to affect health, such as vegetarians smoke less, exercise more or drink less alcohol.