Veggie Blog

The old version of this post told readers that a veggie diet could give them 13 more years on earth, quoting Michael Roizen’s book The RealAge Diet. It is an exciting claim, but I could not trace that number to a published study, so here is what the research does show.

Does a veggie diet really add 13 years?

I found no study that supports a gain of 13 years. The best-known evidence shows a much smaller difference, and it comes from observational research, which shows an association and cannot prove cause and effect. People who choose a vegetarian diet often differ from others in other ways too, such as smoking and exercise.

What does the best evidence show?

The Adventist Health Study 2 followed 73,308 Seventh-day Adventists in the United States and Canada for an average of about 5.8 years. In the 2013 analysis in JAMA Internal Medicine, vegetarians as a group had a 12 percent lower adjusted risk of dying from any cause than non-vegetarians. By type, the figures were 19 percent lower for pesco-vegetarians (who eat fish) and 9 percent lower for lacto-ovo vegetarians. For vegans the estimate was 15 percent lower, but the range of uncertainty was wide enough that it was not statistically significant. The associations were larger in men than in women. That is a real and interesting difference, but it is far from 13 years.

Is it only about meat?

The old post said that the more meat you eat, the worse your immune system gets, and that this is why most old people die of sickness. I could not find support for that, and I have dropped it. What studies point to is the overall pattern of eating: plenty of vegetables, fruit, beans and whole grains, and less processed food. Meat is not the only variable. Our post on diet and disease covers what the World Health Organization says about processed meat.

What should you do if you want to try it?

Plan your meals so that you get enough vitamin B12, iron, calcium and protein. The Academy of Nutrition and Dietetics said in its 2016 position paper that appropriately planned vegetarian diets, including vegan diets, are healthful and nutritionally adequate and may help prevent certain diseases. Our post on vitamin deficiency and who is at risk covers the practical side. If you have a medical condition or take medication, talk to your doctor first.