The internet is full of claims of individuals living longer because of some diet, lifestyle, or supplement living longer. So let us start with this disclaimer: Anyone who gives absolute statements about one person living longer because they only drink Yak milk, or eat raw foods, or are a vegan, or a pescetarian, or eat raw lion meat – etc. – are making an opinion, not based on data.
The classic example is studies done on Seventh Day Adventists in the 1960’s and 1970’s. Seventh Day Adventists are vegetarians by choice. They also do not drink alcohol, and they do not smoke tobacco. Their lifespan was longer when compared to non-vegetarians. However, the study did not adjust for variables such as smoking, alcohol, lower body mass index, and what is called the “healthy volunteer effect.”
In 1999 a metastudy combined data from five western countries and reported mortality ratios. This broad study showed fish eaters (pescetarians) had a the lowest ratio of 0.82, followed by vegetarians at 0.84. Occasional meat eaters were at 0.84 and vegans as well as regular meat eaters had a ratio of 1.0. (The lower the number the longer the lifespan.) – American Journal of Clinical Nutrition Vol 70 (3): 516S-524S – September 1999.
One of the most commonly cited studies is the “China Project” where blood samples were pooled from 65 rural counties in China. Their conclusion was that meat eaters lived less long than those who ate animal proteins. However, analysis of the raw data from that study leads to the opposite conclusion. Ultimately the China Study became a best selling book. The books conclusions are the opinions of the author T Collin Campbell, many of those opinions have been refuted by peer-reviewed papers based on the raw data in the study. One study example came from examination of the stomach cancer data showing that there was an inverse correlation between meat and stomach cancer. Cancer Epidemiol Biomarkers Prev 1992, 1: 113-118.
Recently reported was the risk of meat consumption and colorectal cancers. Previous studies have been inconsistent so a metastudy was performed and there was an increase in risk of colo-rectal cancers with increased consumption of meat—however, this was “processed” meat- defined as cured or nitrate, or sausages. The study did not adjust for other dietary habits, lifestyle, or genetic factors. It should be noted that nitrate cured meats have higher associations with stomach and colo-rectal cancers.
Population studies are flawed, and sometimes, the author’s conclusions may not agree with the raw data. There is not clear evidence that one dietary lifestyle is going to significantly increase lifespan if one does not include obesity, smoking, or consumption of fish.
While there are thousands of internet sites concluding that vegans live much longer- there is no study that agrees with that conclusion. What conclusion can you come to? Probably that eating fish is a good thing- eating too much processed food may not be a good thing. Best to pick great parents, don’t overeat, and a bit of red wine and chocolate are not bad things.