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Who lives longest:

meat eaters or vegetarians?

October 25, 2016 1.23pm BST

Lukasz Szwaj/Shutterstock.com
Our ability to live a long life is influenced by a combination of anything on longevity (you’d have difficulty finding a
of our genes and our environment. In studies that involve scientist willing to wait 90 years for a study to complete).
identical twins, scientists have estimated that no more than Instead scientists either look back at existing health records
30% of this influence comes from our genes, meaning that or recruit volunteers for studies that use shorter time
the largest group of factors that control how long a person periods, measuring death rates and looking to see which
lives is their environment. group, on average, was mostly likely to die first. From this
data, claims are made about the effect certain activities have
Of the many possible environmental factors, few have on longevity, including avoiding meat.
been as thoroughly studied or debated as our diet. Calorie
restriction, for example, is one area that is being investigated. There are problems with this approach. First, finding a link
So far, studies seem to show that restricting calories can between two things – such as eating meat and an early death
increase lifespan, at least in small creatures. But what works – doesn’t necessarily mean one thing caused the other. In
for mice doesn’t necessarily work for humans other words: correlation does not equal causation. It may
appear that vegetarianism and longevity are related but
What we eat – as opposed to how much we eat – is also a hot a different variable may explain the link. It could be that
topic to study and meat consumption is often put under the vegetarians exercise more, smoke less and drink less alcohol
microscope. A study that tracked almost 100,000 Americans than their meat eating counterparts, for example.
for five years found that non-meat eaters were less likely
to die – of any cause – during the study period than meat Nutrition studies also rely on volunteers accurately and
eaters. This effect was especially noticeable in males. truthfully recording their food intake. But this can’t be
taken for granted. Studies have shown that people tend to
Some meta-analyses, which combine and re-analyse data under report calorie intake and over report healthy food
from several studies, have also shown that a diet low in meat consumption. Without actually controlling the diet of groups
is associated with greater longevity and that the longer a of people and measuring how long they live, it is difficult to
person sticks to a meat-free diet, the greater the benefit. Not have absolute confidence in findings.
all studies agree, however. Some show very little or even no
difference at all in longevity between meat eaters and non- So should I avoid meat for a long and healthy life? The
meat eaters. key to healthy ageing probably does lie in controlling our
environment, including what we eat. From the available
What is clear is evidence that meat-free diets can reduce the evidence it is possible that eating a meat-free diet can
risk of developing health problems such as type 2 diabetes, contribute to this, and that avoiding meat in your diet could
high blood pressure and even cancer. There is some evidence certainly increase your chances of avoiding disease as you
to suggest that vegan diets possibly offer added protection age. But there’s certainly also evidence to suggest that this
above a standard vegetarian diet. These findings are far really might work in tandem with avoiding some clearer
easier to interpret as they report the actual event of being risks to longevity including smoking.
diagnosed with a health problem rather than death from any
cause. Author
James Brown
Lecturer in Biology and Biomedical Science,
So can we confidently say that avoiding meat will increase Aston University
your lifespan?
Disclosure statement
James Brown does not work for, consult, own shares in or receive funding from any company
The simple answer is: not yet. or organisation that would benefit from this article, and has disclosed no relevant affiliations
beyond their academic appointment.
The problem with longevity
The first thing that is clear is that, compared with most
other creatures, humans live for a very long time. This
makes it very difficult to run studies that measure the effect