First off, let’s clear up what ‘vegetarianism’ is defined as…

The Vegetarian Society defines a vegetarian as follows:
“A vegetarian is someone who lives on a diet of grains, pulses, legumes, nuts, seeds, vegetables, fruits, fungi, algae, yeast and/or some other non-animal-based foods (e.g. salt) with, or without, dairy products, honey and/or eggs. A vegetarian does not eat foods that consist of, or have been produced with the aid of products consisting of or created from, any part of the body of a living or dead animal. This includes meat, poultry, fish, shellfish*, insects, by-products of slaughter** or any food made with processing aids created from these.” 

The next question is, ‘is choosing this way to eat healthier than having all the animal-based products in your diet?’… it’s often claimed with data that it is, let’s discuss it.

Most, if not all, of the data is based on associations or correlations, but correlation does not always equal causation.
This basically means that just because something appears to be the cause of something, it doesn’t mean it is the cause.

A really simple example of this would be to say when the sun is shining and it’s warm out people buy ice-cream, but people buying ice-cream does not make the sun shine.

This may seem so obvious and simplified, but when you make situations more complicated than that you can see where things might get misinterpreted.

Also, if someone goes into something biased and looking to justify their beliefs…well, you can see how this causes problems with how people interpret things.

A lot of the time people will hold beliefs based on n=1 as well. N=1 basically means personal experience, or a sample size of 1.

You might tell someone ‘scientific research points heavily toward this outcome’, but the person has experienced it differently themselves, so their own version is their held belief.

Everybody is opinionated nowadays and that makes this quite tricky, and I hope you can see where I come from sometimes when I say, ‘you can’t act all elitist just because you follow an evidence-based approach’.

Some people have poor reference points for nutritional knowledge and it’s not their fault. Some people have poor reference points and it is their fault, and even if you show them different they are not prepared to change beliefs.

A great example of rolling the two factors I have described in to one is the area of vegetarians versus omnivores.

So, factor one is that it can be easy to misinterpret data, and factor two is people can use this data to hold strong held beliefs that may not be easy to change.

Associational data consistently finds that vegetarian tendencies are healthier than meat eaters.

Very low meat intake is linked with greater longevity (Singh et al. 2003), lower cholesterol, lower mortality by 25% (Key et al. 1999)…vegetarians win over meat eaters.

There is a flaw here in how this has been interpreted though, and it will seem quite obvious when it’s pointed out.
Vegetarians are health-seeking individuals.

In most of the studies the vegetarians are paired against meat eaters who display less than healthy behaviours in every day life.

They smoke, they drink, they don’t exercise as much as they should.

You won’t find any vegetarians down the pub smoking cigarettes (if you’re out Saturday night and do find one there are no prizes for it!).

Another way of looking at it is someone with poor health behaviours is highly unlikely to choose to become a vegetarian without actively changing all the other things as well.

When vegetarians get matched with health seeking meat eaters there was no statistical significance between the groups (Key et al. 1996).

It is also worth noting the fact that none of the Blue Zones (where people have the longest life spans) are exclusively vegetarian.

There is a variety of different diet types, but the main trend is that people there live healthy, active lifestyles.
If someone tries to preach to you that being a vegetarian is a healthier way of living than eating meat they are wrong. The caveat is that when both are health seeking and living that way.

The meat eater who doesn’t match up with the overall good habit cluster of the vegetarian does comes out the loser…but now you know why it might appear that being a vegetarian is superior from an incorrect correlation.