Vegetarian Diets Associated With Lower Risk of Death! (Really?)

OK, Upgraders.  Time for a little rant.  That was the headline on a prominent health/science related website I was reading this morning.  Let’s look at that again:

“Vegetarian Diets Associated With Lower Risk of Death.”

Holy Upgrading Senior, Martha! Pass the Broccoli!

I have toyed around with a vegetarian diet.  In fact, I was one for a couple of years.  Technically, I was a lacto-ovo-pesco vegetarian.  You didn’t realize being a “vegetarian” could be so complicated did you?  Plain English, I ate veggies, dairy, eggs, and fish.  But, I digress.

As a recovering “vegetarian,” the headline quoted above caught my attention.  I was thinking, “Lower Risk of Death” – that’s a serious benefit.  Maybe I’d better retrograde into vegetarianism.

The Fine Print

I know this is a totally foreign concept in our instant gratification world, but I decided before I alter my lifestyle and diet habits (again), maybe I would read the fine print in the study that lead to the “Lower Risk of Death” headline.

The study in question was reported online by JAMA Internal Medicine, a JAMA Network publication, June, 2013.  The study examined all-cause and cause-specific mortality in a group of 73,308 Seventh-Day Adventists.

The researchers categorized the participants into five groups:

  1. Nonvegetarian
  2. Semi-vegetarian
  3. Pesco-vegetarian (includes seafood)
  4. Lacto-ovo-vegetarian (includes dairy and egg products) and
  5. vegan (excludes all animal products).

Basically, they had these participants to fill out questionnaires and followed them for roughly 6 years. (We won’t get into the unreliability of self-reported dietary habits right now).

Anyway, the authors of the study reported:

These results demonstrate an overall association of vegetarian dietary patterns with lower mortality compared with the nonvegetarian dietary pattern. They also demonstrate some associations with lower mortality of the pesco-vegetarian, vegan and lacto-ovo-vegetarian diets specifically compared with the nonvegetarian diet.

That sounds pretty persuasive, doesn’t it?  But, foolish me, I persisted in reading on and not immediately converting back to vegetarianism.  Then, I came across this interesting comment from the study’s authors:

Some evidence suggests vegetarian dietary patterns may be associated with reduced mortality, but the relationship is not well established.

What are you saying? “Some evidence suggests vegetarian dietary patterns may be associated with reduced mortality, but the relationship is not well established?”

What happened to “Lower Risk of Death?”  Hang on to that broccoli for a minute, Martha!

Not to be deterred, I read on, only to discover the final nail in the coffin for this “revelatory” study.

The study notes that vegetarian groups tended to be older, more highly educated and more likely to be married, to drink less alcohol, to smoke less, to exercise more and to be thinner. (Bolding added by the Upgrading Senior)

Are you kidding me?  Can you say grand-slam of major lifestyle risk factors?

Of course people who drink less alcohol, smoke less, exercise more, and are thin ARE GOING TO LIVE LONGER!  What a revelation that is!  I would never have thought of that on my own.  Good thing they did a “study.”

But What About “Vegetarian Diet Patterns Being Associated With Reduced Mortality”?

It’s important to understand what scientists mean when they say A is “associated” with B.  Association is not, as many laymen seem to believe, synonymous with “causation.”  Just because there is an association (connection) between two things does not establish that one causes the other.

For example, fireworks and the 4th of July are associated with one another.  That would not, however, lead you to conclude that fireworks “cause” the 4th of July.

So, “Vegetarian Diets Associated With Lower Risk of Death” is an accurate statement using the scientific definition of “associated,” but that headline is almost certainly going to be misleading to most lay readers.  Most people are going to conclude (wrongly) that the study showed that if you adopt a vegetarian diet you will lower your risk of death.

What the study really demonstrated is that people who drink less alcohol, smoke less, exercise more, and are thin are likely to live longer than their alcoholic, pack-a-day, couch potato, morbidly obese counterparts.

Pass the steak (and the broccoli), Martha!  Oh, make sure it’s grass-fed, organic, no growth hormones, etc. 😉




Postscript: I  am not criticizing the vegetarian diet, though it may seem otherwise.  I think (just as the study authors noted) that those who follow a vegetarian diet are generally healthier than the population at large.  Whether or not that is a result of vegetarianism is still open for discussion.  What I am really having fun with in this article is our tendency to be misled by media headlines and to jump to inaccurate conclusions.

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