Chocolate lovers rejoiced last week at media reports of a new study proclaiming the benefits of the world’s most popular confection.

A sampling of recent headlines looks like this:

  • Chocolate, Chocolate, It’s Good for Your Heart, Study Finds
  • Study: Eating Chocolate Is Good For Heart Health
  • Munching on 'chocolate' helps cut heart disease, stroke risk (I have no idea why the quotation marks were used here, as far as I know the study looked at consumption of actual chocolate.)
  • Chocolate Found To Be Good For Your Heart!

These are all great, but the winner is definitely:

Chocolate lowers risk of heart disease, red wine helps burn calories, new studies suggest (I’ve been waiting for this news for years!)

At this point you are probably sensing the too-good-to-be-true vibe in these headlines. That’s because the research doesn’t say what these headlines suggest it does.

The study, published in the June issue of cardiology journal, Heart, was an observational study conducted in Europe. Researchers examined a database of patients who were part of a large cancer trial. For this cancer research, patients filled out baseline questionnaires about their diet and other health information in the years 1993-1997. Then the patients were followed through 2008. Authors of this study looked at two key points:

  • How much chocolate did subjects report eating on their baseline reports?
  • How many of them had bad cardiovascular outcomes?

With this information, researchers were able to establish a correlation between higher chocolate consumption at baseline and fewer cardiovascular events.

The key word here, of course, is correlation. The research did not establish a causal effect between chocolate and heart health.

What difference does it make? Shouldn’t we just start munching on Ghirardelli to be safe? Well, here are a few ways the correlation can exist without causation - all straight from my imagination:

  • There could be some weird gene overlap for sensitivity to bitter flavors and coronary artery disease. If this were the case, chocolate consumption would offer no protection to those who don’t like it. It would just make them miserable before they ended up needing cardiac bypass.
  • People who are in poor health tend to overstate the healthiness of their diet, so they actually ate more chocolate than reported. In this case, the under-reporters may have already had a predisposition to heart disease.
  • People who eat chocolate also tend to consume some other food or beverage along with it that offers the real cardioprotection. I’m hoping for gin and tonic, but I’m not holding my breath.

You can come up with your own scenarios that would create the correlation in the absence of any causation. Try it. It’s kind of fun.

So if we see a correlation, but nothing that confirms causation, what do we do with that information?

On an individual level, not much. In this circumstance, there isn’t enough evidence to suggest people who don’t eat chocolate should add it to their diets. But if you do eat chocolate, then there is no reason, based on this study, for you to stop eating it. However, your doctor may have something to say about that, particularly if you are at risk for diabetes.

It is a great lesson to us all about the facts behind the headlines. When making decisions about your health, it isn’t enough to read the headline or even the full news item. Understanding the true meaning of the evidence and putting it in the context of your own health concerns is critical.

On a broader scale, the correlation uncovered in this study does suggest that more research into the impact of chocolate intake on heart disease may be worthwhile. A double-blind, placebo-controlled trial could answer that question. It would also take all the fun out of eating chocolate.