You're listening to Bulletproof Radio with Dave Asprey.

Today's cool fact of the day is that your preference for coffee or tea may boil down.

See what I did there?

To a matter of taste genetics.

That's because people with a version of a gene that increases your sensitivity to the bitter flavor of caffeine tend to be coffee drinkers.

Which is kind of weird because you think if you're more sensitive to bitter flavors you wouldn't like it.

It turns out tea drinkers tend to be less sensitive to the bitter taste of caffeine, but they have versions of genes that increase sensitivity to the bitterness of other chemicals.

So we used to believe, and it's kind of funny because we build all sorts of systems and structures and beliefs on things that we used to believe that we were totally wrong about.

And here we used to believe that people avoid eating bitter foods because bitterness is an indicator of poison.

That's just not true.

In the new study they looked at the DNA variants of genes involved in that bitter taste.

They looked at caffeine at quinine, which is the taste of tonic water, and something called PROP, which is a synthetic chemical that isn't found in food or drink that also tastes bitter.

And researchers in three different countries, Australia, US, and England.

This is kind of a big study.

It looked at DNA from 400,000 participants and added up each person's variance in the taste and created a genetic score.

And they compared those to what people like to drink.

If you had the highest genetic score for caffeine bitterness, you were 20% more likely to be a heavy coffee drinker.

And you probably drank four more cups a day.

And that's remarkable because we were totally wrong on our assumptions about bitterness.

What's interesting too is that bitters, which have long been used, like Swedish bitters, my wife would talk about as a child in Sweden, have been used for various health things.

When you go to Chinese or Ayurvedic medicine and bitters in important flavor, it turns out some of those bitter things talk to your gut bacteria and are metabolized by a gut bacteria, even some of the polyphenols have these strong flavors.

So it's really interesting that we're finding more and more about how our genes, how our mitochondria, and how our taste receptors are all linked in this incredibly intricate dance.

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