Our guts have evolved ways to protect us if we swallow poisonous food - the bitter taste is one way, ensuring that we spit out quickly many harmful substances. How do we taste food?

What molecules taste bitter?  

But there are other mechanisms too - bitter foods trigger the release of a hormone called cholecystokinin (CCK) that makes us feel full, ensuring that we don't eat any more! 

You may have noticed as you travel that people in different parts of the world enjoy their local food, but visitors do not like it - it might even make them sick! Why does this happen? It is an example of being adapted to the food through a change in the expression and pattern of their dietary sensing molecules - says Timothy Osborne, molecular biology and biochemistry professor and study senior author.