Genes explain why coffee seems to have a protective effect for some, and a detrimental effect on others

The evidence that different sub groups of the population react differently to the same environmental factors (of which diet is one) owing to genetic differences is now overwhelming, said Dr El-Sohemy.

For example, pharmaceutical companies have known for years that you can give the same drug to three different people and one will see a benefit, one may see no effect and one even could see a detrimental effect, he said.

“We used to think that people who were showing the opposite results to everyone else in​ intervention trials weren’t complying, when in fact there is usually a genetic explanation.”​

Caffeine, vitamin C, sodium, and genes​

So what about food?

We are still learning, but we know that there is a genetic component to our ability to handle gluten and lactose, for example, he said.

We also know that about half of the population has a genotype that means they are fast metabolizers of caffeine, and seem to benefit from drinking lots of coffee (which has many beneficial components), while the other 50% are slow metabolizers, and struggle to get rid of caffeine.

And this goes a long way to explaining why the scientific data on coffee consumption is so contradictory (it appears to have a protective effect in some people; while apparently putting others at a higher risk of hypertension), he said.

As for sodium, give a group of people a high-sodium diet and some will be much more likely than others to develop hypertension, he said, while we also respond differently to vitamin C according to genotype (some people need more than others).