Need a daily caffeine fix? Coffee addiction could be in your genes

Can you get through the day without resorting to a cup of coffee or can of coke? If the answer is no, the chances are your DNA could be to blame.

Scientists have found people who have two versions of two particular genes are far more likely to crave caffeine.

This is because they are able to metabolise or break down the stimulant more efficiently and this increases their tolerance of the drug.

U.S researchers studied the genes CYP1A2 and AHR. The first is thought to be involved in caffeine metabolism while the second plays a role in how CYP1A2 is regulated. Both are involved in the breakdown of caffeine in the liver.

Senior author, Dr Neil Caporaso, of the National Cancer Institute, said: 'It's really an incredible story.

'People don't really suspect it, but genetics plays a big role in a lot of behaviours, such as smoking and alcohol consumption.

'And now it turns out that it has a part in how much caffeine we drink.'

The team, led by researchers from the Harvard School of Public Health, examined the genes of more than 47,000 middle-aged people in the U.S.

Each person completed a questionnaire about their coffee, tea, soda and chocolate intake.

The team was amazed to find two associated caffeine genes after sifting through more than 300,000 genetic markers.

They found those with the specific genes tended to drink on average 40mg more caffeine per day - equivalent to a can of coke or a third of a cup of coffee - compared to those without it.

They also discovered that those who were driven to drink more caffeine were better able to tolerate it.

Dr Caporaso said: 'It turns out that your liver, more than your brain, determines daily caffeine intake.

'You might think "drink caffeine to feel good, or not to feel bad", but that, in turn, is established by how fast your liver breaks down the caffeine.

'If your liver breaks it down very rapidly, then likely you drink more.'

Coffee is the most commonly consumed substance with psychoactive properties.

The authors believe their findings will help further studies that look into the physical effects of caffeine, including anxiety and sleep disorders.

From: dailymail.co.uk