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Nearly 90% of Americans drink the equivalent of about two cups of coffee daily. But whereas one person can have a rich cup of joe with dessert and sleep like a baby, another can feel hyped up on a weak cup of tea. AncestryDNA® can tell you if people with DNA like yours might be more likely to drink more or less caffeine than average, which may be related to your caffeine metabolism.

What Does Caffeine Do?

There's a reason coffee and tea are two of the world's most popular beverages. It's all about their shared magic ingredient: caffeine. Caffeine stimulates the central nervous system, making people feel more energetic and awake.

It also increases both dopamine and serotonin, chemicals in the brain that help one feel productive and happy.

But caffeine doesn't affect everyone the same way. Some people can handle several cups of strong coffee and feel great, while others find that just a little caffeine makes them jittery or interferes with their sleep.

For everyone, caffeine causes increased urination. And it leads to higher levels of acid in the stomach, which can cause stomach upset.

What Science Says about Caffeine Sensitivity

Whether you feel good or not-so-good after eating or drinking caffeine is partly due to tolerance as well as factors like your age, whether you're male or female, and what medications you're taking. But it turns out there might also be a genetic component.

Two genetic markers seem to play a role in how your body handles caffeine, specifically caffeine metabolism. One is on chromosome 7 near the AHR gene, and the other is on chromosome 15 near the CYP1A1 and CYP1A2 genes.

Variations in the genes that direct how the body processes caffeine mean that it leaves some people's systems quickly, while it lingers for much longer in others. Fast metabolizers tend to drink more caffeine than slow metabolizers.

How Much Caffeine Is Too Much?

Although consuming low to moderate doses of caffeine is thought to be safe, experts recommend most adults have no more than 400 mg of caffeine per day. That's equivalent to about three or four cups of coffee, depending on the strength of the cups. However, women who are pregnant or trying to become pregnant should limit themselves to one or two cups of coffee per day.

Of course if you find you have a caffeine sensitivity, you might consider avoiding caffeine altogether. Signs of caffeine sensitivity include nausea, anxiety, and sleep disruption.

According to the Diagnostic and Statistical Manual, 5th edition, Caffeine Use Disorder and Caffeine Withdrawal are diagnosable conditions.

Interesting Facts about Caffeine

Yes, caffeine is a drug—the most popular psychoactive drug in the world. Research suggests that people have been enjoying caffeine for over 1,000 years.

Although coffee and tea are two common sources of caffeine, the coveted substance can also be found in the leaves, seeds, and fruits of more than sixty plants, including guarana berries and yerba mate. It's also present in chocolate and foods containing chocolate, soda and energy drinks, and over-the-counter painkillers.

Although it's rare, you can die from caffeine toxicity. It's difficult to ingest enough of a caffeinated beverage to reach dangerous levels, so powdered forms of caffeine are often the culprits in these unusual situations.


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