The gene that influences how coffee affects you


If you always get jittery from having some coffee, it’s probably because you are a slow metaboliser of caffeine. — Filepic

Many of us look forward to that first cup of coffee in the morning to get us started and ready for the day, and there’s nothing wrong with that at all.

But as the day goes on, the caffeine starts adding up when we go for that second cup post-lunch, another during tea break, and perhaps one more after dinner.

Even if we switch it up with tea, an energy drink, hot chocolate or a soft drink, those beverages also contain caffeine.

There’s a reason why we love those drinks – they’re delicious!

The benefits of drinking coffee and tea are worth it too, such as:

  • Constipation relief
  • Lowering depression in women
  • Helping with burning off fat
  • Reducing inflammation
  • Lowering the risk of liver disease

But we may also be aware of certain side effects, especially increased hyperactivity, from caffeine consumption.

You may have experienced the symptoms, e.g. talking really fast without stopping, fidgeting, your heart racing, not being able to sleep if your last cup of caffeine was shortly before bedtime, and so on.

On the other hand, you may be that person who can consume caffeine at any time and it doesn’t seem to affect you very much at all.How your body reacts to caffeine is less about the drink (some teas contain more caffeine than coffee!) and more to do with the variations of a gene called CYP1A2.

Let’s take a closer look at this gene, and focus in on how caffeine can either increase or decrease your risk of high blood pressure (hypertension) and heart disease, based on your CYP1A2 genotype.

Breaking down caffeine

The CYP1A2 gene codes for a metabolising enzyme, also called CYP1A2, which plays a critical role in breaking down toxins, drugs, hormones and metabolic waste products, including caffeine.

It is found mainly in the liver.

Depending on your CYP1A2 genotype, caffeine can either increase or decrease your risk of high blood pressure and heart disease.

One of the most-studied SNPs (single nucleotide polymorphisms) in the CYP1A2 gene is called rs762551.

SNPs occur when a single nucleotide at a specific position in the genome is different from the norm in more than 1% of the population.

In this case, the affected nucleotide in rs762551 varies between adenine (A) and cytosine (C) in different people.

Depending on which rs762551 variants you inherit from each of your parents, you can either be a fast caffeine metaboliser, or a slow one.

However, it is important to note that while the CYP1A2 gene is central to caffeine metabolism, several other genes also affect the way you react to caffeine.

Fast metabolisers

If your CYP1A2 genotype is “AA”, your body processes caffeine and the other substances metabolised by this enzyme much more quickly, making you a fast metaboliser.

Therefore, these substances will have less of an effect on your body.

Having the “AA” genotype means that you are unlikely to get nervous or anxious after drinking coffee, and are more likely to benefit from caffeine as an athletic performance booster!

More importantly, drinking coffee may actually protect you against developing high blood pressure and heart diseases.

In one study, people with this genotype who drank two to three cups of coffee per day (moderate drinkers) were 20% less likely to develop high blood pressure than those with the same genotype who didn’t drink coffee.

Meanwhile, the risk for heavy coffee drinkers (more than three cups per day) was 64% lower.

In another study, fast metabolisers aged less than 60 years had a lower risk of heart attack, compared to fast metabolisers who didn’t drink coffee.

The findings were as follows:

  • 52% lower risk when drinking one cup per day
  • 43% lower risk when drinking two to three cups per day
  • 17% lower risk when drinking four or more cups per day.

Slow metabolisers

If you have the “AC” or “CC” genotype, you process caffeine and other substances metabolised by the CYP1A2 enzyme more slowly, making you a slow metaboliser.

These substances will thus have more of an effect on your body.

Therefore, the same amount of caffeine will tend to have more negative effects on CYP1A2 slow metabolisers than on the fast ones.

Moderate coffee drinkers with this genotype have a 72% higher risk of high blood pressure than those with the same genotype who don’t drink coffee.

Moreover, heavy coffee drinkers are three times more likely to develop high blood pressure (200% higher risk).

A study published in the journal JAMA about slow caffeine metabolisers provides further insight into this group.

The study involved more than 4,000 people in Costa Rica.

The participants, who were slow caffeine metabolisers, increased their risk of heart attack by 36% if they drank two to three cups of coffee daily.

Their risk increased to 64% if they drank four or more cups daily.

Know your threshold

Not knowing how to balance your caffeine intake will have negative repercussions on your health and effectiveness at work.

If you’re taking in more caffeine that you can handle, you won’t gain any of the health benefits provided by coffee and tea.

As slow metabolisers can feel those post-caffeine jitters for hours, you may find yourself spending your nights tossing and turning in bed, and ultimately getting too few hours of sleep.

To prevent the risk of heart disease from overconsumption of caffeine, genome testing is the best way to find out if you are a fast or slow metaboliser of caffeine.

Seek a doctor who is a nutrigenomic practitioner for a better explanation on your genetic makeup, and the influence of nutrition and coffee on your genes.

Then you can make an informed smart choice about when and how much coffee you should consume, and your body will thank you for doing right by it.

Datuk Dr Nor Ashikin Mokhtar is a consultant obstetrician and gynaecologist, and a functional medicine practitioner. For further information, email starhealth@thestar.com.my. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this column. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.

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