Try telling any caffeine addict to limit their java and they’ll go on the defensive. “I can’t start my day without it”, “it helps me focus”, “it’s good for me”. And they might well be right. If they’re a fast metaboliser of caffeine…
If you’re a slow metaboliser, caffeine can be more of a poison than a medicine, leading to sleep problems, even heart disease. But if your body processes and eliminates caffeine from your bloodstream very quickly, this can actually lead to a decrease in heart disease risk.
According to new research by Dr J.W. Langer, author of Genetics, Metabolism and Individual Responses to Caffeine, coffee drinkers can now be placed into one of three groups depending on their caffeine sensitivity.
The results are determined by two main genetic factors: whether their liver can metabolise caffeine quickly or slowly and whether they carry a genetic variation that makes their central nervous system more sensitive to caffeine’s stimulating effects.
High sensitivity to caffeine
Slow-metabolism in the liver and high binding in the central nervous system. Even small amounts of caffeine will cause a stimulating effect and higher doses may cause sleep problems.
Regular sensitivity to caffeine
The balance between caffeine inactivation in the liver and binding in the central nervous system means that the individual can typically drink 2-5 cups of coffee during the day without adverse reactions or sleep disturbances. Caffeine is normally not recommended in the evening, but individual differences prevail, as seen in most people.
Low sensitivity to caffeine
Fast-metabolisers of caffeine. Higher intakes can be consumed but they should still stay within the guidelines of no more than 400mg coffee per day. Coffee drinking before bedtime does not typically disturb sleep.
Dr Langer explains: “It’s common for people to ask their doctor questions such as why they are kept awake by one cup of coffee, while their partner easily falls asleep after five cups. The answer is that we are all unique coffee drinkers. Our genetic make-up programmes our reaction to caffeine, just as it programmes our hair colour and eye colour.”
An individual with low sensitivity to caffeine probably will not experience the typically desired effects of caffeine, such as wakefulness, alertness, and increased concentration. But this doesn’t mean that they should exceed the recommended daily caffeine intake trying to achieve the desired effects.
Dr Langer continued: “Most people will self-moderate their caffeine intake based on their personal experience of what they can tolerate. However it’s important that those with a low sensitivity to caffeine stay within the recommended daily caffeine intake of up to 400mg caffeine”
Do a test like IamYIam to see which caffeine sensitivity category you fall into.