Does my DNA file say if I'm a fast or slow caffeine metabolizer?
It gives a hint. The marker rs762551 in CYP1A2, the liver enzyme that clears most caffeine, splits people into a "fast" A A genotype and "slower" C carriers; a second marker, rs4410790 near AHR, is linked to how much caffeine people tend to drink.
Marker 1: CYP1A2 rs762551 — how fast you clear caffeine
Search your raw data for rs762551 (chromosome 15). Files report it as A and C.
| Your letters | Associated with |
|---|---|
| A A | "Rapid" caffeine metabolizer (CYP1A2*1A/*1A). |
| A C | One C (the *1F allele in the study below): slower caffeine clearance. Common. |
| C C | Two C: slow caffeine metabolizer. |
In a Costa Rican study of 2,014 people with a first heart attack and 2,014 matched controls, 54% of controls carried the slow allele. Among slow-allele carriers, drinking 2–3 cups of coffee a day was associated with higher odds of a nonfatal heart attack (odds ratio 1.36) and 4 or more cups with 1.64, compared with under one cup; among A A "rapid" metabolizers there was no such increase (PMID 16522833). This is an association from one observational study, not proof that coffee causes heart attacks in slow metabolizers. The Genomeats knowledge base also cites a study linking coffee intake with hypertension in slow metabolizers (PMID 19451835).
How common
| Population group | C letter | A A (estimated) | C C (estimated) |
|---|---|---|---|
| African | 43.8% | 32% | 19% |
| Admixed American | 24.2% | 58% | 6% |
| East Asian | 32.7% | 45% | 11% |
| European | 32.0% | 46% | 10% |
| South Asian | 46.5% | 29% | 22% |
Carrying at least one C is the majority result in four of the five groups (about 54–71%; 43% in Admixed American participants) — it is normal variation, not a defect.
Marker 2: AHR rs4410790 — how much caffeine you tend to drink
Search for rs4410790 (chromosome 7); files report C and T. In a Costa Rican population, people drinking more than 400 mg of caffeine a day were more likely than those drinking under 100 mg to carry the C allele (odds ratio 1.41) (PMID 22854411). C C and C T lean toward higher habitual intake; T T toward lower. The C letter is common everywhere (37–62% across the 1000 Genomes groups), so none of these results is unusual.
Allele frequencies: 1000 Genomes phase 3 via Ensembl (rs762551, rs4410790), read 2026-10-23. Genotype shares are Hardy–Weinberg estimates.
Limits
- Other genes and non-genetic factors also affect how you handle caffeine. One marker does not measure your enzyme.
- The heart-attack finding comes from one population and one study design; it shows an association, not a personal risk number.
- Not a diagnosis. If caffeine gives you palpitations or you have high blood pressure, talk to a clinician.
What to do with it, in food terms
- Your own experience counts more than the letters. If coffee keeps you up or makes you jittery, an earlier cutoff — for example, no caffeine after early afternoon — is the simplest change.
- With a C at rs762551, there is a reason to be more mindful of large daily amounts, especially if you also have high blood pressure.
- Decaf, tea with less caffeine, or herbal infusions keep the ritual with less caffeine.
References
- Cornelis MC, El-Sohemy A, Kabagambe EK, Campos H. Coffee, CYP1A2 genotype, and risk of myocardial infarction. JAMA 2006;295:1135–41. PMID 16522833
- Josse AR, Da Costa LA, Campos H, El-Sohemy A. Associations between polymorphisms in the AHR and CYP1A1-CYP1A2 gene regions and habitual caffeine consumption. Am J Clin Nutr 2012;96:665–71. PMID 22854411
- Cited in the Genomeats knowledge base for CYP1A2 and blood pressure: PMID 19451835
- 1000 Genomes Project phase 3 allele frequencies via Ensembl.
Genomeats reads these markers on your phone — nothing is uploaded. Full write-ups for this trait are free. Coming soon to the App Store.