Drinking a maximum of 3-4 cups of coffee a day may slow the ‘biological’ aging of people with severe mental illness, by lengthening their telomeres-indicators of cellular ageing-and giving them the equivalent of 5 extra biological years, compared with non-coffee drinkers, finds research published in the open access journal BMJ Mental Health.
But no such effects were observed beyond this quota, which is the maximum daily intake recommended by several international health authorities, including the NHS and the US Food and Drug Administration.
Telomeres sit on the end of chromosomes and perform a role similar to the plastic tips on the end of shoelaces. While telomere shortening is a natural part of the ageing process, it seems to be accelerated in those with major psychiatric disorders, such as psychosis, schizophrenia, and bipolar disorder, note the researchers.
Telomeres are sensitive to environmental factors, including, possibly, diet. And coffee, when drunk in moderation, has been associated with various health benefits, prompting the researchers to explore whether it might influence the rate at which telomeres shorten in people with major mental ill health.
They included 436 adult participants from the Norwegian Thematically Organised Psychosis (TOP) study, recruited between 2007 and 2018: 259 had schizophrenia; the rest (177) had affective disorders, including bipolar disorder and major depressive disorder with psychosis.
Participants were asked how much coffee they drank every day and were grouped into 4 categories: zero (44); 1–2 cups; 3–4 cups (110); and 5 or more cups. And they were asked whether they smoked, and if so, for how long they had done so.
Participants who drank 5+ cups a day were significantly older than those who drank none or 1–2 cups a day. And those with schizophrenia drank significantly more coffee than those with an affective disorder.
Smoking is associated with faster caffeine metabolism. And around three quarters of participants (77%; 337) smoked, and had done so, on average, for 9 years. And those drinking 5+ cups a day had smoked for significantly longer than any of the other groups.
Telomere length was measured from white blood cells (leucocytes) extracted from blood samples, and this revealed a significant difference among the 4 groups, forming a J shaped curve.
Compared with those drinking no coffee, drinking up to 3–4 cups a day was associated with longer telomeres, but not in those participants drinking 5 or more every day.
Those participants getting a daily 4-cup caffeine hit had telomere lengths comparable to a biological age 5 years younger than that of non-coffee drinkers after adjusting for age, sex, ethnicity, tobacco use, type of mental ill health, and drug treatment.
This is an observational study, and, as such, no firm conclusions can be drawn about cause and effect. And the researchers acknowledge that they had no information on potentially influential factors, including the type and timing of the coffee consumed, actual caffeine levels, or other sources of caffeinated drinks.
But there are plausible biological explanations for their findings, they suggest. These include the powerful antioxidant and anti-inflammatory compounds found in coffee.
“Telomeres are highly sensitive to both oxidative stress and inflammation, further highlighting how coffee intake could help preserve cellular ageing in a population whose pathophysiology may be predisposing them to an accelerated rate of ageing,” they explain.
Coffee is popular worldwide, with an estimated 10.56 billion kilos consumed around the globe in 2021-2 alone, they point out.
But despite its potential benefits, “consuming more than the daily recommended amount of coffee may also cause cellular damage and [telomere] shortening through the formation of reactive oxygen species,” they caution, emphasising that international health authorities recommend limiting caffeine intake to a maximum of 400 mg/day (4 cups of coffee).
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Journal reference:
DOI: 10.1136/bmjment-2025-301700