Three to four cups of coffee a day were tied to about five extra years of life.

Coffee occupies an unusual place in nutrition science, a daily habit for hundreds of millions of people that researchers keep circling back to with new studies, some flattering and some cautionary. The latest addition to that body of research zeroes in on a specific population and a specific biological marker, offering one of the more concrete estimates yet of how a moderate coffee habit might correspond to slower biological aging.

The study in question did not simply ask whether coffee drinkers lived longer. It measured something more precise: the length of telomeres, the protective caps on the ends of chromosomes that shorten as cells divide and are widely used by researchers as a biological marker of aging.

What the study measured

The research, covered in a roundup published by Medical News Today, drew on data from 436 people living with major psychiatric disorders, including schizophrenia, bipolar disorder and major depressive disorder with psychosis, recruited from psychiatric units in Oslo, Norway, between 2007 and 2018. That population was chosen deliberately: people with severe mental illness tend to have shorter life expectancies than the general population, driven by a combination of factors including higher rates of cardiovascular disease, smoking and other lifestyle-related risks, making biological aging markers within this group a particularly meaningful area of study.

Researchers found that participants who reported drinking three to four cups of coffee daily had telomere lengths consistent with being roughly five years younger biologically than their actual chronological age would suggest, compared with people in the study who drank little or no coffee. That five-year figure reflects a difference in telomere length, a marker associated with slower cellular aging, rather than a directly measured difference in how long any individual participant went on to live.

The J-shaped pattern researchers found

One of the more notable findings in the research was that the relationship between coffee consumption and telomere length was not simply linear, where more coffee meant more benefit. Instead, the data traced what researchers describe as a J-shaped curve: telomere length increased as coffee consumption rose from none up through three to four cups a day, then reversed direction among heavier drinkers. Participants who reported drinking five or more cups daily showed shorter telomeres and signs of increased biological aging compared with the moderate-consumption group, suggesting a sweet spot rather than a straightforward more-is-better relationship.

That kind of curve is common in nutrition research involving compounds that offer benefits at moderate doses but carry offsetting risks at higher intake, and it lines up with other established caffeine research showing that excessive consumption can disrupt sleep, elevate heart rate and increase anxiety symptoms, particularly relevant concerns for a study population already managing serious psychiatric conditions.

Why researchers think coffee might help

The proposed mechanism behind the finding centers on coffee’s antioxidant content. Coffee is one of the largest dietary sources of antioxidant compounds for many regular drinkers, and those compounds are thought to help neutralize oxidative stress, a cellular process linked to inflammation and to the gradual shortening of telomeres over time. If oxidative stress accelerates telomere shortening, then a dietary source of antioxidants consumed regularly and in moderate amounts could plausibly help slow that process, which is the mechanism researchers point to in explaining the pattern observed in the data.

The study was published in BMJ Mental Health, a peer-reviewed journal focused on psychiatric and mental health research, and its authors framed the findings specifically within the context of trying to understand modifiable lifestyle factors that might help close the life-expectancy gap between people with serious mental illness and the general population.

What the finding does and does not show

It is worth being precise about what this kind of research can and cannot establish. The study identified an association between coffee consumption and telomere length within a defined population of psychiatric patients; it did not track participants over decades to directly confirm that moderate coffee drinkers in the study actually lived five years longer than non-drinkers. Telomere length is a well-established proxy for biological aging, but it is a proxy rather than a direct measurement of lifespan, and observational studies of this kind cannot fully rule out that other factors correlated with coffee habits, such as overall diet quality, activity levels or socioeconomic circumstances, contributed to the pattern researchers observed.

The population studied also matters for how broadly the findings should be applied. Because participants were specifically people managing major psychiatric disorders, the results speak most directly to that group rather than to the general population, even though the underlying biological mechanism involving antioxidants and oxidative stress is not unique to people with mental illness.

People with schizophrenia, bipolar disorder and major depressive disorder with psychosis face a documented life-expectancy gap compared with the general population, a disparity researchers attribute to a combination of higher rates of cardiovascular disease, metabolic conditions, smoking and reduced access to consistent medical care. Identifying a low-cost, widely available lifestyle factor that correlates with slower biological aging within that specific population carries practical significance precisely because it targets a group already known to face elevated mortality risk, rather than describing a marginal benefit within an already long-lived general population.

How the findings fit into broader coffee research

This study adds to a growing body of research examining coffee’s relationship with aging and chronic disease risk, much of which has found associations between moderate coffee consumption and lower rates of conditions including type 2 diabetes, certain liver diseases and some cardiovascular outcomes. Researchers in this area consistently emphasize moderation, generally pointing to a range of roughly three to four cups a day as the point where potential benefits appear strongest before the balance shifts toward the risks associated with excess caffeine intake, a pattern this latest telomere research reinforces rather than overturns.

Morning Overview produced this article with AI assistance and reviewed it against the cited sources.

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