Researchers studying people with severe psychiatric disorders found that consuming up to four cups of coffee may have a positive effect, potentially helping to slow down the biological ageing process in people with such conditions. The study suggests that this amount of coffee is associated with longer telomeres, which are indicators of cellular ageing, and may result in an extension of biological lifespan by up to 5 years compared to people who do not drink coffee, according to the findings published in the open access journal BMJ Mental Health.
However, these potential benefits were not found in the study when coffee consumption exceeded this level. The limit of 3-4 cups is the maximum daily amount recommended by several major health authorities, including the NHS and the US Food and Drug Administration.
Why Coffee is so Attractive to Many
Coffee is one of the most popular drinks in the world. It is estimated that over 2.25 billion cups of coffee are consumed worldwide every day. In many countries, it is part of the daily routine for adults: in the USA, for example, around 66% of adults drink coffee every day, and on average these regular consumers drink around three cups a day. There are also countless coffee lovers in Europe. According to a recent survey, around 92% of Germans drink coffee regularly.
Coffee also remains extremely popular in Austria: according to a recent survey, Austrians drink an average of around 2.75 cups per day, or a total of over 1,000 cups per year. Consumption is particularly high among people aged between 50 and 59, who average over three cups a day. This shows that For many, coffee is more than just a drink – it is part of everyday life, a ritual and often the first step in the morning.
The aroma, the taste, the ritual – coffee has a strong cultural significance. But beyond enjoyment: coffee contains hundreds to thousands of bioactive substances: Vitamins, minerals, acids, oils and a multitude of antioxidants. A key ingredient is caffeine – known for its awakening effect: just 15-30 minutes after consumption, caffeine can reduce tiredness, increase alertness and concentration and last for several hours. But coffee can be more than just a stimulant: in recent decades, research has shown that moderate coffee consumption can be associated with various health benefits – especially when consumed in moderation (often stated as 3-5 cups per day).
Telomeres, Mental Illness and Why they Matter
Telomeres are located at the ends of chromosomes and function much like the plastic caps on shoelaces that prevent fraying. Although telomeres naturally shorten with age, this process appears to progress faster in people with severe psychiatric illnesses such as psychosis, schizophrenia and bipolar disorder, the researchers found.
Since telomeres respond to environmental influences such as diet, the team investigated whether moderate coffee consumption could slow the shortening of telomeres in people with severe psychiatric disorders. Coffee is associated with various health benefits when consumed in moderation, making it a logical area of study.
Study Participants and Coffee Habits
The study looked at 436 adults who participated in the Norwegian Thematically Organized Psychosis (TOP) study between 2007 and 2018. Of these participants, 259 had schizophrenia and 177 had affective disorders, including bipolar disorder and major depressive disorder with psychosis.
Participants reported their daily coffee consumption and were categorized into four groups: zero (44 people), 1-2 cups, 3-4 cups (110 people) and 5 or more cups. They were also asked about their smoking habits and the duration of their smoking. Those who drank 5 or more cups per day tended to be older than those who drank none or only 1-2 cups. Participants with schizophrenia also consumed more coffee on average than participants with affective disorders.
Smoking affects how quickly the body processes caffeine. About three-quarters of the group (77%; 337 people) were smokers with an average smoking history of 9 years. Participants who drank 5 or more cups had smoked significantly longer than those in the other categories.
Telomere Measurements and Key Findings
The researchers measured telomere length using white blood cells (leukocytes) from blood samples. The results showed remarkable differences between the four groups with different coffee consumption, forming a J-shaped curve, according to the researchers.
Compared to participants who did not drink coffee, those who consumed 3-4 cups a day had longer telomeres. This correlation did not occur in the group that drank 5 or more cups. Participants who consumed 4 cups daily had telomere lengths that corresponded to a biological age that was about 5 years younger than that of non-coffee drinkers. This assessment took into account age, gender, ethnicity, tobacco use, type of mental disorder and current treatments.
Biological Explanations and Limitations of the Study
As this was an observational study, the authors emphasize that no direct relationship between cause and effect can be established. They also point out that they lacked details on several potentially important factors, such as the type of coffee consumed, the timing of consumption, the exact caffeine content and whether the participants drank other caffeinated beverages.
Nevertheless, the researchers point to several possible explanations. Coffee contains powerful antioxidant and anti-inflammatory compounds that may help protect cells from age-related damage. “Telomeres are highly sensitive to oxidative stress and inflammation, which further emphasizes how coffee consumption could help slow cell aging in a population whose pathophysiology may predispose them to accelerated aging,” they explain.
Despite its potential benefits, the researchers warn that “consuming more than the recommended daily amount of coffee may also lead to cell damage and telomere shortening through the formation of reactive oxygen species,” and reiterate that international health authorities recommend limiting daily caffeine intake to a maximum of 400 mg/day (4 cups of coffee).
Study Links Coffee Consumption to Lower Risk of All-Cause Mortality; Benefits Diminished by Additives
In an earlier observational study, researchers from the Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University found that the association between coffee consumption and mortality risk varied with the amount of sweeteners and saturated fat added to the beverage.
The study, published online in the Journal of Nutrition, found that consumption of 1-2 cups of caffeinated coffee per day was associated with a lower risk of death from all causes and death from cardiovascular disease. Black coffee and coffee with low added sugar and saturated fat were associated with a 14% lower risk of all-cause mortality compared to no coffee consumption. The same association was not observed for coffee with high added sugar and saturated fat. The health benefits of coffee may be due to its bioactive compounds, but this research suggests that the addition of sugar and saturated fat may reduce the mortality benefits.
The study analyzed data from nine consecutive cycles of the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018, which were linked to mortality data from the National Death Index. The study included a nationally representative sample of 46,000 adults aged 20 years and older who had completed valid 24-hour dietary logs for the first day. Coffee consumption was categorized by type (with or without caffeine), sugar and saturated fat content. Mortality outcomes included all causes, cancer and cardiovascular disease. Low added sugar (from granulated sugar, honey and syrup) was defined as less than 5% of the daily requirement, equivalent to 2.5 grams per cup or about half a teaspoon of sugar. Low saturated fat (from milk, cream and half-and-half) was defined as 5% of the daily requirement, which is 1 gram per cup or the equivalent of 5 tablespoons of 2% milk, 1 tablespoon of light cream or 1 tablespoon of half-and-half.
In the study, consumption of at least one cup per day was associated with a 16% lower risk of all-cause mortality. For 2-3 cups per day, this association increased to 17%. Consumption of more than three cups per day was not associated with a further reduction, and the association between coffee consumption and a lower risk of cardiovascular disease weakened when more than three cups per day were consumed. No significant association was found between coffee consumption and cancer mortality.
“Few studies have examined how coffee supplements might affect the association between coffee consumption and mortality risk, and our study is one of the first to quantify how much sweetener and saturated fat are added,” said lead author Bingjie Zhou. Limitations of the study include the fact that even reported recall data are subject to measurement error due to daily fluctuations in food intake. The lack of significant associations between decaffeinated coffee and all-cause mortality could be due to low consumption in the population studied.
What to Look Out for When Consuming Coffee
Despite the many potential benefits of coffee, there are aspects where moderation is important:
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Moderate consumption recommended: Studies that find positive effects usually assume around 3-5 cups per day. Excessive coffee consumption can – depending on your tolerance – have negative effects such as sleep disorders, nervousness or cardiovascular stress.
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The method of preparation makes a difference: unfiltered coffee can contain certain substances (e.g. diterpenes) that can increase LDL cholesterol levels – this can put the positive effects into perspective.
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Do not see it as a substitute for a healthy lifestyle: Coffee can have a certain protective effect – but is not a substitute for a balanced diet, exercise, sufficient sleep and a healthy environment.