Drinking a maximum of 3 to 4 cups of coffee per day could slow down the “biological” aging of people with serious mental illness, by lengthening their telomeres (cellular indicators) and giving them the equivalent of 5 additional biological years, compared to non-coffee drinkers, according to a study published in the open access journal. BMJ Mental Health.
But no such effects were observed above 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 are found at the ends of chromosomes and play a role similar to the plastic spikes at the end of shoelaces. Although telomere shortening is a natural part of the process, it appears to be accelerated in people with major psychiatric disorders, such as psychosis, schizophrenia and bipolar disorder, the researchers note.
Telomeres are sensitive to environmental factors, including diet. And coffee, consumed in moderation, has been linked to various health benefits, prompting researchers to explore whether it might influence the rate at which telomeres shorten in people with major mental health problems.
They included 436 adult participants from the Norwegian Thematically Organized Psychosis (TOP) Study, recruited between 2007 and 2018: 259 had schizophrenia; the remainder (177) suffered from affective disorders, including bipolar disorder and major depressive disorder accompanied by psychosis.
Participants were asked how much coffee they drank each day and were grouped into 4 categories: zero (44); 1 to 2 cups; 3 to 4 cups (110); and 5 cups or more. And they were asked if they smoked and, if so, for how long.
Participants who drank more than 5 cups per day were significantly older than those who drank none or 1 to 2 cups per day. And people with schizophrenia drank significantly more coffee than those with emotional disorders.
Smoking is associated with faster caffeine metabolism. And around three-quarters of the participants (77%; 337) smoked, and had done so for an average of 9 years. And those who drink more than 5 cups a day have been smoking much longer than any other group.
Telomere length was measured from white blood cells (leukocytes) extracted from blood samples, which revealed a significant difference between the 4 groups, forming a J-shaped curve.
Compared to those who don’t drink coffee, drinking up to 3 to 4 cups per day was associated with longer telomeres, but not among participants who drank 5 or more each day.
Participants consuming 4 cups of caffeine daily had comparable telomere length at a biological age 5 years younger than non-coffee drinkers after adjusting for age, gender, ethnicity, smoking, type of mental illness, and drug treatment.
This is an observational study and as such no definitive 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 coffee consumption, actual levels of caffeine, or other sources of caffeinated beverages.
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 consumption could help preserve cells in a population whose pathophysiology may predispose them to an accelerated rate of “, they explain.
Coffee is popular around the world, with around 10.56 billion kilos consumed worldwide in 2021-2021 alone, they point out.
But despite its potential benefits, “consuming more than the recommended daily amount of coffee can also cause cellular damage and shortening (of telomeres) through the formation of reactive oxygen species,” they warn, noting that international health authorities recommend limiting caffeine consumption to a maximum of 400 mg/day (4 cups of coffee).
