A daily multivitamin may modestly slow biological ageing over two years, though the effect appears small and any health benefit remains unclear.
The study followed 958 healthy participants with an average age of about 70, split into four groups taking either a daily cocoa extract and multivitamin, daily cocoa extract and multivitamin placebo, daily cocoa extract placebo and multivitamin, or two placebos each day.
The study also received funding from confectionery manufacturer Mars.
Blood samples were taken at the start of the trial and after one and two years, then analysed for changes in five measures of DNA methylation, chemical changes to DNA that build up with age and can affect how genes work.
These measures, known as epigenetic clocks, are used to estimate how fast the body is ageing at a cellular level.
After taking account of participants’ age, sex and baseline measures, the researchers found that, compared with those given a placebo, participants who took a daily multivitamin showed a slowdown in biological ageing on two of the five clocks, particularly those used to estimate mortality risk.
Overall, the researchers said the effect equated to about four months less biological ageing over two years.
The effect appeared greater in people whose biological ageing was faster at the start of the study, with further analysis suggesting this may be because those participants had greater nutritional deficits to begin with.
The cocoa extract did not slow biological ageing on any of the five clocks and did not interact with the multivitamin.
However, the authors said it remains unclear what the findings mean for health in everyday life. “Ultimately, it is critical to determine the clinical relevance of our findings.”
Howard Sesso, an epidemiologist at Mass General Brigham department of medicine and senior author, said the findings did not mean all older adults should take multivitamins.
“There are no known risks for taking a multivitamin in our two large clinical trials. At the same time, we do not know for sure who benefits, and how.
“Nutritional status may partly explain the results, but these epigenetic clocks may reflect other age-related risk factors.”
The findings also prompted caution from independent experts.
Marco Di Antonio, an expert in biological ageing at Imperial College London, said the link between epigenetic clocks and the practical effects of ageing was still unclear.
“I do not think that people should start taking multivitamins daily but these results demonstrate that having a healthy diet and lifestyle will have an effect on your biological age, as direct changes in the diet can have impact on the clocks,” he said.
Taking multivitamins daily will be pointless if there is not a healthy lifestyle associated with it, as bad habits will have a negative impact on ageing too that won’t be reverted by multivitamins.
A large study published last year found that daily multivitamins did not help people live longer and might even raise the risk of early death, although Sesso and colleagues said their previous work had suggested daily multivitamins were associated with improved cognition and reductions in lung cancer and cataracts.
Pilar Guallar Castillón, an associate professor at the Autonomous University of Madrid, said the clinical trial associated with the study had found no effect of multivitamin consumption on the main causes of mortality and morbidity.
“My personal advice is to stop taking multivitamins, whether in pill or gummy form,” she said.
“Eat a healthy, varied diet rich in fruit and vegetables, and do not waste your money on nutritional supplements.
“There are huge commercial interests in their consumption and a lack of clinical evidence.”