Eating large amounts of food with added sugar could have a hyperactive effect on the body's ticking biological clock, even when the rest of a person's diet remains otherwise healthy.
A new study among 342 Black and White middle-aged women has found those who eat high quantities of added sugar have 'older-looking' cells.
The findings could help explain why some people seem to age faster or slower than others who have lived the same number of years. Sugar intake could be an important, overlooked factor.
Food scientist Barbara Laraia from the University of California Berkeley says that based on her and her colleagues' results, cutting out 10 grams of added sugar each day was "akin to turning back the biological clock by 2.4 months, if sustained over time."
Along with the occasional mutation, our DNA can accumulate less permanent edits over time. These so-called epigenetic changes often act like chemical padlocks, deactivating genes and altering how the body's genetic code is expressed for a time.
A collection of transient edits is referred to as an epigenetic clock, and can be a useful way to guess at a person's true biological age. Epigenetic changes can be read by scientists to better understand how old a cell is and what damages or stresses it has experienced.
Diet, lifestyle, genetics, and disease are all known to affect how quickly a person's epigenetic clock ticks, but this is one of the first studies to examine how sugar specifically plays a role. It also includes a diverse cohort.
The findings suggest that added sugar can alter epigenetic switches related to aging more quickly than healthier foods can turn them off, regardless of whether healthy nutrients are also present.
Female participants who ate a diet rich in vitamins, minerals, and antioxidants, for instance, had cells with the 'youngest'-looking epigenetic age. Those on the Mediterranean diet were observed to have the slowest epigenetic clocks.
Still, the more added sugar a person consumed each day, the older their salivary DNA appeared to scientists, even when their meals were rich in foods that maintain and repair DNA.
This was true even when accounting for education, lifestyle factors, and the current health of participants.
On average, women in the study ate just over 60 grams of sugar a day, although some ate more than 300 grams a day.
For perspective, the American Heart Association recommends limiting added sugars to about 25 grams for women and 36 grams for men, defining them as the extra dollop of syrup or sprinkle of sweetness put into foods during preparation, on top of their natural monosaccharide and disaccharide content.
The findings suggest that added sugar can significantly accelerate cellular aging, but it is important to note that this study is only based on food records collected over three non-consecutive days, and one salivary swab.
Previous studies have suggested that cells can appear epigenetically 'younger' or 'older' depending on when in the day their DNA was sampled, so longer term studies among both sexes are needed before further conclusions can be drawn.
"We knew that high levels of added sugars are linked to worsened metabolic health and early disease, possibly more than any other dietary factor," explains behavioral scientist Elissa Epel from the University of California San Francisco.
"Now we know that accelerated epigenetic aging is underlying this relationship, and this is likely one of many ways that excessive sugar intake limits healthy longevity."
The study was published in JAMA Network Open.