Drinking sugar-sweetened sodas and other sugary drinks on a regular basis has been linked with weight gain, diabetes and heart attacks, among other health problems. But can a soda habit actually shorten your life?

Possibly, according to a recent study.

Researchers from the University of California San Francisco found that regularly drinking soda can shorten your telomeres. These are the protein caps on the end of chromosomes — picture the plastic ends of your shoelaces — that protect your DNA from damage.

"Telomere length naturally shortens with your biological age," says Cindy Leung, Sc.D., a postdoctoral researcher at the University of California San Francisco, who led the study. "When telomeres get too short, the cell can malfunction and die."

Leung and her team found that soda drinking appears to hasten this natural shortening, which has also been linked with the development of heart disease, diabetes and some cancers.

One daily soda, five years of aging

The researchers looked at DNA specimens from more than 5,300 men and women, ages 20 to 65, who took part in the National Health and Nutrition Examination Survey from 1999 to 2002. They then looked at the dietary records the participants provided, zeroing in on soda consumption.

"We found that drinking 20 ounces of sugar-sweetened soda, the amount commonly found in a [soda] bottle now, was associated with an additional 4.6 years of telomere shortening or aging" compared to those who rarely drank sodas.

The link between soda drinking and shortened telomeres held even after Leung accounted for such other factors as smoking, overall diet and alcohol consumption.

The 4.6 years of shortening was similar to the effect of smoking, the researchers say.

Leung did not follow the men and women to see if the heavy soda drinkers were more likely to die early. But other studies have linked shorter telomere length with an increased death rate.

The researchers found no substantial link between fruit juice, fruit drinks, sport drinks, energy drinks or sweetened waters and shortened telomeres. 

Diet sodas were not linked with shorter telomeres, Leung says. But other research has yielded mixed findings about their effects on health. She considers the research on diet sodas and health inconclusive for now.

One co-author of the study is a shareholder of Telomere Diagnostics, a telomere measurement company.

Soda: the balance sheet

Much research on sodas and health has been done at the Harvard School of Public Health. In a roundup of recent research at Harvard and elsewhere, Harvard experts found that:

  • Drinking one or two cans a day of sugary drinks increases the risk of Type 2 diabetes by 26 percent.
  • Men who had a can of a sugary beverage a day for 20 years had a 20 percent higher heart attack risk than those who rarely drank them.
  • A can a day for two decades boosted the risk of gout by 75 percent in women. A similar risk was found in men.
  • Decreasing sugary drink consumption could reduce the obesity epidemic, Harvard experts say.

Industry weighs in

As research has accumulated about the health effects of sugary drinks, the American Beverage Association, a trade group representing beverage makers, has maintained that ''the total diet and overall pattern of foods and beverages consumed is the most important focus of healthy eating," not a single food or beverage.

On its website, the association says it has been offering smaller portions and lower-calorie options, with a decline of calories from added sugar in soda by 39 percent since 2000.

Take-home advice

When you drink a sugary soda, your blood sugar level increases, Leung says. If you drink soda often, she says, it can increase the inflammation in your body and also increase your insulin resistance — neither of which is good for your health.

With the jury out on diet sodas, Leung says she doesn’t recommend those either. Stick with plain water or unsweetened tea or coffee, she suggests. 

Kathleen Doheny is a Los Angeles journalist specializing in health, behavior and fitness topics.