Washington, Guzzling more than one soft drink a day increases the risk factors for heart disease, and it doesn't matter if the beverage is regular or diet.
The finding is based on a study led by NRI doctor Ravi Dhingra, an instructor in medicine at Harvard Medical School.
The senior author on the study was All India Institute Of Medical Sciences (AIIMS) alumni Dr Ramachandran Vasan, currently working as professor of medicine at Boston University School of Medicine.
Dr Vasan said that the results of the Framingham Heart Study had surprised researchers a bit, because they had not expected diet sodas to increase the risk of heart disease.
"We were struck by the fact that it didn't matter whether it was a diet or regular soda that participants consumed, the association with increased risk was present," he said.
"In those who drink one or more soft drinks daily, there was an association of an increased risk of developing the metabolic syndrome," he said.
Metabolic syndrome is a cluster of cardiovascular disease and diabetes risk factors including excess waist circumference, high blood pressure, elevated triglycerides, low levels of high-density lipoprotein (HDL "good" cholesterol) and high fasting glucose levels.
The presence of three or more of the factors increases a person's risk of developing diabetes and cardiovascular disease. As a part of the study the researchers analysed nearly 9,000 person observations made in middle-aged men and women over four years at three different times.
In a "snapshot in time" at baseline, they found that individuals consuming one or more soft drinks a day had a 48 percent increased prevalence of the metabolic syndrome compared to those consuming less than one soft drink daily.
In a longitudinal study of participants who were free of metabolic syndrome at baseline (6,039 person observations), consumption of one or more soft drinks a day was associated with a 44 percent higher risk of developing new-onset metabolic syndrome during a follow-up period of four years.
The researchers also observed that compared to participants who drank less than one soft drink daily, those who drank one or more soft drinks a day had a 31 percent greater risk of developing new-onset obesity (defined as a body mass index [BMI] of 30 kilograms/meter2 or more); 30 percent increased risk of developing increased waist circumference; 25 percent increased risk of developing high blood triglycerides or high fasting blood glucose and a 32 percent higher risk of having low HDL levels.
They also noted that participants who consumed one or more drinks of diet or regular soda per day had a 50 to 60 percent increased risk for developing new-onset metabolic syndrome.
Lead author Dr Ravi Dhingra, M.D said that though people don't need to stop drinking soft drinks all together, they must moderate the amounts they consume.
"Moderation in anything is the key. If you are drinking one or more soft drinks a day, you may be increasing your risk of developing metabolic risk factors for heart disease," he said.
"It didn't matter whether it was a diet or regular soft drink," he added.
"Results also don't appear to be driven by the dietary pattern of soft drink users, i.e, by other food items that are typically consumed along with soft drinks," Vasan said.
"We adjusted in our analyses for saturated fat and trans fat intake, dietary fiber consumption, total caloric intake, smoking and physical activity, and still observed a significant association of soft drink consumption and risk of developing the metabolic syndrome and multiple metabolic risk factors," he said.
Dhingra and Vasan called for further studies to replicate the results and to understand the mechanisms driving this association before recommendations can be made.