Sugary drinks increase the risk of diabetes, heart disease and stroke, according to the researchers.
The beverages, containing added sugars in the form of high-fructose corn syrup or table sugar (sucrose), are the focus of a comprehensive new study, which also looks at the unique way in which fructose may contribute to these conditions.
The study states that there is an "urgent need for public health strategies that reduce the consumption of these drinks."
It is already well documented that consuming one or more sugar-sweetened beverages a day can cause weight gain and obesity. This is partly because liquid calories are not filling, which means that people drink them alongside their usual food intake.
Sweeteners such as high-fructose corn syrup, produced from corn starch, are widely used in the US as a cheaper alternative to sucrose in foods and beverages. While consumption of sugar-sweetened beverages has decreased slightly in the last 10 years, they remain the single greatest source of added sugar intake in the US diet.
For 1 in 4 Americans, soft drinks provide least 200 calories a day; 5% of the population consume more than 500 calories a day in this way - the equivalent of four cans of soda.
Proven risk of disease
Researchers, led by Dr. Frank Hu, PhD, professor of nutrition and epidemiology at Harvard T.H. Chan School of Public Health in Boston, MA, reviewed data from recent epidemiological studies and meta-analyses of these studies.
- A 12 oz cola contains 136 calories
- A 12 oz sweetened lemon ice tea contains 135 calories
- A 12 oz unsweetened carbonated water contains 0 calories.
They found that consuming one or two servings a day:
- increases the risk of developing type 2 diabetes by 26%
- heightens the risk of heart attack or fatal heart disease by 35%
- raises the risk of stroke by 16%.
They also explored how fructose is metabolized in the body and its link to weight gain and the development of metabolic and cardiovascular conditions.
Unlike glucose, which is directly absorbed into the bloodstream through the gastrointestinal tract to provide fuel, fructose is metabolized in the liver.
There, it can be converted to fatty compounds called triglycerides, which may lead to fatty liver disease and insulin resistance - a key risk factor for developing diabetes and cardiovascular disease.
The researchers point out that since fructose and glucose typically travel together in sugar-sweetened beverages and foods, it is important to reduce total amounts of added sugars, especially in the form of sugar-sweetened beverages.
Dr. Hu and his team conclude that:
"Although reducing the consumption of sugar-sweetened beverages or added sugar alone is unlikely to solve the obesity epidemic entirely, limiting intake is one simple change that will have a measurable impact on weight control and prevention of cardiometabolic diseases."
As substitutes, they suggest water, coffee or tea. They urge caution regarding artificially sweetened drinks, since the long-term effects of these are not yet known.
They also call for more aggressive public policy interventions to help reduce consumption of sugar-sweetened beverages, pointing out that the World Health Organization (WHO) and the 2015 US Dietary Guidelines Advisory Committee recommend that added sugars comprise no more than 10% of total calories consumed.
Dr. Hu hopes that changes to nutritional labeling, which are expected to clearly define the amount of added sugar in a product and the percent daily value for added sugar, will help to educate consumers and ultimately reduce the daily intake of these and other products packed with sugar.
Earlier this year, Medical News Today reported on research linking over 184,000 deaths a year with sugary drinks.