The World Health Organization (WHO) report that at least 19 million yearly deaths are from cardiometabolic disorders – an umbrella term for cardiovascular disease and conditions such as metabolic syndrome and type 2 diabetes.
In the United States, a study from 2012 reports that in that year, 702,308 people died from a cardiometabolic disorder, and dietary factors such as food and beverages seemed to raise the risk of cardiometabolic mortality.
However, as the authors of the new research explain, the results of such studies have been deemed "controversial."
So, in the new review, the researchers — led by M. Faadiel Essop, Ph.D., of Stellenbosch University in Stellenbosch, South Africa — decided to investigate overall trends in the findings of 36 studies, spanning over a decade.
The harms of sugary drinks
Essop and colleagues included clinical trials, both controlled and randomized, as well as observational studies in their analysis.
The studies were from the last decade, ending as recently as September 2017, and predominantly examined participants who consumed over five sugar-sweetened beverages (SSBs) a week – or the equivalent of less than one such drink a day.
Although some of these studies yielded contradictory results, or did not produce enough evidence to support a link between SSBs and cardiometabolic diseases, most of them did reveal a clear association between SSBs and the risk of developing cardiometabolic illnesses.
Overall, the review found a strong correlation between SSBs and metabolic syndrome – a collective name for a range of risk factors that increase the odds of developing cardiometabolic disorders.
These risk factors include a large waistline, a high level of triglycerides (i.e., fats that can be found in our blood), low levels of the "good" kind of cholesterol, high blood sugar, and high blood pressure.
"Most epidemiological studies strongly show that frequent SSB intake contributes to the onset of the [metabolic syndrome] in the long-term," write the authors.
More specifically, a minimum daily consumption of one SSB increased the risk of hypertension, and even as little as two SSBs per week increased the chances of developing type 2 diabetes.
Additional findings include the fact that regular SSB consumption may decrease insulin sensitivity by as much as 17 percent, which explains the raised blood sugar levels.
The senior investigator comments on the findings, saying:
"Sugar-sweetened beverage consumption is steadily rising among all age groups worldwide [...] Our analysis revealed that most epidemiological studies strongly show that frequent intake of these beverages contributes to the onset of the metabolic syndrome, diabetes, and hypertension."
M. Faadiel Essop, Ph.D.
"The findings demonstrate there is a clear need for public education about the harmful effects of excess consumption of sugar-sweetened beverages," Essop adds.
"But our understanding of this topic would benefit from additional research to further clarify how sugar-sweetened beverages affect our health."
"We do see some limitations in the current research on this topic," he concedes, "including a need for longer-term studies and standardized research methods."