Editorial NexoScience
Diet soda was supposed to be the safer choice. Swap the sugary can for the zero-calorie version and your heart gets a break, or so the logic goes. Long-term data on more than 100,000 women who tracked their diets for nearly two decades suggests that logic does not hold up as cleanly as most people assume.
Getting a large share of daily calories from added sugar raises the odds of heart disease. Among 109,034 postmenopausal women followed for an average of 17.4 years as part of the Women’s Health Initiative, those who got 15% or more of their daily energy from added sugar had an 8% higher risk of total cardiovascular disease and a 20% higher risk of coronary heart disease than women who stayed under 10%. Roughly one in five women in the study crossed that 15% threshold.
Drinking sugary beverages daily made the risk climb further. Women who had at least one serving a day of sugar-sweetened drinks, regular soda, fruit drinks, or sweetened juice blends faced a 29% higher risk of total cardiovascular disease, a 35% higher risk of coronary heart disease, a 35% higher risk of heart failure, and a 30% higher risk of stroke compared with women who rarely touched them. Even drinking soft drinks just once a week was tied to a 10% bump in cardiovascular risk and a 17% bump in coronary heart disease risk.
Here is the part that undercuts the usual advice: artificially sweetened diet drinks were not the safe alternative they are marketed as. Women who drank at least one diet beverage a day had a 14% higher risk of total cardiovascular disease and a 24% higher risk of stroke than those who mostly skipped them, a pattern that held even after adjusting for weight, exercise, smoking, and dozens of other factors. A separate pooled analysis of 21 cohort studies conducted alongside this one found artificially sweetened beverages carried the strongest link to cardiovascular death and stroke of the three categories tested, ahead of both sugar-sweetened drinks and added sugar itself.
Not every sweet drink came out looking bad. Fruit juice, at a serving a week or more, was linked to a slightly lower risk of coronary heart disease, a reminder that lumping every sweetened beverage into one bucket misses real differences between them.
The exact mechanism behind the diet drink finding is still unsettled. Researchers point to a few plausible explanations: artificial sweeteners may not fully suppress the urge for sugar and end up encouraging more eating overall, they may alter gut bacteria in ways that affect metabolism, or compounds tied to the caramel coloring used in many diet colas may promote low-grade inflammation. For sugar itself, the pathway is better understood: frequent glucose spikes drive insulin resistance, raise triglycerides, and can nudge blood pressure upward over time, all of which strain the cardiovascular system.
None of this proves any single can of soda causes a heart attack. The study followed people over time rather than assigning them to different diets, so it can show a strong statistical link, not direct cause and effect. Women who drank more soda in the study also tended to smoke more and exercise less, factors the researchers adjusted for but could not eliminate completely. Even so, the size of the cohort, the length of follow-up, and the consistency of the pattern across a separate meta-analysis of 21 other studies make this hard to wave away as noise.
The findings come from Yang et al., published in Nutrients (2022), based on data from the Women’s Health Initiative cohort and a network meta-analysis of prospective studies. DOI: 10.3390/nu14204226.
