From the Guidelines
Diet Coke consumption is associated with an increased risk of metabolic syndrome, weight gain, and type 2 diabetes, and its regular intake should be discouraged due to the potential negative effects on gut bacteria and metabolic processes. The evidence from recent studies, including the 2019 ACC/AHA guideline on the primary prevention of cardiovascular disease 1, suggests that artificially sweetened beverages like Diet Coke may increase the risk of developing type 2 diabetes and cardiovascular disease. Additionally, the phosphoric acid in Diet Coke can contribute to decreased bone density and increased risk of osteoporosis over time by leaching calcium from bones. The acidic nature of the drink may also damage tooth enamel, leading to dental erosion and increased sensitivity.
Some of the key findings from the evidence include:
- A 20% increase in the frequency of diabetes mellitus with 1 daily serving of artificially sweetened beverages 1
- An association between low-carbohydrate diets and a 31% higher risk of all-cause death, with increased cardiac mortality rate 1
- The potential for nonnutritive sweeteners to alter gut microbiota and increase the risk of glucose intolerance, insulin resistance, diabetes, and weight gain 1
- The lack of clear evidence that dietary supplementation with nonnutritive sweeteners can improve outcomes in people with diabetes who do not have underlying deficiencies 1
The most recent and highest quality study, published in 2025, suggests that while nonnutritive sweeteners like those found in Diet Coke have undergone extensive safety evaluation, their use should be assessed individually and in moderation 1. Overall, the evidence suggests that regular consumption of Diet Coke and other artificially sweetened beverages should be discouraged due to the potential negative effects on metabolic health and bone density. Instead, water and other low-calorie, nutrient-dense beverages should be promoted as the healthiest options.
From the Research
Negative Effects of Diet Coke
- The consumption of artificial sweeteners, such as those found in Diet Coke, has been linked to an increased risk of cardiovascular diseases, including coronary heart disease and cerebrovascular disease 2.
- Aspartame, a common artificial sweetener used in Diet Coke, has been associated with an increased risk of cerebrovascular events, including stroke 2.
- Some studies have suggested that artificial sweeteners, including aspartame, may disrupt the oxidant/antioxidant balance, induce oxidative stress, and damage cell membrane integrity, potentially leading to systemic inflammation 3.
- However, other studies have found no significant association between diet soda consumption and incident diabetes, or between artificial sweetener consumption and markers of glucose and insulin homeostasis 4, 5, 6.
- The acute effects of aspartame and acesulfame-K, two non-nutritive sweeteners commonly used in diet cola, on glycaemic response have been found to be similar to those of glucose, with no significant differences in glycaemic index or postprandial glycaemia 5.
- A randomized crossover study found that consumption of a beverage containing aspartame and acesulfame K for two weeks did not adversely influence glucose metabolism in adult males and females 6.