Consuming a higher percentage of calories from added sugars is linked with a higher prevalence of kidney stones, new research suggests.
Though added sugars have been linked with multiple poor health outcomes, their link with kidney stones has been unclear.
Added sugars are sugars or caloric sweeteners added to foods or drinks during processing or preparation to add flavor or shelf life. They do not include natural sugars such as lactose in milk and fructose in fruits.
Researchers, led by Shan Yin, a urologist at Affiliated Hospital of North Sichuan Medical College, in Nanchong, China, compared the added-sugar intake by quartiles in the U.S. National Health and Nutrition Examination Survey 2007-2018.
A total of 28,303 adults were included in this study, with an average age of 48. Women who consumed less than 600 or more than 3,500 kcal or men who consumed less than 800 or more than 4,200 kcal were excluded.
Researchers adjusted for factors including age, race, education, income, physical activity, and marital, employment, and smoking status.
Compared with the first quartile of percentage added-sugar calorie intake, the population in the fourth quartile, with the highest added sugar intake, had a higher prevalence of kidney stones (odds ratio, 1.39; 95% confidence interval, 1.17-1.65).
Compared with the group with fewer than 5% of calories from added sugar, the group that consumed at least 25% of calories from added sugar had nearly twice the prevalence of kidney stones (OR, 1.88; 95% CI, 1.52-2.32).
Findings were published online in Frontiers in Nutrition.
“By identifying this association, policymakers and health professionals can emphasize the need for public health initiatives to reduce added sugar consumption and promote healthy dietary habits,” the authors write.
Added sugar in the U.S. diet
Sugar-sweetened beverages such as soft drinks and energy and sports drinks account for 34.4% of added sugars in the American diet. Previous studies have shown the relationship between consuming sugar-sweetened beverages and a higher risk of obesity, diabetes, and cardiovascular disease, diseases that often co-occur with kidney stones.
Researchers note that even though most added sugars in the United States come from sugar-sweetened beverages, it’s unclear whether the association between added sugars and kidney stones is caused by the beverages or other sources. For instance, fructose intake has been found to be independently associated with kidney stones.
How much is too much?
The recommended upper limit on added sugar is controversial and varies widely by health organization. The American Heart Association says daily average intake from added sugars should be no more than 150 kcal for adult males (about 9 teaspoons) and no more than 100 kcal for women (about 6 teaspoons). The Institute of Medicine allows up to 25% of calories to be consumed from added sugars. The 2020 Dietary Guidelines for Americans and World Health Organization set 10% of calories as the recommended upper limit.
Further investigating what causes kidney stones is critical as kidney stones are common worldwide, affecting about 1 in 10 people in the United States alone, and occurrence is increasing. Kidney stones have a high recurrence rate – about half of people who get them have a second episode within 10 years, the authors note.
The researchers acknowledge that because participants self-reported food intake, there is the potential for recall bias. Additionally, because of the cross-sectional design, the researchers were not able to determine whether sugar intake or kidney stone occurrence came first.
This work was supported by the Doctoral Fund Project of North Sichuan Medical College. The authors declare no relevant financial relationships.