Dietary factors and risk of kidney stone: a case-control study in southern China.
OBJECTIVE
Formation of kidney stones is a multifactorial disease, and diet and lifestyle are suggested to contribute remarkably to increased prevalence. The population of Guangzhou, China has a high prevalence rate of kidney stones; however, its risk factors are still unknown. The aim of this study was to investigate the dietary risk factors for kidney stones in southern China.


DESIGN
A case-control study was carried out.


SETTING
This study was carried out at the Department of Health Management Center, Guangzhou Nanfang Hospital, China.


SUBJECTS
This study involved 1,019 newly diagnosed kidney stone patients and 987 healthy control subjects.


INTERVENTION
A questionnaire regarding dietary patterns and supplements was used to investigate the risk factors for kidney stone formation.


MAIN OUTCOME MEASURE
Food intake frequency, beverage and alcohol consumption, food supplements, and anthropometry were assessed.


RESULTS
In the analysis, we found positive associations of kidney stones with consumption of grains (odds ratio [OR] = 2.08; 95% confidence interval [CI] = 1.08, 4.02) and bean products (OR = 3.50; 95% CI = 1.61, 7.59) in women. The variable "fluid drinking" showed a significant protective effect against kidney stones in men (OR = 0.57; 95% CI = 0.36, 0.88). Consuming leafy vegetables more than 3 times per day was positively associated with stones in both men and women (OR = 2.02; 95% CI = 1.04, 3.91 and OR = 3.86; 95% CI = 1.48, 10.04, respectively). Other dietary factors, dietary supplements, and specific food were not related to kidney stone formation in Guangzhou, China.


CONCLUSION
The results confirmed that specific diet can affect stone formation in the Chinese population, and varied risk factors were found for different genders.