Five modifiable risk factors for kidney stones

This study examined modifiable risk factors for kidney stones in the general population. Over a 12-year follow-up, excess weight, low fluid intake, a poor diet, high calcium intake, and high sugary soft drink consumption were all found to independently increase the risk of kidney stones.

Kidney stones are small mineral deposits that can form in or near the kidneys. It has been estimated that about 9% of women and 19% of men will experience kidney stones at some point in their lives. Studies have shown that the heritability of kidney stones is about 56%. This suggests that approximately half of kidney stone events are caused by modifiable risk factors. Identifying risk factors is important to help prevent the occurrence or recurrence of kidney stones.

The aim of this study was to closer examine risk factors for kidney stones in the general population.

192,126 men and women who participated in long-term general health surveys were included in this study. The surveys started in 1976 and 1989 and were followed up every 2 and 4 years. Kidney stone incidences were recorded as well as factors such as fluid intake, diet, calcium intake, sugary drink consumption, height and weight. Average follow-up was 11.3 to 12.1 years.

6,449 participants (3.4%) developed kidney stones during the study period. All risk factors measured were independently associated with the incidence of kidney stones.

Being overweight as indicated by a high body mass index (BMI; excess weight according to height) increased the risk of stones between 26 and 40% (depending on the survey). An obese BMI increased the risk of stones by 44 to 80% compared to a normal BMI.

Participants who generally drank less than 1 liter per day were 75 to 86% more likely to develop kidney stones compared to participants that drink 2 liters of more.

Following the DASH diet (a specific diet designed to lower blood pressure that is high in fruits, vegetables and low fat dairy products) was found to protect against kidney stones. Those participants who followed the DASH diet most closely showed the greatest protection against kidney stones.

The incidence of kidney stones increased with the intake of calcium in the diet. A high calcium intake was found to increase the risk of kidney stones by up to 27%.

Drinking between 4 and 6 sugary soft drinks per week increased the risk of kidney stones by 18 to 23% compared to drinking less than 4 servings per week. If more than 7 sugary soft drinks were consumed per week, kidney stone risk increased by 31 to 51%.

This study concluded that 5 modifiable risk factors accounted for more than 50% of kidney stone incidences. These risk factors were excess weight, low fluid intake, a poor diet, high calcium intake, and high sugary soft drink consumption.