June 23, 2018
Does High Fluid Intake Prevent Bladder Cancer?
Ask the Experts

Does High Fluid Intake Prevent Bladder Cancer?

by Berkeley Wellness  

Q: Will drinking lots of water help prevent bladder cancer?

A: Research on this has yielded conflicting results. The two key risk factors for bladder cancer are smoking and environmental (often occupational) exposure to toxins, as found in dry cleaning chemicals, pesticides, and paints. Largely because men smoke more and are more likely to have occupational exposure, they have higher rates of bladder cancer than women.

Why the inconsistencies about the role of water intake? Largely because the studies look at different populations and vary in design. Some look at total fluid intake, some at water versus other beverages; most don’t include estimates of fluid supplied by food intake. Others focus on frequency of urination, which may also play a role. Here’s a sampling of the research:

  • A large 1999 study of male health professionals found that those who consumed more than 10 cups a day of fluids were half as likely to develop bladder cancer as those drinking less than 5 cups. However, after 12 more years of follow-up, in a 2015 study, the researchers no longer found a link between fluid intake and bladder cancer.
  • In 2007, a Spanish study linked increased intake of water (but not other fluids) to reduced risk of bladder cancer.
  • In 2011, a study using data from the European Prospective Investigation into Cancer and Nutrition found no link between fluids and the cancer.
  • In 2016, an Italian study in Cancer Epidemiology compared the fluid intake (from food and beverages) of people with bladder cancer to those without cancer and found no associations.

It is theorized that increased fluid consumption may reduce bladder cancer risk by diluting the concentration of any toxins in the bladder and reducing their contact time with cells there. This is supported by some clinical trials, such as one in Disease Markers in 2015, which found that in smokers who drank extra water (6 cups a day) for 50 days, urine was less able to induce DNA changes in bladder cells.

Sure, it’s good to drink sufficient fluids in order to avoid dehydration. Under normal circumstances, this simply means drinking when you are thirsty. The idea that everyone needs to drink eight glasses of water a day is a myth. How much water you need depends on many factors, including how active you are, how hot your environment is, medications you are taking (some increase urination), and how much fluid you are getting from food (fruits and vegetables are more than 90 percent water). Older people may need to make an effort to drink more water, since they tend to cope less well with heat, and their thirst mechanism may be less reliable. People with recurring kidney stones may also benefit from drinking more fluids.

Also see How Much Water Is in Your Food?