Nitrates in Tap and Bottled Water Pose Prostate Cancer Risk: Study

Tap water is seen in this photo illustration in Washington on Aug. 19, 2019. Alastair Pike/AFP via Getty Images

A lifetime of consumption of bottled or tap water containing nitrates could be a risk factor for prostate cancer, a Spanish study has found.

The study, published in Environmental Health Perspectives on March 8, was led by the Barcelona Institute for Global Health (ISGlobal). It looks at the link between waterborne nitrate and trihalomethanes (THMs) and prostate cancer risk. Both nitrate and THMs are some of the most common contaminants in drinking water. Nitrate in drinking water is the result of fertilizers and manure from livestock farming washed by rainfall into rivers and aquifers, and THMs are byproducts of water disinfection.

The research team studied 697 cases of prostate cancer between 2008 and 2013, including 97 aggressive tumors. The control group was composed of 927 men between the ages of 38 and 85 who at the time hadn’t been diagnosed with cancer.

The team then estimated the average nitrate and THM exposure of all individuals from the age of 18. The analysis found that a higher intake of nitrate was associated with prostate cancer.

Individuals classified as having higher waterborne nitrate ingestion were found to be 1.6 times more likely to develop medium-grade or low-grade prostate cancer. They were also three times more likely to develop an aggressive prostate tumor when compared to individuals with lower nitrate intakes.

“It has been suggested that aggressive prostate cancers, which are associated with a worse prognosis, have different underlying aetiological causes than slow-growing tumors with an indolent course, and our findings confirm this possibility,” ISGlobal researcher Carolina Donat-Vargas said in a press release.

Diet Effects

The link between nitrate ingestion and prostate cancer was found only among men who had a low intake of fiber, vitamin C, fruits, and vegetables in their diet.

Among participants who consumed less than 11 grams of fiber per day, higher nitrate intake was found to have raised the likelihood of prostate cancer by 2.3 times.

In comparison, among those who consumed more than 11 grams of fiber, higher nitrate intake wasn’t associated with a greater likelihood of prostate cancer.

“Antioxidants, vitamins, and polyphenols in fruits and vegetables may inhibit the formation of nitrosamines—compounds with carcinogenic potential—in the stomach,” Donat-Vargas said.

“Moreover, vitamin C has shown significant anti-tumor activity. And fiber, for its part, benefits the intestinal bacteria, which protect against food-derived toxicants, including nitrosamines.”

Prostate cancer is the most common cancer among men in Spain, accounting for 22 percent of all tumors diagnosed in this demographic.

Prostate Cancer in US, Low Vitamin D Risk

The American Cancer Society (ACS) estimates that there will be about 288,300 new cases of prostate cancer in the United States this year, with 34,700 deaths. About one in eight men is estimated to be diagnosed with prostate cancer during their lifetime.

Older men and non-Hispanic black men are more likely to develop prostate cancer, according to the ACS. About 60 percent of cases are among men aged 65 or older, and the cancer is rarer in men younger than 40.

A 2017 study found a link between low vitamin D and prostate cancer. Men who were deficient in vitamin D were found to have more aggressive prostate cancer.

Adam Murphy, an assistant professor of urology at Northwestern University and lead investigator in the study, said: “Men with dark skin, low vitamin D intake, or low sun exposure should be tested for vitamin D deficiency when they are diagnosed with an elevated PSA or prostate cancer. Then a deficiency should be corrected with supplements.”

Earlier research by Murphy and colleagues found that black men who live in areas with low sunlight have up to 1.5 times more vitamin D deficiency than white men.