Water UK

Cancer and water consumption

During our lifetime one in three of us will be diagnosed with cancer and one in four will die from cancer. Of the many different types of cancer, the four most common are cancer of the breast, lung, large bowel and prostate. These four alone account for over half of all cases diagnosed and are reflected in the most common causes of cancer death.(1) Research suggests that drinking enough water every day, could reduce the risk of developing cancer of the large bowel, breast and prostate.

The reason why good hydration protects against cancer is thought to be due to the way in which cells respond to dehydration. Dehydration causes cells to shrink and this, in turn, stimulates catabolic processes, whereby complex molecules in the cell, such as proteins, are broken down.(2) These responses are designed to protect the cell against dehydrating conditions. However, they may also impair the cells ability to remove harmful substances, such as those that cause cancer(3) and make it more susceptibility to stress-induced damage.(4) Thus, it is thought that some of the adaptations that cells make to compensate for perpetually inadequate water intakes may actually increase our risk of chronic diseases such as cancer.

Breast cancer
Drinking adequate amounts of water can reduce the risk of developing breast cancer by 33% for premenopausal women and 79% for postmenopausal women.(5) This evidence is, however, based on data from one small pilot study and more research is needed to confirm these findings. It has also been suggested that dehydration may contribute to the increased risk of breast cancer in flight attendants.(6)

Colon cancer and colorectal cancer

Water plays a major role in digestion and gut function. Four studies in which the effect of water was considered, found that people who maintained good levels of hydration had a reduced risk of large bowel cancer compared with people whose water intake was low. The extent to which the cancer risk was reduced varied between the studies. In one study, the risk of colon cancer was reduced by 45% in women and 32% in men who drank four or five glasses of water per day, compared to those who drank only two or less glasses per day.(7) In the other two studies the protective effect was found to be greatest for men, with risk reductions for rectal cancer of 92%(8) and 30%,(9) and for colorectal cancer 42%.(10) The studies support the theory that adequate water intake is potentially beneficial in reducing colorectal cancer risk.

Colorectal cancer is of particular concern, since patients with this type of cancer are more likely to develop other primary cancers (ie, excluding recurrence of the original tumour, or secondary cancers resulting from the spread of the original cancer to other sites (metastasis)). These primary cancers may occur in the small intestine, eye, cervix, uteri, corpus uteri and ovary.(11)

Good hydration may protect against large bowel cancer because the water helps to dilute toxic compounds in the bowel and speed up the passage of stools so that any harmful substances (carcinogens) spend less time in contact with the bowel lining.(12) Water enhances the cancer-protective effect of dietary fibre by helping to promote the movement of food through the gut. In men, low water intake and low fibre consumption increases the risk of rectal cancer to a greater extent than for either factor alone.(9)

Prostate and urinary tract cancer

People with low fluid intake (less than 2.4 litres per day) may be more likely to develop urinary tract cancers (including prostate, bladder, kidney, and testicular cancer) than those who are better hydrated.(13) In women, the risk of urinary tract cancer (bladder, renal pelvis, ureter) has been shown to decline in proportion to the total amount of fluid consumed, with tap water having the strongest protective effect.(14)

Maintaining good hydration can also help reduce the risk of bladder cancer in men. Compared with other fluids, water has been shown to have the biggest protective effect. For example, in one study the consumption of more than 2.5 litres of water per day was associated with a 51% reduction in bladder cancer risk, compared to the consumption of other fluids, which were associated with only a 37% risk reduction. The researchers noted that for every additional 240ml of water drunk per day, bladder cancer risk was reduced by 11%.(15) In a study comparing workers in urban and rural areas, the higher incidences of bladder cancer in urban residents was considered, at least in part, to be due to their reduced fluid intake and higher urine concentration.(16)

The evidence of a protective effect for increased fluid intake and bladder cancer is controversial, and other studies have found no association between total fluid intake and the risk of bladder cancer(17,18,19) or even a slightly increased risk.(20) These findings may arise because the cause of bladder cancer is not well understood. One explanation is that higher levels of fluid consumption may reduce contact between the bladder and carcinogens by diluting the urine and increasing the frequency of urination.(15) Frequent urination is known to protect against bladder cancer.(19) However, if the fluids taken in contain substances that are carcinogenic to the bladder, any increase in the total consumption of such drinks would also increase the amount of carcinogens to which the bladder was exposed.(20) Coffee and alcohol are examples of substances that can increase the risk of bladder cancer.(21,22)

Increased fluid intake has not been shown to affect the risk of tumour recurrence in patients already diagnosed with bladder cancer. These findings are, however, from a small scale study which did not specifically look at water consumption. The authors concluded that the types of fluid consumed may have been more important than total fluid intake in protecting against tumour recurrence.(23)

Chlorination and bladder cancer

There has been some concern that long-term exposure to chlorinated water may increase the risk of bladder cancer. Although, where there is evidence of an association between chlorinated water and bladder cancer, the increased risk, compared to individuals with no exposure, appears to be small.

Chlorine is used to disinfect drinking water. However, a disadvantage of chlorine is that it can react with natural organic matter in the water to produce trihalomethanes and other halogenated disinfection by-products (DBPs).(24) The amount of chlorine in water leaving treatment works in the UK is safe and well within the World Health Organisation guidelines for drinking-water quality.(25)

In 1999 the Department of Health Committee on Carcinogenicity of Chemicals in Food statement(26) noted a weak association (relative risks below 2) between consumption of chlorinated drinking-water and an increase in bladder cancer especially for groups with the highest estimated duration of level of exposure. They concluded that the studies of bladder cancer at that time (in 1999) did not show any consistent dose-response relationship with estimated exposures to DBPs or trihalomethanes.

A large meta-analysis of chlorinated drinking water and bladder cancer in 2003 found that long term consumption of chlorinated drinking water was associated with a moderate increased risk for bladder cancer, particularly in men. The combined risk estimate for men was 1.4 and for women 1.2. For both sexes combined risk estimate was 1.2. Although the relative risk was not high, the authors concluded that, given the large number of people exposed to DBPs for long time periods, further studies were desirable.(27)

(see also Urinary)

Last updated: December 2006

(1)Cancer statistics from: Cancer research UK: http://www.cancerresearchuk.org/
Office for National Statistics: http://www.statistics.gov.uk/default.asp
(2)Ritz P, Salle A, Simard G, Dumas JF, Foussard F and Malthiery Y. Effects of changes in water compartments on physiology and metabolism. Eur J Clin Nutr 300;57(Suppl 2):S2-5
(3)Stookey JD. Another look at: fuel + O2 --> CO2 + H2O. Developing a water-oriented perspective. Med Hypotheses 1999;52:285-290
(4)Schliess F, Haussinger D. The cellular hydration state: a critical determinant for cell death and survival. Biol Chem 2002;383:577-83
(5)Stookey JD, Belderson PE, Russell JM, Barker Me. Correspondence re: J. Shannon et al. Relationship of food groups and water intake to colon cancer risk. Cancer Epidemiol Biomarkers Prev 1997;6:657-658
(6)Barker ME, Stookey JD. Flight attendants, breast cancer, and melatonin. Comment on Lancet 1998;352:626. Lancet 1998;352:1389
(7)Shannon J, White E, Shattuck AL, Potter JD. Relationship of food groups and water intake to colon cancer risk. Cancer Epidemiol Biomarkers Prev. 1996;5:495-502
(8)Tang R, Wang J-Y, Lo S-K and H L-L. Physical activity, water intake and risk of colorectal cancer in Taiwan: a hospital-based case-control study. Int J Cancer 1999;82:484-9
(9)Murtaugh MA, Ma K-N, Cann B and Slatterly M. Association of fluids from beverages with risk of rectal cancer. Nutr Cancer 2004;49:25-31
(10)Slattery ML, Caan BJ, Anderson KE and Potter JD. Intake of fluids and methylxanthine-containing beverages: association with colon cancer. Int J Cancer 1999;81:199-204
(11)Evans HS, Moller H, Robinson D, Lewis CM, Bell CMJ, Hodgson SV. The risk of subsequent primary cancers after colorectal cancer in South East England. Gut. 2002; 50:647-52
(12)Altieri A, La Vecchia C and Negri E. Fluid intake and risk of bladder and other cancers. Eur J Clin Nutr 2003;57 (Suppl 2):S59-S68
(13)Bitterman WA, Farhadian H, Abu S-C, Lerner D, Amoun H, Krapf D, Makov UK. Environmental and nutritional factors significantly associated with cancer of the urinary tract among different ethnic groups. Urologic Clinic of North America 1991;18:501-8
(14)Wilkens LR, Kadir MM, Kolonel LN, Nomura AM, Hankin JH. Risk factors for lower urinary tract cancer: the role of total fluid consumption, nitrites and nitrosamines, and selected foods. Cancer Epidemiol Biomarkers Prev 1996;5:161-166
(15)Michaud DS, Spiegelmann D, Clinton SK, Rimm EB, Curham GC, Willett WC. Fluid intake and the risk of bladder cancer in men. New Engl J Med 1999;340:1390-7
(16)Braver DJ, Modam M, Chetrit A, Lusky A, Braf Z. Drinking, micturition habits and urine concentration as potential risk factors in urinary bladder cancer. J Natl Cancer Inst. 1987;78:437-40
(17)Risch HA, Burch JD, Miller AD, Hill GB, Steele R, Howe GR. Dietary factors and the incidence of cancer of the urinary bladder. Am J Epidemiol 1988;127:1179-91
(18)Bruemmer B, White E, Vaughn TL, Cheney CL. Fluid intake and the incidence of bladder cancer among middle-aged men and women in a three-county area of western Washington. Nutr Cancer 1997;29:163-8
(19)Radosavljevic V, Jankovic S, Marinkovic J, Djokic M. Fluid intake and bladder cancer: a case control study. Neoplasma 2003;50:234-238
(20)Geoffroy-Perez B, Cordier S. Fluid consumption and the risk of bladder cancer: results of a multicenter case-control study. Int J Cancer 2001;93:880-887
(21)Clavel J, Cordier S. Coffee consumption and bladder cancer risk. Int J Cancer 1991;47:207-12
(22)Kunze E, Chang-Claude J and Frentzel-Beyme R. Life style and occupational risk factors for bladder cancer in Germany. A case-control study. Cancer 1992;69:1776-90
(23)Donat SM, Bayuga S, Herr HW and Berwick M. Fluid intake and the risk of tumor recurrence in patients with superficial bladder cancer. J Urology 2003;170:1777-80
(24)WHO guidelines for drinking-water quality http://www.who.int/water_sanitation_health/dwq/gdwq0506_8.pdf
(25)Drinking Water Inspectorate. Information leaflets. Chlorine, smell, taste. Updated 10 July 2002. http://www.dwi.gov.uk/pubs/chlorine/index.htm
(26)Department of Health. Chlorinated drinking water and cancer. COC statement (COC/99/S2, May 1999) http://www.advisorybodies.doh.gov.uk/coc/drink.htm
(27)Villanueva CM, Fernandez F, Malats N, Grimalt JO, Kogevinas M. Meta-analysis of studies on individual consumption of chlorinated drinking water and bladder cancer. J Epidemiol Commun H 2003;57:166-173