EatingWell

Fructose, Calcium and Prostate Cancer

 

May 25 2000. About one-third of the cancer deaths in the United States are due to dietary factors, according to American Cancer Society. Risk can be lowered, ACS nutrition experts say, by eating a diet high in plant foods (fruits, vegetables, grains, and beans) and low in meat, dairy, and other high-fat foods. It is important not to overeat and to balance intake of food calories with output of energy in physical activity.

Dr. E. Giovannucci at Harvard Medical School says: "Higher consumption of selenium and vitamin E, fructose/fruits, and tomatoes all have been associated with reduced occurrence of prostate cancer, but as yet their efficacy for prevention remains unproven." Five or more servings of fruit a day, according to a study that Dr. Giovannucci conducted, lowered the risk of prostate cancer by half.

In the group he studied, men who regularly avoided fruit while favoring foods high in calcium (ice-cream, cottage cheese, hard cheese and milk...) were at higher risk for prostate cancer.

Men who got 2,000 mg/day or more of calcium from food sources and supplements were almost three times as likely to have advanced prostate cancer, and 4.5 times as likely to have metastatic prostate cancer. That's the calcium in 6 glasses of milk.

This study looked at the eating habits and health outcomes of 47,781 male health professionals. All the men were free of cancer in 1986 when the study began. "Between 1986 and 1994, 1369 non-stage A1 and 423 advanced (extraprostatic) cases of prostate cancer were diagnosed."

Higher consumption of calcium, the researchers found, was related to advanced prostate cancer and metastatic prostate cancer. "Calcium from food sources and from supplements independently increased risk."

High fructose intake was related to a lower risk of advanced prostate cancer. "Fruit intake was inversely associated with risk of advanced prostate cancer...." Five or more servings of fruit a day made a measurable difference in risk of prostate cancer. "Non-fruit sources of fructose similarly predicted lower risk of advanced prostate cancer."

This study has been attacked by Dr. William Fair, a leading US urologist and a colon cancer survivor. Dr. Fair says that he himself takes 1,200 mg calcium a day. Any idea that calcium in the diet encourages prostate cancer "flies in the face of all the evidence we have about vitamin D and prostate cancer, " Fair has said.

Giovannucci confirmed his results on repeating the study on a smaller group of men in Sweden. In 1999, though, a Dutch study of 58,279 men aged 55-69 followed for six years found "no associations" between prostate cancer and "consumption of fresh meat, fish, cheese and eggs. Positive trends in risk were found for consumption of cured meat and milk products ..... For calcium and protein intake, no associations were observed." But this study in the Netherlands did not compare fruit versus calcium consumption.

Vitamin D does protect men from prostate cancer. In the USA and many countries, milk is fortified with vitamin D. Even so, calcium in mik and other foods lowers the amount of usable vitamin D in the body. Eating several servings of fruit a day keeps the level of vitamin D raised.

A high circulating level of the biologically active form of vitamin D (1,25(OH)2 vitamin D [1,25(OH)2D) is known to inhibit formation of cancer in the prostate. Eating a diet high in meat and milk and low in fruit reduces the level of this anti-prostate cancer vitamin. "High intakes of calcium and phosphorus, largely from dairy products, lower circulating 1,25(OH)2D level, and sulfur-containing amino acids from animal protein lower blood pH, which also suppresses 1,25(OH)2D production."

On this evidence:

• Consuming a lot of calcium in foods or supplements may suppress the body's production of the active form of vitamin D.

• Eating fruit stimulates the body to make the active form of vitamin D. Dietary fructose reduces plasma phosphate levels by 30 to 50% for more than 3 hours.

Fat in the diet might play a role in the development of prostate cancer -- and milk and meat are sources of fat. A recent study of men diagnosed with prostate cancer in Quebec, Canada found that the men who consumed the hiegest amount of saturated fat were significantly more likely to die of prostate cancer than of other causes.

The Harvard researchers say they took account of fat in calcium-rich foods and that still the balance between calcium and fructose was more important. "Our findings provide indirect evidence for a protective influence of high 1,25(OH)2D levels on prostate cancer," they say, "and support increased fruit consumption and avoidance of high calcium intake to reduce the risk of advanced prostate cancer.

LINKS to References

The American Cancer Society: The Importance of Nutrition In Preventing Cancer

Cancer Res 1998 Feb 1;58(3):442-7 Calcium and fructose intake in relation to risk of prostate cancer. Giovannucci E, Rimm EB, Wolk A, Ascherio A, Stampfer MJ, Colditz GA, Willett WC Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.

Cancer Causes Control 1998 Dec;9(6):559-66 Dairy products, calcium, phosphorous, vitamin D, and risk of prostate cancer. Chan JM, Giovannucci E, Andersson SO, Yuen J, Adami HO, Wolk A Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA.

Cancer Causes Control 1998 Dec;9(6):567-82 Dietary influences of 1,25(OH)2 vitamin D in relation to prostate cancer: a hypothesis. Giovannucci E Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. [email protected]

Br J Cancer 1999 Jun;80(7):1107-13 Animal products, calcium and protein and prostate cancer risk in The Netherlands Cohort Study. Schuurman AG, van den Brandt PA, Dorant E, Goldbohm RA Department of Epidemiology, Maastricht University, The Netherlands. "No associations were found for consumption of fresh meat, fish, cheese and eggs. Positive trends in risk were found for consumption of cured meat and milk products ... . For calcium and protein intake, no associations were observed.

Semin Urol Oncol 1999 May;17(2):77-84 Vitamin D in the prevention and treatment of prostate cancer. Konety BR, Johnson CS, Trump DL, Getzenberg RH Department of Surgery, University of Pittsburgh Cancer Institute, PA 15213, USA.

Indian J Exp Biol 1999 Jul;37(7):623-6 Phosphorus balance and prostate cancer. Kapur S Ranbaxy Research Laboratory, New Delhi, India.

Eur Urol 1999;35(5-6):392-4 Vitamin D and prostate cancer risk. Peehl DM Department of Urology, Stanford University School of Medicine, Stanford, Calif. 94305, USA. [email protected]

J Clin Invest 1989 May;83(5):1494-9 Physiologic regulation of the serum concentration of 1,25-dihydroxyvitamin D by phosphorus in normal men. Portale AA, Halloran BP, Morris RC Jr Department of Pediatrics, University of California, San Francisco 94143.

Eur Urol 1999;35(5-6):388-91 Dietary fat and prostate cancer progression and survival. Fradet Y, Meyer F, Bairati I, Shadmani R, Moore L Laval University, Quebec, Que., Canada. [email protected]