Prostate cancer – the dietary links

Dr Paul Clayton 2002


The American Cancer Society predicted that final figures for new prostate cancer patients in 2001 would exceed 198,100. Approximately 31,500 of those diagnosed would die of the disease, making it the second leading cause of cancer deaths in men.

The benefits of screening and early detection (secondary prevention) in reducing the incidence of prostate cancer remain controversial; however, primary prevention is promising, and strongly linked to constituents in the diet such as lycopene (tomatoes),isoflavones (soy), and selenium. (All these factors are reviewed in Health Defence chapter 13.)

In a study at Stanford University, USA (Brooks et al, J Urol 166:2034-2038, 2001), men with low plasma selenium levels were shown to have a 4- to 5-fold increase in risk of developing prostate cancer. This study confirms earlier reports of the significance of selenium in the development of prostate cancer by teams at the University of Arizona and the US National Cancer Institute.

For North Americans who want to contribute to science,and perhaps gain some protection in the process, the NCI is currently running SELECT – the Selenium and Vitamin E Cancer Prevention Trial.

In the meantime, you should seriously consider eating more tomatoes.


Prostate Cancer – Vitamin D and Tomatoes cut risk

Dr Paul Clayton 2006


Vitamin D

Vitamin D is already thought to protect against breast and colon cancer, but a new study at Harvard University has produced strong evidence that it may protect against prostate cancer as well.

Dr Haojie Li and the Harvard team analysed blood samples from 1,029 men with prostate cancer, and the same number of matched men without prostate cancer,and compared their vitamin D levels. The results showed that in men with higher levels of vitamin D, the incidence of aggressive prostate cancer was effectively halved. The researchers concluded that all men should try to maintain high vitamin D levels, either through
sunbathing or via the diet.

In a footnote, they mentioned that the risks of aggressive and fatal prostate cancer were higher in overweight and obese men. This is a complex issue, but I suspect that one factor may have been the high calorie,low micronutrient diet that is so often associated with overweight and obesity.

Tomatoes

The scientific establishment has effectively conceded that a high consumption of tomato products reduces the risk of prostate cancer. Some supplement companies claim that this is all due to lycopene, the red colouring in the fruit; but new evidence shows that other compounds
in the tomato (or ‘love apple’ as it was first known)contribute to the health benefits as well.

In addition to lycopene, tomatoes also contain a variety of flavonoids, and a recent series of cell culture studies has conclusively shown that extract of whole tomato is more effective at killing cancer cells than lycopene alone.

The first conclusion to draw from these studies is that micro- and phyto-nutrients do not work well when used singly, as if they were drugs. Instead, they work best in combinations, such as those that occur in foods. The second conclusion is that if we were to take all the
micro- and phytonutrients that reduce risk (by adding, for example, vitamin D to the tomato extract as is done in NutriShield), the risks would be reduced even further.Who knows – if we could assemble the total nutritional package, maybe prostate cancer could be made to disappear.


References

1 Li H, Multidisciplinary Prostate Cancer Symposium, February 17-19, 2005, Hyatt Grand Cypress, Orlando, Florida

2 Campbell JK, Canene-Adams K, Lindshield BL, Boileau TWM, Clinton SK and Erdman JW Jr, Supplement: International Research Conference on Food,Nutrition, and Cancer: ‘Tomato Phytochemicals and Prostate Cancer Risks’, Journal of Nutrition 134:3486S-3492S, December 2004