Thursday, February 11, 2010

Cancer, Diet, and Angiogenesis

Over the years there have been a multitude of reports on the anti-cancer properties of various foods. There is valuable truth in these reports and it does pay to adopt your diet so as to include a variety of these foods into your lifestyle. For example, it has long been known that a carotenoid found in tomatoes, lycopene, appears to confer protection against prostate cancer. Watermelon also contains good amounts of this carotenoid. However when eating tomatoes at least you really need to cook the tomatoes as this maximises the absorption of lycopene. This study highlights an unusual trend that is appearing in the data. As they state:

"The intake of isolated lycopene does not protect from the development of PCA."
That statement is concordant with recent findings that taking supplements appear to confer few benefits. A study from the Cleveland Clinic of Journal Medicine states that both antioxidant and hormonal strategies to slow the rate of aging have proved disappointing. The full article can be downloaded at this link. A comprehensive analysis by JAMA even found increased mortality arising from some supplement use. I am wary of such large scale studies because there are just too many variables at play. Nonetheless it has long been known that smokers should avoid beta carotene supplements because a number of studies have found a distinct association between beta carotene intake and lung cancer risk in smokers. The concluding statement from the JAMA study is:

"Treatment with beta carotene, vitamin A, and vitamin E may increase mortality. The potential roles of vitamin C and selenium on mortality need further study."

Under certain conditions beta carotene can be an oxidant. Actually most antioxidants can also act as oxidants. Vitamin C together with iron loading is capable of generating so much oxidative stress it used as a experimental strategy in assessing oxidative load. Vitamin A may carry increased risk simply because it plays a critical role in cell proliferation. Some anti-cancer drugs specifically target this function. Beta carotene is converted to Vitamin A and that may explain its increased risk in smokers. I don't know.

Intravenous injections of vitamin C do show promise but has largely been neglected by the clinical community. More research is needed. Oral dosing of vitamin C is not possible because the gut simply won't absorb sufficient quantities of vitamin C. All those vitamin C supplements people take have largely gone down the sewer and this is also true of many vitamins. Selenium does show promise and given that various studies point to selenium deficiency in the general population it is worthwhile to find good sources of selenium. The best source is brazil nuts, only a few a day will do the job. The reason why selenium is so important is because it is an essential substrate a the major antioxidant function(glutathione, catalase).

In spite of the above negative findings which are concordant with various other studies I am still not of the opinion the supplementation per se is not warranted. People need to make choices based on the lifestyle and risk factors. Ideally we should be able to obtain all our nutrients through food and all the available evidence suggests this is the ideal means of absorption. Practically, in part because modern agriculture is depleting many micronutrients from foods, the judicious use of supplements is probably doing more good than harm. In relation to cancer it is clear that a high intake of fruits and vegetables is a critical factor in reducing risk.

The current big research interest in cancer treatment is about inhibiting angiogenesis. Angiogenesis refers to the formation of new blood vessels. Take any person off the street and chances are you will find a number of micro tumours in that person. These tumours have never progressed because angiogenesis is a critical requirement for tumour growth. So if you have ever wondered why someone after a severe illness or emotional trauma months later is found to have cancer it may well be the case that the tumour origin had been present in their bodies for years if not decades. Under certain physiological conditions, including stress, the factors that drive angiogenesis can be increased and can be just enough of a change to allow angiogenesis to take hold in the tumour.

This news release highlights the various foods we can take that have been demonstrated to have anti angiogenesis properties. It is good advice and well worth heeding. It is certainly true that taking these foods will not eliminate the risk of cancer, that is just a dream of charlatans and those who should know better. My perspective on these matters relates to probability. We can never completely eliminate risk but by becoming aware of the risk factors and adjusting our lifestyle accordingly we can reduce the risk. Of particular relevance in regard to risk management is to take note of the illnesses that occur in your family tree. This can provide valuable information about the particular risks you should pay heed too.

The subject of nutrition is exceedingly complex and we have only just begun to develop a more comprehensive understanding of nutrition. We are in a fortunate situation in that no generation before us has had so much solid research to utilise in developing risk management strategies. Take advantage of this growing knowledge base.


diet for cancer said...

This will be one of the proofs that monitoring diet can help stop or maybe prevent cancer. I read the article and I do think that all statements are true and accurate.

xlpharmacy said...

I think we need to take care what with eat, and of course look for a very good diet that can be healthy for ourself