Sunday, May 02, 2010
There is a new study out of Harvard by the well respected Walter Willett that is making headlines. I've seen some headlines say "Fruits and Vegetables Do Not Reduce Cancer Risk" or "Eating Vegetables Does Not Stop Cancer" which is incorrect at best. The headlines is not what this study reports, but the media needs to sell newspapers and thanks to the dumbing down of our society (with Fox leading the way) they need the sensationalist headlines to garner attention.
What the study does convey is that fruits and vegetables when grouped together so that all fruits and vegetables are created equal may not reduce total cancer risk. And that is very true and something we've known from previous studies because it depends on the types of vegetables and types of cancer.
This study has failures in several areas:
1) It does not differentiate the types of vegetables as acknowledged by Dr Willet. Eating a diet of kale, collards, brocolli is a lot different than iceberg lettuce, bananas and potatoes. I feel this information was lost under the headlines as all vegetables are not created equal. If the study had differentiated between vegetable types there may have been a statistically significant benefit. For example cruciferous vegetables have known cancer fighting effects. In <a href="http://www.ncbi.nlm.nih.gov/pubmed/19685491" target="_blank">fact one was released in February</a> showing a reduction of non-Hodgskin's lymphoma for those that ate yellow/orange and cruciferous vegetables. There are also several studies that show that <a href="http://www.ncbi.nlm.nih.gov/pubmed/15949687" target="_blank">lycopene a photonutrient in tomatoes protects against prostate cancer.</a> Last month in the <a href="http://www.ajcn.org/cgi/content/abstract/ajcn.2009.28796v1" target="_blank">American Journal of Clinical Nutrition a meta analysis study </a>showed that healthier diet (vegetables,fruit, grains) significantly reduced breast cancer risk. And <a href="http://www.ncbi.nlm.nih.gov/pubmed/1408943" target="_blank">older study showed</a> that people that ate a diet low in fruits and vegetables had twice the risk of developing cancer than those that ate adequate fruits and vegetables. So yes there are studies that show healthier diet and certain vegetables do reduce cancer risk in a significant way.
2) This study looked not only at ALL vegetables, but ALL cancers. There are plenty of studies that show specific cancers respond to phytonutrients to reduce risk.
3)This is more a failure in the media reporting,but the study did in fact show that for every two portions of fruit and vegetable consumption there was a 2.5% risk reduction in cancer. What is more is that the people that ate the most vegetables - more than 6 servings a day had an 11% risk reduction in cancer. Currently 1 out of every 3 people will get cancer sometime in their life, so an 11% reduction is small. However I guarantee you that if a pharmaceutical company could make a pill that would reduce cancer risk by 11% it would be widely prescribed.
4) Other points to consider....Corn is not a vegetable even though many people think it is...how a vegetable is cooked can alter the cancer fighting nutrients. For example cabbage contains a known anti-cancer nutrient called isothiocynate. Cooking cabbage can reduce the isothiocynate content by up to 90%. So an overcooked cabbage is a lot different than homemade sauerkraut in terms of photochemical cancer protection.
Don't believe everything you read as those reporting these studies do not read the actual study.
Of course fruits and vegetables add all sorts of other benefits such as reduced cardiovascular disease, eye health, digestive health etc. So continue to eat your fruits and vegetables they will reduce your risk of cancer as well as offering other benefits.
Yours In Health
George Mandler LDN LicAc