Cruciferous Vegetables and Cancer

A radio broadcast on this topic aired on September 4, 2008.

In 2004, the American Institute of Cancer Research (AICR) estimated that cancer could decline by up to 20% with only one dietary change: an increase in the consumption of fruits and vegetables to 5 servings per day. 1 Modern science is only beginning to discover the numerous benefits of these foods, yet it is already clear that they are extraordinarily beneficial for our health.

It is important to distinguish, however, that not everything that is a plant is a fruit or vegetable. For example, often people think of corn as a vegetable. In fact, however, it is a grain - even when it's eaten sweet and fresh from the field. And although a potato isn't a grain, it doesn't fit into the category of "fruits and vegetables" either. Though there are nutrients in the skin of the potato, it is predominantly a starchy root that doesn't provide the anti-cancer benefits that the AICR states is possible. Instead, fruits such as strawberries, raspberries, blackberries, blueberries, and cranberries, and cruciferous vegetables such as broccoli, cabbage, cauliflower, kale, and brussel sprouts are the foods that will give us the most anti-cancer benefits.

The cruciferous vegetables have received the most attention in scientific studies because they have some of the most potent anti-cancer compounds known. Looking at these vegetables in detail, especially broccoli, we will see why it is that these vegetables are so helpful in the prevention of cancer.



Can Foods Affect Our Genes?

In February of 2006, Professor Eliot Rosen of Georgetown University proclaimed, "It is now clear that the function of crucial cancer genes can be influenced by compounds in the things we eat." 2 He had just been published in the British Journal of Cancer reporting his discovery that certain cancer genes are affected by the indole-3-carbinol (I3C) found in broccoli (and others). Specifically, he had found that this I3C boosts certain genes' production of repair proteins.

There are two genes (BRCA1 and BRCA2) which, when faulty, are known to be associated with breast, ovarian, and prostate cancer. The role of these genes is to produce proteins that assist in proper reproduction of cells by preventing bad or incorrect information from being passed on. In cancer cells, the amounts of these proteins are usually low. So the researchers theorized that eating more I3C could result in a protective effect against cancer. 3

More recently, in June 2008, Dr. Dean Ornish reported that diet and lifestyle changes in men with low-risk prostate cancer resulted in significant changes in activity in several genes. Biopsies were performed to evaluate the changes, and it was found that the activity of over 500 genes was effected.

What did the men do? They ate a nutrient-dense, whole-foods, plant-based diet, exercised moderately, and utilized stress management techniques and group support. Over the course of 3 months, they changed the genetic activity of their cancer cells, generally improved their health, and lowered their risk factors (overweight, blood pressure, and cholesterol) for several diseases. 4



How Does Broccoli Increase Our Resistance to Cancer?

Broccoli doesn't just affect genetic activity - it does a whole lot more. Here are some examples:

• It's an antioxidant, preventing free radicals from causing damage to cells.
• It improves how estrogen is processed (a factor in cancer for both men and women).
• It assists in the detoxification of toxins that would otherwise contribute to cancer.
• It slows the growth of cancer cells and helps them die. 1

For more information about how cancer develops, please refer to Cancer Prevention Through Diet.

These beneficial effects are found in compounds called glucosinolates. Don't let the names deter you - the overall process is easily understood. When broccoli is chopped up, cooked, chewed, and digested, the glucosinolates break down into other compounds: indoles (I3C was mentioned earlier) and isothiocyanates (the most well known is sulforaphane). These are the compounds that specifically stop the growth of cancer cells and improve the detoxification processes which render potential toxins harmless. 5, 6, 7

But there's still another way that broccoli helps us prevent cancer: it strengthens the immune system. (Remember, the immune system is what helps us recover from colds as well as prevent the development of cancers.) Some researchers gave some older mice sulforaphane and measured the strength of their immune response. What they found was that the older mice began to have the immune response of younger mice. 8



How Do We Best Get the Benefits From Broccoli?

Perhaps you've heard that eating foods like broccoli in their raw state is better. The theory behind this is that there are enzymes in the plant that facilitate digestion, and that if the food is cooked, then the enzymes are inactivated and don't work. There is a certain amount of accuracy to this, but it's not as simple as it seems.

For example, the beneficial compounds in broccoli can be broken down and activated not only by enzymes in the plant, but alsoby intestinal bacteria. 9,10 Furthermore, a certain amount of cooking has been shown to be beneficial in increasing the presence of anti-cancerous compounds. Scientists have actually determined the ideal cooking conditions for producing the maximum amount of beneficial compounds.

My apologies to the British and the Germans, but it does appear that boiling your vegetables is not the way to go. One group of researchers found that boiling broccoli for 30 minutes reduced the glucosinolate content by 77%, brussel sprouts by 58%, cauliflower by 75%, and green cabbage by 65%. Yet steaming up to 20 minutes and stir-frying up to 5 minutes did not reduce the beneficial compounds significantly. 11 Another group of scientists refined the findings even futher. Heating broccoli for 10 minutes at 140 degrees Farenhaeit maximizes the sulforaphane content. Their recommendation for consumers: lightly steam your broccoli for 3-4 minutes. 12

But what about the freshness of vegetables and how to store them? The first group of researchers found that room temperatures and refrigerator temperatures only resulted in a small loss of glucosinolates after 7 days. However, thawing frozen vegetables might result in a loss of almost one-third. And when it comes to preparing them, it seemed that the only way to really decrease their content was to shred them and then let them sit for over 6 hours. 11



What's Even More Potent Than Broccoli? Broccoli Sprouts!

The compound sulforaphane that prevents cancer and improves the immune system is even more highly concentrated in broccoli sprouts than it is in broccoli. In fact, there's 50 times more of it in the sprouts. One study reported that people who simply ate broccoli sprouts on top of a bagel with cream cheese had measurable genetic changes. 13

The benefits of broccoli sprouts don't stop at the liver. Although the liver is the primary site of detoxification, there are detoxification enzymes in the skin, lungs, kidneys, and the lining of your digestive tract. Some researchers were curious if broccoli could be beneficial topically, so first they tested some mice and then some humans. What they found is that applying a topical ointment prepared from broccoli sprouts offered several days worth of protection from UV radiation - far more than your typical sunblock. 14, 15 The ointment allowed the UV radiation to penetrate the skin, but it was inhibited from burning the skin and the development of carcinogenic cells was prevented.



East Meets West

It seems that East really does meet West in the oriental wok after all. For hundreds if not thousands of years, the Asians have been cooking their vegetables over very high temperatures for a very short time. When the food comes to your table, the vegetables are hot, moist, easy to chew, and still a bit crunchy. Science has clearly demonstrated that it is necessary to break down the fiber of the broccoli in order to release the beneficial compounds. The question is: What's the best way for you?

Some people have a hotter constitution and can eat raw broccoli without a problem. Others are colder and experience digestive difficulty with raw vegetables. You probably already know this about yourself based on what you gravitate towards at parties. Do you go for the raw veggies and dip? Or do you wait for the main dishes which are warm easier to chew? By paying attention to your own preferences, you can pick the preparation method that's best for you. And if you decide to make a vegetable juice, be sure to drink it right away.



References

1. March 2004, Integrative Cancer Therapies

2. February 2006, BBC News

3. January 2006, British Journal of Cancer

4. June 2008, Proceedings of the National Academy of Sciences

5. October 2002, Journal of Nutrition

6. December 2004, Journal of Nutrition

7. September 2001, Mutation Research

8. May 2008, The Journal of Allergy and Clinical Immunology

9. December 1998, Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology

10. January 2004, Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology

11. May 2007, Physorg.com

12. April 2005, Science Daily

13. May 2007, Science Daily

14. October 2007, Telegraph.co.uk

15. September 2007, Proceedings of the National Academy of Sciences