In my last two posts, Which Fruit is Best at Fighting Cancer? and Anti-Cancer Nutrient Synergy in Cranberries I described what various common fruits could do to human cancer cells in a petri dish. Studies showing which foods can best suppress the growth of cancer in a test tube are all well and good, but we need to know if they can do the same thing within the human body. It’s considered unethical to withhold conventional cancer therapies to test out some fruit or vegetable, so what do you do?
One direction researchers have taken is to use so-called “combinatorial strategies,” for example adding phytonutrients from the spice turmeric and green tea along with chemotherapy to see if that works better than chemo alone, but this gets complicated because chemo and radiation often work by killing cancer cells with free radicals and so though antioxidants may certainly reduce the toxicity of the treatment there’s a theoretical concern it could reduce the efficacy as well.
Another way you can study the effects of plants on cancer is by testing dietary interventions on slow growing cancers like prostate, which is how Ornish and colleagues were able to show his apparent reversal in cancer growth with a plant-based diet (see Cancer Reversal Through Diet?). They could get away with treating cancer with a vegan diet alone (no chemo/surgery/radiation) because prostate can be such a slow growing cancer that patients with early disease can be placed in a holding pattern. So if you’re not going to do anything but watch and wait, you might as well test out a dietary intervention. Are there other cancers like that we can try plants on?
Esophageal cancer is not the cancer to get. Five-year survival is only about 13 percent, with most people dying within the first year of diagnosis, but the development of esophageal cancer is a multistage process. We start out with a normal esophagus (the tube that connects you mouth to your stomach), then precancerous changes start to take place, then localized cancer starts to grow, then eventually it spreads and we most likely die.
Because of the well-defined, stepwise progression of esophageal, researchers jumped on it as a way to test the ability of berries—the healthiest fruits—to reverse the progression of cancer. A randomized phase 2 clinical trial of strawberries for patients with precancerous lesions of the esophagus was undertaken. Six months of eating the equivalent of over a pound of fresh strawberries a day, and the progression of disease was reversed in 80 percent of the high dose strawberry treatment.
At the beginning of the study, no subjects had a normal esophagus. They either had mild or moderate precancerous disease. But by the end of the study most lesions either regressed from moderate to mild, or disappeared completely. If you watch my 5-min video Strawberries versus Esophageal Cancer you can see some representative before and after pictures of the lesions literally disappearing. By the end of the study half of those on the high dose of strawberries walked away disease free.
This landmark study is one of the most important papers I’ve seen recently. Why isn’t this headline news? If there was instead some new drug that reversed cancer progression, you can bet it would be all over the place. But who’s going to profit from revelations about berries? Other than, of course, the millions of people at risk for this devastating cancer.
The findings were heralded as groundbreaking in an editorial in the journal of the American Association for Cancer Research. Given that it was written by a pair of pharmacy professors, though, they of course concluded “that the active components and molecular targets responsible for the efficacy of strawberries must be identified.” Instead of just eating strawberries they suggested that Big Pharma should try to make a strawberry-derived drug.
Recent population studies suggest that other plant foods may be protective against esophageal cancer as well. Diets with lots of meat and fat appear to double the odds of cancer; and lots of fruits and vegetables may cut one’s odds of esophageal cancer in half. Studies have shown diets rich in foods from animal origin and poor in plant foods appear to increase esophageal cancer risk. And now we know at least one plant that may even reverse the course of disease if caught early enough.
Ornish’s line of anti-cancer work was continued by the Pritikin Foundation in an elegant series of experiments that I describe starting with Ex Vivo Cancer Proliferation Bioassay (along with the “prequel” Engineering a Cure).
For more berried treasure, see Black Raspberries versus Oral Cancer.
-Michael Greger, M.D.
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