Groenten en fruit tegen prostaatkanker*
Uit twee studies blijkt het belang van het eten van voldoende groenten en fruit tegen het ontstaan van
prostaatkanker. Uit de eerste studie onder ruim 2.000 Amerikanen blijkt dat voeding rijk aan
flavonoïden zoals in groenten, fruit, kruiden en
thee de kans op een agressieve vorm van prostaatkanker wel met 25% kan verminderen. Uit de tweede studie blijkt dat
resveratrol een bioactieve stof die veel gevonden wordt in druivenschillen en druivenpitten kankercellen duidelijk kan verzwakken waardor ze makkelijker te doden
zijn door bijv. bestraling.
Plant-Based Foods May Offer Reduced Risk for Aggressive Prostate Cancer)
President George W. Bush made no secret that he detested broccoli. With all due respect to our former leader, researchers have found one more great reason to add fruits, vegetables, herbs and tea to your diet.
A study by Susan Steck of the Arnold School of Public Health finds that a high intake of flavonoids, a group of compounds found in plants, may lower the risk for highly aggressive prostate cancer.
"Incorporating more plant-based foods and beverages, such as fruits, vegetables, herbs and tea, into the diet may offer some protection against aggressive prostate cancer," said Steck, an associate professor at the Arnold School and an affiliated scholar with the Center for Research in Health Disparities.
"Filling your plate with flavonoid-rich foods is one behavior that can be changed to have a beneficial impact on health," she said.
Steck presented her findings at the International Conference on Frontiers in Cancer Prevention Research. The annual event is sponsored by the American Association for Cancer Research, whose mission is to prevent and cure cancer through research, education, communication and collaboration.
Prior preclinical studies have shown that flavonoids have beneficial effects against prostate cancer, but few studies have examined the effect of flavonoids on prostate cancer in humans.
Steck and her colleagues used data from 920 African-American men and 977 white men in the North Carolina-Louisiana Prostate Cancer Project who were newly diagnosed with prostate cancer. Participants completed a self-reported dietary history questionnaire to assess flavonoid intake, which was measured using the U.S. Department of Agriculture's 2011 Database for the Flavonoid Content of Selected Foods.
Men with the highest total intake of flavonoids had a 25 percent lower risk for aggressive prostate cancer compared with those men with the lowest flavonoid intake.
"We found that higher total flavonoid intake was associated with reduced odds for aggressive prostate cancer in both African-American and European-American men, but no individual subclass of flavonoids appeared to be protective independently, suggesting that it is important to consume a variety of plant-based foods in the diet, rather than to focus on one specific type of flavonoid or flavonoid-rich food," Steck said.
In addition, the risk for aggressive prostate cancer was even lower in those men younger than 65 and in current smokers with the highest levels of flavonoid intake. Dietary questionnaire results revealed that citrus fruits and juices, such as oranges and grapefruits, tea, grapes, strawberries, onions and cooked greens were the top contributors to total flavonoid intake among the participants. "The results support public health recommendations and guidelines from organizations such as the American Institute for Cancer Research to consume a more plant-based diet," Steck said. "In particular, consuming more flavonoid-rich foods may be beneficial for those people who are at increased risk for cancer, such as smokers."
Compound in Grapes, Red Wine Could Be Key to Fighting Prostate Cancer
Resveratrol, a compound found commonly in grape skins and red wine, has been shown to have several beneficial effects on human health, including cardiovascular health and stroke prevention. Now, a University of Missouri researcher has discovered that the compound can make prostate tumor cells more susceptible to radiation treatment, increasing the chances of a full recovery from all types of prostate cancer, including aggressive tumors.
"Other studies have noted that resveratrol made tumor cells more susceptible to chemotherapy, and we wanted to see if it had the same effect for radiation therapy," said Michael Nicholl, an assistant professor of surgical oncology in the MU School of Medicine. "We found that when exposed to the compound, the tumor cells were more susceptible to radiation treatment, but that the effect was greater than just treating with both compounds separately."
Prostate tumor cells contain very low levels of two proteins, perforin and granzyme B, which can function together to kill cells. However, both proteins need to be highly "expressed" to kill tumor cells. In his study, when Nicholl introduced resveratrol into the prostate tumor cells, the activity of the two proteins increased greatly. Following radiation treatment, Nicholl found that up to 97 percent of the tumor cells died, which is a much higher percentage than treatment with radiation alone.
"It is critical that both proteins, perforin and granzyme B, are present in order to kill the tumor cells, and we found that the resveratrol helped to increase their activity in prostate tumor cells," Nicholl said. "Following the resveratrol-radiation treatment, we realized that we were able to kill many more tumor cells when compared with treating the tumor with radiation alone. It's important to note that this killed all types of prostate tumor cells, including aggressive tumor cells."
Resveratrol is present in grape skins and red wine and available over-the-counter in many health food sections at grocery stores. However, the dosage needed to have an effect on tumor cells is so great that many people would experience uncomfortable side effects.
"We don't need a large dose at the site of the tumor, but the body processes this compound so efficiently that a person needs to ingest a lot of resveratrol to make sure enough of it ends up at the tumor site. Because of that challenge, we have to look at different delivery methods for this compound to be effective," Nicholl said. "It's very attractive as a therapeutic agent since it is a natural compound and something that most of us have consumed in our lifetimes."
Nicholl said that the next step would be to test the procedure in an animal model before any clinical trials can be initiated. Nicholl's studies were published in the Journal of Andrology and Cancer Science. The early-stage results of this research are promising. If additional studies, including animal studies, are successful within the next few years, MU officials will request authority from the federal government to begin human drug development (this is commonly referred to as the "investigative new drug" status). After this status has been granted, researchers may conduct human clinical trials with the hope of developing new treatments for
cancer. (Januari 2013)
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