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BRUCE ROSEMAN, M.D.
Grapefruit may cause breast cancer
Grapefruit link to breast cancer Eating grapefruit every day could raise the risk of developing breast cancer by almost a third, US scientists say.
A study of 50,000 post-menopausal women found eating just a quarter of a grapefruit daily raised the risk by up to 30%.
The fruit is thought to boost levels of oestrogen - the hormone associated with a higher risk of the disease, the British Journal of Cancer reported.
But the researchers and other experts said more research was still needed.
This is an interesting study, but is simply a piece of the jigsaw that will eventually help us to understand how our diets affect our health
Dr Joanne Lunn
The women had to fill in questionnaires saying how often they ate grapefruit and how big their portions were.
The researchers, at the universities of Southern California and Hawaii, found that women who ate one quarter of a grapefruit or more every day had a higher risk of breast cancer than those who did not eat the fruit at all.
Previous studies have shown that a molecule called cytochrome P450 3A4 (CYP3A4) is involved in metabolising oestrogen hormones.
And grapefruit may boost blood oestrogen levels by inhibiting this molecule, allowing the hormones to build up.
The researchers found that in women who ate at least a quarter of a grapefruit daily, levels of oestrogen were higher.
They said: "It is well established that oestrogen is associated with breast cancer risk.
"Therefore, if grapefruit intake affects oestrogen metabolism leading to higher circulating levels, then it is biologically plausible that regular intake of grapefruit would increase a woman's risk of breast cancer."
And they said this was the first time a commonly eaten food had been linked to an increased risk of breast cancer in older women.
However, they warned that more research was needed to confirm the findings which may have been affected because they only took into account intake of the fruit, but not grapefruit juice.
Breast cancer accounts for almost a third of all cancers in women, and previous lifestyle factors linked to the disease include drinking alcohol and being overweight.
Dr Joanne Lunn, a nutrition scientist at the British Nutrition Foundation said: "This is an interesting study of a large group of post-menopausal women whose diet and health have been followed for many years.
"However, this study is simply a piece of the jigsaw that will eventually help us to understand how our diets affect our health.
"Although we are beginning to get a better awareness of how our diets can modify the risk of diseases such as cancer, we are still a long way from identifying particular foods that might specifically increase or decrease risk."
However, she said that some dietary patterns are associated with a reduced risk of certain cancers and that a diet rich in a variety of different fruits and vegetables could help reduce the risk of heart disease and some cancers.
Story from BBC NEWS:
NSAIDs and Cancer
Tracy Hampton, PhD
Researchers at Beth Israel Deaconess Medical Center, in Boston, in collaboration with scientists at the Salk Institute for Biological Studies, in La Jolla, Calif, and Columbia University Medical Center, in New York City, have discovered a mechanism by which nonsteroidal anti-inflammatory drugs (NSAIDs) halt cancer growth, a finding that could lead to new tests for monitoring patients' responses to these therapies and to safer drugs that act in a similar manner (Zerbini LF et al. Cancer Res. 2006;66:11922-11931).
While NSAIDs are known to exhibit anticancer effects through inducing cell death by inhibition of cyclooxygenase enzymes, scientists have suspected that other antitumor mechanisms are at play.
Using gene expression analyses, the researchers found that exposure to NSAIDs caused cancer cells to increase expression of the gene that encodes a cancer-specific cytokine, MDA-7/IL-24 (melanoma differentiation associated gene 7/interleukin 24). This cytokine induces cell death and inhibits tumor growth, acting through a cascade of molecules including GADD45 and GADD45 (growth arrest and DNA damage inducible 45 and ). By blocking these molecules, the researchers successfully abrogated cell death caused by NSAIDs, pointing to the pathway's critical role in cancer cells' response to these drugs.
Vitamin D prevents pancreatic cancer!!!
Wed Sep 13, 8:06 AM ET
People who take vitamin D tablets are half as likely to get deadly pancreatic cancer as people who do not, U.S. researchers reported on Wednesday.
Now they are checking to see if getting the vitamin from food or sunlight also cuts the risk.
The study suggests one easy way to reduce the risk of pancreatic cancer, the fourth-leading cause of death from cancer in the United States. This year, the American Cancer Society estimates that 32,000 new cases of cancer will be diagnosed, and only 5 percent of patients will survive more than five years.
"Because there is no effective screening for pancreatic cancer, identifying controllable risk factors for the disease is essential for developing strategies that can prevent cancer," Halcyon Skinner of Northwestern University in Chicago, who helped lead the study, said in a statement.
"Vitamin D has shown strong potential for preventing and treating prostate cancer, and areas with greater sunlight exposure have lower incidence and mortality for prostate, breast, and colon cancers, leading us to investigate a role for Vitamin D in pancreatic cancer risk."
Working with colleagues at Harvard University, Skinner's team examined data from two large, long-term health surveys involving 46,771 men aged 40 to 75 and 75,427 women aged 38 to 65.
They found that people who took the U.S. Recommended Daily Allowance of Vitamin D, 400 IU a day, had a 43 percent lower risk of pancreatic cancer.
Those who took doses of less than 150 IU per day had a 22 percent reduced risk of cancer.
Writing in the journal Cancer Epidemiology Biomarkers & Prevention, the researchers said taking more than 400 IU a day did not reduce the risk further.
Vitamin D is produced by the body when sunlight hits the skin, but most Americans do not get enough sunlight to produce the needed amount. Milk, both dairy and soy, is fortified with the vitamin. Some foods such as fish, eggs and liver also contain vitamin D.
"In concert with laboratory results suggesting anti-tumor effects of Vitamin D, our results point to a possible role for Vitamin D in the prevention and possible reduction in mortality of pancreatic cancer," Skinner said.
"Since no other environmental or dietary factor showed this risk relationship, more study of Vitamin D's role is warranted."
Vitamin D Studies Show Promise for Reducing Cancers
Mon Feb 12, 12:15 PM ET
MONDAY, Feb. 12 (HealthDay News) -- Certain amounts of vitamin D may be able to prevent up to half of breast cancer cases and two-thirds of colorectal cancer cases in the United States, according to two studies by researchers at the Moores Cancer Center at the University of California, San Diego, and colleagues at other centers.
In one study, the researchers reviewed two previous studies of 1,760 women and found that those with the highest blood levels of 25-hydroxyvitamin D, or 25(OH)D, had the lowest risk of breast cancer.
"The data were very clear, showing that individuals in the group with the lowest blood levels (less than 13 nanograms of 25(OH)D per milliliter) had the highest rates of breast cancer, and the breast cancer rates dropped as the blood levels of 25-hydroxyvitamin D increased," study co-author Cedric Garland said in a prepared statement.
"The serum level associated with a 50 percent reduction in risk could be maintained by taking 2,000 international units of vitamin D3 daily, plus, when the weather permits, spending 10 to 15 minutes a day in the sun," Garland said.
The study appears online in the current issue of the Journal of Steroid Biochemistry and Molecular Biology.
In the second study, researchers reviewed data from 1,448 people who took part in five previous colorectal cancer studies.
"Through this meta-analysis, we found that raising the serum level of 25-hydroxyvitamin D to 34 ng/ml would reduce the incidence rates of colorectal cancer by half," study co-author Edward G. Gorham said in a prepared statement.
"We project a two-thirds reduction in incidence with serum levels of 46ng/ml, which corresponds to a daily intake of 2,000 IU of vitamin D3. This would be best achieved with a combination of diet, supplements and 10 to 15 minutes per day in the sun," Gorham said.
The study was published online Feb. 6 in the American Journal of Preventive Medicin
FOODS FOR CANCER PREVENTION
Of the many diseases that affect people these days, cancer is among the most feared. But despite a wealth of scientific data, most people remain unaware of how they can reduce their risk of developing cancer. According to the National Cancer Institute, as much as 80 percent of all cancers are due to identified factors, and thus are potentially preventable. Thirty percent are due to tobacco use, and as much as 35 to 50 percent are due to foods. It is easy to control these and other risk factors.
What Is Cancer?
Cancer begins as a single abnormal cell that begins to multiply out of control. Groups of such cells form tumors and invade healthy tissue, often spreading to other parts of the body. Carcinogens are substances that promote the development of cancerous cells. They may come from foods, from the air, or even from within the body. Most carcinogens are neutralized before damage can occur, but sometimes they attack the cell's genetic material (DNA) and alter it. It takes years for a noticeable tumor to develop. During this time, compounds known as inhibitors can keep the cells from growing. Some vitamins in plant foods are known to be inhibitors. Dietary fat, on the other hand, is known to be a promoter that helps the abnormal cells grow quickly.
Fiber Fights Cancer
In 1970, British physician, Dennis Burkitt, observed that a high-fiber diet reduces diseases of the digestive tract. He observed that in countries where diets are high in fiber (that is, plant-based diets), there were fewer cases of colon cancer. Around the world, this has proven true. The highest fiber intakes are found in non-industrialized nations where meat is scarce and plant foods fill the menu. Animal products contain no fiber. The U.S. and other Western nations whose diets are based upon animal products have the highest rates of colon cancer.
While no one is certain exactly how fiber protects against digestive tract disorders, there are several possibilities. By definition, fiber cannot be digested by humans early in the digestive process. It moves food more quickly through the intestines, helping to eliminate carcinogens. It also draws water into the digestive tract. The water and fiber make fecal matter bulkier, so carcinogens are diluted.
Bile acids are secreted into the intestine to help digest fat; there, bacteria can change the acids into chemicals which promote colon cancer. Fiber may bind with these bile acids and evict them from the intestines.1 Also, bacteria in the colon ferment the fiber creating a more acidic environment which may make bile acids less toxic.
Fiber is also protective against other forms of cancer. Studies have shown that stomach cancer and breast cancer are less common on high-fiber diets.2,3 Fiber affects levels of estrogens in the body. Estrogens are normally secreted into the intestine, where the fiber binds with the hormone and moves it out of the body.4 Without adequate fiber, the estrogen can be reabsorbed from the intestine into the bloodstream. High levels of estrogen are linked to a higher risk of breast cancer.
In the U.S., the average daily fiber intake is 10 to 20 grams per day. Experts recommend 30 to 40 grams per day. The best sources of fiber are whole grains, beans, peas, lentils, vegetables, and fruits. Foods that are closest to their natural state, unrefined and unpeeled, are highest in fiber.
Fat Raises Cancer Risks
Cross-cultural studies have revealed that the populations with the highest levels of fat consumption are also the ones with the highest death rates from breast and colon cancer. The lowest rates are in groups with the lowest consumption of fats.5 Migration studies help to rule out the influence of genetics.6
Many studies indicate that fat in foods increases one's risk for cancer, and it may also adversely affect breast cancer survival rates for those who have cancer.7
Although the total amount of fat one eats is of concern, there is evidence that animal fat is much more harmful than vegetable fat. One study noted a 200 percent increase in breast cancer among those who consume beef or pork five to six times per week. Dr. Sheila Bingham, a prominent cancer researcher form the University of Cambridge, notes that meat is more closely associated with colon cancer than any other factor.8 Meat and milk are also linked to both prostate and ovarian cancers.9
How Fat Affects Cancer Risks
Fat has many effects within the body. It increases hormone production and thus raises breast cancer risks. It also stimulates the production of bile acids which have been linked to colon cancer.
The average diet in the U.S. is about 37 percent fat. The National Cancer Institute suggests that people lower that percentage down to 30 percent; however, studies have shown that fat intake should be well below 30 percent to have an anti-cancer affect. Ten to 15 percent is more likely to be helpful.
The Importance of Vegetables
Not only are vegetables low in fat and high in fiber, they also contain many cancer-fighting substances. Carotenoids, the pigment that gives fruits and vegetables their dark colors, have been shown to help prevent cancer. Beta-carotene, present in dark green and yellow vegetables, helps protect against lung cancer and may help prevent cancers of the bladder, mouth, larynx, esophagus, breast, and other sites.
Vegetables such as cabbage, broccoli, kale, turnips, cauliflower, and Brussels sprouts contain flavones and indoles which are thought to have anti-cancer activities.
Vitamin C, found in citrus fruits and many vegetables, may lower risks for cancers of the esophagus and stomach. Vitamin C acts as an antioxidant, neutralizing cancer-causing chemicals that form in the body. It also blocks the conversion of nitrates to cancer-causing nitrosamines in the stomach.
Selenium is found in whole grains and has the same antioxidant effects as vitamin C and beta-carotene. Vitamin E also has this effect. Caution is advised in supplementing selenium, which is toxic in large doses.
Excessive intake of alcohol raises one's risks for cancers of the breast, mouth, pharynx, and esophagus. When combined with smoking, these risks skyrocket. It also raises risks for stomach, liver, and colon cancers.10
Vegetarians Are Better Off
All the evidence points to a low-fat, high-fiber diet that includes a variety of fruits, vegetables, whole grains, and beans, as being the best for cancer prevention. Not surprisingly, vegetarians, whose diets easily meet these requirements, are at the lowest risk for cancer. Vegetarians have about half the cancer risk of meat-eaters.11
Vegetarians have higher blood levels of beta-carotene. They consume more vitamin C, beta-carotene, indoles, and fiber than meat-eaters. Vegetarians also have stronger immune systems. German researchers recently discovered that vegetarians have more than twice the natural killer cell activity of meat-eaters.12 Natural killer cells are specialized white blood cells that attack and neutralize cancer cells. Also, vegetarians tend to eat more soy products than meat-eaters. Soybeans contain many substances that are anticarcinogens, including lignans and phytoestrogens. A diet that is rich in soybeans may be one reason for the lower incidence of breast cancer in Asia.
A cancer prevention diet is one that is high in fiber, low in fat (especially animal fat), and includes generous portions of fruits and vegetables. It also minimizes or excludes alcohol. The best diets are pure vegetarian diets.
Diet Linked to One in Three Cancers
By Ray Dunne
LONDON (Reuters Health) - Almost one in three cancers could be prevented through healthier eating, a major international conference heard this week.
Researchers making presentations at the European Conference on Nutrition and Cancer in Lyon, France, linked thousands of cases of cancer in the western world to poor diet and a lack of exercise.
Conference attendees were also told of the preliminary findings of one of the world's largest studies investigating the relationship between the disease and what people eat.
The European Prospective Investigation into Cancer and Nutrition (EPIC)--one of the biggest in terms of individual data--has confirmed many previous studies showing that some food can increase the risks of cancer while others can have a protective effect on the human body.
However, it has also provided some new ideas and raised doubts about previously long-held theories.
The study, which is looking at the diets of more than 500,000 people from nine European countries, has confirmed once again that eating fruit and vegetables can ward off the disease, in particular colon and rectal cancer.
However, it casts doubts on the protective effects of fruit and vegetables on other cancers. For instance, the study found no evidence to suggest they can ward off cancers of the stomach and lungs.
``We do confirm that the consumption of fruit and vegetables reduces the risk of colorectal cancer and cancers of the mouth, pharynx and oesophagus,'' Dr. Elio Riboli, one of the organisers of the conference and one of those heading up the study, told Reuters Health.
``But we were surprised not to find at this early stage a clear protection for cancer of the stomach and lungs...for the time being the protection for lung and stomach cancer is a little weaker than we expected,'' he added.
The preliminary results have also raised questions about the long-held belief that eating red meat can increase the risk of cancer.
``For years there has been a fear that red meat, particularly beef, lamb and pork, could increase the risk of colorectal cancer,'' said Riboli. ``We have been looking very closely at this issue and the results don't support that. We cannot exclude a 10% to 15% increase for heavy consumption of meat, but the risk is not as we may have thought maybe 10 years ago.''
Riboli said the study would now examine the effects of different meats. ``This is interesting because it is the first time a large study has made a clear separation between processed and fresh meat. Previously, we were only concerned with total meat consumption.''
He added, ``We are now looking into the different types of meat and why processed meat may be a greater risk than fresh meat and to see what is in processed meat that may increase the risks.''
The study also highlights the long-established risks of alcohol and tobacco. Its latest findings suggest that smoking more than a pack of cigarettes each day can increase the risk of cancer by eight times.
Similarly, drinking a bottle of wine every day can boost the chances of getting the disease by nine times.
But the study found that excessive smoking and drinking combined can increase the risks by 50 times.
Riboli acknowledged that the findings could prove confusing for patients who want to change their diet to protect against cancer.
``From the point of view of advice, one can only have one diet and it is better that the diet is globally healthy rather than aimed at just one particular cancer. It has to take into account other diseases, such as cardiovascular disease. It should not be focused on just one particular cancer but on health generally,'' he said.
``We continue to recommend that people have a diet which has a little bit of everything but a lot fruit and vegetables and not necessarily a vegetarian diet, that they eat dairy products and remain physically active, don't smoke and drink only in moderation,'' the researcher advised.
The study, which is ongoing, is not due to finish until at least 2003. But the research team is planning to publish a scientific paper examining the links between cancer and food in 2002.
High Fiber Diet Can Cut Cancer Risk by 40 Percent-Study
Updated: Sat, Jun 23 6:34 AM EDT
LONDON (Reuters) - A high fiber diet can slash the risk of developing deadly cancers by as much as 40 percent, scientists said Saturday.
Results from the biggest ever study into diet and cancer involving 400,000 people from nine countries, presented at an international conference in France, showed fiber was particularly important in reducing cancer of the colon and rectum.
"These are the first positive results for the benefits of fiber from such a large group. We placed 400,000 people on the study into five sets according to their consumption of fiber," Professor Sheila Bingham of the Dunn Human Nutrition Unit at Cambridge University said in a statement released in London.
"The group eating the most fiber reduced their risk of colorectal cancer by as much as 40 percent," she added.
The findings were part of the EPIC (European Prospective Investigation of Cancer and Nutrition) that was reported at the European Conference on Nutrition and Care in Lyon, France.
Medical experts believe up to 30 percent of all cancers in the developed world are associated with nutritional factors and could be avoided by better-balanced diets.
The EPIC study, which began 15 years ago, also showed a decreased chance of developing colon cancer in people eating lots of fish, but a raised risk in those consuming large amounts of preserved meats such as ham, bacon and salami.
People are advised to eat five portions of fruit and vegetables a day to achieve optimum health and avoid cancer.
Professor Nick Day said the landmark study should set the record straight on diet and cancer.
"There have been reports recently that appear to suggest fruit and vegetable consumption isn't important in reducing the risk of colorectal cancer," Day said.
"This wide-ranging study is likely to give us a much truer picture of the links between cancer and diet," he added.
The EPIC study also showed that people who smoke a packet of cigarettes a day and drink more than a bottle of wine are 50 times more likely to suffer from throat cancers.
Eating poultry did not increase the risk of cancer and may have a protective effect, according to the report.
"These finding are important because of the sheer scope of the EPIC study. They put fiber firmly back on the menu as an important part of a healthy diet," said Professor Gordon McVie, the director general of the Cancer Research Campaign, which sponsored Bingham's research.
The European Conference on Nutrition and Cancer, which began Thursday, is looking at the impact of different types of food on the disease.
Obesity Raises Risk for 9 Cancer Types
By LAURAN NEERGAARD, AP Medical Writer
WASHINGTON - Heart disease and diabetes get all the attention, but expanding waistlines increase the risk for at least nine types of cancer, too. And with the obesity epidemic showing no signs of waning, specialists say they need to better understand how fat cells fuels cancer growth so they might fight back.
What's already clear: Being overweight can make it harder to spot tumors early, catch recurrences, determine the best chemotherapy dose, even fit into radiation machines.
That in turn hurts chances of survival. One major study last year estimated that excess weight may account for 14 percent to 20 percent of all cancer deaths — 90,000 a year.
"Obesity makes taking care of cancer patients much more complicated," says Dr. Christopher Desch, a medical oncologist in Richmond, Va.
So why is cancer often the afterthought when listing obesity's multiple risks?
"The cancer picture is a little bit more subtle," says American Cancer Society (news - web sites) epidemiologist Eugenia Calle, one of the nation's leading specialists on the link.
The risks of heart disease and diabetes from packing on pounds are much higher, and more immediate because cancer typically develops more slowly than those illnesses, she explains.
But with nearly two-thirds of U.S. adults now overweight plus an aging population — cancer is predominantly an older person's disease — oncologists want more attention to the link.
Fat is known to increase the risk of developing cancers of the colon, breast, uterus, kidney, esophagus, pancreas, gallbladder, liver and top of the stomach.
How big a role girth plays varies greatly, and the strongest connections are actually in less common cancers.
Weight is most strongly linked to cancer of the uterine lining, or endometrium. An overweight woman has twice the risk of developing that cancer as a lean one; once she becomes obese, the risk rises as much as 3.5- to 5-fold.
The obese have up to triple the risk of kidney cancer and a type of esophageal cancer as do the normal-weight.
The risk is somewhat smaller among two of the nation's most common cancers:
_Overweight or obese men are 50 percent to twice as likely as lean men to get colon cancer. For women, the extra risk is 20 to 50 percent. No one can yet explain the gender difference.
_Fat is linked to breast cancer in postmenopausal women only, increasing risk of the disease by 30 percent among the overweight and 50 percent among the obese.
For the other four cancers, the obesity risk falls somewhere in between.
The reason for the variation: Fat cells apparently play different roles that can spur different types of cancer growth.
"Fat cells are not just static storage depots," explains Calle. The worst, because it's most metabolically active, is visceral fat, the kind that builds up in the abdomen and surrounds organs there.
But exactly how fat cells work isn't well understood. They can spur surges of insulin and proteins that may in turn unleash out-of-control growth among certain cell types.
They also trigger inflammation, a known culprit in heart disease that's now increasingly suspect in cancer, too.
Another role: Fat cells make estrogen, which fuels breast cancer. After menopause, fat becomes a woman's leading source of estrogen. While anti-estrogen therapies are common, the fatter a woman is, the harder it is to lower hormone levels — one reason why the obese have at least a 50 percent greater chance of dying from breast cancer than lean patients, Calle says.
Then there are organ-by-organ reactions. For example, the obese are particularly prone to "gastroesophageal reflux," frequent heartburn where a backup of stomach acid onto the delicate esophagus eventually can lead to esophageal cancer.
Sorting out fat's roles could lead to new therapies, and while there's no clear evidence yet, it makes sense that losing weight would lower cancer risk, Calle says.
For the already diagnosed, the stereotype of cancer treatment causing dangerous weight loss isn't true for every cancer. Breast cancer chemotherapy, in fact, often causes weight gain, says Desch, speaking for the American Society of Clinical Oncology (news - web sites).
His advice: Exercise as much as possible, eat lots of fruits and vegetables and take a multivitamin during treatment — and try to achieve a healthy weight after battling the initial cancer.