Friday, November 21, 2008

Vitamins E and C don't prevent cancer, landmark study finds

This is just the latest study to show that "antioxidants" do no good but do do some harm but the believers in the antioxidant religion will sail on regardless, as they have done before

Nearly 10 years of testing on thousands of doctors show two hugely popular vitamins don't prevent cancer. In the latest antioxidant letdown, researchers who followed nearly 15,000 male physicians found no evidence vitamin E or vitamin C supplements protect against cancer. "We're kind of rocking the foundation of what we were always brought to believe," Ottawa Hospital urologist Dr. John Mahoney said after learning the results. "We all think that we should be taking vitamins because it makes us more healthy, and yet we can't prove that."

The new research involves preliminary findings from the U.S. Physicians' Health Study II. Researchers tracked 14,641 doctors, aged 50 and older. Each was given either 400 IU (international units) of vitamin E every other day, 500 milligrams of vitamin C daily, or their placebos. After an average eight years of treatment and followup, about 2,000 men had been diagnosed with cancer, including about half with prostate cancer. Neither vitamin E nor vitamin C supplements reduced the risk of prostate cancer, "total cancer" or other cancers such as colorectal or lung.

There were 490 cases of prostate cancer in men who took vitamin E, versus 523 in the placebo group. For total cancer, there were 978 cases in men randomized to vitamin E, compared to 951 who got placebo. It was a similar story for vitamin C: 964 cancers in the vitamin C group, versus 965 in placebo.

Millions of Canadians - an estimated 10 to 15 per cent of adults - take the supplements, even though evidence of any clear benefit for cancer prevention has been "shaky at best," says Howard Sesso, an assistant professor of medicine at Brigham and Women's Hospital in Boston. "Until you do these much larger-scale, randomized clinical trials, you don't really know what the actual answer is." Based on their trial, as well as others, "we feel that there are no compelling reasons for people to take either vitamin E or C for the prevention of cancer at this time," Sesso says.

The findings will be presented Monday at a meeting of the American Association for Cancer Research in Washington, D.C. Sesso says the results held after they took age, smoking status, personal history of cancer and other factors into account. Last week, the same team found vitamin E and C supplements had no effect on the risk of heart attacks, stroke, cardiovascular death, congestive heart failure, angina or heart bypass surgery in the same group of middle-aged and older doctors. They did find an increase in hemorrhagic stroke with vitamin E use. [In other words, antioxidants could kill you]

Last month, 35,000 men from the U.S., Puerto Rico and Canada enrolled in a study testing whether 400 IU daily of vitamin E daily, or 200 micrograms of selenium, can prevent prostate cancer. They were told to stop taking their supplements after a data and safety committee found vitamin E may slightly increase the chance of getting prostate cancer, and that selenium may increase the chance of getting diabetes. The findings aren't proven.

With annual vitamin supplement sales in the billions of U.S. dollars, the latest run of disappointing news could have broad public health implications, researchers say. The doctor's study involved men exclusively, but researchers believe the results could be extrapolated to women as well. A study published three years ago involving nearly 40,000 mostly middle-aged women found those who swallowed 600 IU of vitamin E every other day were no less likely to develop breast, lung, colon or other cancers than women taking a placebo.

Vitamins E, C and other antioxidants are thought to prevent damage to the body's cells by mopping up free radicals - toxic molecules the body produces when it burns sugar and fat. Some studies had found that people who reported eating diets rich in vitamins E and C had less cancer. They suggested taking the vitamins as supplements might offer protection, particularly vitamin E for prostate cancer.

Sesso says critics could argue that the doses they tested were too low. People who prescribe to the vitamin C theory that Linus Pauling and others pushed for decades "would argue 500 mg may not be enough" to show an effect. "But the doses we utilized are very common doses that are still far exceeding what you can get from diet alone," Sesso says. The supplements didn't cause any harm.

Other vitamins, especially vitamin D, are showing promise, and the final piece of the doctors' health study involves testing daily multivitamin supplements. "Until you do the trials, you really can't close the door on all antioxidants," Sesso says.

But Mahoney says he could never understand, biologically, how vitamin supplements might prevent cancer later in life. "Often the cancer 'hits' have happened when you or I are 20 and 30. You just take a guy who's 50 and you give him some vitamins and he's supposed to reduce his cancer? That doesn't seem to go along with the biology of cancer formation. It doesn't seem to make that much sense."

Doctors recommend a healthy diet, exercise, weight management and not smoking to reduce cancer risk. [And most of that is guesswork too]


Vaccine hope in MS link to virus

THE debilitating disease multiple sclerosis, which affects more than 18,000 Australians, could be prevented with a vaccine being trialled in Europe. Researchers from the University of Queensland yesterday confirmed a link between the Epstein-Barr virus, which causes glandular fever and is carried by more than 90 per cent of the world's population, and multiple sclerosis, saying the vaccine, developed to combat glandular fever, could save thousands of lives.

But some doctors are cautious, warning that the vaccine has not been fully tested as a preventive for multiple sclerosis and does not take into account the influence of genetic and environmental factors which can also trigger the disease. Previous studies have shown that people with a parent, child or sibling with multiple sclerosis are at a greater risk of contracting the disease themselves, and the further someone lives from the equator, the higher their risk, indicating that exposure to sunlight and vitamin D play a significant role. [Really? I don't suppose there could be racial and cultural differences among people living near the equator]

In people with multiple sclerosis, the body's immune system attacks the nervous system, causing bladder and bowel dysfunction, memory loss, tremors, vision problems, hearing loss, anxiety, depression, dizziness and difficulty in walking. There is no cure and medications can only ease symptoms.

More than 99 per cent of people with multiple sclerosis have been infected with Epstein-Barr virus during their lifetime but those who contract the virus in the first few years of life, such as children in developing countries where the virus is endemic, show no symptoms. Those who contract the virus in their teens or early 20s, as in most Western countries, usually develop glandular fever, or infectious mononucleosis, and suffer from extreme fatigue, muscle aches, headaches, throat inflammation and weight loss. Research has shown those people are more likely to go on to develop multiple sclerosis later in life.

The study's lead researcher and a neurologist at Royal Brisbane and Women's Hospital, Michael Pender, said yesterday the glandular fever vaccine, once fully tested, could be included in Australia's childhood vaccine program for people who had a diagnosed relative. "It may only help some people, but it is a step in the right direction," he said.

But Robert Booy, a professor in pediatrics with the National Centre for Immunisation Research at the Children's Hospital at Westmead, said yesterday it was still too early to label the Epstein-Barr virus as the main driver behind the disease, and until scientists could establish the exact cause, it was impossible to ensure a vaccine did not contain proteins which could trigger multiple sclerosis.

The scientific chairman of MS Research Australia, Bill Carroll, agreed, saying he was excited that the link between Epstein-Barr and multiple sclerosis had been further confirmed, but remained cautious about the efficacy of a vaccine. "EBV is an important prerequisite in multiple sclerosis but it is not the only factor which causes the disease. There is also often a 20-year time lag between contracting EBV and MS, so it is impossible to say that other factors, influenced by genetics and the environment, do not come into play during that time and can still result in a person developing the disease," Dr Carroll said.


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