July 20, 2013

THROW OUT YOUR FLINTSTONES:

The Vitamin Myth: Why We Think We Need Supplements : Nutrition experts contend that all we need is what's typically found in a routine diet. Industry representatives, backed by a fascinating history, argue that foods don't contain enough, and we need supplements. Fortunately, many excellent studies have now resolved the issue. (PAUL OFFIT, JUL 19 2013, Atlantic)

On October 10, 2011, researchers from the University of Minnesota found that women who took supplemental multivitamins died at rates higher than those who didn't. Two days later, researchers from the Cleveland Clinic found that men who took vitamin E had an increased risk of prostate cancer. "It's been a tough week for vitamins," said Carrie Gann of ABC News.

These findings weren't new. Seven previous studies had already shown that vitamins increased the risk of cancer and heart disease and shortened lives. Still, in 2012, more than half of all Americans took some form of vitamin supplements. What few people realize, however, is that their fascination with vitamins can be traced back to one man. A man who was so spectacularly right that he won two Nobel Prizes and so spectacularly wrong that he was arguably the world's greatest quack. [...]

Antioxidation vs. oxidation has been billed as a contest between good and evil. The battle takes place in cellular organelles called mitochondria, where the body converts food to energy, a process that requires oxygen and so is called oxidation. One consequence of oxidation is the generation of electron scavengers called free radicals (evil). Free radicals can damage DNA, cell membranes, and the lining of arteries; not surprisingly, they've been linked to aging, cancer, and heart disease. To neutralize free radicals, the body makes its own antioxidants (good). Antioxidants can also be found in fruits and vegetables--specifically, selenium, beta-carotene, and vitamins A, C, and E. Studies have shown that people who eat more fruits and vegetables have a lower incidence of cancer and heart disease and live longer. The logic is obvious: if fruits and vegetables contain antioxidants--and people who eat lots of fruits and vegetables are healthier--then people who take supplemental antioxidants should also be healthier.

In fact, they're less healthy.

In 1994, the National Cancer Institute, in collaboration with Finland's National Public Health Institute, studied 29,000 Finnish men, all long-term smokers more than fifty years old. This group was chosen because they were at high risk for cancer and heart disease. Subjects were given vitamin E, beta-carotene, both, or neither. The results were clear: those taking vitamins and supplements were more likely to die from lung cancer or heart disease than those who didn't take them--the opposite of what researchers had anticipated.

In 1996, investigators from the Fred Hutchinson Cancer Research Center, in Seattle, studied 18,000 people who, because they had been exposed to asbestos, were at increased risk of lung cancer. Again, subjects received vitamin A, beta-carotene, both, or neither. Investigators ended the study abruptly when they realized that those who took vitamins and supplements were dying from cancer and heart disease at rates 28 and 17 percent higher, respectively, than those who didn't.

In 2004, researchers from the University of Copenhagen reviewed fourteen randomized trials involving more than 170,000 people who took vitamins A, C, E, and beta-carotene to see whether antioxidants could prevent intestinal cancers. Again, antioxidants didn't live up to the hype. The authors concluded, "We could not find evidence that antioxidant supplements can prevent gastrointestinal cancers; on the contrary, they seem to increase overall mortality." When these same researchers evaluated the seven best studies, they found that death rates were 6 percent higher in those taking vitamins.

In 2005, researchers from Johns Hopkins School of Medicine evaluated nineteen studies involving more than 136,000people and found an increased risk of death associated with supplemental vitamin E. Dr. Benjamin Caballero, director of the Center for Human Nutrition at the Johns Hopkins Bloomberg School of Public Health, said, "This reaffirms what others have said. The evidence for supplementing with any vitamin, particularly vitamin E, is just not there. This idea that people have that [vitamins] will not hurt them may not be that simple." That same year, a study published in the Journal of theAmerican Medical Association evaluated more than 9,000 people who took high-dose vitamin E to prevent cancer; those who took vitamin E were more likely to develop heart failure than those who didn't.

In 2007, researchers from the National Cancer Institute examined 11,000 men who did or didn't take multivitamins. Those who took multivitamins were twice as likely to die from advanced prostate cancer.

In 2008, a review of all existing studies involving more than 230,000 people who did or did not receive supplemental antioxidants found that vitamins increased the risk of cancer and heart disease.

On October 10, 2011, researchers from the University of Minnesota evaluated 39,000 older women and found that those who took supplemental multivitamins, magnesium, zinc, copper, and iron died at rates higher than those who didn't. They concluded, "Based on existing evidence, we see little justification for the general and widespread use of dietary supplements."

Two days later, on October 12, researchers from the Cleveland Clinic published the results of a study of 36,000 men who took vitamin E, selenium, both, or neither. They found that those receiving vitamin E had a 17 percent greater risk of prostate cancer. In response to the study, Steven Nissen, chairman of cardiology at the Cleveland Clinic, said, "The concept of multivitamins was sold to Americans by an eager nutraceutical industry to generate profits. There was never any scientific data supporting their usage." On October 25, a headline in the Wall Street Journal asked, "Is This the End of Popping Vitamins?" Studies haven't hurt sales. In 2010, the vitamin industry grossed $28 billion, up 4.4 percent from the year before. "The thing to do with [these reports] is just ride them out," said Joseph Fortunato, chief executive of General Nutrition Centers. "We see no impact on our business."

How could this be? Given that free radicals clearly damage cells--and given that people who eat diets rich in substances that neutralize free radicals are healthier--why did studies of supplemental antioxidants show they were harmful? The most likely explanation is that free radicals aren't as evil as advertised. Although it's clear that free radicals can damage DNA and disrupt cell membranes, that's not always a bad thing. People need free radicals to kill bacteria and eliminate new cancer cells. But when people take large doses of antioxidants, the balance between free radical production and destruction might tip too much in one direction, causing an unnatural state in which the immune system is less able to kill harmful invaders. Researchers have called this "the antioxidant paradox." 
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Posted by at July 20, 2013 8:12 AM
  

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