3/4/07
Study Finds Vitamins May Cause More Harm Than Good
A new study finds that vitamin supplements can cause more harm than good and could actually kill you.
The study published in the Journal of American Medical Association says that the use of antioxidant supplements like beta carotene, vitamin A, and vitamin E to examine their effects showed that there was no significant association between antioxidant use and mortality. In 47 low-bias trials involving 180,938 participants, the antioxidant supplements were associated with a 5 percent increased risk of mortality. Among low-bias trials, use of beta carotene, vitamin A, and vitamin E was associated with 7 percent, 16 percent and 4 percent, respectively, increased risk of mortality, whereas there was no increased mortality risk associated with vitamin C or selenium use.
The conclusion was that the treatment with beta carotene, vitamin A, and vitamin E may increase mortality, while the potential roles of vitamin C and selenium on mortality still need further investigations.
"Our systematic review contains a number of findings. Beta carotene, vitamin A, and vitamin E given singly or combined with other antioxidant supplements significantly increase mortality. There is no evidence that vitamin C may increase longevity. We lack evidence to refute a potential negative effect of vitamin C on survival. Selenium tended to reduce mortality, but we need more research on this question," the authors write.
"Our findings contradict the findings of observational studies, claiming that antioxidants improve health. Considering that 10 percent to 20 percent of the adult population (80-160 million people) in North America and Europe may consume the assessed supplements, the public health consequences may be substantial. We are exposed to intense marketing with a contrary statement, which is also reflected by the high number of publications per included randomized trial found in the present review."
"There are several possible explanations for the negative effect of antioxidant supplements on mortality. Although oxidative stress has a hypothesized role in the pathogenesis of many chronic diseases, it may be the consequence of pathological conditions. By eliminating free radicals from our organism, we interfere with some essential defensive mechanisms . Antioxidant supplements are synthetic and not subjected to the same rigorous toxicity studies as other pharmaceutical agents. Better understanding of mechanisms and actions of antioxidants in relation to a potential disease is needed," the researchers conclude.
However the scientific community and the pharmaceutical industry received with reservation the conclusions of the new study, underlining the benefits humans get from ingesting vitamin-supplements.
Andrew Shao, vice president for science and regulatory affairs at the Council for Responsible Nutrition, a trade association representing the dietary supplement industry, said that "They included every trial under the sun," Shao said. "Some [studies] were a day long, some were several years long. The majority of trials involved very sick patients - treatment trials that were very, very different from how antioxidant supplements are used by most consumers, which is to maintain health."
The antioxidants in the study have widely different modes of action, one other critic of the study noted. "It's like putting two very different drugs together and drawing one conclusion," he explained.
In addition, he said, "they do not mention anywhere in the report what people are dying of," which makes it is difficult to attribute the deaths to the supplements and not to some other causes.
"You don't see people dropping dead right and left from overdoses of antioxidant supplements," he added. "It is just not happening. You have to explain to me how some essential nutrients kill you in a couple of years."
Antioxidant supplements "have been shown in a number of studies to have no adverse effects," Blumberg said. "They are not toxic, but evidence that they prevent heart disease and cancer is equivocal."
Biochemist Balz Frei, director of the Linus Pauling Institute at Oregon State University, also argued that all the original studies used the supplements to try to produce an improvement in patients who already had a disease.
"That may work with a drug, but it is never going to work with a dietary supplement," he said. "You can't undo the damage of decades by giving a dietary supplement for a couple of years."
Usually, vegetarians receive only about 5% of their energy from saturated fat (versus 10% for meat eaters), have greater blood levels of antioxidants, and have far less free radical-promoting iron in their blood. All of these factors may contribute to heart health. Vitamin E studies are frequently conducted using subjects who already have heart disease.
In a University of North Carolina study based on a questionnaire, vitamin E supplements significantly reduced the risk of mortality from breast cancer in women who had been previously treated for it. The women, who were studied for 12-14 years, had to take vitamin E for at least three years to see benefit, which included a significantly reduced risk of breast cancer recurrence.
In another extensive and intensive study, the American Cancer Society queried 991,522 US adults about their use of vitamin supplements. Following up 16 years later, it was found that people who took vitamin E supplements for 10 years or longer reduced their risk of death from bladder cancer by 40%. Vitamin E supplementation of shorter duration was not protective.
Moreover, researchers reported in 2006 that a derivative of vitamin E causes the death of cancer cells and have used this knowledge to make the agent an even more potent cancer killer. The substance, called vitamin E succinate, or alpha tocopheryl succinate, kills cancer cells by causing them to undergo a natural process known as programmed cell death, or apoptosis.
Also, the majority of scientific studies indicate that vitamin C is not only safe, but that it may actually help to prevent certain types of cancer, including cancers of the stomach, bladder and colon. Researchers from the National Institutes of Health have become so impressed with the safety and cancer-fighting ability of vitamin C that they have recommended raising the RDA (Recommended Daily Allowance) for vitamin C from the current 60 mg/day to 200 mg/day. The NIH based their proposal on the growing body of research showing that five servings a day of fruit and vegetables high in vitamin C can help to prevent cancer.(AXcess News)
¶ 5:22 AM
A new study finds that vitamin supplements can cause more harm than good and could actually kill you.
The study published in the Journal of American Medical Association says that the use of antioxidant supplements like beta carotene, vitamin A, and vitamin E to examine their effects showed that there was no significant association between antioxidant use and mortality. In 47 low-bias trials involving 180,938 participants, the antioxidant supplements were associated with a 5 percent increased risk of mortality. Among low-bias trials, use of beta carotene, vitamin A, and vitamin E was associated with 7 percent, 16 percent and 4 percent, respectively, increased risk of mortality, whereas there was no increased mortality risk associated with vitamin C or selenium use.
The conclusion was that the treatment with beta carotene, vitamin A, and vitamin E may increase mortality, while the potential roles of vitamin C and selenium on mortality still need further investigations.
"Our systematic review contains a number of findings. Beta carotene, vitamin A, and vitamin E given singly or combined with other antioxidant supplements significantly increase mortality. There is no evidence that vitamin C may increase longevity. We lack evidence to refute a potential negative effect of vitamin C on survival. Selenium tended to reduce mortality, but we need more research on this question," the authors write.
"Our findings contradict the findings of observational studies, claiming that antioxidants improve health. Considering that 10 percent to 20 percent of the adult population (80-160 million people) in North America and Europe may consume the assessed supplements, the public health consequences may be substantial. We are exposed to intense marketing with a contrary statement, which is also reflected by the high number of publications per included randomized trial found in the present review."
"There are several possible explanations for the negative effect of antioxidant supplements on mortality. Although oxidative stress has a hypothesized role in the pathogenesis of many chronic diseases, it may be the consequence of pathological conditions. By eliminating free radicals from our organism, we interfere with some essential defensive mechanisms . Antioxidant supplements are synthetic and not subjected to the same rigorous toxicity studies as other pharmaceutical agents. Better understanding of mechanisms and actions of antioxidants in relation to a potential disease is needed," the researchers conclude.
However the scientific community and the pharmaceutical industry received with reservation the conclusions of the new study, underlining the benefits humans get from ingesting vitamin-supplements.
Andrew Shao, vice president for science and regulatory affairs at the Council for Responsible Nutrition, a trade association representing the dietary supplement industry, said that "They included every trial under the sun," Shao said. "Some [studies] were a day long, some were several years long. The majority of trials involved very sick patients - treatment trials that were very, very different from how antioxidant supplements are used by most consumers, which is to maintain health."
The antioxidants in the study have widely different modes of action, one other critic of the study noted. "It's like putting two very different drugs together and drawing one conclusion," he explained.
In addition, he said, "they do not mention anywhere in the report what people are dying of," which makes it is difficult to attribute the deaths to the supplements and not to some other causes.
"You don't see people dropping dead right and left from overdoses of antioxidant supplements," he added. "It is just not happening. You have to explain to me how some essential nutrients kill you in a couple of years."
Antioxidant supplements "have been shown in a number of studies to have no adverse effects," Blumberg said. "They are not toxic, but evidence that they prevent heart disease and cancer is equivocal."
Biochemist Balz Frei, director of the Linus Pauling Institute at Oregon State University, also argued that all the original studies used the supplements to try to produce an improvement in patients who already had a disease.
"That may work with a drug, but it is never going to work with a dietary supplement," he said. "You can't undo the damage of decades by giving a dietary supplement for a couple of years."
Usually, vegetarians receive only about 5% of their energy from saturated fat (versus 10% for meat eaters), have greater blood levels of antioxidants, and have far less free radical-promoting iron in their blood. All of these factors may contribute to heart health. Vitamin E studies are frequently conducted using subjects who already have heart disease.
In a University of North Carolina study based on a questionnaire, vitamin E supplements significantly reduced the risk of mortality from breast cancer in women who had been previously treated for it. The women, who were studied for 12-14 years, had to take vitamin E for at least three years to see benefit, which included a significantly reduced risk of breast cancer recurrence.
In another extensive and intensive study, the American Cancer Society queried 991,522 US adults about their use of vitamin supplements. Following up 16 years later, it was found that people who took vitamin E supplements for 10 years or longer reduced their risk of death from bladder cancer by 40%. Vitamin E supplementation of shorter duration was not protective.
Moreover, researchers reported in 2006 that a derivative of vitamin E causes the death of cancer cells and have used this knowledge to make the agent an even more potent cancer killer. The substance, called vitamin E succinate, or alpha tocopheryl succinate, kills cancer cells by causing them to undergo a natural process known as programmed cell death, or apoptosis.
Also, the majority of scientific studies indicate that vitamin C is not only safe, but that it may actually help to prevent certain types of cancer, including cancers of the stomach, bladder and colon. Researchers from the National Institutes of Health have become so impressed with the safety and cancer-fighting ability of vitamin C that they have recommended raising the RDA (Recommended Daily Allowance) for vitamin C from the current 60 mg/day to 200 mg/day. The NIH based their proposal on the growing body of research showing that five servings a day of fruit and vegetables high in vitamin C can help to prevent cancer.(AXcess News)
Labels: American Medical Association, supplements, Vitamins
¶ 5:22 AM
