October 11, 2011
Vitamins Could Pose A Health Risk For Older Women
A new study highlights concerns about the long-term use of vitamins in older people who do not have increased nutritional deficiencies, notably in women, whom authors say have an increased risk of death from taking too many vitamins and supplements.
The study, conducted by researchers at the University of Minnesota and published Monday in the Archives of Internal Medicine, analyzed data from 39,000 women followed over nearly two decades and found that those who took multivitamins, vitamin B6, folic acid, magnesium, zinc, copper and iron died at higher rates during the course of the research than those who did not use supplements.
An accompanying editorial of the study noted that the findings “add to the growing evidence demonstrating that certain supplements can be harmful.”
Past studies have raised concerns about the value of supplements and vitamins, but the new findings are “puzzling,” according to many researchers and nutrition experts, who say more research is needed.
All of the women in the study, in their 50s and 60s, were generally well nourished, yet many had decided to take supplements. The findings lead researchers to believe that consumers are buying supplements with no evidence that they will provide any benefit.
About half of American adults take multivitamins, and sales from vitamins and supplements top more than $25 billion in the US each year.
The researchers said the findings suggest that supplements should only be used if there is a strong medically-based cause for doing so because of the potential to cause harm.
“Based on existing evidence, we see little justification for the general and widespread use of dietary supplements,” Dr Jaakko Mursu, a nutritional epidemiologist at the University of Minnesota in Minneapolis, and his research colleagues said according to BBC News.
“I think the main message is researchers are finding very little benefit from these substances,” Mursu told Janice Lloyd of USA TODAY. “Other studies have not shown the mortality risk our study shows, but those studies have not seen any positive effect either.”
Of 15 supplements analyzed, only calcium was associated with lower risk of death. “This paper contributes to the growing amount of studies showing no benefits for supplement use in the prevention of chronic diseases,” Mursu, who also is affiliated with the University of Eastern Finland, told Eryn Brown of the Los Angeles Times.
The research team found in the study data that supplement use was widespread and increased over the years. In 1986, 65 percent of the women reported taking one supplement daily. By 1997, that number was up to 75 percent; and by 2004, up to 85 percent.
Among the 38,772 women who started the study in 1986, 15,594 died within the course of the 19 year study. However, the research did not explore whether supplements contributed to the causes of death among the women.
Mursu said the findings focus on the higher risk of death from cardiovascular disease, cancer and other causes, but not on how the supplements and vitamins may have affected health. “There is much more research needed to begin to understand that,” he told USA Today.
“This study is very puzzling and calls for more research,” Miriam Pappo, director of clinical nutrition at Montefiore Medical Center in New York, told USA Today on Monday. “I wouldn´t conclude from this that you stop taking a standard multivitamin. Very few people eat the required amount of fruits and vegetables a day. It's best to get your daily needs from food, but few people do that.”
A spokesman for the vitamin industry was skeptical. “The study may make for interesting scientific water cooler discussion, but certainly does not warrant sweeping, overstated concerns for elderly women,” Duffy MacKay of the Council for Responsible Nutrition told USA Today in a statement.
In the study, iron pills were linked to a small -- 2.4 percent -- increase in the risk of death, as were many of the other supplements. The link with iron was dose-dependent, meaning the more an individual took, the higher the risk of death was.
Mursu said the result could be an indication that iron is toxic in high amounts, or it could reflect the possibility that the women who took the supplements were more likely to be sick from other causes and died from their underlying disease.
“We don´t have the detailed information why the women were using it,” he told the Los Angeles Times.
Such limitations led some to question the significance of the findings. “I wouldn´t recommend anyone change what they're doing based on this study,” Dr. David Heber, director of the UCLA Center for Human Nutrition, told the Los Angeles Times. “It´s very hard to conclude cause and effect.”
But Bonnie Jortberg, a registered dietitian and senior instructor at the University of Colorado School of Medicine in Denver, said the research strengthened arguments against using supplements other than in cases of known nutritional deficiency.
“Millions of Americans take these, but there just don't appear to be a lot of benefits,” Jortberg told the Los Angeles Times. “People take handfuls of supplements and they think that's a substitution for a good diet. It's just not.”
“We think the paradigm ℠The more the better´ is wrong,” said Drs Christian Gluud and Goran Bjelakovic, who review research for the Cochrane Database of Systematic Reviews to evaluate best evidence.
They said dietary supplementation has shifted from preventing deficiency to trying to promote wellness and prevent diseases. “We believe that for all micronutrients, risks are associated with insufficient and too-large intake,” they cautioned to BBC health reporter Michelle Roberts.
Helen Bond of the British Dietetic Association said some people, like the elderly, might need certain supplements and vitamins. For example, vitamin D is recommended for those over 65. But in general, people should be able to get all the vitamins and minerals they need from a healthy, balanced diet.
She said some took supplements as an insurance policy, wrongly assuming that they could do no harm. “But too much can be toxic and it is easy to inadvertently take more than the recommended daily amount.”
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