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New study sees little need for vitamins, cites risks

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Published : Oct. 11, 2011 - 10:28

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WASHINGTON (AFP) -- There is no need for most people to take vitamin supplements and some may even be linked to a higher risk of dying in older women, according to a study published Monday in the United States.

(MCT) (MCT)

Iron stood out among supplements as a particular concern, while calcium appeared to be linked to lower death risk, said the study in the Archives of Internal Medicine, a journal of the American Medical Association.

With about half of Americans taking vitamin pills of some kind, the study aimed to examine whether the $20 billion supplement industry was having any effect on extending lifespan in an already well-nourished population.

The researchers confirmed their theory -- that supplements were not helping people ward off death. But the reasons for the link to higher risk of overall mortality, or the risk of dying for any reason, were less clear.

"Based on existing evidence, we see little justification for the general and widespread use of dietary supplements," wrote the study authors from the University of Eastern Finland and the University of Minnesota.

"We found that several commonly used dietary vitamin and mineral supplements, including multivitamins, vitamins B6, and folic acid, as well as minerals iron, magnesium, zinc, and copper, were associated with a higher risk of total mortality."

The US and Finnish researchers examined data from the Iowa Women's Health Study, including surveys filled out by 38,772 women with an average age of 62.

Women self-reported their supplement use in 1986, 1997 and 2004, and data showed their use rose from 66 percent of survey-takers at the start to 85 percent by 2004.

Those who took supplements showed a range of healthy lifestyle factors, and were more likely than non-supplement users to be non-smokers, eat low-fat diets and exercise.

But in many cases they showed a higher risk of dying than their supplement-free counterparts.

"Of particular concern, supplemental iron was strongly and dose dependently associated with increased total mortality risk," said the study.

On the other hand, "supplemental calcium was consistently inversely related to total mortality rate," meaning that calcium-takers showed a lower death risk, though the same dosage relationship was not visible.

The authors said they could not rule out the possibility that the reason for the higher death rate in iron users could have been due to underlying conditions for which they were taking supplements, and more research is needed.

In the meantime, doctors urged patients to consider the risks of taking supplements unless they are needed to stave off deficiencies.

"We think the paradigm 'the more the better' is wrong," wrote doctors Goran Bjelakovic of the University of Nis in Serbia and Christian Gluud of Copenhagen University Hospital in Denmark in an accompanying commentary.

These findings "add to the growing evidence demonstrating that certain antioxidant supplements, such as vitamin E, vitamin A, and beta-carotene, can be harmful," they said.

"We cannot recommend the use of vitamin and mineral supplements as a preventive measure, at least not in a well-nourished population."

Bjelakovic and Gluud said the only supplement that may be beneficial to older women, and possibly older men, is vitamin D3, if they do not already get enough through their diet or from sun exposure.

"The issue of whether to use calcium supplements may require further study," they added.

 

<한글 기사>

종합비타민 복용, 건강에 효과 없다

종합 비타민은 나이 든 여성의 수명을 연장하는 효과가 없다는 연구결과가 나왔다.

미국 미네소타 대학의 자코 무르수(Jaakko Mursu) 박사는 55-69세 여성 3만9천 명을 대상으로 19년에 걸쳐 실시한 조사 분석 결과 각종 비타민과 미네랄 등 영양보충제를 복용하는 여성이 복용하지 않는 여성보다 더 오래 살지 못하며 오히려 사망률이 약간 높은 것으로 나타났다고 10일(현지시간) 밝혔다.

다만 칼슘보충제만은 복용한 그룹의 사망률이 평균 37%로 복용하지 않은 그룹의 43%에 비해 낮았다.

기타 영양보충제를 복용한 노인들은 복용하지 않은 노인들에 비해 오래 살지 못 한 것으로 나타났다. 예를 들어, 종합비타민은 복용자의 사망률이 41%로 비복용자의 40%보다 약간 높았다.

이 결과는 당뇨병, 고혈압, 과체중 등 여러 가지 건강문제들을 감안한 것이다.

무르수 박사는 이 연구결과는 노인 여성만을 대상으로 한 것이지만 노인 남성도 마찬가지일 것으로 생각한다고 말하고 그러나 이 연구결과가 영양보충제가 해가 된다는 뜻은 아니라고 강조했다.

이 결과는 비타민 결핍이 흔치 않은 서방국가들에서는 영양보충제가 별 효과가 없다는 앞서 발표된 연구결과들과 일치하는 것이라고 그는 덧붙였다.

이 연구결과는 '내과학 기록(Archives of Internal Medicine)' 최신호에 실렸다.