食品伙伴網(wǎng)報道，據(jù)美國營養(yǎng)成分（nutraingredients-usa.com）消息，一個來自meta分析的數(shù)據(jù)表明，補鈣會增加心血管疾病發(fā)作的風險。這份研究報告是來自英國醫(yī)學雜志（BMJ），奧克蘭大學的研究稱，根據(jù)數(shù)據(jù)分析結果，補鈣所引發(fā)的心血管疾病（如心臟病和中風）的人數(shù)，遠遠大于他們所預防骨折的人數(shù)。
該網(wǎng)站同時也發(fā)布了各界對此研究結果的看法：補鈣是最佳選擇。對于建立和維護健康的骨骼、防止骨質疏松，攝入充足的鈣質是至關重要的。大多數(shù)人沒有從飲食中得到足夠的鈣，而這正是為什么對所有年齡的消費者來說補鈣都是重要的。在那個meta分析的15個試驗評價中有7個關于心血管的數(shù)據(jù)結果沒有或不完整，15個研究中只有5個包括了幾乎所有心血管疾病的研究結果，并且，該分析未對在補充鈣的同時也補充維生素D的案例進行分析，而根據(jù)“婦女健康倡議”在補鈣時添加維生素D可降低心臟病和中風的危險。
Meta分析作為科學評價有用的工具，我們必須認識到其局限性，其結果是基于過去的研究，不同的實驗設計、研究人群和劑量補充。這種分析不應該勸阻采取補鈣的消費者，尤其是年輕婦女。
食品伙伴網(wǎng)編者注：Meta分析是指用統(tǒng)計學方法對收集的多個研究資料進行分析和概括，以提供量化的平均效果來回答研究的問題。其優(yōu)點是通過增大樣本含量來增加結論的可信度、解決研究結果的不一致性。meta分析是對同一課題的多項獨立研究的結果進行系統(tǒng)的、定量的綜合性分析。它是文獻的量化綜述，是以同一課題的多項獨立研究的結果為研究對象，在嚴格設計的基礎上，運用適當?shù)慕y(tǒng)計學方法對多個研究結果進行系統(tǒng)、客觀、定量的綜合分析。
本報道由食品伙伴網(wǎng)編譯整理，僅供食品行業(yè)相關人士參考，詳細內容以國外原文報道為準。
原文地址：
http://www.nutraingredients-usa.com/Research/Risks-outweigh-benefits-for-calcium-supplements-Meta-analysis
http://www.nutraingredients-usa.com/Research/Industry-Calcium-research-cherry-picked-results
原文報道：
‘Risks outweigh benefits’ for calcium supplements: Meta-analysis
By Nathan Gray, 30-Jul-2010New research suggests that regularly taking calcium supplements might increase the risk of heart attack.
The study, published in the British Medical Journal, indicates that calcium supplements cause more cardiovascular events (such as heart attacks and stroke) than the number of fractures they prevent.
Calcium supplements are commonly taken by older people as a measure to reduce the effects of osteoporosis. The widely used supplements have been shown to marginally reduce the risk of fracture for osteoporosis sufferers and improve bone density, but very little research has been compiled on the risks of calcium supplementation.
The new study, led by Professor Ian Reid at the University of Auckland, is a meta-analysis of fifteen randomized trials on calcium supplements conducted in the last twenty years, with the aim to investigate the links between calcium supplementation and cardiovascular events.
From analyzing the data on the 12,000 people involved in the 15 trials, the researchers found that calcium supplements increase the risk of heart attack by about 30 percent. Although this increase in heart attack risk is modest, the researchers suggest that the widespread use of calcium supplements means “even a small increase in incidence of cardiovascular disease could translate into a large burden of disease in the population.” The researchers wrote: “The likely adverse effect of calcium supplements on cardiovascular events, taken together with the possible adverse effect on incidence of hip fracture and its modest overall efficacy in reducing fracture (about 10% reduction in total fractures) suggest that a reassessment of the role of calcium supplements in the prevention and treatment of osteoporosis is warranted.”
The results observed in this study only saw an increased risk in people using supplementation, and do not affect people with high dietary intakes of calcium. Professor Reid explained that this could be related to higher blood calcium levels from supplementation compared to dietary calcium – higher blood calcium levels are believed to lead to hardening of the arteries, which can cause heart attacks.
Prof. Reid also told NutraIngredients.com that he believes the findings of the study indicate a need to review the use of calcium supplements in the general population, saying that the industry needed to “sit back and not just look at the benefits, but the clearly demonstrated risks”. Prof. Reid continued: “When you do the arithmetic, then it just doesn’t add up. The risks outweigh the benefits.”
Prof. Reid also believes that the study has broader implications for all nutritional supplements. He told NutraIngredients.com: “We have tended to focus on just the benefits of supplements without really looking at their safety. In the future I think we need to look at both the efficacy and the safety of supplements.
People assume that these supplements are natural. A high calcium meal is natural, but taking highly concentrated calcium tablets is not, and does not have the same effects” said Prof. Reid.
The Health Supplement Information Service responded to the research findings saying: “While the results of this meta-analysis are interesting and should encourage more research, the authors did not include the totality of the evidence on calcium supplementation and there were limitations to the analysis. For these reasons, it is not appropriate at this stage to change public health advice on the use of calcium supplements to maintain bone health."
Industry : Calcium research “cherry picked” results
By Nathan Gray, 30-Jul-2010Following publication of new research suggesting calcium supplements could increase the risk of heart attack, industry has been keen to give its response to NutraIngredients-USA.com
One of the main responses to the study’s findings is to point out that the adequate intake of calcium plays an important role in building and maintaining bone mass, and that the study published in the BMJ should not cause consumers to doubt the importance of calcium supplements in maintaining bone health.
“Adequate calcium intake is vital to building and maintaining healthy bones, and to preventing osteoporosis. Most people do not get enough calcium from diet alone, and this is where a calcium supplement can be important to consumers of all ages,” said Andrew Shao.
Both Shao, Ph.D, Senior Vice President of Scientific & Regulatory Affairs for the Council for Responsible Nutrition (CRN), and Daniel Fabricant Ph.D, vice president of scientific regulatory affairs for the Natural Products Association, have told NutraIngredients-USA.com that the results of the recent study go against years of research that show the benefits of calcium supplementation. Mr. Fabricant suggests that the authors of the research ‘cherry picked’ the fifteen studies from hundreds of available research studies in the area.
Reassessment
The authors of the BMJ meta-analysis called for a reassessment of the role of calcium supplements for osteoporosis, and suggested to NutraIngredients that the whole supplement market should test their products for safety and not just efficacy.
According to CRN, such conclusions are ‘dramatically overstated’. Shao said: “Seven of the 15 trials evaluated had no, or incomplete, data on cardiovascular outcomes, and only five of the 15 studies accounted for almost all of the cardiovascular outcomes. Further, the researchers chose to exclude any trials administering calcium plus vitamin D – including the Women’s Health Initiative which found calcium plus vitamin D had no effect on the risk of coronary heart disease or stroke.”
Professor Ian Reid, the lead researcher of the new research responded to these claims by telling NutraIngredients that they are currently conducting further research that will look at vitamin D with calcium supplements. Reid said that early indications show that the research, which should be published later this year, may have similar findings to the present study.
Fabricant pointed out that none of the original studies included in the meta-analysis were designed to evaluate cardiovascular events, and even if they had been “one meta-analysis on eight studies, will never prove to be conclusive evidence.”
“Meta-analysis can be a useful tool for scientific evaluation, but we have to recognize its limitations, and keep in mind that its findings are based on a collection of past studies that may have different designs, doses and study populations,” added Shao “This analysis should not dissuade consumers, particularly young women, from taking calcium supplements”.
Diet or supplements?
However, according to the National Osteoporosis Foundation (NOF), food will always be the best source of calcium: “People who get the recommended amount of calcium from foods do not need to take a calcium supplement. These individuals still may need to take a vitamin D supplement. Getting too much calcium from supplements may increase the risk of kidney stones and other health problems.”
But Shao drew attention to other health benefits that may be associated with calcium supplementation, such as reduction of colon cancer risk. “This is not even considered by the authors” he said.
