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作者：Laurie Barclay, MD  
出處：WebMD醫學新聞

　　October 9, 2009 — 根據發表於美國臨床營養學期刊、一項為期兩年、多中心、隨機分派、雙盲與控制組控制研究顯示，健康的停經後女性，每天補充黃豆可能降低整體骨質流失。
　　
　　德州休士頓Baylor醫學院的William W. Wong博士與其同事們寫到，大豆異黃酮是黃豆中富含的天然植物固醇；雖然據稱可以保護骨質流失，但是大豆異黃酮補充品在停經後女性預防骨質疏鬆的療效仍然是有爭議的，我們的目的在於測試大豆異黃酮補充品對於骨質流失的效應。
　　
　　在這項研究中，403位停經後女性被隨機分派接受每天補充80或120 mg的大豆胚軸非醣異黃酮或是安慰劑加上鈣與維生素D。接著，每年評估來確定整體與局部骨密度（BMD）、骨質內容（BMC）、T指數的改變，以及骨骼代謝血清生物標記的變化。
　　
　　在控制研究地點、攝取的大豆與治療前數值後，相較於安慰劑，服用120 mg大豆異黃酮組在一年時，治療後整體BMD顯著下降（P<0.03），在兩年時同樣有此效應（P<0.05）。120 mg的大豆異黃酮在一年時，整體BMD T指數也些微下降（P<0.03），但在治療兩年後沒有太大差異。相較於安慰劑，補充大豆異黃酮顯然對於局部BMD、BMC、T指數或骨骼代謝的生化標記沒有影響。
　　
　　研究作者們寫到，健康停經後女性每天補充120 mg的大豆胚軸非醣異黃酮降低整體骨質流失，但卻不會影響經常骨折部位的骨質流失。健康停經後女性使用兩年後整體BMD下降減緩可能轉化出些許的臨床好處；但尚未達到長期的顯著效益，特別是在骨折預防，仍然需要更多研究。
　　
　　美國農業/州聯合研究、教育、以及未來農業與食物系統延伸服務/機構、國家衛生研究院（NIH）一般臨床研究中心贊助這項研究。研究作者們表示已無相關資金上的往來。
　　
　　大豆異黃酮材料由Frutarum荷蘭BV（荷蘭Veenendaal公司）提供。安慰劑及異黃酮錠劑由Pharma諮詢與工業BV（Eede，荷蘭）提供。每日一次的綜合維生素補充品由北達科塔法哥Swanson健康產品提供。碳酸鈣補充品由加州斯科茨谷Source Naturals公司提供。
　　
　　這篇期刊文章的內容並不代表美國農業部或NIH的觀點或政策，也未提到商品名、商品，也不代表組織的背書。

Daily Soy Supplement May Reduce Whole Body Bone Loss in Healthy Postmenopausal Women

By Laurie Barclay, MD
Medscape Medical News

October 9, 2009 — A daily soy supplement may reduce whole body bone loss in healthy postmenopausal women without slowing bone loss at common fracture sites, according to the results of a 2-year, multicenter, randomized, double-blind, placebo-controlled, clinical trial reported online in the September 16 issue of the American Journal of Clinical Nutrition.

"Isoflavones are naturally occurring plant estrogens that are abundant in soy," write William W. Wong, PhD, from Baylor College of Medicine in Houston, Texas, and colleagues. "Although purported to protect against bone loss, the efficacy of soy isoflavone supplementation in the prevention of osteoporosis in postmenopausal women remains controversial....Our aim was to test the effect of soy isoflavone supplementation on bone health."

In this study, 403 postmenopausal women were randomly assigned to receive daily supplementation with 80 or 120 mg of soy hypocotyl aglycone isoflavones or placebo plus calcium and vitamin D. Annual evaluations allowed determination of changes in whole body and regional bone mineral density (BMD), bone mineral content (BMC), T scores, and changes in serum biochemical markers of bone metabolism.

Compared with the placebo group, the 120-mg soy isoflavones group had a significantly smaller reduction in whole body BMD both at 1 year (P < .03) and at 2 years (P < .05) of treatment, after controlling for study site, soy intake, and pretreatment values. The 120-mg soy isoflavones group also had smaller decreases in whole body BMD T score at 1 year (P < .03) but not at 2 years of treatment. Soy isoflavone supplementation at either dose appeared to have no effect vs placebo on changes in regional BMD, BMC, T scores, or biochemical markers of bone metabolism.

"Daily supplementation with 120 mg soy hypocotyl isoflavones reduces whole body bone loss but does not slow bone loss at common fracture sites in healthy postmenopausal women," the study authors write. "The attenuated WB [whole body] BMD in healthy postmenopausal women for 2 years probably translates to minimal clinical benefits; yet the long-term significance, particularly with regard to fracture prevention, remains to be determined."

The US Department of Agriculture/Cooperative State Research, Education, and the Extension Service/Initiatives for Future Agriculture and Food Systems, and the National Institutes of Health (NIH) General Clinical Research Center supported this study. The study authors have disclosed no relevant financial relationships.

The soy isoflavone material was provided by Frutarum Netherlands BV (Veenendaal, the Netherlands). The placebo and isoflavone tablets were made and packaged by Pharma Consulting Industries BV (Eede, the Netherlands). The one-a-day multivitamin supplement was provided by Swanson Health Products, Fargo, North Dakota. The calcium carbonate supplement was provided by Source Naturals, Scotts Valley, California.

The contents of this journal article do not necessarily reflect the views or policies of the US Department of Agriculture or the NIH, nor does the mention of trade names, commercial products, or organizations imply endorsement.

Am J Clin Nutr. Published online September 16, 2009.