本帖最後由 goodcat1111 於 2009-4-30 15:02 編輯
作者：Laurie Barclay, MD
出處：WebMD醫學新聞
April 9, 2009 — 一項發表在4月號糖尿病照護期刊的護士健康研究分析結果顯示，攝取較多的鋅與女性罹患第二型糖尿病風險較低有關。
麻州哈佛大學公衛學院的Qi Sun醫師寫到，雖然來自動物研究的證據顯示攝取鋅可能具有對抗第二型糖尿病的保護性作用，但是很少有研究檢驗其間的關聯性。
有關於飲食中的鋅攝取量與第二型糖糖尿病風險下降之間的關係並未在前瞻性的研究中檢驗。除此之外，分開檢驗補充鋅或是來自食物中的鋅將會是有幫助的，因為前者的生物可獲得性比後者高。
這項分析的目標在於決定鋅攝取量與美國女性第二型糖尿病風險之間的關係，研究族群包括了82,297位女性，這些受試者的年齡在1980年代時介於33至60歲之間，且在護士健康研究分析研究中追蹤直到2004年。從1980年到2002年，一份已確效的食物頻率問卷（FFQ）被用於評估飲食攝取鋅與其他營養成分。
在24年間的後續追蹤中，總共有6,030件第二型糖尿病事件；在校正生活型態與飲食危險因子後，比較整體鋅攝取量最高與最低的四分位數，發生第二型糖尿病的相對風險（RR）為0.90（95%信賴區間[CI]為0.82-0.99；趨勢P值為0.04），飲食中鋅攝取的RR為0.92（95% CI為0.84-1.00；趨勢P值為0.009）。
第二型糖尿病與飲食中鋅及血基質鐵的比值也呈反比。在多變項校正共變項後，不同四分位數比值的RR分別是1.0（對照值）、0.93（95% CI為0.86-1.01）、0.86（95% CI為0.79-0.94）、0.82（95% CI為0.75-0.90）、0.72（95% CI為0.66-0.80），這些比較的趨勢P值小於0.0001。
研究作者們寫到，攝取較多的鋅與女性罹患第二型糖尿病風險較低有關；需要更多的研究來確認這之間的關係與可能的機轉。
這項研究的限制包括可能的殘餘影響因子；在評估鋅攝取量上的部分量測誤差；可能缺乏應用到非白人女性或是其他族群的一般性；只在使用累積平均飲食後才觀察到顯著的關聯，且在受試者發生慢性疾病後即停止更新飲食記錄。
研究作者的結論是，其研究結果顯示，高鋅與血基質鐵比值的飲食顯著地與第二型糖尿病風險較低有關。這些發現被認為是初期的，因此需要進一步的研究來確認這些發現。
國家衛生研究院贊助這項研究。Sun醫師接受Unilever集團研究博士後研究人員經費贊助，另一位研究作者是美國心臟醫學會研究獎得主。研究作者們表示沒有相關資金上的往來。
Zinc Intake Linked to Slightly Lower Risk for Type 2 Diabetes in Women
By Laurie Barclay, MD
Medscape Medical News
April 9, 2009 — Higher zinc intake may be associated with a slightly lower risk for type 2 diabetes in women, according to the results of an analysis from the Nurses' Health Study reported in the April issue of Diabetes Care.
"Despite the evidence from animal studies that zinc intake may have protective effects against type 2 diabetes, few studies in humans have been conducted to examine this relationship," write Qi Sun, MD, ScD, from Harvard School of Public Health, Boston, Massachusetts, and colleagues.
"The hypothesis that dietary zinc intake is associated with a reduced risk of type 2 diabetes has not been examined in a prospective study. Also, it would be useful to examine the associations for supplemental zinc and zinc from food sources separately because the former is more bioavailable than the latter."
The goal of this analysis was to determine the interaction of zinc intake with risk for type 2 diabetes in US women. The study cohort consisted of 82,297 women who were aged 33 to 60 years at baseline in 1980 and who were followed up to 2004 in the Nurses' Health Study. From 1980 to 2002, a validated food frequency questionnaire (FFQ) was administered to measure dietary intakes of zinc and other nutrients.
There were 6030 incident cases of type 2 diabetes during 24 years of follow-up. Comparing the highest with the lowest quintiles of intake, the relative risks (RRs) of type 2 diabetes were 0.90 (95% confidence interval [CI] 0.82 - 0.99; P trend = .04) for total zinc and 0.92 (95% CI, 0.84 -1.00; P trend = .009) for dietary zinc from food sources, after adjustment of lifestyle and dietary risk factors.
There was also an inverse association between type 2 diabetes and dietary zinc–to–heme iron ratio. RRs across quintiles of this ratio, after multivariate adjustment of covariates, were 1.0 (reference), 0.93 (95% CI, 0.86 - 1.01), 0.86 (95% CI, 0.79 - 0.94), 0.82 (95% CI, 0.75 - 0.90), and 0.72 (95% CI, 0.66 - 0.80), respectively (P trend < .0001).
"Higher zinc intake may be associated with a slightly lower risk of type 2 diabetes in women," the study authors write. "More studies are warranted to confirm this association and to explore potential mechanisms."
Limitations of this study include possible residual confounding; some measurement error in assessment of zinc intake; possible lack of generalizability to nonwhite women or to those of other professions; and significant associations observed only after using cumulative average of diet and stopping diet updates after participants developed chronic diseases.
"Our results also suggest that a diet with high zinc-to-heme iron ratio is significantly associated with lower risk of type 2 diabetes," the study authors conclude. "These findings are considered preliminary, and, thus, further studies are warranted to confirm these findings."
The National Institutes of Health supported this study. Dr. Sun. is supported by a Postdoctoral Fellowship from the Unilever Corporate Research, and another study author is a recipient of the American Heart Association Established Investigator Award. The study authors have disclosed no relevant financial relationships.
Diabetes Care. 2009;32:629-634. |
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