摘要:據月日刊上的一則研究披露挪威是一個食物中沒有增補葉酸的國家該國的心臟病患者如果接受了葉酸和維生素的治療其罹患癌癥及死于任何原因的風險都會有相關的增加根據文章的背景資料大多數的流行病學調查發現在葉酸是一種族維生素的攝取與結腸直腸癌風險之間存在著逆相關盡管這種相關性在其它的癌癥中是不一致的或是闕如的文章的作者寫道

 

據11月18日刊JAMA上的一則研究披露,挪威是一個食物中沒有增補葉酸的國家。該國的心臟病患者如果接受了葉酸和維生素B12的治療,其罹患癌癥及死于任何原因的風險都會有相關的增加。

 

根據文章的背景資料,大多數的流行病學調查發現,在葉酸(是一種B族維生素)的攝取與結腸直腸癌風險之間存在著逆相關,盡管這種相關性在其它的癌癥中是不一致的或是闕如的。文章的作者寫道:“實驗室的證據表明,葉酸缺乏可促進初始階段的癌癥發生,而高劑量的葉酸可能會促進癌細胞的生長。自1998年以來,許多國家,其中包括美國,開始在面粉和谷類產品中進行葉酸增補以降低出生時發生神經管缺陷的風險。” “最近,人們對葉酸的安全性,尤其是有關其致癌風險的擔心開始出現。”

 

Haukeland University Hospital, Bergen, Norway的Marta Ebbing, M.D.及其同僚對挪威的2個在缺血性心臟病患者中進行的降低同型半胱氨酸的試驗結果進行了分析。在該試驗中,那些被分配接受葉酸治療的小組的癌癥發生率發生了統計學上沒有顯著意義的增加。

 

這2則隨機化的、有安慰劑作對照的臨床試驗中包括了6837名有缺血性心臟病的患者,他們在1998年和2005年之間接受了B族維生素或是安慰劑的治療。對這些患者的隨訪一直持續到2007年的12月31日。這些患者被隨機分配接受口服葉酸(0.8 mg/天)加葉維生素B12 (0.4 mg/天)加維生素B6(40 mg/天)[n = 1708] ; 葉酸(0.8 mg/天)加維生素B12(0.4 mg/天)[n = 1703] ;僅僅服用維生素B6(40 mg/天)[n = 1705];或服用安慰劑 [n = 1721] 。在研究治療期間,中位(中點)血清葉酸濃度在服用葉酸的參與者中增加了6倍以上。

 

研究人員發現,在經過中位數為39個月的治療及另外38個月的試驗后觀察隨訪之后,在沒有接受葉酸加維生素B12的人中有288人(占8.4%)被診斷患有癌癥,而在接受了葉酸和維生素B12治療的人中,被診斷罹患癌癥者有341人(10.0%),癌癥風險的增加幅度為21%。在沒有接受葉酸加維生素B12治療者中,共有100位患者死于癌癥(占2.9%),而在接受了葉酸加維生素B12的治療者中,共有136名患者死于癌癥(占4.0%),其死于癌癥的風險增幅為38%。在沒有接受葉酸加維生素B12的治療者中,共有16.1%的患者死于任何的原因,而在接受了葉酸加維生素B12的治療者中,共有13.8%的患者死于任何的原因。

 

 

文章的作者寫道:“這些結果主要是受到這些接受了葉酸加維生素B12的參與者中肺癌發生率增加的影響。維生素B6的治療與任何其它的明顯的功效都沒有相關性。”

 

 

“我們的結果需要在其它的人群中得到確認。但它強調了在人們從食品補充劑及強化食品中廣泛攝取葉酸之后對其安全性監控的訴求。”(生物谷Bioon.com)

 

 

生物谷推薦原始出處:

 

 

JAMA. 2009;302(19):2119-2126.

 

 

Cancer Incidence and Mortality After Treatment With Folic Acid and Vitamin B12

Marta Ebbing, MD; Kaare Harald B?naa, MD, PhD; Ottar Nyg?rd, MD, PhD; Egil Arnesen, MD; Per Magne Ueland, MD, PhD; Jan Erik Nordrehaug, MD, PhD; Knut Rasmussen, MD, PhD; Inger Nj?lstad, MD, PhD; Helga Refsum, MD, PhD; Dennis W. Nilsen, MD, PhD; Aage Tverdal, PhD; Klaus Meyer, PhD; Stein Emil Vollset, MD, DrPH

Context Recently, concern has been raised about the safety of folic acid, particularly in relation to cancer risk.

Objective To evaluate effects of treatment with B vitamins on cancer outcomes and all-cause mortality in 2 randomized controlled trials.

Design, Setting, and Participants Combined analysis and extended follow-up of participants from 2 randomized, double-blind, placebo-controlled clinical trials (Norwegian Vitamin Trial and Western Norway B Vitamin Intervention Trial). A total of 6837 patients with ischemic heart disease were treated with B vitamins or placebo between 1998 and 2005, and were followed up through December 31, 2007.

Interventions Oral treatment with folic acid (0.8 mg/d) plus vitamin B12 (0.4 mg/d) and vitamin B6 (40 mg/d) (n = 1708); folic acid (0.8 mg/d) plus vitamin B12 (0.4 mg/d) (n = 1703); vitamin B6 alone (40 mg/d) (n = 1705); or placebo (n = 1721).

Main Outcome Measures Cancer incidence, cancer mortality, and all-cause mortality.

Results During study treatment, median serum folate concentration increased more than 6-fold among participants given folic acid. After a median 39 months of treatment and an additional 38 months of posttrial observational follow-up, 341 participants (10.0%) who received folic acid plus vitamin B12 vs 288 participants (8.4%) who did not receive such treatment were diagnosed with cancer (hazard ratio [HR], 1.21; 95% confidence interval [CI], 1.03-1.41; P = .02). A total of 136 (4.0%) who received folic acid plus vitamin B12 vs 100 (2.9%) who did not receive such treatment died from cancer (HR, 1.38; 95% CI, 1.07-1.79; P = .01). A total of 548 patients (16.1%) who received folic acid plus vitamin B12 vs 473 (13.8%) who did not receive such treatment died from any cause (HR, 1.18; 95% CI, 1.04-1.33; P = .01). Results were mainly driven by increased lung cancer incidence in participants who received folic acid plus vitamin B12. Vitamin B6 treatment was not associated with any significant effects.

Conclusion Treatment with folic acid plus vitamin B12 was associated with increased cancer outcomes and all-cause mortality in patients with ischemic heart disease in Norway, where there is no folic acid fortification of foods.

 

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