【大西洋月刊】维生素B6和B12似乎会导致男性患癌 [美国媒体]

Vitamin B6 and B12 Supplements Appear to Cause Cancer in Men

维生素B6和B12似乎会导致男性患癌

——A newly discovered risk associated with common energy and metabolism pills

——新发现的风险与普通能量代谢药物有关



Energy. If you’re not taking vitamin B12, forget about having energy. As The Dr. Oz Show has recommended, “End your energy crisis with Vitamin B12.” The nice thing about sublingual pills is “you don’t need a doctor, you don’t need a prescription.”

精力——如果你不摄入维生素B12的话，那精力注定与你无缘。正如奥兹医生秀(美国张悟本)推荐的，“用维生素B12终结你的精力危机吧！”这种舌下含服药品好的一点是“你不需要医生，也不需要处方。”

And don’t get me started on metabolism. If you want to “supercharge your metabolism and energy levels,” Amazon can deliver you a tall bottle of B12 supplements by the end of the day. Your metabolic processes will be the envy of the neighborhood. (“Is Janice ... on something?” “Yes—B12!”)

好了，现在别逼我扯新陈代谢了。如果你想要“增强代谢和精力水平”，亚马逊当天就能送到一大瓶B12补充剂——邻居们将无比嫉妒你的新陈代谢。(“Janice……是不是在吃什么？”“是的——B12！”)

These are the sort of vague marketing claims that have propelled the cobalt-based compounds sold as B12 into American hearts and minds and blood in ever-growing quantities. They are extrapolations from the fact that B12 deficiency causes anemia, and correcting that deficiency will alleviate symptoms of fatigue and weakness. But as the National Institutes of Health notes, “Vitamin B12 supplementation appears to have no beneficial effect on performance in the absence of a nutritional deficit.”

这类模糊不清的市场宣传使得这种钴基化合物(维生素B12，化学名Coα-[α-(5，6-二甲基苯并咪唑基)] –Coβ氰钴酰铵，含有钴元素)深入美国人民内心，其销量在不断增长。缺乏维生素B12会导致贫血，而纠正这种缺乏会减轻疲劳和虚弱的症。但是，根据美国国立卫生研究院的注释，“在营养充分的情况下，额外补充维B12未能对人体机能显示出有益效果。”

Nonetheless around 50 percent of people in the United States take some form of “dietary supplement” product, and among the most common are B vitamins. Worse than just a harmless waste of money, this usage could be actively dangerous. In an issue of the Journal of Clinical Oncology, published this week, researchers reported that taking vitamin B6 and B12 supplements in high doses (like those sold in many stores) appears to triple or almost quadruple some people’s risk of lung cancer.

虽然如此，美国有近50%的人摄入某种“膳食补充剂”，最常见的就是B族维生素。比只浪费钱更糟的是，这种用法可能相当的危险。《临床肿瘤学期刊》本周发布的一篇文章中，研究者发现大量服用B6和B12(正如商店卖的那些)似乎会导致一些人患肺癌的风险提早至三倍，最多可达四倍。

This is a heavy claim about a very common substance, so it’s worth spending a minute on the methodology. Concerns about B-vitamin supplements and cancer have been percolating for years. They came up quietly in a large trial in Norway that concluded ten years ago. Starting in 1998, researchers assigned 6,837 people with heart disease to take either B vitamins or a placebo.

对于这种非常普通的物质来说，这是很严重的指控，所以值得我们花上一分钟审读下研究方法。对B族维生素补充剂与癌症有关联的担忧已经出现很多年了。他们在挪威悄悄开展了一项大规模临床试验，于十年前结束。从1998年开始，研究人员在6837名心脏病患者中分发B族维生素和安慰剂。

The researchers then watched as people died and contracted diseases in ensuing years—and the vitamin group raised concerns. In 2009, the researchers reported in the Journal of the American Medical Association that taking high doses of vitamin B12 along with folic acid (technically vitamin B9) was associated with greater risk of cancer and all-cause mortality.

研究人员之后观察接下来一年人们的死亡和染病情况——服用维生素组引起了关注。2009年，研究者在《美国医学协会志》报告，同时服用大剂量的B12和叶酸(严格来说叫维生素B9)与高患癌率和全病因死亡率有关联。

——Using more than 55 micrograms daily appeared to quadruple cancer risk——

——每日服用超过55微克使癌症风险提高四倍——

The largest increase in cancer risk was in the lung. Still, the number of cases of lung cancer among these 6,837 Norwegians was relatively small—so the actual risk was difficult to quantify. But it was big enough to catch the attention of Theodore Brasky and Emily White, two researchers at the Fred Hutchinson Cancer Research Center in Seattle. White had been overseeing a cohort study that involved more than ten times as many people as the Norwegian trial, some 77,000 people across the state of Washington. The cohort is tracking their supplement intake as we speak, and it is also being followed for cancers by the National Cancer Registry.

肺部患癌风险提高最多，然而，6837名挪威人中真正患肺癌的人数相对还是很少的——所以真正的风险系数很难量化。但这吸引了Theodore Brasky 和Emily White 的注意，他们两个是西雅图福瑞德哈金森肿瘤研究中心研究员。White 一直在监管一项比挪威试验规模大十倍的群体研究——涉及到华盛顿州近77000人。这项研究追踪他们的摄入补充剂的情况，同时跟访其患癌情况。

The Washington study was specifically designed to examine the roles of “dietary supplements”—compounds known as vitamins, minerals, and non-vitamin non-mineral compounds like ginseng—in cancer risk. This was an ideal setup to look at the relationship between B vitamins and cancer, and see if it was indeed worthy of concern. So Brasky and White, along with Chi-Ling Chen at National Taiwan University, broke down this population by B-vitamin use and looked at cancers. Unfortunately their findings were even more significant than the Norwegian trial.

华盛顿的研究是专门设计用来检测“膳食补充剂”在患癌风险中扮演的角色的——例如维生素、矿物质，其他成分如人参。所以这是很好的研究B族维生素的机会。不幸的是，华盛顿研究的结果比挪威试验更加显着。

Lung-cancer risk among men who took 20 milligrams of B6 daily for years was twice that of men who didn’t. Among people who smoke, the effect appeared to be synergistic, with B6 usage increasing risk threefold. The risk was even worse among smokers taking B12. Using more than 55 micrograms daily appeared to almost quadruple lung-cancer risk.

日服用20毫克B6多年的男性患肺癌风险是不服用者的两倍。在吸烟人群中，服用同样量的B6，风险增加到了3倍，服用B12者更甚，每日服用超过55微克B12似乎使患肺癌风险提高到了4倍。 

There was no apparent risk among women—which is not to say it doesn’t exist, only that it wasn’t apparent.

在女性中没有发现这种风险——也不能因此就说不存在了，可能只是没有显现出来。

Why or how would B vitamins increase a person’s risk of cancer?

为什么B族维他命会增加一个人的患癌风险？

I asked Brasky what he thought was going on. It’s all hypothetical, and he has no clear idea about the sex discrepancy. What he does know is that  B vitamins all contribute enzymes and coenzymes to a metabolic pathway that breaks down folate in order to make the bases that comprise DNA. The pathway also regulates the expression of genes (by creating methyl groups that can essentially turn genes on and off). When we have too little of these B vitamins, this pathway can go wrong, leading to problems like incorporation of the wrong types of bases into DNA, which can cause breaks in the strands, and, in theory, lead to cancer.

我请Brasky 解释一下是什么情况。他说目前一切只是假说，而且他无法解释性别差异。他所知道的是，B族维生素全都有助于某些酶和辅酶发挥作用，这些酶催化叶酸分解代谢途径，进而形成DNA合成所需的基团(叶酸参与嘌呤和胸腺嘧啶的合成，进一步合成DNA和RNA)。该代谢途径同时控制着基因表达(通过生成甲基基团开启、关闭基因)，当我们严重缺少B族维生素时，该代谢途径就会出错，导致DNA合成错误之类的问题，这可以造成DNA双链崩解——理论上，这会引发癌症。

——We’re best to treat vitamins more like pharmaceuticals than like panaceas to be shoveled into us——

——我们最好更多地把维生素当成药物，而不是可以随意服用的灵丹妙药——

Deficiency can also mean genes that should be inhibited are no longer inhibited, also potentially meaning cancer. Sufficiency of certain vitamins is important in cancer prevention, but avoiding excess appears to be similarly important.

维生素缺乏同时可能导致应该被抑制表达的基因没有被抑制，这同样可能引发癌症。所以充分的维生素对于预防癌症十分重要，但避免过量同样重要。

The research team is quick to note that the doses of B vitamins in question are enormous. The U.S. Recommended Dietary Allowance for B6 is 1.7 milligrams per day, and for B12 it’s 2.4 micrograms. The high-risk group in the study was taking around 20 times these amounts.

研究团队注意到研究人群摄入的B族维生素剂量是巨大的。美国膳食推荐中B6是每日1.7毫克，B12为2.4毫克。而高风险组人群的服用量是推荐量的近20倍。

That could seem nonsensical, except that these are the doses for sale at healthy-seeming places like Whole Foods and GNC. Many sellers offer daily 100-milligram B6 pills. B12 is available in doses of 5,000 micrograms.

看起来很荒谬是吧？可惜的是，这就是那些表面上非常健康的地方销售的剂量，例如全食公司和健安喜。许多销售商提供日剂量达100毫克的B6药片和50毫克的B12。

I asked Brasky if his finding means that products like these should be more closely regulated—at least to require selling more reasonable doses, or to disclose risks, as is required for pharmaceuticals. Currently, supplements are absolved from this sort of requirement, or even to prove safety or efficacy before going to market. This is dictated by a 1994 law called the Dietary Supplement Health and Education Act (DSHEA).

我问Brasky 他的研究发现是否意味着对此类膳食补充剂的管理应该更加严格——最起码要求销售更加合理的剂量，或公布其风险，正如对药品要求的那样。当前补充剂产品不受此类要求的限制，甚至上市前也不需要证明其安全性和有效性。这是由1994年的“膳食补充剂健康与教育法”规定的。

“The law was created by industry lobbying to keep the FDA away from regulation, so the industry self-regulates,” said Brasky. But he deferred and said he hoped this article wouldn’t be about regulation. “I don’t want to pick a fight with the vitamin industry for any reason.”

“这部法律是由行业游说团体设立的，为的是把FDA(美国食品药品管理局)排除在监管控制之外，这样该行业就能自我控制了，” Brasky 说，他犹豫了一下，又说希望这篇文章不要谈及管理规则，“我不想以任何理由，挑起与维生素制造业的争端。”

So that falls to me. There are legitimate and important uses for B-vitamin supplements, but the emerging evidence suggests we’re best to treat them more like pharmaceuticals than like panaceas to be shoveled into us in pursuit of energy, metabolic fortitude, “cardioprotection,” “bone wellness,” or whatever way in which we’d like to be better.

所以这事儿就落在了我头上。B族维生素补充剂的使用是合法的、重要的。但是新的证据表明我们最好把维生素更多地当成药物，而不是可以随意服用的灵丹妙药——为了精力充沛、代谢强劲、“保护心脏”、“骨骼健康”之类的。

The enduring theme in health is that more doesn’t mean better. What’s healthy for one person may be unhealthy for another. The fact of a product being sold without a prescription does not mean it is exempt, or that it’s good or even harmless. Any ingested bioactive substance will come with risks and benefits.

健康领域不变的主题是“更多不意味着更好”。对一个人健康的可能对另一个人来说不健康。非处方药品也不例外。任何摄入类的生物有效成分的益处和风险都是共存的。

The current law gives consumers no reason to expect that risks will be listed on the labels of these products, or that health claims are accurate. A product like a high-dose B6 and B12 supplement hits shelves, and only decades later do researchers begin to understand the long-term health effects, who might benefit from taking it, and who might be harmed.

现有法律下，消费者不能指望产品标签列出风险，也不能指望准确的健康宣传。类似高剂量的B6和B12这样的产品冲击着货架，只有几十年后，研究人员才会开始理解长期健康效应，才会知道谁会从服用中获益，谁又会受害。