吃辣椒对人体有害吗?

编辑:给力英语新闻 更新:2017年11月12日 作者:维农尼克.格林伍德(Veronique Greenwood)

(图片来源: iStock)
(图片来源: iStock)

对于许多人来说,大汗淋漓、满脸通红地体验咖喱、墨西哥沙司(salsa)或者四川火锅带来的麻辣口感是生活中最大的乐趣之一。寻找最辣食物灼烧自己的口腔也成了很多人的业余爱好,对此乐而不疲的也大有人在。

大家都知道,辣椒是一种安全食品。红辣椒中的辣味来源–辣椒素分子能够通过刺激口腔内的痛觉神经元受体而产生辣感,但实际上它并没有对人体产生危害。仅仅在几分钟过后,口腔中的灼烧感就会消失。一天以后再吃辣就能够再一次体会这种感觉,这好像是一场好玩的游戏。

不过先等等,吃辣椒吃出问题的也大有人在。

辣椒以其辣度(Scoville)分为多个等级,从等级最低的青椒(辣度为0)一直到令人望而色变的“卡罗莱纳死神辣椒(Carolina Reaper)”(辣度220万)。尽管人们每天正常饮食中摄入的辣椒对人体不会产生什么危害,但是嗜辣者的疯狂行为则不在此列。2014年,英国布莱顿市(Brighton)《百眼巨人报》(The Argus)的两位记者到当地获得猫途鹰网站(TripAdvisor)高分平价的一家餐馆吃汉堡。他们每人嚼了一口XXX级超辣汉堡–这种汉堡是餐馆老板为了招徕人气,用比防狼喷剂辣度还高的辣酱做成的。


某些超辣辣椒能够产生类似于心脏病的体感。 (图片来源: Getty Images)

口腔里的巨大灼痛立即超出了他们的忍耐极限–一位记者迅速喝下大量牛奶以求压制辣感,报纸报道说。另一位记者则开始出现严重腹痛,双手失去知觉,并开始浑身颤抖、用力呼吸。他的同事尽管喝了牛奶,但还是熬不住剧痛。最后两人都被送进医院。“当时感觉太疼了,”一名记者说,“我感觉快死掉了。”(点击阅读全文。)

在摄像机镜头前尝试世界最辣辣椒的勇敢嗜辣者们最后无不以失控呕吐而告终。Youtube上的系列吃辣椒表演以及最终结果十分引人入胜,亚伦·斯耶(Aaron Thier)在为美食杂志《福桃》(Lucky Peach)写的一篇文章中描述了一场1000人同吃魔鬼辣椒的丹麦活动的慢动作回放。“和往常的类似反应一样,每个人都在大汗淋漓,不停打嗝。但是剪辑师却营造了一种神话般的、永恒的、抒情性的效果。就连人们呕吐时的表情都显得那么兴高采烈,”他在文章中写道。

马特·格罗斯(Matt Gross)也为美食杂志《好胃口》(Bon Appetit)写了一篇关于辣椒的文章,文章是以冷冰冰的数字开始的。“我花了21.85秒才吃完三根世界上最辣的辣椒–卡罗莱纳死神辣椒。之后的剧烈身体反应足足让我花了将近14小时才恢复过来,”他写道。(《破坏者:小小辣椒让你体验心脏病发病症状》)

其中究竟有什么机制?如果辣椒只不过是通过在你口腔中引发灼痛而欺骗你的身体,那么它为什么会引发如此剧烈的躯体反应?

我们不妨先分析一下辣椒素的基本生物学效应。辣椒素分子最初是由植物的抗真菌成分演化而成。然而人类却由于它对痛觉神经元受体的刺激作用而对它产生了喜好、迷恋或恐惧。无论受到火焰灼烧还是辣椒素的刺激,痛觉神经元都会向大脑发出同样的受热信号。神经元本身无法分辨二者–对于人体来说,在有可能受伤的情况下避开威胁,远比仅仅受到愚弄更为合理。


吃辣椒–即便是非常辣的辣椒–也不会对你的身体造成持续性伤害。(图片来源: Getty Images)

吃辣椒后的身体反应可以看作是人体自认为遭到烧伤后的应激措施,费城莫奈尔化学感觉中心(Monell Chemical Senses Center)的生物学家布鲁斯·布莱恩特(Bruce Bryant)说。出汗是人体进行自我冷却的过程。受到激发的痛觉神经元会释放导致血管扩张的物质,从而引发炎症反应,向受损部位输送更多血液及急救物质。

”卡罗莱纳死神辣椒接触你的胃壁后会引发呕吐,“胃里分布有痛觉神经末梢,”布莱恩特说。“我们的身体会说,‘我不管是灼热物质还是化学刺激物质,我只想把它清除出去。’”

分布在你口腔、胃和其他部位的痛觉神经元会促使你摄入大量碱性物质以中和体内的大量辣椒素,而无论你在乱中喝下的物质会造成你的死亡,还是仅仅是让你在卫生间上吐下泻。

然而,吃了极辣辣椒几个小时或者一天过后,尽管不适感依然存在,但人体本身并没有受到长期性威胁。然而,生物学家已经发现,如果长期以辣椒素喂养幼年哺乳动物,会造成痛觉神经元的死亡,布莱恩特说。不断激发神经元会造成其出现疲劳受损情况,并且受损的神经元不会再生。

有趣的是,辣椒这种植物进化出辣椒素分子的目的就在于避免让哺乳动物吞下它的种子。将辣椒种子囫囵吞下并通过粪便加以传播的鸟类则没有会产生灼烧感的神经受体。然而,辣椒现在却不幸遇到了以追逐辣感而取乐的人类,这种追逐已经超出了理性的范畴。

幸好,辣椒这种植物不大可能因此而遭到衰亡的厄运。

Can you hurt yourself eating chilli peppers?

The delicious burn of a really good curry or salsa or Sichuanese hot pot – that fiery goodness that makes you sweat and flush – is for many people one of life’s great pleasures. The search for the most profound scorch is a hobby of sorts, perhaps even an obsession.

And hot-hunters are safe in the knowledge that although capsaicin, the spicy molecule in hot peppers, is activating receptors in pain neurons in their mouths, it’s not really causing any damage. Give it a few minutes, and the feeling that you’ve torched yourself will fade, only returning when the meal – ah – leaves the premises, a day or so later. It’s all fun and games. Right?

Well, until someone gets hurt.

Chillies are rated on a spiciness scale known as Scoville – a grading of heat that goes from the lowly bell pepper (0) right up to the fearsomely named Carolina Reaper (2.2 million). And while everyday amounts of spicy food are unlikely to do any harm, thrill-seekers have had some disconcerting experiences. In 2014, two journalists from The Argus, a newspaper in the British city of Brighton, went to test out burgers at a local restaurant rated highly on TripAdvisor. They each took a bite of the XXX Hot Chilli Burger, a specialty of the house made with hot sauce touted by the owner to score higher on the Scoville scale than pepper spray.

The pain was unendurable – one reporter immediately swallowed a great deal of milk to try to stave it off, the newspaper reported. The other began to have severe stomach pains, lost the feeling in his hands, and began to shake and hyperventilate. His colleague was also seized with pain despite his efforts, and both had to go to the hospital. “I was in so much pain,” one said, “I felt like I was dying.” (Read the whole story here.)

Daring pepper eaters who consume some of the world’s hottest specimens on camera have found themselves vomiting for an audience. A miniature YouTube film festival of hot pepper eating and its regurgitatory consequences is a rivetting spectacle, writes Aaron Thier for Lucky Peach, who describes a slowed-down recording of a Danish event where a thousand people ate ghost peppers. “Everyone sweats and hiccups, as usual, but the editing gives it a mythic, eternal, lyrical quality. The vomiting seems exultant,” he writes.

Matt Gross’s account of hot debauchery for Bon Appetit, on the other hand, starts with the cold, hard numbers. “It took me 21.85 seconds to consume three Carolina Reapers, the world’s hottest chillies. And it took me approximately 14 hours to recover from the aftermath,” he says. (Spoiler: The aftermath involved the symptoms of a heart attack.)

The physical effects of eating peppers can be seen as reactions to what might be – from the body’s perspective – real burns

So what is going on here? If all hot peppers are doing is fooling your body into thinking there’s a small fire in your mouth, why can they provoke such a serious reaction?

Let’s come back to the basic biology of capsaicin. This molecule may have evolved as an anti-fungal agent for the plants that bore it. But, to humans’ joy and fascination and fear, it happens to activate certain neurons responsible for the perception of pain. Those particular neurons send a message of heat to the brain, whether the cells are activated by an actual burn or by a hot pepper. It’s not their business to distinguish between these noxious options – as far as the body is concerned, it’s better safe than sorry.

The physical effects of eating peppers can be seen as reactions to what might be — from the body’s perspective — real burns, says Bruce Bryant, a biologist at the Monell Chemical Senses Center in Philadelphia. Sweating is an adaptation for cooling off. Triggered pain neurons release substances that cause blood vessels to widen, resulting in inflammation, the better to supply the damaged area with blood and the body’s first responders.

When that Carolina Reaper hits your stomach lining and you retch, “that response is because there are pain-sensing nerve endings in the stomach”, says Bryant. “The body says, ‘I don't care if it’s a thermal burn or a chemical, but I’m going to get rid of it.’”

Very serious discomfort aside, there don’t seem to be long-term dangers, per se, in eating very hot peppers

The responses that your body might have if you’d swallowed a caustic substance come into play with high levels of capsaicin because that is, after all, what the molecule mimics. Those burn-sensing neurons, in your mouth, stomach, and elsewhere, are going to do their thing whether what you’ve swallowed will really kill you or just give you some discomfort on the toilet.

But, hours or a day or so of very serious discomfort aside, there don’t seem to be long-term dangers, per se, in eating very hot peppers. Biologists have observed, however, that administering capsaicin over long periods of time in young mammals does result in the death of the pain neurons, Bryant says. Setting the neurons off repeatedly wears them out, and they don’t grow back.

Interestingly, there is even a theory that pepper plants might have developed the molecule as a way to deter mammals from chewing up their seeds. Birds, which eat pepper seeds whole and helpfully spread them in their faeces, do not have the necessary receptors to feel the burn. But in humans, pepper plants have encountered a special kind of mammal that courts the feeling, to the edge of reason and probably a little bit beyond.

Luckily for the pepper, this does not seem to have damaged its fortunes.