在过去的十年里 Over the last decade,
牛奶已经变得有点有争议了 milk has become a bit controversial.
有些人说它是骨骼健康必不可少的营养食物 some people say it's a necessary and nutritious food vital for healthy bones,
但也有人说它会导致癌症 导致早逝 but others say it can cause cancer and lead to an early death.
那么谁是对的 我们为什么要喝它呢 So who's right and why are we drinking it anyway?
的吗 The?
当我们的消化系统还不成熟和小的时候 牛奶是每一个哺乳动物出生后的基本饮食 Milk is the basis of every mammals diet after birth when our digestive systems are immature and small.
基本上 Basically,
它能让我们的身体恢复活力 帮助我们成长 it's powerful to kickstart our bodies and help us grow.
牛奶富含脂肪 Milk is rich in fat,
维生素 vitamins,
矿物质和牛奶 minerals and milk,
糖 sugar,
乳糖 lactose.
最重要的是出生后的一段时间 On top of that for a while after birth,
它还含有抗体和蛋白质 it also contains antibodies and proteins,
感染的保护剂 调节我们的免疫系统 the protectors for infections and regulate our immune system.
但对母亲来说 要生产出这样的产品需要付出很大的努力 But it's a lot of effort for mothers to produce.
最终 Eventually,
人类停止喝母亲的奶 并过渡到他们父母的饮食 humans stop drinking mother's milk and transition to the diet of their parents.
几千年来都是这样 This is how it's been for thousands of years.
直到大约一万一千年前 Until about eleven thousand years ago,
当我们的祖先在第一批农业社区定居下来后 他们很快就驯养了第一批奶类动物 when our ancestors settled down in the first agricultural communities soon they domesticated the first dairy animals,
山羊 goats,
羊和牛 sheep and cattle.
他们发现 奶类动物可以变成无用而丰富的东西 并把它们变成营养丰富 美味可口的食物 They found that dairy animals are able to be useless and abundant stuff and turn it into nutritious and tasty food.
这对生存产生了巨大的影响 This made a huge difference in terms of survival,
尤其是在困难时期 especially in hard times,
因此 有牛奶供应的群体具有进化优势 通过自然选择 它改变了大量饮用牛奶的群体的基因 so groups that had a milk available had an evolutionary advantage and through natural selection it changed the genes of communities who consumed a lot of it.
这种适应与一种特殊的乳糖酶有关婴儿的系统中有很多乳糖酶 This adaptation has to do with a specialized enzyme lactase babies have a lot of it in their system,
这样它们就能分解牛奶 so they can break down the milk,
糖 乳糖和消化牛奶容易 sugar lactose and digest milk easily.
但随着年龄的增长 But the older we grow,
我们的身体在世界范围内产生的乳糖酶越来越少 the fewer lactose enzymes our body produces worldwide.
大约65%的人在婴儿期后没有这种酶 About sixty five percent of the population do not have the enzyme after infancy,
这意味着他们不能消化超过100个 which means they are not able to digest of more than about one hundred.
每天50个米兰人 and fifty Milanese is each day.
这种格容是不均匀地分布在世界各地的 This lattice and tolerance is not spread evenly around the world dope.
在一些东亚社区 In some East Asian communities,
例如 for example,
高达90% it's up to ninety per cent.
在北欧和北美 In northern Europe and North America,
这些比率是总体上最低的 the rates are the lowest overall.
造成这种不均匀分布可能有几个原因 There are probably a few reasons for this uneven distribution.
这种特性最初是由随机突变引入的 The trait was first introduced by a random mutation,
这在少数种群中是独立发生的 which happened independently of each other in a few populations.
事实上 农业取代了狩猎和采集越来越有创造性的自然选择压力 The fact that farming replaced hunting and gathering more and more creative natural selection pressure.
能够消化乳糖的人手边有更多食物 People who were able to digest lactose had more foods at hand,
这是一个优势 which was an advantage.
奶农向北方的迁移进一步扩大 The migration of dairy farmers to the north then spread further,
这可能会导致那里的人口减少 which probably pushed back populations there.
没有这种特质 That didn't have the trait.
好吧 Okay,
但如果说牛奶几千年来一直是我们饮食中有价值的一部分 but if milk has been a valuable part of our diet for thousands of years,
为什么争议如此之大 why is it so controversial?
有很多关于牛奶对健康的正面和负面影响的说法 There are a number of claims regarding the negative and positive health effects of milk.
负面的影响范围很广 The negative ones cover a wide variety.
从骨质疏松到癌症和心血管疾病到不耐受和过敏 From brittle bones to cancer and cardiovascular diseases to intolerance and allergies,
那么他们是如何坚持下来的呢 so how did they hold up?
一些较早的研究发现 母乳和乳房风险之间存在联系 Some older studies found a connection between milk and a high risk of breast,
结肠癌和前列腺癌 colon and prostate cancer.
但是metro的分析发现这对你患癌症的风险没有影响 But metro analyses found no impact on your cancer risk.
相反 On the contrary,
牛奶中的钙甚至可以预防结肠癌 the calcium in milk might even have a protective effect against colon cancer.
虽然这可能是一般的钙 Although this could be calcium in general,
目前还不清楚牛奶在这一作用中起到了什么作用 it's not clear milk plays a role in this effect.
只有关于前列腺癌的研究表明 每天饮用超过1 25升牛奶的人患前列腺癌的风险会增加 Only studies on prostate cancer showed an increased risk for people who consumed more than one and a quarter liters of milk a day.
但是这种联系是不一致的 其他研究也没有发现任何影响 But again the association is inconsistent and other studies don't find any effect.
我们在源文件中更详细地讨论了这些研究 We discussed these studies in more detail in our sources document.
总而言之 All in all,
这项研究似乎表明 如果你每天喝100到2 5亿升牛奶 the research seems to show that if you drink between one hundred to two hundred and fifty million liters of milk per day,
癌症不是问题 cancer is not a concern.
同样的 Similarly,
综合分析没有发现牛奶或乳制品对心脏病风险有任何影响 meta analyses could not find any impact from milk or dairy products on your risk of heart disease,
中风或死亡总人数 stroke or your total mortality.
一些研究甚至表明 高血压可能比吃大量乳制品的人更少见 Some studies even suggested that high blood pressure might be rarer than people who eat a lot of dairy.
尽管证据还不够有力 不足以让人对此有信心 Although the evidence is not strong enough to claim this with confidence.
情况变得更加复杂 The case gets more complicated,
不过 though,
当我们看船的时候 when we look at boats.
许多研究发现 对成年人既没有正面影响 也没有负面影响 A number of studies found neither positive nor negative effects for adults.
大多数人最担心的是 What most people worry most about,
不过 though,
都是有害的杀虫剂 are harmful amounts of pesticides,
抗生素或激素 antibiotics or hormones.
牛奶中有激素 There are hormones in milk,
但只有在非常低的浓度下 but only in very low concentrations,
例如 for example,
从药片中获得相同数量的激素 to get the same amount of hormones as from the pill.
你需要喝大约5000升牛奶 You'd need to drink about five thousand liters of milk.
即使你这么做了 And even if you did,
大多数激素在影响你之前就已经被你的消化系统破坏了 most hormones would be destroyed by your digestive system before they could affect you,
这就是为什么这么多的药物被包裹起来以保护它不被我们消化的原因 which is the reason why so much medication is coated to protect it from our digestion.
杀虫剂和抗生素 for pesticides and antibiotics.
世界上大多数地方都有规定 只有完全无害的量 超过这些门槛的牛奶才不允许上架 There are regulations in most parts of the world that only allow completely harmless amounts of milk that surpasses these thresholds is not allowed to go on the shelf.
所以没有什么特别需要担心的 So there's nothing in particular to worry about.
除此之外 Besides,
过敏和乳糖不耐症患者最为人所知 allergies and those suffering from lactose intolerance is the best known.
喝牛奶的负面影响可能是痤疮和全身不适 Negative effects of milk are probably acne and general discomfort.
在饮用牛奶或食用乳制品后 After drinking milk or eating dairy products,
这里的效果是非常真实的 and here the effects are very real.
例如 For example,
据统计 脱脂牛奶会使粉刺增加24% Skimmed milk has been found to statistically increase the rate of acne by twenty four per cent.
乳制品的平均值在儿童中尤其普遍 Averages against milk products are especially prevalent among children,
在德国 每18个孩子中就有一个患有这种疾病 with one in eighteen kids in Germany suffering from them.
一般来说 In general.
随着年龄的增长 这些能量趋向于变得更好或消失 These energies tend to get better or disappear as they grow older.
虽然好了 Though OK,
牛奶是健康的 is milk healthy,
然后 then.
牛奶 Milk,
不管是来自母亲 no matter if it comes from mothers,
牛 cows,
羊 sheep,
山羊或骆驼是一种营养素 goats or camels is a nutrient.
密集的食物 Dense food.
它含有所有必需的宏观营养素和许多微量营养素 It contains all necessary macro nutrients and many micro nutrients.
尤其是在那些人们很难获得足够卡路里的地区 Especially in regions where people struggle to get enough calories,
牛奶可以促进健康生活 降低儿童死亡率 milk can contribute to a healthy life and lower child mortality.
对于那些生活在发达国家的人来说 如果你不过敏或不耐受 普通牛奶是无害的 For those living in the developed world and general milk is not harmful if you are not allergic or intolerant to it,
尤其是对孩子 especially for children,
对于素食者来说 这是摄取大量钙质的好方法 it's a good way to get large amounts of calcium and for vegetarians.
它富含维生素B It's a good source of vitamin B,
12和B族维生素 twelve and B vitamins in general.
这并不意味着没有其他选择 This does not mean there are not other alternatives.
效果是一样的 With the same effects.
你不需要喝牛奶来保持健康 You do not need to drink milk to be healthy.
牛奶也绝对不是水的替代品 Milk is also definitely not a substitute for water.
牛奶是能量食物 经常喝很多牛奶会增加额外的热量 这可能会导致超重 Milk is power food and the additional calories from drinking a lot of it on a regular basis can contribute to being overweight.
尤其是调味牛奶或巧克力 Especially flavored milk or chocolate,
比起健康零食 牛奶更像柠檬水之类的饮料 milk is more comparable to beverages like lemonade than a healthy snack,
另外 牛奶生产对全球气候有重大影响 and there's another thing to consider Milk production has a significant impact on the global climate.
大约33%的农田被用来喂养食草动物 About thirty three per cent of cropland is used to feed grazing animals,
包括奶牛 including dairy cattle,
尽管乳制品的碳足迹已经下降 even though the carbon footprint of dairy products has declined since.
一千年 one thousand.
990个乳制品生产仍然占所有温室气体排放的3% Nine hundred and ninety dairy production is still responsible for three percent of all greenhouse gas emissions,
比所有飞机加起来还要多 even more than all aeroplanes combined.
牛奶是一个巨大的产业 Milk is a huge industry and sadly,
在工厂化农场生产的大部分玉米造成了难以置信的痛苦 most of its production in factory farms causes incredible suffering.
母牛在出生后不久就被一次又一次地受孕 与它们的幼崽分开 然后被屠宰 Cows are impregnated over and over separated from their young shortly after birth and slaughtered.
一旦他们被折磨 once they are tortured,
身体不再有生产力 bodies are not productive anymore.
我们不能忽视这一点 We can't ignore that.
我们消耗的大部分牛奶来自一个基本上是折磨人的行业 并导致了气候变化 Much of the milk we consume stems from an industry that is basically torture and contribute to climate change.
那么植物奶呢 What about plant based milk?
就蛋白质水平和营养价值而言 In terms of protein levels and nutritional value,
只有豆奶可以和牛奶相比 only soy milk can compare to cow milk.
其他的则需要人工强化以达到类似的维生素和钙水平 The others need to be artificially enriched to reach similar levels of vitamins and calcium,
所以它们可以作为牛奶的替代品 so they can be an alternative to milk.
另一种选择可能很快就会出现 And another option might be available soon.
有几家初创公司已经生产出了营养成分与牛奶相同的非动物奶 Several startups have created non animal milk that is nutritionally identical to dairy milk,
例如 for example,
jean通过发酵 through fermentation by jean,
修改后的细菌 modified bacteria.
实验室培育的牛奶甚至可以变成奶酪 This lab grown milk can even be turned into cheese,
一些以李子为基础的替代品因为缺乏酪蛋白和乳清蛋白而挣扎 something that plum based alternative struggle with because they lack casein and whey protein.
赋予乳制品风味和结构的关键成分 The key ingredients that give dairy its taste and structure.
对环境的影响则是另一回事 The environmental impact is a different story,
虽然 though.
许多牛奶替代品使用的能源要少得多 Many milk alternatives use significantly less energy,
土地和更少的水 land and less water to produce,
所以它们对环境的影响比动物奶要低得多 so they have a much lower environmental impact than animal milk.
如果你想对地球造成尽可能少的负面影响 If you want to have the lowest possible negative impact on the planet,
最好的选择是原味的牛奶 the best choice is whatever milk alternative is original.
和几乎所有的话题一样 As with almost any topic,
牛奶是复杂的 milk is complicated,
它对大多数人都没有害处 it's not harmful for the majority of the population,
这对世界上很多人来说都至关重要 and it's crucial for many people around the world.
这是很好的营养食物 It's good nutritious food,
但也对地球有害 并造成很多痛苦 but also harmful to the planet and causes a lot of suffering.
作为一个社会 我们需要决定如何处理这些事实 We need to decide as a society how we want to deal with these facts.
啊 Ah.