Food · Meat & Seafood · 红肉
Organ Meat · Liver
营养密度之王 · 一份猪肝的维 A 就超每日上限数倍 · 胆固醇 myth 现场 · 以形补形无机制
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Story path
- 1What organ meat is · underrated and overrated at onceWhat organ meat is · underrated and overrated at once
- 2Macros · high protein, not low-calorieMacros · high protein, not low-calorie
- 3Fat & cholesterol · the myth siteFat & cholesterol · the myth site
- 4Rich in what · extreme vitamin-A and iron densityRich in what · extreme vitamin-A and iron density
- 5What it lacks · how to pairWhat it lacks · how to pair
- 6Key knowledge · the vitamin-A toxicity boundaryKey knowledge · the vitamin-A toxicity boundary
- 7How to choose · cook · how muchHow to choose · cook · how much
- 8Debunking · 'like-shape-cures-like' and 'liver is toxic'Debunking · 'like-shape-cures-like' and 'liver is toxic'
Chapter 1
What organ meat is · underrated and overrated at once
What organ meat is · underrated and overrated at once
Organ meat (offal) means the non-muscle parts — liver, kidney, heart, stomach, brain, intestine. It is common in Chinese cooking: pork liver, chicken liver, stir-fried kidney, braised tripe, maoxuewang.
The common thread of organ meat: the more metabolically active the organ, the denser its micronutrients. The liver is the body's metabolic hub and nutrient warehouse, which is why liver is among the most nutrient-dense foods of all — vitamin A, iron, B12, folate, copper and selenium in one serving.
That also explains its overrated side: because it is so dense, overshooting with portion size is easy (especially vitamin A, see special-knowledge), and cholesterol and purines are not low. It is neither miracle food nor poison — a good ingredient that needs a known dose.
This story centres on liver (the best data, most representative); kidney, heart, stomach and brain are touched on, sharing the same mechanisms.
The common thread of organ meat: the more metabolically active the organ, the denser its micronutrients. The liver is the body's metabolic hub and nutrient warehouse, which is why liver is among the most nutrient-dense foods of all — vitamin A, iron, B12, folate, copper and selenium in one serving.
That also explains its overrated side: because it is so dense, overshooting with portion size is easy (especially vitamin A, see special-knowledge), and cholesterol and purines are not low. It is neither miracle food nor poison — a good ingredient that needs a known dose.
This story centres on liver (the best data, most representative); kidney, heart, stomach and brain are touched on, sharing the same mechanisms.
机制 · 干活多的器官, 为什么营养就密
器官越忙、营养越密不是一句修辞, 它是零件的问题.细胞里真正干活的是酶. 酶是蛋白质, 但很多酶光有蛋白质那一段是发动不起来的: 它得先在活性位点上卡进一个金属离子, 或者夹住一个由维生素改造成的辅助分子, 才能开始拆分子、接分子. 铁、铜、锌、硒、核黄素这些微量营养, 在细胞里几乎全部是以这种零件的身份存在的 — 它们不提供热量, 它们让流水线转得起来.
于是结论很直接: 一个器官要同时跑很多条流水线, 就必须常年备着这些零件, 备的量还得跟工作量成正比.
肝要接住你吃下去的一切、改造药物、造血浆蛋白、存糖又放糖, 是全身流水线最密的地方, 所以它的零件库存最厚. 心脏一刻不停地收缩, 能量几乎全靠线粒体烧脂肪现供, 而线粒体那条产能的链条上串着一整排含铁和含铜的零件, 所以心也密. 相比之下, 一块里脊的主业是收缩, 流水线少, 库存自然薄.
你吃内脏, 吃到的其实是那个器官为了干活而常年备着的库存. 这一句可以直接往下推两件事.
第一, 内脏真正的优势是微量营养, 不是蛋白质 — 蛋白质里脊也有, 而且质量不比它差. 有人把内脏当成更高级的蛋白来源, 这一层其实是平的.
第二, 那批库存是按那只动物的身体量攒出来的, 你一顿吃掉一大块, 拿到手的剂量对你自己的身体来说就可能过头. 剂量问题从这里就开始了, 不是到维 A 那一幕才开始.
Chapter 2
Macros · high protein, not low-calorie
Macros · high protein, not low-calorie
Cooked (braised) pork liver runs ~165 kcal per 100 g, 26.0 g protein, ~4.4 g fat and 3.8 g carbohydrate; raw pork liver is 134 kcal and 21.4 g protein. It is high-protein, moderate-calorie — but it is not denser in protein than lean pork, and that layer is flat.
Compare like with like. Raw pork liver is 21.4 g protein and raw lean pork loin is also 21.4 g — identical. Braise both and lean loin comes out at 28.6 g, above braised liver. So 'organ meat is a superior protein source' does not survive the numbers: organ meat's real advantage is micronutrients, not protein.
Raw and cooked are different rows — and not every column moves the same way. That is the most-inverted point in this scene; the next page unpacks it.
One overlooked difference: liver is not zero-carb (~3.8 g per 100 g cooked, largely glycogen), unlike pure muscle — irrelevant for most people, but it is liver's fingerprint. Dive to protein for the mechanism.
Compare like with like. Raw pork liver is 21.4 g protein and raw lean pork loin is also 21.4 g — identical. Braise both and lean loin comes out at 28.6 g, above braised liver. So 'organ meat is a superior protein source' does not survive the numbers: organ meat's real advantage is micronutrients, not protein.
Raw and cooked are different rows — and not every column moves the same way. That is the most-inverted point in this scene; the next page unpacks it.
One overlooked difference: liver is not zero-carb (~3.8 g per 100 g cooked, largely glycogen), unlike pure muscle — irrelevant for most people, but it is liver's fingerprint. Dive to protein for the mechanism.
机制 · 炖煮到底浓缩了什么, 又冲走了什么
熟的那一列为什么普遍比生的高? 差在水. 加热让肉里的蛋白质收紧, 把细胞之间原本含着的水挤出去, 同一块肉变轻了, 于是同样 100 g 里剩下的蛋白和热量都往上跳. 网上把生的热量安到熟的头上, 是这一栏最常见的一种串行.但不是每一栏都跟着往上跳, 这一点几乎所有人都想反了.
炖煮是带水的做法. 能溶进水里的东西会跟着跑到汤里, 而肉本身在变轻 —— 两股力方向相反, 最后哪一栏升、哪一栏降, 取决于它跑掉得多还是水跑掉得多. 同一份猪肝, 生 → 熟 (每 100 g):
| 项目 | 生 | 炖熟 | 方向 |
|---|---|---|---|
| 蛋白 | 21.4 g | 26.0 g | ↑ 浓缩 |
| 热量 | 134 kcal | 165 kcal | ↑ 浓缩 |
| 胆固醇 | 301 mg | 355 mg | ↑ 浓缩 |
| 钠 | 87 mg | 49 mg | ↓ 跑进汤里 |
| 铁 | 23.3 mg | 17.9 mg | ↓ |
| 维 A | 6500 µg RAE | 5400 | ↓ |
| 叶酸 | 212 µg | 163 µg | ↓ |
所以炖煮是一边浓缩、一边冲走: 蛋白和热量留在肉里, 一部分矿物质和水溶性维生素留在了汤里. 钠尤其反直觉 —— 很多地方写煮过之后钠也被浓缩, 实测是掉了将近一半.
两个能自己往下推的结论:
喝汤不是没有道理的. 跑掉的那部分不是消失了, 是在锅里. 这也解释了为什么焯水、久泡会让内脏的营养数字继续往下走 — 那是同一件事的更极端版本.报数字必须说清生熟, 而且不能假设所有栏一起动. 这条规矩下一页会再用一次, 而且下一页会给你看它被违反时长什么样.
数字 · 各个部位的家底 (以及一张被拼出来的表)
内脏的蛋白质量同样优秀 (完全蛋白, 氨基酸齐备). 至于数量, 这里得立一条规矩 — 因为这张表是全篇最容易被做坏的地方: 同一张表里, 生和熟不能混排.把 USDA 的炖熟那一列摆齐 (每 100 g):
| 部位 (炖熟) | 蛋白 | 脂肪 |
|---|---|---|
| 猪肝 | 26.0 g | 4.4 g |
| 猪腰 | 25.4 g | 4.7 g |
| 猪心 | 23.6 g | 5.1 g |
| 猪脑 | 12.1 g | 9.5 g |
这张表说的话, 和到处流传的那个版本不一样. 常见写法是猪肝 26 g、猪腰 16-17 g、猪心 17 g, 看上去有一条漂亮的梯度: 器官越忙, 蛋白越密. 但那条梯度是拼出来的 —— 肝用的是熟的数, 腰和心用的是生的数. 摆到同一种状态上, 肝腰心几乎持平 (26.0 / 25.4 / 23.6), 梯度就不见了.
(生的那一列自己也自洽: 猪肝 21.4 g、猪腰 16.5 g、猪心 17.3 g、猪脑 10.3 g. 但它同样撑不起那条梯度 —— 因为生猪肝的 21.4 g 和生瘦里脊的 21.4 g 一模一样.)
真正没被拼出来的差别只有脑. 它蛋白明显低、脂肪明显高, 而这一条是有机制的: 脑的工作是传导信号, 传导靠的是一层层裹起来的膜, 膜是脂质做的, 所以脑天生高脂 — 这也是它胆固醇高的原因, 见下一幕.
所以这一页真正该带走的不是那四个数字, 是那条规矩: 看到任何一张营养对比表, 先问一句 —— 这几行是不是同一种状态量出来的? 生熟混排能凭空造出一条并不存在的规律, 而且它看起来和真规律一模一样.
顺带说清那条真规律落在哪儿: 器官越忙, 密的是微量营养, 不是蛋白. 同样炖熟, 铁是猪肝 17.9 mg 对猪腰 5.29、猪心 5.83、猪脑 1.82; 维 A 是 5400 µg RAE 对 78、7、0. 这才是上一幕那条库存逻辑真正的落点.
机制 · 为什么偏偏是肝存着糖
肌肉里也存糖原, 而且总量比肝多得多. 但肌肉的糖原出不了肌肉, 肝的糖原能出去. 这一个差别, 解释了肝在全身代谢里的位置.糖原是一大团葡萄糖串成的树. 要动用它, 细胞先把一颗葡萄糖从枝头掰下来, 掰下来的这颗身上带着一个磷酸标签. 这个标签相当于一张厂内通行证: 带着它, 葡萄糖能在细胞内部被烧掉供能, 但没法穿过细胞膜出去 — 细胞膜上的糖运输通道不认带标签的货.
差别就在这里. 肝细胞有一把专门撕标签的酶, 能把磷酸摘掉, 让葡萄糖恢复成自由身, 于是它可以直接走出肝细胞、进入血液, 送到全身. 肌肉细胞没有这把酶, 所以肌糖原一旦掰下来就只能自己烧掉, 一克也送不给别人.
所以肝的糖原是全身的血糖缓冲池, 肌肉的糖原是它自己的油箱. 你两顿饭之间血糖没掉下去, 靠的就是肝在一点一点往血里放糖.
这也顺带解释了餐桌上的现象: 肝之所以能测出一点碳水, 是因为它平时就得替全身备着这批糖. 而这批糖会随着放血、冷藏和时间被慢慢用掉, 所以不同来源、不同新鲜度的肝, 碳水数字本来就会飘 — 遇到数据对不上不必意外.
再往下推一步, 一件常被误解的事也就清楚了: 有人担心肝是储糖器官, 糖尿病人不能吃. 但你吃下去的那点糖原, 到了你的肠道一样是被拆成葡萄糖吸收, 和吃一小口米饭没有本质区别; 真正需要注意的从来不是这几克碳水, 而是维 A 的剂量和内脏的嘌呤.
Chapter 3
Fat & cholesterol · the myth site
Fat & cholesterol · the myth site
Organ fat is generally moderate (pork liver 4-5 g/100 g), but cholesterol is organ meat's signature number: cooked pork liver ~355 mg/100 g (raw 301 mg), pork brain higher still — ~2200 mg raw and ~2550 mg braised per 100 g — among the highest of any common food (same rule as before: say which state a number is).
That scared a generation. But two decades of evidence have clarified that for most people, dietary cholesterol moves blood lipids far less than total saturated fat — the body compensates by down-regulating its own synthesis. eggs and shrimp already dismantle the dietary-cholesterol myth in detail; here is the conclusion: organ cholesterol deserves attention, not fear; total amount and frequency are the real variables.
Worthier of attention are saturated fat and sodium: brain and intestine are fatty, and sodium depends on the *method* — plain water-braised pork liver is only 49 mg/100 g (lower than raw's 87 mg), but soy-braised, cured and marinated preparations add salt and can run one to two orders of magnitude higher. Organ meat's sodium problem is never in the meat; it is in the pot. For the fat structure, dive to fat-types and omega-3-6-balance.
That scared a generation. But two decades of evidence have clarified that for most people, dietary cholesterol moves blood lipids far less than total saturated fat — the body compensates by down-regulating its own synthesis. eggs and shrimp already dismantle the dietary-cholesterol myth in detail; here is the conclusion: organ cholesterol deserves attention, not fear; total amount and frequency are the real variables.
Worthier of attention are saturated fat and sodium: brain and intestine are fatty, and sodium depends on the *method* — plain water-braised pork liver is only 49 mg/100 g (lower than raw's 87 mg), but soy-braised, cured and marinated preparations add salt and can run one to two orders of magnitude higher. Organ meat's sodium problem is never in the meat; it is in the pot. For the fat structure, dive to fat-types and omega-3-6-balance.
机制 · 身体会补偿, 具体是哪里在补偿
身体会下调自身合成来补偿这句话, 落到解剖上是两个地方.第一个在小肠. 你吃进去的胆固醇不会自己钻进血里, 它得先被小肠细胞朝向肠腔那一面上的一个专门通道接进去. 这个通道的数量不是固定的: 餐里胆固醇多的时候, 真正被搬进去的比例会往下走. 也就是说, 吃得越多, 吸收的比例反而越低 — 吸收从来不是照单全收.
第二个在肝. 肝细胞自己就会造胆固醇, 而且造的量比一般人吃进去的多得多. 这条生产线上有一台限速的机器 (HMG-CoA 还原酶, 他汀类药物压住的就是它). 当肝细胞内部感觉到胆固醇已经够用, 它会直接把这台机器的产量调下来.
一进一出合起来看, 结果就是: 多吃的那一部分, 一头被少吸收, 一头被少合成, 真正落到血里的净增量远比账面上小. 这才是那句结论背后的机械原理, 不是一句安慰话.
那为什么还要加对大多数人这个限定? 因为这套补偿的灵敏度存在个体差异. 同样一份肝, 有的人调得又快又足, 血脂几乎不动; 有的人调得慢半拍, 血脂就会出现看得见的抬升. 你属于哪一类, 光凭感觉判断不出来, 这是少数需要看化验单才能回答的问题.
顺带把饱和脂肪为什么更狠说清楚. 它的作用点根本不在进来多少, 而在出去多快: 饱和脂肪会让肝细胞表面那些负责把血里的低密度脂蛋白 (LDL) 回收进来的接收站变少. 接收站少了, LDL 在血里待的时间就长. 一个是往池子里多倒了一点水, 一个是把出水口关小了 — 后者当然影响更大.
钠 · 问题不在肉里, 在锅里
把内脏钠高这句话拆开, 它其实是两句完全不同的话 —— 混在一起是这一栏最常见的误会.第一句: 肉本身的钠不高, 而且炖煮还会让它更低. 生猪肝每 100 g 有 87 mg 钠, 清水炖熟之后是 49 mg, 掉了将近一半. 原因上一页讲过: 钠溶在水里, 带水的做法会把它带进汤里.
第二句: 你在餐桌上遇到的内脏钠确实很高 —— 但那是锅给的, 不是肉给的. 卤味、酱烧、腌腊、麻辣拌, 这些做法的本质都是往里加盐; 内脏切面多、吸味强, 入味的同时也把盐吃了进去. 一份卤味拼盘的钠可以比同重量的清炖肝高出一两个数量级.
这条判断可以迁移到任何食材上: 听到某某食物钠高, 先问一句 —— 说的是这个食材本身, 还是它最常见的那种做法? 前者你换不了, 后者你只需要换个锅.
落到实操: 想拿内脏的营养又不想拿它的钠, 清炒、清炖、少放酱油和卤汁就够了. 这比少吃内脏精确得多 —— 它砍掉的是盐, 不是维 A 和铁.
机制 · 猪脑为什么是胆固醇冠军
正文里那个吓人的数字, 有一个非常朴素的解释, 而且理解了它, 你就不会再把胆固醇高和这东西有害画等号.神经细胞靠一根根很长的突起互相通话, 而这些突起外面裹着一层像电线胶皮一样的绝缘鞘. 这层鞘不是别的材料做的, 它就是一圈一圈缠上去的细胞膜. 而胆固醇正是动物细胞膜的结构材料 — 它像插在砖缝里的楔子, 卡在磷脂分子之间, 让膜既不散架也不至于太僵.
绝缘鞘要缠很多圈, 于是单位体积里的膜面积极大, 于是胆固醇的浓度极高. 脑的胆固醇高, 不是因为脑出了什么问题, 是因为脑主要由膜构成.
再往下推一步, 一个常见的联想就断了: 既然脑里的胆固醇是它自己的建筑材料, 那它和你吃下去之后血里发生什么, 没有对应关系. 事实上你自己脑里的胆固醇几乎全部是脑就地合成的 — 血里的胆固醇过不了血脑屏障那道关卡, 送不进去. 所以吃脑补脑在这一层也是断的, 详见 debunking 那一幕.
那吃猪脑到底该怎么想? 把它当成一种高脂食物来安排份量, 比盯着胆固醇那一栏更有用. 正文里点到的另外两件事 — 脑和肠部位脂肪偏高、卤制腌制的钠很高 — 对大多数人日常血压和热量的影响, 都比那个胆固醇数字实在得多.
Chapter 4
Rich in what · extreme vitamin-A and iron density
Rich in what · extreme vitamin-A and iron density
This is why organ meat exists: no other food category delivers so many micronutrients in one serving.
The standout is preformed vitamin A (retinol): cooked pork liver holds about 5400 µg RAE per 100 g (raw liver 6500), versus an adult RDA of 700-900 µg RAE. So 50 g of cooked liver covers roughly three days of vitamin A. Dive to vitamin-a for the vision and immunity mechanisms.
Other highlights:
Iron: heme iron (hunt-2003-heme-bioavailability), absorbed better than plant iron; cooked pork liver ~17.9 mg/100 g and raw ~23.3 mg, several times red meatVitamin B12 (vitamin-b12): extremely high, one serving covers daysFolate (folate): liver is one of the best animal sourcesCopper, selenium, riboflavin (B2)
For iron-deficient people (especially women and new omnivores), liver is one of the most efficient iron foods; for replete people, that density is a burden — see the toxicity boundary in the next scene.
The standout is preformed vitamin A (retinol): cooked pork liver holds about 5400 µg RAE per 100 g (raw liver 6500), versus an adult RDA of 700-900 µg RAE. So 50 g of cooked liver covers roughly three days of vitamin A. Dive to vitamin-a for the vision and immunity mechanisms.
Other highlights:
Iron: heme iron (hunt-2003-heme-bioavailability), absorbed better than plant iron; cooked pork liver ~17.9 mg/100 g and raw ~23.3 mg, several times red meatVitamin B12 (vitamin-b12): extremely high, one serving covers daysFolate (folate): liver is one of the best animal sourcesCopper, selenium, riboflavin (B2)
For iron-deficient people (especially women and new omnivores), liver is one of the most efficient iron foods; for replete people, that density is a burden — see the toxicity boundary in the next scene.
数字 · 一份肝的完整家底
除了维 A, 其它亮点:铁: 血红素铁 (hunt-2003-heme-bioavailability), 吸收率高于植物铁; 熟猪肝约 17.9 mg/100 g、生猪肝约 23.3 mg, 是红肉的好几倍维生素 B12 (vitamin-b12): 极高, 一份够好几天叶酸 (folate): 动物肝脏是最佳来源之一铜、硒、核黄素 (B2)
这张单子读起来像一份复合维生素, 但它和药片有一个本质区别: 这些营养在肝里不是散装粉末, 而是已经装配在蛋白上的成品零件. 铁夹在血红素环里, 铜卡在含铜的酶上, 核黄素接在辅酶上. 这就是所谓的食物基质, 也是同样剂量下食物往往比补剂温和的一部分原因: 它们被拆解、被吸收、被分配, 都得排在正常的流程里走, 不会在肠道里一下子全放出来.
对缺铁人群 (尤其女性、素食转杂食者), 肝是最高效的补铁食物之一; 但对不缺的人, 这份密度就是负担 — 见下一幕的毒性边界.
最后提醒一件容易被这张单子带偏的事: 这里每一项都很高, 唯独没有纤维、维 C 和钙. 单子越亮眼, 越容易让人误以为吃了它这一餐就够了, 而恰恰相反 — 见 lacking-and-pairing.
机制 · 肝里的铁为什么比菠菜里的好用
铁在食物里有两种长相, 身体接它们的门也不是同一扇.植物和蛋奶里的铁是裸的铁离子, 松松地挂在别的分子上. 它到了小肠, 得先被卸下来、被还原成能通过的那种形态, 才能被小肠细胞表面的转运蛋白搬进去. 裸着走完这一路的问题在于: 沿途谁都能抓它. 茶和咖啡里的多酚、全谷和豆子里的植酸、同一餐里大量的钙, 都会跟它结合成一坨不溶的东西; 这坨东西转运蛋白搬不动, 只能随粪便走掉.
肉里的铁是另一种. 它被一个叫血红素的环形分子夹在正中间, 四周都被护住. 小肠细胞对整个血红素环有单独的接收方式, 把环连着铁一起收进细胞, 进去之后才在细胞内部把铁从环里拆下来. 因为铁从头到尾没有裸露过, 那些抓铁的东西抓不到它 — 这就是血红素铁吸收率更高、而且不太受同餐食物影响的原因.
肝是全身处理血红素最忙的器官之一, 自己又常年备着铁, 所以肝里的铁绝大部分就是这种被环护住的铁.
有了这条机制, 两件事你可以自己推出来.
第一, 吃肝的时候喝茶, 影响远没有吃菠菜时喝茶那么大 — 茶里的多酚抓不到被环护住的铁. 那些吃铁不能喝茶的说法, 真正适用的是植物性铁源.
第二, 反过来也成立: 你在同一餐里配的青菜和豆子, 它们的铁仍然是裸的, 仍然会被抓. 所以给这一餐配一点维 C, 帮的是青菜自己的铁, 不是肝的铁 — 但它依然值得配, 理由见 lacking-and-pairing.
Chapter 5
What it lacks · how to pair
What it lacks · how to pair
What organ meat lacks is as clear as its strengths: no fiber, no vitamin C, no complex carbohydrate, low calcium. Nutrient-dense, but not complete.
Practical pairings:
Dark leafy greens: calcium and vitamin C; vitamin C also helps non-heme iron from the mealWhole grains or tubers: fiber and carbohydrate for a complete plateOnion and garlic: a home-style pairing that balances texture
An easy-to-miss point: because liver's vitamin A is extreme, adding vitamin-A-fortified foods or supplements to the same meal duplicates it — especially for children, do not stack pork liver and cod-liver oil as 'supplements'.
For whole-plate balance, dive to fruit-vegetables and carbs-fiber.
Practical pairings:
Dark leafy greens: calcium and vitamin C; vitamin C also helps non-heme iron from the mealWhole grains or tubers: fiber and carbohydrate for a complete plateOnion and garlic: a home-style pairing that balances texture
An easy-to-miss point: because liver's vitamin A is extreme, adding vitamin-A-fortified foods or supplements to the same meal duplicates it — especially for children, do not stack pork liver and cod-liver oil as 'supplements'.
For whole-plate balance, dive to fruit-vegetables and carbs-fiber.
机制 · 它缺的那几样, 是身份决定的
内脏缺的那几样不是巧合, 是动物组织这个身份直接决定的, 想清楚了就再也不会记错.纤维: 纤维是植物细胞壁的材料. 动物细胞没有细胞壁, 所以任何一块动物组织都必然是零纤维的, 肝也不例外. 你不可能通过换一种肉来解决纤维问题.
维 C: 维 C 是一个很不耐热也很怕氧的分子, 切开、放置、下锅这一路会损失大半, 所以熟肉基本不是维 C 的来源. 这一条对所有肉都成立, 不只是内脏.
钙: 钙的库存在骨头里, 不在软组织里. 你吃的是软组织, 自然拿不到多少. 这也是为什么带骨熬的汤和一块肝, 在钙这一栏上完全不是一回事.
所以这一餐的完整性只能由盘子里的其它东西来给: 绿叶菜负责钙和维 C, 全谷或薯类负责纤维和碳水. 这不是口味偏好, 是分工.
有一件事值得单独说清楚, 因为它经常被搞反: 配菜里的铁和肝里的铁走的不是同一扇门. 青菜豆子里的铁是裸的, 会被同餐的多酚和植酸抓住; 肝里的铁被血红素环护着, 抓不到. 所以那一勺维 C 在这一餐里帮的是青菜自己的铁, 不是肝的铁. 明白这一点, 你就不会因为反正已经吃了肝而觉得配菜可有可无 — 配菜补的是肝根本给不了的那几样.
最后是反过来的那个风险. 肝的维 A 已经极高, 同一餐再叠加强化维 A 的食品或者鱼肝油, 等于往一个已经装满的仓库里继续倒. 儿童尤其要当心: 他们的仓库本来就小, 而给孩子补一补恰恰是最容易连续投喂的场景.
Chapter 6
Key knowledge · the vitamin-A toxicity boundary
Key knowledge · the vitamin-A toxicity boundary
Organ meat's key knowledge: good things have doses. Preformed vitamin A is fat-soluble — the body stores it and does not flush it out, and long-term excess accumulates in the liver to toxicity.
The adult tolerable upper intake level (UL) is 3000 µg RAE/day. And 100 g of cooked pork liver holds about 5400 µg RAE — one serving is close to twice the UL. An occasional serving is fine (the body buffers), but several servings a week plus fish-liver-oil or vitamin-A supplements enters the risk zone.
The classic acute story is Arctic explorers and people eating dog or polar-bear liver: one large dose of preformed vitamin A can cause headache, dizziness and vomiting within hours. Chronic excess is subtler: bone pain, liver damage, dry skin.
Pregnancy is a different matter, and a much stricter one: the UK NHS puts liver and liver products on the avoid list for pregnancy outright. Why, and why the risk lands on the face and the heart, gets its own page.
So can a non-pregnant adult eat liver? Yes — and the portion can be derived rather than asserted: adults 1-2 servings a week of 50-100 g, children once a week at 30-50 g. Those numbers are back-calculated from the UL; the arithmetic is on the 'hold the warehouse' page later in this scene.
The key is putting portion and frequency into habit rather than eating it by the bowl. Consult a doctor for personal medical questions.
The adult tolerable upper intake level (UL) is 3000 µg RAE/day. And 100 g of cooked pork liver holds about 5400 µg RAE — one serving is close to twice the UL. An occasional serving is fine (the body buffers), but several servings a week plus fish-liver-oil or vitamin-A supplements enters the risk zone.
The classic acute story is Arctic explorers and people eating dog or polar-bear liver: one large dose of preformed vitamin A can cause headache, dizziness and vomiting within hours. Chronic excess is subtler: bone pain, liver damage, dry skin.
Pregnancy is a different matter, and a much stricter one: the UK NHS puts liver and liver products on the avoid list for pregnancy outright. Why, and why the risk lands on the face and the heart, gets its own page.
So can a non-pregnant adult eat liver? Yes — and the portion can be derived rather than asserted: adults 1-2 servings a week of 50-100 g, children once a week at 30-50 g. Those numbers are back-calculated from the UL; the arithmetic is on the 'hold the warehouse' page later in this scene.
The key is putting portion and frequency into habit rather than eating it by the bowl. Consult a doctor for personal medical questions.
机制 · 仓库满了会发生什么
仓库这个词不是比喻. 肝里真有一批专职囤维 A 的细胞, 而中毒的全部症状, 都可以从这个仓库的运作方式里推出来.维 A 进了肝以后, 肝不会让它裸着放. 肝会给每一个视黄醇分子挂上一条脂肪酸尾巴, 变成更稳定、更油的形态, 然后打包塞进一类叫星状细胞的细胞里 — 这类细胞肚子里全是油滴, 囤油就是它们的本职工作. 身体哪天要用, 肝再把尾巴剪掉, 把视黄醇装到一个专门的运输蛋白上, 送进血里发货.
关键在于发货这一步是有配额的: 运输蛋白的产量有限, 所以血里挂在运输蛋白上的视黄醇被稳稳压在一个很低的水平. 这套设计的目的很明确 — 不让游离的视黄醇在血里乱跑.
为什么不能让它乱跑? 因为视黄醇分子一头亲水一头亲油, 这恰好是洗洁精分子的结构. 裸着的视黄醇碰上细胞膜, 会像洗洁精插进油污那样插进膜的脂质层里, 把膜撑松、撑漏.
于是过量维 A 的那几个症状, 全都是同一件事在不同组织上的样子:
脑那边: 膜的通透性乱了, 脑脊液的产生和回收失衡, 颅内压升高 — 于是头痛、恶心呕吐、视物模糊, 严重时看东西重影. 急性大剂量最典型的就是这一组皮肤那边: 表皮细胞之间的连接被削弱, 角质层整片整片地松脱 — 于是干裂、脱屑, 严重时大面积脱皮骨头那边: 骨在一生中都在被拆掉重建. 过量的维 A 把拆的那一侧推快、把建的那一侧压慢, 天平长期偏向拆 — 于是骨痛, 长期还会让骨变脆肝自己那边: 星状细胞被长期撑着, 会从囤油模式切换成造疤模式, 开始往周围铺纤维. 这就是慢性维 A 过量伤肝的方式, 不是一次烧坏, 是慢慢变硬
把这一页和正文合起来看, 那两个数字就不再是两个数字了: UL 是仓库容量和发货配额的量化版本. 一份肝顶到上限的近两倍, 意思是这一次进货远超今天的出货能力. 偶尔一次, 仓库还有余量接得住; 顿顿如此, 余量就没了, 多出来的只能溢到血里.
临床 · 急性和慢性长得不一样
急性和慢性是同一个机制的两种时间尺度, 分开认会更有用.急性: 一次进来的量瞬间打爆发货配额, 血里游离的视黄醇短时间内飙上去. 经典的故事是北极探险者和吃了狗肝或北极熊肝的人 — 那些动物的肝里存着极高浓度的预成维 A, 一餐就够. 表现是几小时到一天内的头痛、眩晕、恶心呕吐, 之后往往接一次大面积脱皮. 它来得快, 去得也相对快, 因为一旦停止摄入, 血里那批游离的会被肝重新收回去.
慢性: 仓库长期是满的, 每天都溢出去一点. 它没有那个戏剧性的起点, 所以症状常被归到别的原因头上 — 骨痛被当成劳损, 皮肤干裂被当成季节, 疲乏被当成没睡好. 它的恢复也慢得多: 停下来之后, 血里的游离视黄醇几天内就降下去, 但肝里那批存货要靠身体一点一点用掉, 通常要几个月. 这和停咖啡因第二天就没事完全不是一个量级.
从这里可以推出一个很实用的判断: 偶尔一顿爆量和长期天天吃, 风险类型根本不一样. 前者的风险是急性反应, 后者的风险是骨和肝的慢性变化. 所以这周吃了两次肝要不要担心和我连着几个月天天吃肝是两个问题, 后者才是真正需要停下来重新算账的那一个.
如果出现持续的骨痛、说不清原因的头痛, 或者皮肤大面积脱屑, 请去看医生, 不要自己在网上对症状.
孕期 · 为什么风险偏偏落在脸和心脏
孕期这一段值得单独展开, 因为它是维 A 的另一种危险: 不是母亲中毒, 是胚胎的施工图被人改了.先把证据放在这里. 孕妇要特别当心: 一项前瞻队列发现, 补充剂来源的预成维 A 每天超过约 10,000 IU 与颅神经嵴来源的出生缺陷相关 (RR 4.8, 95% CI 2.2-10.5); 同一项研究里, 食物 + 补充剂合计超过 15,000 IU/天那一档, 相对于 ≤ 5000 IU/天的患病比是 3.5; 而 β-胡萝卜素 (蔬果里的那种) 没有致畸性 (rothman-vitamina-1995).
现在把这个阈值和盘子里的东西乘一遍 —— 这一步本篇之前一直没做, 而它才是这一段的重点.
100 g 熟猪肝含 5400 µg RAE 预成维 A, 换成上面那个单位就是 18,000 IU. 于是:
一份 100 g 的猪肝, 本身就是可耐受上限 (3000 µg RAE ≈ 10,000 IU) 的 1.8 倍它也已经越过了上面那条食物 + 补充剂合计 15,000 IU/天的线就算按份量减半吃, 50 g 也有 9,000 IU —— 仍然是那条 10,000 IU 线的九成, 而这还没算孕期复合维生素里的那一份
所以份量减半这条建议, 在孕期是不够用的: 它把一份从 1.8 倍压到 0.9 倍, 落点还是贴着阈值.
英国 NHS 因此给的是更干脆的一条: 孕期把肝和肝制品 (包括肝酱) 列入不吃的清单, 理由就是维 A 太高. 各国指南在限量和回避之间并不完全一致, 但方向是同一个 —— 在你拿到自己产科医师的意见之前, 按回避处理是更保险的默认值.
为什么是颅神经嵴这一片, 而不是随机的哪里? 因为维 A 在体内还有一个更活跃的下游形态: 视黄酸. 视黄酸不是营养, 它是信号分子 — 它能进细胞核, 直接按住一批负责分区的基因, 告诉早期胚胎的每一段将来该长成什么.
胚胎里有一群叫神经嵴细胞的移民. 它们从背侧神经管的旁边出发, 沿着预设路线迁移到脸、下颌、耳朵和心脏的流出道, 到了地方再分化成软骨、骨头和结缔组织. 而这批细胞什么时候出发、走哪条路、在哪里停, 恰恰是被视黄酸的浓度梯度指挥的.
所以视黄酸多了会怎样, 就很好理解: 相当于施工图还没画完就有人乱改比例尺, 移民队伍出发早了、走岔了、停错了地方. 缺陷因此集中在这批细胞本来要去的那几个地方 — 颅面和心脏 — 而不是均匀散在全身. 一个看似抽象的分子剂量, 落地就是这样一条具体的因果链.
那为什么 β-胡萝卜素没事? 因为它是原料, 不是成品. 身体把它转成视黄醇的那一步是按需调节的: 库存够了, 转化就慢下来. 所以你吃再多胡萝卜也堆不出致畸的剂量 — 顶多是胡萝卜素本身堆在皮下, 手掌脚掌发黄, 停几周就退, 那不是中毒.
落到行动上, 关键词只有一个: 预成维 A. 它在肝里、在鱼肝油里、在标着视黄醇或视黄醇酯的补充剂里. 孕期最稳妥的做法是按 NHS 那条来: 不吃肝和肝制品; 如果你和医生商量后决定仍然吃, 那也必须是很小的份量、很低的频率, 并且绝不与维 A 补充剂或鱼肝油叠加 —— 关键词是预成维 A, 不是胡萝卜. 这一段涉及具体的医学决策, 请以你的产科医生的意见为准.
推演 · 握住仓库, 这几件事你能自己算
把仓库、发货配额、溢出这三样握在手里, 下面几个问题就不用再去查了.先把这一幕的份量算出来 —— 它不是拍脑袋的.
成人 UL 是每天 3000 µg RAE. 而脂溶性维生素看的是一段时间的平均, 不是某一天 (理由见本页最后一条). 于是: 每周 1-2 次、每次 50-100 g, 一周合计 100-200 g 熟猪肝 = 5400-10800 µg RAE, 摊到 7 天是每天 770-1540 µg RAE —— 稳稳在 UL 之下, 同时已经是每日推荐量 (700-900 µg) 的一到两倍, 足够把缺口补上.
儿童要按他们自己的上限算: 1-3 岁 UL 600 µg RAE、4-8 岁 900、9-13 岁 1700. 按同样的算法倒推, 落点是每周一次、每次 30-50 g. 再多就不是补一补, 是往一个小得多的仓库里硬塞.
鱼肝油和胡萝卜为什么不能算成一回事? 鱼肝油里是预成维 A, 直接进仓库, 占额度; 胡萝卜里是原料, 按需转化, 不占. 所以今天吃了很多胡萝卜, 那肝就少吃点是一笔错账; 而今天吃了肝, 鱼肝油照吃才是真正危险的那一笔.
为什么缺维 A 的人吃肝见效特别快? 仓库空着, 进来多少存多少, 而且身体正需要, 发货端也不堵. 同一份肝, 在缺的人身上是补给, 在不缺的人身上是压力. 同样的食物, 剂量的意义取决于你的库存 — 这也是为什么它很有营养从来不足以推出你应该多吃.
为什么儿童的份量要更小? 不只是因为孩子体重轻. 孩子的肝按比例也小, 仓库容量本来就低, 同样一份肝在他们的仓库里占掉的比例大得多; 而孩子又恰好是最容易被大人以补一补的名义连续投喂的对象.
为什么维 A 过量不会像食物中毒那样吃完就吐? 因为它不是刺激胃肠, 是溢出之后作用在细胞膜上. 急性反应要等血里的游离视黄醇升起来, 所以是几小时之后的事; 慢性过量则根本没有那一顿, 是几个月一点点堆出来的. 这也是它比大多数食物风险更难自己察觉的原因.
为什么脂溶性维生素要看长期平均? 因为会积累的东西, 今天多一点、明天少一点会互相抵消, 真正决定库存的是这几个月的平均值. 所以对脂溶性的那几种维生素, 今天吃了多少从来不是关键问题, 这几个月平均每天吃了多少才是.
Chapter 7
How to choose · cook · how much
How to choose · cook · how much
To the market and the stove.
Choosing: buy from reliable sources (regulated markets, inspected); pork liver should be bright red, moist but not slimy, odorless. On 'liver is the detox organ so it's toxic' — see debunking; it is not a reason to avoid liver, but veterinary-drug and heavy-metal residues are real quality issues, and the more regulated the source the safer.
Cooking: cook thoroughly (same bacterial risk as muscle; internal temperature matters), no 'rare with blood'; the home-style thin-sliced quick stir-fry is fine once cooked through.
How much: the most important sentence about organ meat — small portions, low frequency. Adults 1-2 servings a week of 50-100 g capture the benefits (that figure is back-derived from the vitamin-A upper limit; the arithmetic is in special-knowledge); children scale to their own limits at once a week, 30-50 g. Do not treat liver as a daily supplement, and never stack it with vitamin-A supplements or cod-liver oil.
Who can lean on it: people at risk of iron-deficiency anemia, new omnivores.
Who should hold back: pregnant people — and here halving is not enough. The UK NHS advises avoiding liver and liver products in pregnancy outright, because 100 g of cooked pork liver carries 18,000 IU of preformed vitamin A and a halved 50 g portion is still 9,000 IU, right against the threshold from the teratogenicity cohort (arithmetic in special-knowledge). Also: gout patients (organ purines are high — see the purine discussion in crab), and cholesterol-sensitive people watch frequency. Consult a doctor for personal medical questions.
Choosing: buy from reliable sources (regulated markets, inspected); pork liver should be bright red, moist but not slimy, odorless. On 'liver is the detox organ so it's toxic' — see debunking; it is not a reason to avoid liver, but veterinary-drug and heavy-metal residues are real quality issues, and the more regulated the source the safer.
Cooking: cook thoroughly (same bacterial risk as muscle; internal temperature matters), no 'rare with blood'; the home-style thin-sliced quick stir-fry is fine once cooked through.
How much: the most important sentence about organ meat — small portions, low frequency. Adults 1-2 servings a week of 50-100 g capture the benefits (that figure is back-derived from the vitamin-A upper limit; the arithmetic is in special-knowledge); children scale to their own limits at once a week, 30-50 g. Do not treat liver as a daily supplement, and never stack it with vitamin-A supplements or cod-liver oil.
Who can lean on it: people at risk of iron-deficiency anemia, new omnivores.
Who should hold back: pregnant people — and here halving is not enough. The UK NHS advises avoiding liver and liver products in pregnancy outright, because 100 g of cooked pork liver carries 18,000 IU of preformed vitamin A and a halved 50 g portion is still 9,000 IU, right against the threshold from the teratogenicity cohort (arithmetic in special-knowledge). Also: gout patients (organ purines are high — see the purine discussion in crab), and cholesterol-sensitive people watch frequency. Consult a doctor for personal medical questions.
机制 · 为什么肝对来源比里脊更敏感
买来源可靠的这句话对任何肉都成立, 但对肝格外要紧, 原因在它的工位.这头猪吃进去、吸进去、被打进去的东西, 只要要被身体处理掉, 几乎都得先经过肝. 肝把它们改造成能排掉的形态, 再交给胆汁或者肾. 麻烦在于, 这条流水线只对能被改造的分子有效.
兽药、饲料里的杂质这类有机分子, 肝能改也能排, 改完就走了, 留不下多少. 而重金属这类金属离子没有可以被改造的把手, 肝细胞对付它们的办法是造出一种专门抓金属的小蛋白, 把它们扣在原地, 免得它们到处乱撞去破坏别的酶. 扣住的意思, 就是留下来.
于是同一头猪, 肝和肾里的金属残留浓度天然会高于里脊 — 不是因为肝有毒, 是因为肝是必经之路, 而且正好是那个负责扣押的岗位.
这条推论的实际含义只有一个: 对肝, 挑来源比对里脊更值得花心思. 正规渠道、有检疫的产品, 意味着这头猪吃什么、用过什么药是被管过的; 上游干净, 下游那个仓库里就没什么可扣的.
请注意这和维 A 是两件完全不同的事: 残留是质量问题, 靠挑渠道解决; 维 A 是剂量问题, 靠控份量和频率解决. 把两件事混成一句肝不能吃, 结果是两件都没管上.
厨房 · 挑和做, 各自在防什么
挑肝看三样, 每一样背后都是一个具体的过程, 知道过程就不用背口诀.颜色: 新鲜的肝是明亮的红褐色, 因为里面的血红素还带着氧. 放久了, 血红素中心那个铁被慢慢氧化, 颜色就往暗褐、发灰的方向走. 所以颜色发暗通常不是品种差异, 是时间.
手感: 表面湿润是正常的, 发黏不是. 那层黏是细菌在表面繁殖时分泌出来的东西, 摸到黏, 说明表面的菌量已经不是零头了.
气味: 新鲜内脏有血腥味, 但不该有酸味或者氨水味. 那两种气味来自细菌把蛋白质拆开之后的产物, 闻到了就说明分解已经开始.
下锅要防的是另一件事. 肝和肌肉一样可能带致病菌, 而且内脏在屠宰线上更容易沾到肠道内容物. 细菌真正怕的是温度 — 高温让菌体内的蛋白质变性, 结构一散就活不了. 所以判据是内部真的到温度, 而不是外表变色. 切薄片快速滑炒之所以是个好办法, 正是因为薄片的中心很快就能到温度, 熟透和不老可以同时做到. 追求嫩得带血在肝上性价比很低: 换来的口感有限, 换掉的是那一层保障.
至于焯水和长时间浸泡: 它们主要冲走的是血水和腥味物质, 对细菌几乎没用 (细菌靠加热杀, 不靠冲), 对已经被扣在细胞里的金属也没用. 别把它当成消毒或者去毒的步骤 — 它是个口味步骤.
Chapter 8
Debunking · 'like-shape-cures-like' and 'liver is toxic'
Debunking · 'like-shape-cures-like' and 'liver is toxic'
Two claims orbit organ meat: one to debunk, one to clarify.
'Like-shape-cures-like' (eat liver for liver, brain for brain, kidney for kidney): a folk association with no physiological mechanism. Liver is indeed nutrient-dense, but it corrects whole-body iron, vitamin-A and B12 gaps — not specifically the liver. 'Brain for brain' especially lacks basis: brain is high-fat, high-cholesterol food with no correspondence to cognition. The test: for any 'eat X for Y' claim, ask by what mechanism the food reaches organ Y and acts there; if none, it is association.
'The liver detoxifies, so it is toxic to eat': half-true, needs layers. The liver is indeed the metabolic organ — it processes toxins, then excretes the products (bile/urine); it is not a toxin warehouse. The real risks are two: vitamin-A excess (a nutritional risk, unpacked last scene) and veterinary-drug/heavy-metal residues (a food-quality issue, about the source). Both are manageable; neither means 'liver itself is toxic'.
The debunked conclusion: organ meat is good food; its troubles are entirely about dose and source, not about 'shape' or 'toxin' folklore.
'Like-shape-cures-like' (eat liver for liver, brain for brain, kidney for kidney): a folk association with no physiological mechanism. Liver is indeed nutrient-dense, but it corrects whole-body iron, vitamin-A and B12 gaps — not specifically the liver. 'Brain for brain' especially lacks basis: brain is high-fat, high-cholesterol food with no correspondence to cognition. The test: for any 'eat X for Y' claim, ask by what mechanism the food reaches organ Y and acts there; if none, it is association.
'The liver detoxifies, so it is toxic to eat': half-true, needs layers. The liver is indeed the metabolic organ — it processes toxins, then excretes the products (bile/urine); it is not a toxin warehouse. The real risks are two: vitamin-A excess (a nutritional risk, unpacked last scene) and veterinary-drug/heavy-metal residues (a food-quality issue, about the source). Both are manageable; neither means 'liver itself is toxic'.
The debunked conclusion: organ meat is good food; its troubles are entirely about dose and source, not about 'shape' or 'toxin' folklore.
机制 · 消化那一步就把以形补形拆掉了
以形补形为什么在生理上讲不通? 顺着食物走一遍就清楚了.肝里的蛋白质是一堆各司其职的分子: 有的是酶, 有的是运输蛋白, 有的是结构件. 但它们一进你的胃, 胃酸先把它们的立体形状拆散, 然后胃和小肠里的一批剪刀酶沿着链条一节一节地剪, 剪到只剩单个氨基酸和很短的片段, 才被小肠吸收进血.
关键就在这里: 拆到这一步, 来源信息已经不存在了. 猪肝里的一个亮氨酸和猪腿里的一个亮氨酸是同一个分子, 血里的接收方无从分辨. 你的身体拿到的是一批通用建材, 接下来盖什么, 由你自己的基因和当下的需求决定, 不由这批建材来自哪个器官决定.
所以吃肝补肝这个说法在消化那一步就断了. 肝确实能补东西 — 它补的是全身都可能缺的铁、维 A 和 B 族, 而这些补进去之后是按全身的需要分配的, 不会因为它来自肝就特意排队去修你的肝.
吃脑补脑尤其没有依据. 脑是高脂高胆固醇的食物, 而你脑子里的脂质和胆固醇几乎都是脑自己就地合成的, 吃进去的那些过不了血脑屏障. 中间那一段路根本不通.
给一个可以随身带走的判断法: 听到任何吃 X 补 Y的说法, 只问一个问题 — 吃进去的东西以什么形式到达 Y, 又以什么方式在那里起作用? 两步都说得出来的 (比如钙进骨头、铁进红细胞), 是机制; 说不出来、只能靠它长得像来接上的, 是联想.
机制 · 解毒器官到底在做什么
肝是解毒器官, 所以肝里全是毒 — 这句话错在把肝当成了垃圾桶. 它其实是一条流水线.肝处理外来分子分两步走. 第一步, 一批酶在分子上开个口 (加上一个氧, 或者剪掉一小块), 让它多出一个可以接东西的位置. 第二步, 另一批酶把一个亲水的小零件焊上去 — 葡萄糖醛酸、硫酸根、谷胱甘肽都是常用的零件. 焊完之后, 原本油溶的分子一下变得亲水, 它就再也赖不住细胞膜了, 只能随胆汁流进肠道, 或者交给肾随尿排掉.
两步做完, 东西离开了肝. 这就是代谢和储存的区别: 对毒物而言, 肝是处理站, 不是仓库.
那肝到底存什么? 存的是身体自己要用的东西: 糖原、维 A、铁、铜. 所以肝里确实有高浓度的东西这句话本身没错, 只是那些东西是营养, 不是毒素. 而真正的风险恰恰从这里长出来 — 存得太多的营养也会出事, 这正是维 A 那一幕的全部内容.
唯一真正留下来的外来物, 是那些没有把手可焊的东西, 主要是重金属. 它们不能被改造, 只能被抓住扣在原地, 于是随时间累积.
所以精确的说法不是肝有毒. 肝对毒物是通道, 对少数金属是扣押点, 对营养是仓库; 三件事各有各的应对办法, 混成一句话就一件也管不了了. 这也解释了为什么别吃肝是个很差的建议: 它同时否定了三件事, 却没有给出任何一件的解法.
References · 11
- U.S. Department of Agriculture, Agricultural Research Service. (2019). FoodData Central: Pork, fresh, variety meats and by-products, liver — cooked, braised (SR Legacy, FDC ID 167863) and raw (FDC ID 167862). Cooked per 100 g: 165 kcal, 26.0 g protein, 4.4 g fat, 3.76 g carbohydrate, 64.3 g water, 5400 µg RAE (18,000 IU) preformed vitamin A, 17.9 mg iron, 49 mg sodium, 18.7 µg vitamin B12, 163 µg folate, 67.5 µg selenium, 0.634 mg copper, 355 mg cholesterol. Raw per 100 g: 134 kcal, 21.4 g protein, 3.65 g fat, 2.47 g carbohydrate, 71.1 g water, 6500 µg RAE (21,600 IU), 23.3 mg iron, 87 mg sodium, 26.0 µg B12, 212 µg folate, 301 mg cholesterol. Braising concentrates protein, energy and cholesterol by driving off water, but it is a WET method: sodium falls 87 -> 49 mg, iron 23.3 -> 17.9 mg, vitamin A 6500 -> 5400 µg RAE and folate 212 -> 163 µg, because those leach into the cooking liquid. Read the raw and cooked rows separately, and do not assume every column moves the same way. fdc.nal.usda.gov
- U.S. Department of Agriculture, Agricultural Research Service. (2019). FoodData Central (SR Legacy), pork variety meats and loin, per 100 g. COOKED, BRAISED — kidneys (FDC 167860): 151 kcal, 25.4 g protein, 4.7 g fat, 5.29 mg iron, 78 µg RAE, 480 mg cholesterol; heart (FDC 168268): 148 kcal, 23.6 g protein, 5.05 g fat, 5.83 mg iron, 221 mg cholesterol; brain (FDC 168265): 138 kcal, 12.1 g protein, 9.51 g fat, 2550 mg cholesterol; loin, whole, separable lean only (FDC 168231): 204 kcal, 28.6 g protein, 9.12 g fat, 1.13 mg iron. RAW — kidneys (FDC 168270): 16.5 g protein; heart (FDC 168267): 17.3 g protein; brain (FDC 168264): 10.3 g protein, 9.21 g fat, 2200 mg cholesterol; loin, whole, separable lean only (FDC 168230): 21.4 g protein. On matched cooked rows liver 26.0, kidney 25.4 and heart 23.6 g protein are nearly flat, and braised lean loin (28.6 g) exceeds braised liver; raw lean loin and raw liver are both 21.4 g. fdc.nal.usda.gov
- Dietary Guidelines Advisory Committee. (2015). Scientific report of the 2015 Dietary Guidelines Advisory Committee. USDA & HHS. Removed the prior 300 mg/day dietary-cholesterol limit; cholesterol no longer treated as a nutrient of concern for overconsumption. health.gov/our-work/nutrition-physical-activity/dietary-guidelines/previous-dietary-guidelines/2015/advisory-report
- Carson, J. A. S., Lichtenstein, A. H., Anderson, C. A. M., Appel, L. J., Kris-Etherton, P. M., Meyer, K. A., et al. (2020). Dietary cholesterol and cardiovascular risk: A science advisory from the American Heart Association. Circulation, 141(3), e39-e53. Saturated and trans fats raise LDL more than dietary cholesterol itself. 10.1161/CIR.0000000000000743
- National Institutes of Health, Office of Dietary Supplements. (2025). Vitamin A and Carotenoids — Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/VitaminA-HealthProfessional
- National Institutes of Health, Office of Dietary Supplements. (2024). Iron — Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Iron-HealthProfessional
- Hunt, J. R. (2003). Bioavailability of iron, zinc, and other trace minerals from vegetarian diets. The American Journal of Clinical Nutrition, 78(3 Suppl), 633S-639S. Heme iron is absorbed far more efficiently than non-heme iron and is less affected by dietary inhibitors. 10.1093/ajcn/78.3.633S
- National Institutes of Health, Office of Dietary Supplements. (2024). Vitamin B12 — Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional
- National Institutes of Health, Office of Dietary Supplements. (2022). Folate — Fact Sheet for Health Professionals. ods.od.nih.gov/factsheets/Folate-HealthProfessional
- Rothman, K. J., et al. (1995). Teratogenicity of high vitamin A intake. New England Journal of Medicine, 333(21), 1369-1373. In a prospective cohort, preformed vitamin A above about 10,000 IU/day from supplements was associated with cranial-neural-crest birth defects (RR 4.8); beta-carotene was not teratogenic. 10.1056/NEJM199511233332101
- UK National Health Service. Foods to avoid in pregnancy (page last reviewed 15 June 2026). Lists liver and liver products among the foods to avoid, stating: 'Liver and foods containing liver have high levels of vitamin A, which can be harmful to your baby.' www.nhs.uk/pregnancy/keeping-well/foods-to-avoid