Alcohol Metabolism

酒精 · Alcohol Metabolism

Place · Level 3 · Macro

ADH → 乙醛 → ALDH2 → 乙酸 · 东亚 ALDH2*2 6 亿人 · IARC 1 类致癌物 · 适量护心 J 曲线被推翻

Connected to · 10

synergy · 1

Fructose Metabolism
Alcohol + fructose both converge on hepatic acetyl-CoA → DNL. Ethanol's NADH surplus stacks with fructose's KHK-driven ATP collapse — NAFLD risk multiplies, not adds.

depletes · 3

Folate
Chronic alcohol depletes folate via 3 pathways: (1) inhibits intestinal γ-glutamyl hydrolase → ↓absorption; (2) accelerates renal excretion; (3) disrupts hepatic one-carbon metabolism. Alcohol + low folate → ↑homocysteine + aberrant DNA methylation → accelerated alcoholic liver injury. Pregnancy drinking is especially dangerous (NTD risk stacking).
Thiamin
Chronic alcohol → ↓thiamine absorption (gut + liver) + ↑demand (ALDH consumes NAD → more cofactors needed). Alcoholic Wernicke-Korsakoff is the most severe B1 deficiency consequence. Classic triad: ophthalmoplegia + ataxia + confusion. B1 must be given before glucose infusion (glucose accelerates depletion → acute Wernicke).
Protein
Chronic alcohol → protein-energy malnutrition + B1/B12/folate malabsorption + accelerated sarcopenia. Alcoholic myopathy isn't only heavy-drinker territory — moderate intake + elderly = high risk.

regulates · 4

Gout & Hyperuricemia
Dual mechanism: (1) ADH/ALDH lactate output competes with urate for renal OAT excretion → serum urate ↑; (2) beer adds purine load (guanosine). Choi 2004 Lancet (N=47,150): beer ≥2/d × 2.5 gout risk, spirits 1.6×, wine neutral.
Liver
Chronic drinking induces CYP2E1. That route generates ROS which keeps damaging the liver, and it pushes acetaminophen toward its toxic metabolite — so a chronic drinker can reach acute liver failure on a normal dose of the painkiller.
Hepatitis B
Ethanol and hepatitis B grind away at the same organ. In carriers who drink, liver-cancer risk climbs with daily intake and is further amplified. The evidence here is grade C (association, not causation), but the direction is consistent and the mechanism plausible.
Hypertension
Alcohol is one of the reversible pressors: above 20-30 g a day systolic pressure climbs, and stopping brings it down 3-5 mmHg within weeks. One of the few levers on this island that shows up within the month.

contrast · 2

Carbs & Fiber
One ruler, two substances: both supply energy without being essential, so neither has an RDA. The body makes glucose itself (gluconeogenesis); ethanol is pure empty energy. The 11 things it genuinely cannot make are 9 amino acids and 2 fatty acids.
Milk Thistle
Milk thistle is often treated as permission to keep drinking, yet in alcoholic liver disease it showed no significant effect on mortality or complications; what changes outcome is the load on the ethanol-dismantling pathway itself.

Ethanol · the molecule

Stop 1/5

乙醇 · 一个化学物

Ethanol (CH₃CH₂OH) is a small, simple, fast-moving molecule. Molecular weight is only 46 g/mol — four times smaller than glucose (180 g/mol). It's also amphipathic, with a water-soluble hydroxyl (-OH) and a fat-soluble ethyl (-CH₂CH₃). Being small and amphipathic means ethanol crosses every membrane in the body without a transporter — stomach, gut, liver, brain, heart, gonads, bone marrow, no exception. It also doesn't need to be digested: blood ethanol is measurable 5–10 minutes after drinking and peaks at 30–60 minutes.

The route into the body is short: about 20% is absorbed directly in the stomach (faster on an empty stomach; food slows gastric emptying), and the remaining 80% in the upper small intestine; from there it enters the portal vein and the first stop is the liver — which is why the liver is always the main battlefield for alcohol metabolism.

There's a caloric trap: ethanol provides 7 kcal/g, sitting between carbohydrate (4), protein (4), and fat (9), but those calories are nearly empty — no vitamins, minerals, or fiber. One US 'standard drink' is 14 g of pure ethanol (the UK uses 8 g and Japan 20 g), roughly 350 ml of beer, 150 ml of red wine (12% ABV), or 45 ml of spirits (40% ABV), all landing around 98 kcal.

In the end, ethanol is a small toxic solvent the body has no metabolic role for and must immediately get rid of. The next four scenes show how the body handles it — and the real damage produced along the way.

Fitnuhealth doesn't moralize about drinking on this island; it just lays out mechanism and evidence clearly. All the latest evidence (GBD 2018 Lancet / Anderson 2022 NEJM) converges on the same conclusion: safe drinking quantity = 0 — any dose carries measurable health cost. So what we're doing here is letting you make your own informed choice after understanding the mechanism.

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Educational content, not medical advice — consult a clinician.

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