How many apples until you die?

Have you ever heard that apple seeds contain cyanide? Cyanide as in the highly lethal rapidly acting chemical that asphyxiates you.

Have you ever thought: if I eat apple seeds, is it poisonous? Can I die? How does it stack up against our good old alcohol poisoning from a few beers or vodka shots?

Let’s do the guesstimate!

Round 1: The Apple

Apple seeds hold amygdalin, aka sugar with some cyanide attached. Your stomach converts it into hydrogen cyanide (HCN) - the poison. The good news: swallow a seed whole and it sails through you intact, too hard for your great stomach to break, releasing nothing.¹ ²

How much cyanide kills you? Cyanide blocks the cell’s ability to use oxygen, so in spite of breathing normally, your cells stop breathing. The acute lethal dose is about 1.5 mg/kg of body weight (range 0.5–3.5 mg/kg)³, and until then you barely have symptoms. Your body has a couple of systems to fight it, namely an enzyme specialized in converting cyanide into a far less toxic byproduct that is excreted in urine.

Let’s work it out as an uncertainty range, so we know both the cautious floor and the generous ceiling. For a 70 kg adult:

0.5-3.5 \frac{\text{mg}}{\text{kg}} \times 70 \text{ kg} \approx 35-245 \text{ mg HCN}

How many seeds to kill you? Popular news about this will say about 200 apples crushed will kill you. Let’s verify.

Details

Seeds contain 1-4 mg of amygdalin per gram, varying by variety.^a ⁴
Amygdalin (C₂₀H₂₇NO₁₁, molar mass ≈ 457 g/mol) releases one cyanide molecule (27 g/mol), so the mass yield from amygdalin to cyanide is:
$\frac{27}{457} \approx 6\%$
That is roughly 0.06-0.24 mg of cyanide per gram of seed.
Given an apple seed weighs about 45 mg⁵ (though other sources vary between 20-70 mg), it works out that each seed has about 1-17μg of cyanide.
We then reach toxicity at roughly 2k-250k seeds.
Apples have 5-8 seeds⁶, so we end up at a safe range of 250-50k apples.

Conclusion: you are in grave danger somewhere in a range of 250 to 50k apples. If you go with the approximately median values (1.5 mg/kg toxicity, 70kg, 3 mg of amygdalin per gram, 45 mg per seed, 7 seeds per apple), you end up with danger at about ~2000 apples, 10x popular estimates.

The 200 figure is very likely an exaggeration, but given our estimate has 250 on the lower side, you should probably avoid eating 200 apples with their seeds chewed in one go anyway, even if you are very likely to be safe on that range. That is, if you can, given that if you are eating the whole apple this is more than 30 kg of food 🙃.

Clearly you have nothing to worry about.⁷ In fact, most people do not eat the seeds; the ones that do, do not chew the seeds properly; and the ones that do, do not eat many apples in a row.

Estimate: lethal dose of apples is 250 - 50k apples, with a median of 2000 apples.

Round 2: The Beer (and the Shot)

The poison in alcohol is ethanol. A U.S. “standard drink” contains 14 g of pure ethanol⁸ - this means a beer with 5% alcohol has about 14 g, and also a ~40 mL shot of vodka (with 40% alcohol) also has 14 g.

\text{beer} = \text{shot} = 14 \text{ g ethanol}

The estimated human lethal dose of ethanol is about 5 g/kg.⁹ ¹⁰ For a 70 kg adult:

5 \frac{\text{g}}{\text{kg}} \times 70 \text{ kg} \approx 350 \text{ g ethanol}

So the number of drinks to reach a lethal dose:

\frac{350 \text{ g}}{14 \text{ g/drink}} \approx 25 \text{ drinks}

Each drink is about 4% of a lethal dose.

To conclude: if the lethal apple dose is around 2000 apples, then one beer or one shot of vodka is about the same as 80 apples.

Interactive Calculator 💡

The Verdict

Apple seeds really do make cyanide, so the myth isn’t invented - but the dose math is high. Reaching a lethal dose means crushing the seeds of roughly 2000 apples in one sitting, about 10x the scary headlines, and only if you grind every seed (as when swallowed whole, they pass through the digestive system harmless).

For perspective, a single beer or a shot of vodka is about as dangerous as 80 apples.

Still, our lower bound lands near 250 apples, so for a safety margin keep well away from the 200 apple mark - not that anyone realistically could, since that’s over 30 kg of fruit in one sitting.

Eat apples, core and all if you like, and save your real caution for the beer.

Notes

^a Amygdalin content varies by apple variety. Among those measured by Bolarinwa et al. (2015): green apples (Granny Smith) ≈ 2.4 mg/g, Pink Lady ≈ 2.6 mg/g, Royal Gala ≈ 3.0 mg/g, and Golden Delicious ≈ 3.9 mg/g.

Sources

¹ Britannica: Can Apple Seeds Kill You? https://www.britannica.com/story/can-apple-seeds-kill-you

² Africa Check: Apple seeds do contain cyanide-producing amygdalin, but apple seed poisoning extremely unlikely (2021). https://africacheck.org/fact-checks/meta-programme-fact-checks/apple-seeds-do-contain-cyanide-producing-amygdalin-apple

³ EFSA CONTAM Panel (2016), Scientific opinion on the acute health risks related to the presence of cyanogenic glycosides in raw apricot kernels, EFSA Journal 14(4):4424. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2016.4424

⁴ Bolarinwa, Orfila & Morgan (2015), Determination of amygdalin in apple seeds, fresh apples and processed apple juices, Food Chemistry 170:437–442. https://pubmed.ncbi.nlm.nih.gov/25306368/

⁵ Manzoor, Singh & Gani (2021), Assessment of physical, microstructural, thermal, techno-functional and rheological characteristics of apple (Malus domestica) seeds, Scientific Reports 11:22785. https://www.nature.com/articles/s41598-021-02143-z

⁶ Texas A&M AgriLife Extension (Aggie Horticulture), Apples: an apple has five carpels, each containing one or more seeds. https://aggie-hort.tamu.edu/archives/parsons/fruit/apple.html

⁷ Biology Insights: Are Apple Seeds Poisonous? https://biologyinsights.com/are-apple-seeds-poisonous-cyanide-risk-explained/

⁸ NIAAA: What Is a Standard Drink? https://www.niaaa.nih.gov/health-professionals-communities/core-resource-on-alcohol/basics-defining-how-much-alcohol-too-much

⁹ EBM Consult: Ethanol (Ethyl Alcohol) Level - minimal lethal oral dose in a nontolerant adult ≈ 5-6 g/kg. https://www.ebmconsult.com/articles/lab-test-ethanol-alcohol-level

¹⁰ CyAlcohol: Human ethanol lethal-dose estimate ~4–5 g/kg. https://cyalcohol.com/article/does-ethyl-alcohol-have-a-lot-of-ld50