By Dr. Mercola
Many a grandmother has warned her grandkids against eating "poisonous" apple seeds. Perhaps you've had the experience of accidentally swallowing a few and wondering if you'd soon fall to the floor, gasping for breath.
Then there are those individuals who've been eating apples whole — seeds and all — for decades with no ill effects.
Many did not even know there were supposed "ill effects" to speak of. Are there? This is the question of the day, and, to answer it in a nutshell, or shall I say in an apple core, there's little to be afraid of.
Apple Seeds Release Cyanide When Crushed
Apple seeds contain amygdalin, a plant compound known as a cyanogenic glycoside. It's part of the seeds' chemical defenses, but when apple seeds are chewed or crushed and metabolized, the amygdalin turns into hydrogen cyanide.
Hydrogen cyanide, in turn, is a poisonous substance that prevents your cells from using oxygen properly, leading to death within minutes at high-enough exposure levels.
It's perhaps most known for its use as a chemical warfare agent by the Germans during World War II, but it was also reportedly used during the Iran-Iraq War in the 1980s, also as a chemical weapon.1
Apple seeds aren't the only food to contain cyanide precursors. Amygdalin is also found in apricot, peach and cherry pits, for instance, and much more (over 2,500 plant species in all2).
But consuming a few apple seeds is not the same thing as being exposed to straight hydrogen cyanide, and here's why: apple seeds have a protective coating that's resistant to digestion.
If you've ever eaten whole apple seeds, you may have noticed that they pass through your body basically unharmed. The cyanide is only produced if the seeds are damaged (i.e., crushed or chewed), so swallowing a few seeds whole is likely to be of little consequence.
It's one of mother nature's ingenious protections, as the seeds' ability to produce cyanide when crushed discourages animals from chewing them, thus allowing for the whole undamaged seeds to return to the Earth and grow new apples.
You'd Have to Eat a Lot of Crushed Apple Seeds for Them to Be Dangerous
While consuming the number of apple seeds in one apple (the average apple contains 5 seeds, according to the Washington State Apple Commission3) is not cause for alarm, it is possible to be harmed by apple seeds — if you crush them and consume a large enough quantity.
Children and pets, due to their smaller size, may be at increased, though still infinitesimal, risk.
To put things in perspective, the Illinois Poison Center (IPC) blog noted that cyanide toxicity resulting from unintentional ingestion of amygdalin-containing pits, such as cherry pits, is extremely rare in the U.S., explaining:4
"Realistically, the pits and seeds are more of a choking hazard than a poisoning risk. At least a couple of times a year here at IPC, we get called about a child who has ingested 10-20 cherry pits whole. These kids have done just fine and developed no symptoms at all.
… Intentional large ingestions however, have resulted in toxicity, including a few cases of ingestion of 20 [to] 40 chewed apricot pits by adults, which resulted in cyanide toxicity but no fatalities."
To look at it in more mathematical terms, 1 gram of apple seeds contains anywhere from 1 to 4 milligrams (mg) of amygdalin. If chewed, the same amount of apple seeds may turn into 0.06 to 0.24 mg of cyanide, with a lethal dose of cyanide from apricot kernels reported as being 0.5 to 3.5 mg/kg body weight.5,6
As Authority Nutrition noted, "The exact lethal dose of apple seeds varies widely. It depends on body weight, individual tolerance and the type of apple." They offered the following table as a guide to how many apple seeds (crushed) could potentially be fatal:7
|Body weight (pounds)
||Body weight (kg)
||Apple seeds (grams)
||Apple seeds (number)
| 20 (toddler)
Laetrile, Purported Cancer Treatment, Is Made From Amygdalin
As an aside, the same compound that makes apple seeds questionable — amygdalin — has been used to make the patented anti-cancer drug Laetrile.
Cyanide is believed to be the active cancer-toxic ingredient in Laetrile, also known as Amigdalina B-17 or vitamin B17 (although there is very little evidence it warrants classification as a vitamin).
By 1978, it was estimated that more than 70,000 Americans had tried it — despite its being banned in the U.S. since 1963. Most people obtain Laetrile from Tijuana clinics, as the agent is still legal in Mexico.8 Some have also tried to make their own anti-cancer treatment by consuming crushed apricot seeds, which can be dangerous.
New York's Memorial Sloan Kettering Cancer Center's highly respected cancer scientist Kanematsu Sugiura found that Laetrile significantly reduced the spread of lung cancer in mice,9 but the cancer research center reportedly brushed positive Laetrile studies under the rug, bowing to politics and conflicts of interest.
You're More Likely to Get Cyanide Poisoning From Cassava Than Apple Seeds
Cassava is a tropical root plant used in Asia, Africa and South America because it's plentiful and inexpensive. It has some notable nutritional benefits, as does tapioca, a digestive-resistant starch that's extracted from this root.
What cassava has to do with apple seeds is that they both contain cyanogenic glycosides, cassavas' being a different type than that found in apples.
Cassava roots contain the toxic compound linamarin, which converts to hydrogen cyanide. Improper cooking of cassava root is associated with cyanide poisoning, which can cause symptoms of vomiting, nausea, dizziness, stomach pains, headache, irreversible paralysis from a disease called konzo10 and even death.
Cassava should not be eaten raw, however, if the cassava are peeled and cooked, toxic substances are removed. It should be noted that the tapioca you buy at the store or prepare from a package does not contain harmful cyanide levels, so it's perfectly safe to eat.
What's the Healthiest Part of an Apple?
While the debate rages on over whether apples should be consumed whole—core, seeds and all — what's not controversial is the importance of eating the peel, where much of apples' antioxidant power is contained.11 Apple peels also contain ursolic acid, which may help prevent age-related and illness-related muscle wasting.12
Since you'll be eating the peel, look for organic apples, which will be free from pesticides and other chemicals. Apples are one of the most pesticide-contaminated fruits there is, so if you're planning to eat more apples, make them organic. In addition, a wealth of research suggests that eating apples may impact your health in a number of beneficial ways
• Brain Health: Apples have been found to protect neuron cells against oxidative stress-induced neurotoxicity and may play an important role in reducing the risk of neurodegenerative disorders, such as Alzheimer's disease.13
• Stroke: Eating apples is linked to a decreased risk of stroke.14
• Diabetes: Three servings of apples (and other fruits, such as blueberries and grapes) is linked to a 7 percent lower risk of type 2 diabetes.15 This may be due to their beneficial role in blood sugar regulation, as apples contain compounds that may:16
• Lessen absorption of glucose from your digestive tract
• Stimulate beta cells in your pancreas to secrete insulin
• Increase uptake of glucose from your blood by stimulating insulin receptors
• Cancer: Apples have a number of properties that may help reduce the risk of cancer, including antimutagenic activity, antioxidant activity, anti-inflammatory mechanisms, antiproliferative and apoptosis-inducing activity, as well as "novel mechanisms on epigenetic events and innate immunity." According to the journal Planta Medica:17
"Apple products have been shown to prevent skin, mammary and colon carcinogenesis in animal models. Epidemiological observations indicate that regular consumption of one or more apples a day may reduce the risk for lung and colon cancer."
• Heart Disease: Eating apples is associated with a lower risk of death from heart disease, an association that's thought to be related to their content of antioxidant flavonoids.18
Why Else Should You Eat Apples?
Apples contain a wealth of nutrients and antioxidants, including quercetin, which is known to fight cancer and prevent histamine release, the latter of which may be helpful against allergy symptoms. Interestingly, children born to women who eat apples during pregnancy are also less likely to have asthma at age 5.19 Further, according to the New York Fruit Quarterly:20
"Since apples are so high in antioxidants, it is no surprise that apples, specifically, are associated with a decreased risk of chronic disease. Three studies have specifically linked apple consumption with a decreased risk for cancer … [and] a study has shown that apple and pear consumption has been associated with a decreased risk of asthma.
Apple consumption has also been associated with a decreased risk of coronary heart disease … [and] a reduced risk of Type II diabetes was associated with apple and berry consumption in another major Finnish study.
In the laboratory, apples and the compounds in them have properties that may explain their effects in protecting against disease. Our lab has found that apples, and especially apple peels, have powerful antioxidant activity and can greatly inhibit the growth of liver cancer and colon cancer cells. Based on results from all of these studies, it appears that apples may play a significant role in reducing the risk of a wide variety of diseases."
Despite their healthy attributes, apples are a relatively high-fructose fruit, with 9.5 grams in a medium-sized apple. They should, therefore, be consumed in moderation. In addition, apple juice will contain considerably more, which is why you're far better off eating apples in their whole — not juiced — form. As for consuming the seeds, as mentioned, the amount contained in your average apple is virtually harmless.