Nutrition Myths
Is avocado seed edible?

SUMMARY

  • Avocado seeds have not been declared safe to consume, since there have been very few studies investigating the toxicity and safety of the avocado seed constituents.
  • Tannins contained in higher concentrations in the fresh seeds may be harmful, if consumed in excessive amounts. Nevertheless, it is currently not known what their safe limit is.
  • The available studies done on the health benefits of the avocado seeds only used dried avocado seed extracts (not the whole seeds). Their potential health benefits currently under investigation are anti-carcinogenic, anti-oxidant, anti-inflammatory, anti-diabetic, cholesterol-lowering and anti-hypertensive properties.
  • These studies were conducted either in vitro (in the lab) or using animals. Studies on humans were only for cosmetic purposes.
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Is avocado seed edible?

In recent years, avocado seeds have become the new trendy, alternative food. Many general health websites and popular food blogs publish information on how to eat avocado seeds, claiming their extraordinary nutritional health benefits.

Historically, avocado seeds have been mostly used to extract ink for writing (produced from polyphenol oxidase).

Although dried avocado seed powder is known in the native American and African folk medicine, where they are added to foods in the belief that they treat ailments such as hypertension, there are no records of avocado seeds being a part of the human diet.

Even the inhabitants of tropical countries, where avocados are abundant and form a big part of the diet, don’t eat avocado seeds.

Find out if avocado seeds are edible or toxic and what science says about their potential health benefits.

Where did this new trend of eating avocado seeds come from?

Blending the avocado’s fresh or dried seeds into a powder and adding them to a smoothie or breakfast cereals is becoming a “thing” and avocado seed is becoming a new trendy “superfood”.

Eating avocado seeds was popularized only a few years ago, by a handful of non-scientific “health” websites. The information usually includes instructions on how to eat the avocado seeds and claims of their exceptionally high nutritional value.

However, the health claims in these blogs don’t have any references to scientific evidence and rather vaguely mention that “studies show” or provide links to other non-scientific websites.

This trend is rapidly spreading with the help of popular recipe blogs, but the uncertainty still remains. What evidence do we have that this new food is edible and is not going to be toxic to us?

On the other hand, there are other sources that warn against eating avocado seeds due to the potential toxicity of tannins, or other substances that are not fit for human consumption. These sites, however, have no references, so the basis of these warnings is not clear.

In order to answer the question whether avocado seeds are edible, beneficial or toxic, I have investigated all of the available studies on the avocado seeds’ composition, toxicity and health benefits.

The following is a comprehensive summary, which will allow you to make an informed decision whether to add it to your smoothie or not.

What are avocado pits and seeds?

The avocado is often confused with drupe fruits, such as a peach, since it has a hard seed, often referred to as a “stone” or “pit”.

The avocado is actually a single seeded berry fruit. It has three tissue layers: the skin (the outer layer called the exocarp), the fleshy, edible part (the middle layer called the mesocarp) and the seed or pit (the inner layer called the endocarp). (1)

Since the endocarp (avocado pit) surface is hard and leathery, it needs to be cracked and peeled off in order to get to the softer part. The surface of the pit is then discarded.

Some people peel the outer layer of the fresh pit, while others first dehydrate the pit in the oven and then discard the outer layer.

Studies done on the health properties or the potential usage in the food industry (e.g. flour) use the avocado extracts prepared from dried seeds.

Since it is a storage organ of the plant, the avocado pit/seed contains a high concentration of various nutrients (see below).

Why would you want to eat the avocado seed?

The avocado seed accounts for about 16% of the total weight of the fruit. Since the current production of avocados in the U.S. exceeds 350 million tons per year, the seeds weigh about 56 million tons.

Wouldn’t it be great to find a way to incorporate it into our diet, especially if it had some health benefits? (2)

An avocado seed is large and looks like a giant nut. It is rich in nutrients and phytochemicals with healing properties. (3, 4)

Many studies show promising results in a wide variety of health benefits. Therefore, tossing them out seems like a big waste and bad for the environment. It must be good to eat it, right?

While it sounds like a good idea, how do we know that it is safe? It would definitely be an extraordinary discovery, if the avocado seeds turned out to be a superfood.

Historical and current usage of avocado seeds

Throughout history and even currently in some parts of the world, the avocado seeds have been used for various folk medical practices.

Here are some of the known uses in folk medicine (5, 6):

  • Aztecs and Mayas used avocado seeds for mycotic and parasitic infections
  • Used in diabetes
  • To treat gastrointestinal issues
  • In the treatment of anemia
  • To relieve toothache, by placing a decoction of the seed on the tooth
  • To reduce dandruff with dried avocado seed powder
  • Used topically for arthritis with the seed paste
  • In Nigeria, it is believed that avocado seeds are useful in managing chronic hypertension. The powdered seed is added to soups, pap and puddings.
  • Used to treat snakebites
  • As a contraceptive and an abortive agent
  • Used in some countries in Africa to treat whitlows and dysentery

Scientists are currently investigating the potential medicinal and culinary applications of the avocado seeds.

Various substances were extracted, showing promising results in medicine and food production, such as a low-cost flour that is higher in carbohydrates, minerals and fiber than wheat flour.

Nevertheless, more studies are needed, to ensure the safety and improvement of the avocado seed flour quality. (7)

Other studies are looking at the avocado seed application in industrial food technology, due to its fiber contents, that can retain four times their weight in water and six times in oil. (8)

Known facts about avocado seeds

Only in recent years, have scientists begun to explore the culinary and medicinal potential uses of the avocado seed. Most studies, done on animals or in vitro, are only preliminary.

The following is a summary of what we currently know (5, 9, 6):

  • Chemical composition of avocado seeds:
    – Moisture – 54.1%
    – Starch – 27.5%
    – Sugars – 3.5%
    – Protein – 2.4%
    – Ash (mineral contents) – 1.2%
    – Fat – 0.8%
    – Phytochemicals (phytosterols, alkaloids, triterpenes, tannins, fatty acids, furanoic acids, abscisic acid, proanthocyanidins, two new glucosides of abscisic acid, saponinis, persin and polyphenols).
    – High concentration of potassium and phosphorus, and a lower concentration of magnesium, and calcium
  • Contain substances that, in a lab environment, show potentially powerful health properties (see below).
  • Most of the nutrients and phytochemicals that exist in the flesh of the avocados also exist in the pit in a higher concentration.
  • Contain a high proportion of soluble dietary fiber and neutral detergent fiber.
  • Fresh seeds, not the dry ones, contain tannins and polyphenols (flavonoids). It is not currently known what the safe limit of these tannins is in humans.
  • From a culinary perspective, avocado seeds taste awful.

    However, there are studies under way that investigate the potential use of avocado seeds in flour production. High levels of minerals (about double that of normal flour), carbohydrates and fiber sound promising. More studies are needed.

    Nevertheless, the avocado seed flour was found not suitable for baking due to the low level of gluten. (7)

  • Insecticidal properties were found in the in vitro experiments.

Considering everything that is known, there haven’t been any studies suggesting that avocado seeds are safe to eat. For more information on safety, see below.

Is the avocado seed poisonous?

Animals

Avocados (the fruit, leaves, stems and seeds) contain a fungicidal toxin called persin. The highest amount of this toxin is found in the leaves, but is also in the pit and flesh.

There are no reports of harmful effects of persin in humans. It is actually being studied as an anti-carcinogenic agent in breast cancer.

However, this toxin is dangerous to animals, if taken in large quantities. The animals usually affected are mammals (cattle, horses, goats, sheep, cats, dogs, mice, rats, rabbits, guinea pigs), birds (budgerigars, canaries, cockatiels, ostriches, chickens, turkeys) and fish.

The toxicity in animals is associated with the death of the heart cells (myocardial necrosis), and with sterile mastitis (inflammation) of the lactating mammals. (10)

Humans

Some blogs mention that avocado seeds are perfectly safe to consume because there is no cyanide in them, unlike in apricot seeds. Those authors seem to ignore the fact that cyanide is not the only toxic element in plants.

Even if the cyanide amounts in avocado seeds are negligent, there may be other substances characteristic to this seed that may be poisonous in certain quantities (5)

Eating avocado pits may be unsafe

High concentrations of toxic tannins (responsible for the bitter taste) are present in unripe fruit. Their presence tends to decline with time and during ripening.

These tannins are also present in the seeds of fresh and ripened avocados, but disappear when the seed is dried.

While it appears that the amount of these tannins are not dangerously high, even in the fresh avocado seeds, their safe limits are still untested. (3).

Some scientists suggest that dry seeds are safer to consume than the fresh ones due to the presence of tannins in the fresh seeds. Tannins may also cause allergic reactions in some people. (3)

The toxicological assessment on rats and mice has found that dried avocado seed extract appears to be safe, even when used in doses much higher than what has been used in folk medicine in Nigeria for management of hypertension.

Acute toxicology studies are a good, but not a definite indication of what to expect if the substance is used chronically.

Although these studies indicate a potential of using the dried avocado seeds in foods, their authors don’t advise consuming high quantities of the avocado extract. (11, 12)

Upon contacting the FDA about the potentially toxic substances in avocado seeds, I received (14th May 2017) the following response: “FDA does not have any available information to support avocado seeds being harmful, if consumed by a human.”

The California Avocado Commission warns against eating avocado seeds due to insufficient studies on their safety. It also warns that the avocado pits contain certain elements inappropriate for human consumption, although no references were provided to related studies. (13, 14)

California Avocado Comission warns about avocado seeds

MAIN POINTS

  • To date no harmful substances to humans have been identified in the avocado seeds, but at the same time there are no studies showing that it is safe eat them.
  • The FDA database has no information suggesting that the avocado seed consumption is harmful for humans.
  • Tannins, which are potentially toxic in high amounts, are contained in the avocado pits. For that reason, some scientists advise against the high intake of avocado seeds.
  • The safe limit of tannins is unknown at this stage.
  • Dried avocado seeds seem to be safer for consumption, since tannins are not present or only in small quantities. By contrast, fresh avocado seeds have higher concentrations of these tannins. Most of the studies used dried avocado seed extract, and so even less is known about the safety or health benefits of fresh seeds consumption.

Health benefits of the avocado seed

NOTE: We are only in the initial stage of the avocado seeds’ scientific research. The studies are still preliminary, conducted only on animals or in vitro.

In many cases, it is not yet known which substances are responsible for these properties and what effect these extracts have on humans, since the only studies conducted on humans were dermatological, related to topical application on skin, not for consumption or usage of the extract.

This preliminary stage of the investigation found evidence of beneficial properties of the avocado seed extracts. The potential health properties are thought to be due to the phenolic compounds that are abundant in these seeds.

Properties found in the avocado seed extract (5):

  • Anti-cancer properties – one in vitro study on breast cells showed that the avocado seed extract contains anti-carcinogenic substances, such as triterpenoid.

    Avocatin B, also found in the seed, has been shown to inhibit fatty acid oxidation in the leukemia Other vitro studies found evidence of cytotoxic effects on breast cancer cells and potential inhibitory properties of liver cancer. (15)

    More studies (especially in vivo) are needed to establish if the extract has similar effects in humans. (16)

  • Anti-oxidant properties – it has been found that avocado seeds have a higher antioxidant activity than the pulp, thanks to their high contents of phenolic compounds and ascorbic acid.
  • Anti-inflammatory properties – one in vitro study showed that lipidic polyols and phospholipase A (PFA), extracted from the avocado seed, inhibit the activity and production of inflammatory mediators.
  • Anti-diabetic properties – studies on rats using the avocado seed extract, showed a reduction in blood glucose concentration in diabetic and non-diabetic rats.
  • Cholesterol-lowering properties – studies on mice and rabbits showed that the avocado seed extract reduced cholesterol and triglycerides in blood.
  • Anti-hypertensive properties – studies on rats found evidence that the avocado seed extract reduces blood pressure, heart rate, cholesterol, triglycerides and glucose.
  • Dermatological properties – in vitro studies on mice showed that the avocado seed extract promotes the growth of keratinocytes, enhances skin DNA repair and reduces sunburned cells.

    Studies on skin were the only type that were performed on humans. However, these were only of a cosmetic nature – using topical applications.

    The avocado seed extracts have been shown to improve stretch marks, and keratosis, reduce hypo and hyper pigmentation, ridging and redness, increase skin moisture retention, and thickness and improve skin elasticity.

  • Antimicrobial properties – in vitro studies showed a potential antimicrobial activity (e.g. against Salmonella, Staphylococcus) and fungicidal effects (e.g. against Candida).

    It is unclear which phytochemicals exert this action and how this extract will work in humans. More studies are needed.

  • Derivatives of the oil extract (such as alkyl polyols) from the avocado seeds are used for the prevention or treatment of several disorders, such as arthrosis, rheumatism, gingivitis or periodontitis. (17)

Except for the dermatological studies, none of remaining studies have been tested on humans or been proven to be effective on humans. (5, 9)

So..should we eat them?

There are many reasons why people eat avocado seeds, and irresistible taste is definitely not one of them.

Any health claims related to the consumption of avocado seeds on the web are not proven by any studies. Neither avocado seeds consumption, nor avocado seed extracts have been tested on humans for their health benefits.

Avocado seeds contain some nutrients but so do other foods that are palatable.

Since this is a “new” food, we don’t know enough about other constituents that may be potentially harmful. However, if regardless of all the above information, you still decide to blend avocado seeds into your smoothies, current science indicates that for safety reasons you should not consume high amounts of them and preferably select the dry rather than the fresh ones due to potentially toxic tannins present in fresh seeds.

Personally, I would advise you to rather wait for more studies that prove that avocado seeds are safe to eat, and are of exceptional health benefit.

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