Eat dirt. It’s a phrase which is not meant to be taken literally.
Now that’s changing.
Some people are literally recommending you should eat dirt. Daily, in fact!
That seems ironic, considering how thoroughly we rinse our vegetables and fruits, not to mention all our other hygiene.
Many of the folks who insist on drinking highly purified water are the same ones gobbling down this unrefined goo from the ground. That seems hypocritical, given that it too can be contaminated with heavy metals and who knows what else!
At least most – but not all – people who say we should eat dirt are recommending a specific form. It’s a fairly rare type of clay, not one you can just dig up in your backyard.
What is bentonite clay?
What scientists consider to be the first formally written medical records date back to around 2,500 B.C.
Discovered in Mesopotamia, not only were they written on clay tablets, but among other herbal remedies, they talk about uses of clay for wound treatment (1).
Fast forward a few centuries to the island of Lemnos. By the first century A.D., their clay was a hot commodity export (2).
Until supplies were exhausted, the famous red Lemnian clay was used for purported benefits of eye pain (from lachrymal duct drainage), hemorrhages, snake bites, and “complaints” about the the kidneys and spleen. Medicinal use of it took place all the way up until the 19th century. This Lemnian clay was still listed in pharmacopoeia as recently as 1848, as discussed in as in Essentials of Medical Geology.
In short, using clay for medical treatments is an ancient practice. Not all, but most applications were about topical usage. Most of the claimed health benefits of eating dirt/clay do not have historical support.
One exception was dissolving a small ball in water to take with meals, in order to prevent poisoning. This was practiced by the Australian Aborigines to prevent “sick stomach.” Other indigenous people on completely different continents – South America and Africa – had similar practices. You can read about this fascinating history in Nutrition and Physical Degeneration.
Bentonite is perhaps the most popular medicinal clay in use today. Discovered in 1898, its name comes from Benton Shale, which is a fine-grained sedimentary rock found throughout parts of Wyoming, Montana, South Dakota, North Dakota, Nebraska, and Colorado. Bentonite clay is used mostly for drilling, construction, and other industrial purposes. In cosmetics, it’s used as a skin cleanser and there are some medicinal uses it has been researched for.
Even though it was originally found in the United States, today only around 1/3 of production is from domestic sources. Here are the top 5 countries currently producing, according to the British Geological Survey (3).
Almost all of this production is for industrial use. Further down on there, so called food grade bentonite clay from Australia (15th on the list) and New Zealand (40th) has become quite popular. As to be expected, not many people are excited about sourcing something you might eat from China!
Bentonite vs. Montmorillonite (and others)
You will also hear the term montmorillonite clay. That name comes from the small town of Montmorillon, France. A similar clay was discovered there in 1847. It has been researched for chelation therapy and topically for dermatitis (4) (5).
It contains microscopic crystals which are officially called montmorillonite minerals.
Even though that clay comes from the other side of the world, bentonite also contains these same montmorillonite crystals. Both of these clays have a very similar composition and as a result, the terms are used interchangeably and both mean the same thing.
Unless a product specifically says made in France, don’t assume a montmorillonite clay actually comes from there. Likewise for bentonite, since China and other countries are now producing large amounts.
The difference between bentonite clay vs. diatomaceous earth (DE) is that the latter comes from fossilized phytoplankton. Bentonite is believed to be the result of volcanic ash.
When hot lava flows into a body of water, zeolite is formed. An example of this is what takes place in Hawaii today. Zeolite powder is sold as a supplement, too.
Also known as China clay, kaolinite clay is less drying than bentonite and is considered a more gentle exfoliant for face and skin masks.
Fuller’s earth is a name used to describe any clay that can naturally de-colorize oil and liquids upon contact. While it can include bentonite, it’s an umbrella term that also covers other varieties like palygorskite. Fuller’s earth is used more for skin lightening rather than alleged detox.
The benefits of activated charcoal are the closet to bentonite overall, at least in terms of what people are choosing to use it for. Some even combine them, such as for making a facial mask.
Like the clay, charcoal is dramatically overhyped and some detoxification uses are quite dangerous, as they can interfere with the absorption of medicines and essential minerals.
Types of bentonite and what they’re made of
All types contain high amounts of two key components (6):
- 50% to 60% silica (SiO2)
- 17% to 20% alumina oxide (Al2O3)
Those are averages which can and do vary. For example, the brand Redmond is sourced from Utah and it has significantly less silica (22.1%) and alumina oxide (5.8%).
The silica and alumina are bound together with hydrogen and oxygen, to form microscopic crystal layers (montmorillonite crystals).
Above is what each layer of crystal looks like. The space between each layer is what expands and absorbs. The atomic bonds pictured above stay tightly joined regardless.
Can you get aluminum toxicity from bentonite clay? The alumina oxide found in it has a negative (ionic) electrical charge, which as you see above is tightly bound to other minerals. That’s quite different than pure aluminum (like that used in manufacturing) and as such, the aluminum-containing crystals in clay are not absorbed.
These bound forms – the crystal layers – are quite large molecules and are believed to be too big for bioavailability in the human body.
The remaining 20% of bentonite’s composition includes iodine, gold, manganese, molybdenum, palladium, platinum, selenium, silver, zinc, and several dozen trace minerals, each of which measures as being a tiny fraction of 1%.
The highest are calcium, sodium, magnesium, and potassium. Each of those four can range from 0.5% to 3%. Whichever is most prevalent is the label that gets assigned to the clay.
Light green to grey in color, sodium bentonite is used in waterproofing materials and sealants, because it can expand up to 15 times its volume when the dry powder comes in contact with moisture. While all types expand, the amount is amplified by the high salt (sodium) content.
An advantage for skin care is that it can help absorb oil and dead skin cells. This is why Clearasil Ultra Acne + Marks wash makes use of it. Even if it was deemed a food grade, sodium bentonite is not safe to ingest in large quantities, as it can cause blockages in the intestines and constipation due to expansion. It also may absorb zinc, which could be bad for you (7)
Mountain Rose Herbs bentonite brand reports having a pH of 8.5 to 10.5. To put those numbers in perspective, baking soda is 9. While each brand and batch will vary, the sodium tends to be the most alkaline type.
Despite being one of the more rare types in nature, it rivals sodium in terms of popularity for alternative health. Greenish in color, natural calcium bentonite clay is probably the most popular for internal use and it’s often purported to be a detox remedy.
The popular brand Aztec Secrets is the calcium form for external use. It’s sourced from Death Valley, CA.
The Aztec Indian Healing Clay company does not claim a specific pH, third-party analysis have found it to be around 8 (8).
This offers proven health benefits, but outside of the body. Magnesium bentonite has been found to be an excellent medium for the defluoridation of drinking water. It absorbs fluoride upon contact (9).
Also called K-bentonite, in reference to the symbol K for potassium, you will see this used for brickmaking since it is the least absorbent type (no one wants their masonry work damp after construction). The illite clay in it works good for that purpose. Potassium bentonite uses for health are practically unheard of.
What is it used for?
The sky is the limit as to what people online are alleging bentonite clay can be used for:
Skin care – acne, athlete’s foot, anti-wrinkle, bee stings, brown recluse spider bites, brown spots, cellulitis, diaper rash, eczema, keratosis pilaris, pore cleansing
Digestive – acid reflux, Candida yeast infections, constipation, Crohn’s disease, diarrhea, heartburn, food poisoning, gas and bloating, irritable bowel syndrome (IBS), ulcerative colitis
Hair – mask for low porosity hair moisturizing (curly and afro), mixed with a psyllium powder drink for hair loss related to toxins
Oral – removing stains/teeth whitening, gingivitis and gum disease
Immune system – allergies, asthma, bacterial infections
Metabolic – acidosis, heavy metal detoxification, weight loss
Orthopedic – arthritis
Neurological – autism
With a list like that, it sounds like you can just skip the pharmacy! Does bentonite clay work for these diseases and disorders?
Or at least there’s no scientific research for the vast majority of what you see listed. Despite that fact, you will see countless websites claiming it offers those “proven benefits” for health. Some go so far as to call it a cure. They tell readers to take capsules, tablets, and powders internally, or use poultices externally. That type of advice can be quite dangerous.
It’s similar to how people greatly exaggerate apple cider vinegar benefits.
Is bentonite clay safe to ingest?
There are so called “food grade” versions, but that label doesn’t mean the clay is safe to eat. This substance is addressed by the FDA in Section 184.1155 of Title 21.
The affirmation of this ingredient as generally recognized as safe (GRAS) as a direct human food ingredient is based upon the following current good manufacturing practice conditions of use:
(1) The ingredient is used as a processing aid as defined in 170.3(o)(24) of this chapter.
(2) The ingredient is used in food at levels not to exceed current good manufacturing practice. Current good manufacturing practice results in no significant residue in foods. (10)
The last part was bolded by us. Why would they allow for its use and at the same time, require “no significant residue” of it?
Because it’s GRAS for food packaging, not eating!
Clay (kaolin) is GRAS only as an ingredient of paperboard products used in food packaging.
There isn’t concrete data available concerning the amounts of clay (kaolin) that might migrate to foods from this source, but the Select Committee believes them to be very small.
They list uses like juice/beverage clarification and as a coating for food packaging. In other words, only things which come in contact with what you eat or drink.
In support of its safety for those purposes, they do layout some interesting facts about bentonite clay (11):
- If consumed orally, “as much as” 3% gets absorbed and in animal studies and there were “no observable adverse effects.”
- Growth stunting in the animal studies were only observed when 10 to 25% of their diet was clay.
- The 50% kill rate in rats took about 150g per kg of body weight. In other words, how much it took to kill rats was them eating an amount equal to 15% of their body weight.
- Research using bentonite clay for diarrhea in humans involved a therapeutic dosage of “about 250 to 1,000 mg per kg” (that’s about 0.025% to 0.1% of body weight).
Reading those out of context though can be misleading. You have to remember all of those facts were listed by the committee in support of using it for food packaging, NOT for intentionally eating clay as a food or supplement!
When you see the phrase “food grade” that does not mean it has been tested or approved for consumption by a government agency.
In Canada, United Kingdom, and Australia, you will similar products for sale advertised as being edible and safe to ingest, but their regulation is similar to the United States… none have approved for use as a food. Buyer beware, as if you choose to consume them orally, you are doing so at your own risk.
The reason there are some ingestible bentonite supplement capsules and powders for sale is because they are not food (they’re being sold as dietary supplements).
Bentonite clay side effects
Since no form of dirt is officially considered a food, information on adverse reactions is limited to what has been reported by third-parties (12) (13). Reactions appear to be more common with larger dosages.
- Abdominal pain
- Low potassium (hypokalemia)
- Body aches
- Muscle pain
- Joint stiffness
When a reaction occurs, many websites claim they’re “secondary effects” from “detoxifying the body” of heavy metals and toxic substances, but there is literally no scientific validation of that.
For health effects seen in people who were exposed occupationally, the U.S. Department of Health & Human Services reports case studies (14). They have included:
- In a sample of 32 workers who had been breathing the dust for various lengths of time, nearly half of them (14) had silicosis as confirmed by radiological testing. That’s a lung disease you get from breathing in tiny particles of silica.
- “Very high incidence of bronchial asthma (25%)” was seen in a case study of workers at a processing plant, which was attributed to breathing the dust in the air.
- A 20 year old dental assistant was using bentonite clay for teeth whitening. Deposits of the dust were blown into her face and got embedded in her cornea. It was safely removed within 2 hours.
It seems the biggest occupational danger is with the dust, not the damp mud or coming in contact with liquid bentonite clay. A recent analysis of past case studies concluded the same (15):
“The available studies on toxicity and epidemiology indicate that the principal exposure pathway of concern is inhalation of respirable dust by occupationally exposed cohorts. Bentonite itself is probably not more toxic than any other particulate…”
Risks of parasites and lead content
Despite how alkaline this dirt may be, environmental bacteria can thrive in pH values ranging from 5.5 to 9.0.
Specific types, such as those found in the gut flora of humans and animals, can survive in parts of the host where a pH as high as 12 may be reached (16).
Some home remedy sites suggest using bentonite clay as a stomach virus treatment. Whether that may work or not we will address in a moment, but how about the risks of introducing other parasites likes bacteria and fungus?
More than parasites, the biggest danger seems to be the possibility of lead, arsenic, cadmium, cesium, lithium, and other toxic metals in high amounts. Even trace amounts of radioactive uranium and thorium may be present!
Back in 2016, the FDA warned people not to buy Best Bentonite Clay due to lead poisoning. Places like GNC and Vitamin Shoppe were not the types of places where to buy this clay. The FDA reported this Oklahoma company was only selling their product online, direct to consumers (17).
That brand was about as mom ‘n pop of an operation as you could find. Their website looked like something from the 90’s.
But even buying from a respectable store doesn’t guarantee safety.
In another warning by the FDA, they said this about a brand of bentonite for sale at Target and Sally Beauty Supply (18):
“Consumers should not purchase or use “Bentonite Me Baby.” Anyone who has used this product or provided it to a child should consult a health care professional immediately. FDA laboratory analysis of the product found elevated lead levels.”
Whether those two examples involved the calcium or sodium form is unclear. Regardless, the risk of lead poisoning and the potential for parasites with any form are just a couple reasons why it’s so important to buy from trusted brands.
When you cut through all the hype, what is it good for?
When you search for this term in the NIH’s PubMed database you get over a thousand results, but out of those, only a few are clinical trials involving humans.
Blocking aflatoxin absorption
Aflatoxins are produced by certain types of fungi which grow on crops. Without careful monitoring, the consumption of contaminated foods can lead to liver cancer (19).
In a double-blind, placebo-controlled study, 63 children in Ghana were given calcium bentonite clay capsules (which they called calcium montmorillonite clay) for a period of 14 days (21).
- 21 received placebo
- 21 received a low dosage of bentonite equal to 750 mg per day
- 21 received a high dosage of 1,500 mg per day
Using a biomarker of aflatoxin M1 (AFM1), they evaluated their urine and here were the results…
While far from proven, the results do suggest the possibility that the aflatoxins attached to the clay in the digestive tract and exited the body in the feces, instead of being absorbed by the body and processed through the kidneys (which would have ended up in the urine).
Blocking fumonisin B1 (FB1)
This is a co-contaminant which is found with aflatoxins in grains and is believed to boost the cancer causing effects.
Similar to the above study, researchers studied 186 Ghanaians and when they were given 3 grams per day of the calcium bentonite, the median FB1 levels in their urine decreased by more than 90% (22).
Irritable bowel syndrome (IBS)
This double-blind, placebo-controlled, and randomized study was conducted at a hospital in France (23).
524 patients with IBS participated. They covered the spectrum of the disease:
- 174 had IBS with diarrhea (IBS-D)
- 175 had IBS with constipation (IBS-C)
- 175 had IBS with alternating constipation and diarrhea (IBS-A)
263 patients were given a calcium montmorillonite supplement for IBS treatment at a dosage of 3 grams, taken 3x daily.
261 received a placebo version.
Both groups took them for 8 weeks and here were the results…
IBS with diarrhea or constipation appeared to benefit, but those with alternating did not. The most noticeable improvement, which was statistically significant, was in the IBS-C which is why they concluded:
“…this study demonstrates that beidellitic montmorillonite is efficient for C-IBS patients (P < 0.016). This effect of beidellitic montmorillonite on pain cannot be explained by changes in bowel habits. The efficacy of this well-tolerated therapy warrants further confirmatory therapeutic trials in C-IBS patients.”
Vitamin and mineral absorption
Researchers at Texas A&M University conducted a study involving 177 people who were divided into 3 groups (24):
- High dose of 3 grams per day of bentonite clay
- Low dose of 1.5 grams per day
Each group took these for 3 months. The essential vitamins A, E, and other minerals (15 nutrient and 15 non-nutrient minerals) were measured in their blood at baseline, 1 month, and at the end of the 3 months.
Here’s what they found…
“These results, combined with safety and efficacy data, confirm that NS clay is highly effective in reducing aflatoxin exposure and acts as a selective enterosorbent that does not affect the serum concentrations of important vitamins and nutrient minerals in humans.“
The only significant difference was seen in levels of strontium, which increased significantly for both men and women in the high dosage group.
Strontium is a non-essential trace mineral that can increase calcium retention in the body, so higher amounts – if caused by the clay – may be good for you. Research has suggested strontium may decrease fracture risk in osteoporosis and support bone health (25).
Other evidence of detoxification
The following are not clinical trials, nor do they always involve humans, but the findings supports the theory that ingesting bentonite clay might help with detoxifying the body.
Binds to antibiotics
Tylosin is a veterinarian antibiotic used for dogs, cats, chickens, and other livestock.
Researchers in Belgium wanted to see if the antibiotic (added to drinking water) and bentonite (mixed in feed) would interact in chickens (26).
“The results prove unambiguously the binding of tylosin by bentonite.”
Another study found that calcium and magnesium bentonite were more likely to trap the antibiotic tetracycline (27).
While it would be bad for it to bind to a helpful medicine, the clay could be healthy for you if it binds to harmful bacteria.
Does not bind to PAHs
Polycyclic aromatic hydrocarbons (PAHs) are a type of carcinogen found in cooked meats and polluted air.
Using a PAH urinary biomarker, there was no statistical difference between the placebo and the clay group (28).
While this may be disappointing, it does support the theory that only selective compounds bind to the clay.
Rotavirus and coronvirus
A laboratory experiment reported that absorbent agents like bentonite clay and activated charcoal had (31):
- 99% absorption rate for coronavirus
- 74 to 99.89% rate for rotavirus
The control used was white sand, which had less than a 0.01% absorption rate…. so perhaps eating dirt versus these clays really are a difference of night and day!
Researchers at Arizona State University proposed that specific minerals in clay “may prove valuable in the treatment of bacterial diseases, including infections for which there are no effective antibiotics” (32).
They tested a clay mineral in the lab (CsAg02) and found it to be effective against E. coli, penicillin-resistant S. aureus (PRSA), methicillin-resistant S. aureus (MRSA), and other dangerous bacteria.
In an attempt to prove this wasn’t some fluke, they tested the same antibiotic-resistant strains with a very similar mineral structure (CsAr02) and that one had no effect… that suggests the other may really be something special.
Removing harmful algae from water
Using modified montmorillonites, Chinese researchers found that it appeared to be useful for absorbing harmful algal blooms in the water (33).
Titanium dioxide binding
Colgate, Crest, and even most flavors for Tom’s of Maine use titanium dioxide for whitening. Not to whiten your teeth, but to make their paste look bright and pretty.
It’s also added to deodorant, shampoo, soap, and countless other chemicals around your house.
Given the suspected side effects of titanium dioxide and the plethora of foods it’s added to, many consumers are trying to reduce their dietary intake. That’s not easy to do, since lower concentrations don’t even need to be legally disclosed on ingredient labels.
The brand Redmond makes a bentonite clay toothpaste which is gaining popularity because it is a fluoride-free alternative. Though it may offer another benefit, too.
According to one study, apparently this clay is a magnet for this controversial coloring agent (34):
“The attachment of nTiO2 [titanium dioxide] onto clay particles (both bentonite and kaolinite) were observed under all experimental conditions.”
Not only is it TiO2 free in itself, but it might also absorb these particles when it comes in contact with them. Now consumers may have two reasons to use bentonite clay for teeth and gums. These are the 4 good flavors for Redmond Earthpaste.
Acne and skin exfoliation
The history of using clay masks and body wraps for their exfoliative properties is a practice which dates back to the earliest human recordings.
In modern times, you can walk into CVS, Walgreens, or an Ulta Beauty where you can buy products touting the benefits of bentonite clay for skin and hair.
Now whether or not they can moisturize low porosity hair when left on as a mask overnight is subject to debate. The website naptural85 may have a homemade recipe for this with rave reviews, but that’s not proof.
If the face masks help wrinkles or complexion, there has yet to be clinical validation of that. A bentonite bath may feel good, but there’s no proof it’s sucking toxins out of your skin and body as many websites allege. Though removing dead skin cells on the skin’s surface, as well as oily residue, is an advantage which can be claimed.
Using montmorillonite clay for acne might make sense, given its ability to absorb oily sebum on the skin’s surface. While its effectiveness for pimples and blackheads hasn’t been proven, there is research spanning back at least three decades where bentonite clay was actually used to collect and measure sebum secretion rates.
A layer was put on the subjects’ foreheads for 14 hours and after being removed, they analyzed the collected lipids using chromatography. That method was first published in the Journal of the American Academy of Dermatology in 1983 (35).
Whether using it as a face mask will help acne has yet to be clinically studied, but there is plenty of evidence that at minimum, this clay absorbs sebum from the skin’s surface.
Most of the hype is about allegedly detoxing from heavy metals and chemicals, but what if it also binds to unwanted fats that you eat?
In a study using rats fed a high-fat diet, it was found that the crystals appear to have fat-absorbing characteristics. As a result, more fat passed through the rat’s digestive tract and exited unabsorbed (36).
“In summary, our results indicate that DLA-M [dietary lipid adsorbent- montmorillonites] prevent HFD [high-fat diet] induced obesity. This novel dietary lipid-adsorbing agent can help prevent obesity and its comorbidities.”
Those who claim the juice fast with bentonite clay for your waistline are doing so prematurely, given that this is only one study involving animals. No one knows yet if it can help with dieting and losing weight.
How does the clay work?
Understanding how a poultice absorbs things on the surface of skin and hair is a more straightforward science.
When it comes to the possibility of internal detox from edible calcium bentonite, and related clays like diatomaceous earth or zeolite volcanic clay, at this point it’s only theoretical as to how any of these might work.
It is believed that bentonite works through its molecules which have a strong negative charge and large surface area. Those act as a magnet to attach to positively charged molecules in the body, including some toxins. Since the clay molecules are too big to pass through the intestinal wall, any heavy metals or other toxins which bind to them pass through the digestive system unabsorbed.
Of course any health benefits are purely theoretical and unproven at this point, but based on what has been observed in some of the aforementioned laboratory experiments – where scientists can actually see how the molecules bind – the chance of some being for real seem like a viable possibility.
The title of this scientific review says it all.
80% of the uses for bentonite or montmorillonite clay have little to no proof to back them up. In fact, many appear to be completely bogus. Being a treatment for Candida yeast, hair loss, autism spectrum disorder, and dozens of other topics had literally nothing even remotely related to them. Cruel hoaxes is what those are!
For up to around 20% of the claims, based on research, there does seem to be a real possibility that something beneficial might be happening. Though as of today, not even those claims have sufficient clinical data to be called “proven” as some websites allege.
Where to buy
Whether you want to use it externally for skin or internally as a supplement, it’s important that the brand is one that can be trusted and ideally, one that specializes in the clay.
Brands like Frontier (organic spice manufacturer), Now Foods (supplement company) and Queen Helene (a hair care company) are respectable companies which sell it, but they don’t specialize in it.
Since even the name brands are quite affordable, it doesn’t seem to make sense to buy a generic private label version from Vitacost, Trader Joe’s, or Whole Foods.
Now just because a name brand product is popular and has been on the market for years, that doesn’t guarantee purity from contaminants. But they do seem like a safer bet versus a mom ‘n pop operation who may literally be digging the stuff from their backyard in Wyoming, without testing.
Since it’s an inorganic material – not coming from a plant or animal – there’s no such thing as USDA certified organic bentonite. However one trait of organic foods is that they are non-irradiated. You can find clays with that characteristic (most have not been irradiated).
Some of the best brands based on reviews and length of time on the market are:
Is there a difference between Redmond bentonite clay vs. bentonite clay?
The manufacturer claims yes, that their unique deposit is “high in both calcium and sodium.” As mentioned above, the minerals in Redmond are different than most other clays on the market. Their large source in Utah, which they own, was used by the Indians and dates back to the Jurassic period. It’s definitely a unique product with perhaps the longest track record.
Aztec and Redmond are probably the two biggest companies who specialize in this.
Aztec Secret is a green clay which is 100% pure calcium bentonite. No fragrances or additives are used.
It’s non-irradiated. They sun-dry it for up to 6 months in Death Valley, where temperatures regularly hit 110 to 120° during the summer months.
The one pound container is a popular choice.
Great Plains Yerba Prima
For those who want an easy to use supplement that you can drink, this is a sodium version.
Despite the name, yerba mate bentonite clay is not what this is – it’s just clay mixed in a solution of water. The similar sounding Yerba Prima is the name of the company and has nothing to do with the caffeinated tea beverage.
The serving size listed is 1 tablespoon. Some combine it with their organic psyllium husk for regularity.
Check out the 32 ounce bottle of Yerba Prima Detox.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.