Geophagy - The Dirt on Eating Dirt! By Karen Read

Jun 20, 2024
Dr Conor Brady
Geophagy - The Dirt on Eating Dirt! By Karen Read

Have you ever gone into your garden and found your dog digging at the ground and eating or licking the soil? I’m sure you’ve shooed them away, and if they are particularly persistent, you may have even been told that it’s just unwanted behaviour and that you should seek the help of a dog trainer.

But did you know that there is usually a much deeper reason for a dog eating the soil than just a behavioural issue?

Your clever canine is most likely practising Geophagy—intentionally eating earth, soil, or clay-like substances to seek out nutrients/minerals, antibacterial or antifungal agents, and even detoxification compounds.


When your dog is digging down into the soil to avoid bacteria on the top spoil, they may also be looking for clay. Clay has many healing properties, one of the most important being its ability to aid detoxification.

Clay has a negative charge whereas most toxins and pathogens are positively charged, so they are drawn to the clay where they are adsorbed - meaning that they stick to the surface of the clay as opposed to being absorbed (passing all the way through the clay). With the toxins/pathogens attached to its surface, the clay then passes out of the body. Clay can also help to balance the bacteria and fungi in the microbiome.


Soil is packed full of nutrients and minerals such as magnesium, potassium, calcium, manganese, iron zinc and Vitamin B-12. Having learnt all about animals self-medicating and using natural compounds to heal themselves using Zoopharmacognosy, it comes as no surprise that our dogs also have the innate ability to seek out minerals and nutrients that they may be lacking, from the soil.

Some soil is packed full of Humic Acid & Fulvic Acid

Humic and Fulvic acids are natural, organic substances that have been in our environment for millions of years. They originate from decaying plant and animal matter over time, a natural process that creates nutrient-rich compounds and shows us how decay and decomposition in nature can sometimes nourish us and ensure that we thrive!

Hard to recreate in a lab, as nothing better than mother nature creates them, these soils would be the best way for your dog to get a good dose of humic and fulvic acid. So what’s so good about them anyway? Let’s delve into the benefits….

  • Great for itchy skin - there’s a reason we humans enjoy being smothered in mud and clay at the spa. Humic & Fulvic acids are natural antibiotics, anti-inflammatory, and antifungal. These wonderful acids were also shown to enhance the healing of wounds infected with drug-resistant pathogens! This could be why your dog loves nothing more than to roll around in the mud in certain parts of the garden or fields you walk in.
  • Supports healthy digestion and gut health—These compounds are full of nutrients, such as amino acids, phytochemicals, and trace minerals, like zinc, manganese, copper, selenium, and iron. They also support the gut microbiome by creating an environment where beneficial bacteria can thrive.
  • Supports a healthy immune system—These clever compounds pack a nutrient-rich punch, and fulvic acid has the unique ability to puncture cell walls and deliver the nutrient directly into cells in the body, enhancing immune function. It can even help to balance electrolyte levels, giving your dog more energy!
  • They help to remove toxins - Humic and Fulvic acid are masters at detoxification! They are natural chelators binding heavy metals and toxins and eliminating them from the body quickly and efficiently. They can even repair damage to cells caused by toxins. I’m sure you’ve all heard of the dreaded glyphosate, well humic acid is the boss when it comes to removing glyphosate from the body. It does this by binding to glyphosate which is sadly present in most kibble (and possibly fresh food if the ingredients have been sprayed) and destroys it before it reaches the intestines where all of the vital bacteria would be destroyed by this sadly all too common toxin. Humic acid can also support the gut in general so great if your dog has eaten something nasty, this is where you may see them seeking out dirt, to help support their gut.
  • They can support cognitive health - Studies on humans showed that fulvic acid has several nutraceutical properties, including the potential to protect against cognitive impairment, especially in Alzheimer's disease.

Digging, rolling and eating soil (as long as it has not been sprayed with any kind of pesticide) is the best way for your dog to find humic and fulvic acid (they innately know where to find it and how much they need) but if you want to add this to your dog's diet, there are many companies who sell these in supplement form, some soil based probiotics also contain them. Always work with a holistic vet before adding humic or fulvic acid as they can have an impact on thyroid levels, especially if your dog has an existing thyroid issue.

The search for helpful bacteria and anti-fungal agents

When your dog is having a good old dig or eating the soil, they could also be looking for bacteria in that soil such as Streptomyces. This species is known for its antibiotic properties and some antibiotics used in conventional medicine such as Tetracycline contain Streptomyces.

Oligomycin is a natural anti-fungal found in soil that can help to battle issues such as yeast infections. 

Propythium could help here too! 

So is your itchy dog seeking the soil to help with what could be a yeast issue? Propythium is an incredible microscopic, non-pathogenic (doesn’t harm plants or animals) algae-like organism that normally lives in the soil. Over 50 species have been discovered so far, but among the most useful are those discovered around the roots of many plants worldwide, particularly Pythium oligandum.

It works via mycoparasitism. In essence, it consumes other fungi for survival. It attacks those organisms, extracting nutrients such as nitrogen, carbon, and nutrients for reproduction, and killing the organism in the process. It then creates zoospores that actively seek out more of those fungi and its spores.

P. oligandum is also antibacterial. It secretes enzymes that curb bacterial growth in the area so it is not disturbed while it’s doing its thing. Better still, studies show that despite reducing any pathogenic bacteria present, it does not induce significant shifts in the hosts bacterial flora in the process (Vallance et al. 2009 & 2012). Best of all, once resources (any yeast/fungi present) are depleted, P. oligandum encapsulates and soon leaves its host to its natural environment, at which point all normal microflora activity can return to the area.

You can buy Propythium from us, we have an ear cleaner and effervescent tablets for skin and very soon, the moisturising oil will be available

Herbivores and birds practise geophagy too

It’s not only our domesticated dogs that practice Geophagy. Other species do this for similar reasons but geophagy is vital for the survival of some. Herbivores such as horses and cattle rarely vomit, unless they are very ill, and often rely on geophagy to eliminate toxins or to help settle their stomachs.

Researchers in New Guinea observed many different species of birds, from parrots to hornbills, descending on a particular area, some species having never been seen in the area before, to eat the soil. The soil was too fine to be selected for grit, which birds use to aid digestion, but when the soil was tested, it was found to contain high levels of tannic acid and quinine, suggesting that the birds were likely eating the soil to bind and eliminate poisonous toxins and to counteract the bitter tasting secondary compounds in the fruits and seeds that they consume.

An interesting study with rats, who do not have the ability to vomit, found that when they were given an emetic (a drug that induces sickness) they would seek out Kaolin clay which adsorbs the chemicals in the drug. When they were given an antiemetic, they stopped seeking out the clay.

When soil eating and digging might be an issue

We can clearly see that our dogs' eating and digging the soil have many benefits. However, like everything in life, if this activity has become excessive, then it may need further attention.

Of course, this can be due to boredom leading to attention-seeking behaviour when the dog is “told off” for digging up the garden, it’s a great way to get our attention. If you feel that this is likely due to more behavioural issues than self-selection/medication, then seek the help of a dog behaviourist. Ensure your dog has adequate mental stimulation and is not left alone for long periods where they become bored and anxious, leading to these types of behaviours.

If your dog starts obsessively eating soil, it is worth considering what issues could be going on with their health. As stated above, soil contains many amazing healing properties and could show you what may be wrong with your dog. Are they seeking soil because of digestive upset? Do they have a yeast issue? A B12 deficiency? Or could they have ingested some toxins?

Natural Additions

If you think your dog is eating the soil more than usual and they are showing signs of digestive upset, itchy skin or yeast issues, there are some natural additions we recommend giving a go


S. boulardii is a little yeast. We're always focused on probiotics as bacterial-based but here's a little yeast coming up with the goods and is very much classified as a probiotic as a result. One issue S.boularddi is VERY good at solving is Giardia.

Studies show S.boulardii, a soil-based probiotic, is as effective as the antibiotic Metronizadole at clearing Giardia in dogs only its side effects include reducing the damage caused by infection, preserving gut integrity AND inhibiting oxidative stress that results from the parasite with Metronizadole!

Other studies show that S. boulardii helps the gut biome stabilise and recover, unlike Metronizodole, which annihilates it, leaving the door open to re-infection.

Gut flora tests and FMT

If your dog’s gut is not functioning properly, and you have tried all of the recommendations in Conor’s Canine Allergy Course and in our various gut clinics you may want to perform a gut biome test to see what is really going on.

Then of course there is FMT - Faecal Microbial Transplant (more on this in a future blog!)
We highly recommend you check out Legacy Biome - Use the discount code DOGSFIRST15 for 15% off your first purchase with them.


Sudden and obsessive eating of dirt may need some further investigation by a vet, just to see what might be going on and if your dog is deficient in a mineral etc

But if your dog enjoys a good dig, roll, and chomp off the soil occasionally, I know it can mean a messy walk and some muddy footprints on your carpet, but if you know it hasn’t been sprayed with any pesticides, let them at it. It’s so good for them, and they know what they are doing, even if it looks crazy to us.

As my nan used to say when I came in from the garden covered in mud as a kid, “A bit of dirt never hurt,” and how right she was.


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