The stuff people get wrong about eating clay

If you've spent any time in pica or geophagia circles, you'll know there's no shortage of "facts" floating around. Some are spot on, some are harmless old wives' tales, and a few are completely wrong despite being repeated like gospel. Mid-craving, it's tempting to cling to anything that makes you feel better about giving in, but bad information spreads fast in this space, and once something's been repeated enough times it starts sounding true whether it is or not.

This isn't about spoiling anyone's fun. It's about understanding the actual risks so you can make informed choices, because your cravings aren't going anywhere and you may as well learn to enjoy them safely.

Chalk doesn't cause a calcium deficiency. It's the other way round. If you're craving chalk or pale clays, it's usually because you're already low in calcium, and the craving is a symptom, not a cause. Low calcium can come from pregnancy, breastfeeding, hormonal changes or kidney issues, so if you suddenly find yourself dreaming about a good chalk crunch, it's worth getting your calcium and vitamin D checked before you tuck in. Eating chalk won't fix the underlying issue if your body isn't absorbing calcium properly in the first place.

Same story with iron. If you're drawn to deep reds and browns, terracottas, red nakumatts, red khadi, that's usually your body craving the iron oxide because it's already running low. Here's the twist though: some clays can actually make anaemia worse. The really absorbent ones, white khadi in particular, can bind to nutrients in your gut and stop your body taking in the iron it actually needs. I stopped eating white khadi for exactly that reason, it was dragging my iron down rather than helping. If you're anaemic, keep track of what you're eating and how you feel afterwards. It's the easiest way to work out which clays are on your side.

Constipation is the oldest side effect in the book, and it makes sense once you know clay's been used for thousands of years to treat diarrhoea. It's brilliant at firming things up. Too much of it and you'll be sitting there regretting it. If you're getting blocked up regularly, that's your body telling you to slow down, drink more water, and give your gut a break.

Parasites aren't a huge risk but they're not zero either, particularly with clay dug from areas where animals have been. If you forage your own, stick to clean sources and get it tested where you can. Ebola isn't a common concern in most places, but outbreaks in parts of Africa have been linked to handling contaminated natural products, so knowing exactly where your clay comes from actually matters, it's not just a nice-to-have.

A few other things worth knowing. Yeast infections aren't common but can happen if overconsumption throws off your body's pH. Clay cravings can pick up around your period, especially if you're already low in iron, so it's worth watching how you respond during that time. Poorly processed clay can carry plant fibres or hard particles that irritate your gut. And pavement chalk, school chalk, coloured chalk, "non-toxic" is not the same claim as "edible," they can contain binders, dyes or fillers you genuinely don't want anywhere near your mouth.

On the mental health side, pica isn't a mental illness. People, and plenty of animals, have been doing this for thousands of years, sometimes for nutrients, sometimes purely for the sensory side, and both are completely fine reasons. Some autistic people experience heightened sensory cravings, including for textures and tastes like clay or chalk, and that's just part of how some brains take in the world, not a problem to be solved. Paying close attention to texture and crunch is normal, and enjoying clay safely is entirely possible with a sense of your own limits.

Not all clays behave the same way once they're in your stomach either. Some break down quickly, some take their time. Raw clays tend to move through faster, shale stone slower, and slate pencils can sit there considerably longer. The slower it breaks down, the longer it's with you, which isn't always comfortable. Know what you're actually swallowing before you commit to a slow one.

For what it's worth, my own limit is no more than a tablespoon a day. That's a personal cut-off, not a universal rule. I'm lucky enough to be able to check my own bloods at home thanks to my NHS training, so I know fairly quickly if something's affecting me. Most people can't do that, so keep quantities small and give yourself proper breaks. Eating clay in small, mindful amounts isn't going to kill you. The whole point is understanding your own limits and actually paying attention when your body tells you something.

If you're going to crunch, the short version: stick to vendors you trust, go easy on slow-breakdown clays like slate pencils, learn about the source and processing before trying something new, pay attention to how different clays actually affect you, and don't beat yourself up about any of it. Pica is ancient and completely natural. Just keep it within your own limits.

Cravings are your body talking. Listen to them, but look after yourself while you're at it. The best crunch is the one that satisfies you without a trip to the GP afterwards.

Disclaimer: This is written for informational and hobbyist purposes and is not medical advice. My products aren't certified food-grade and are sold for collection, crafting and sensory enjoyment. Any consumption is entirely a personal decision and entirely at your own risk. If you have ongoing health concerns related to pica or geophagia, please speak to a GP or another qualified healthcare professional.