Are crisps bad for you? What's really in the bag

By Dr Catriona Walsh, former NHS consultant paediatrician. Last updated October 2026.

When I was a medical student in Cambridge, visitors from home weren't allowed through the door without a box of Tayto crisps (potato chips, if you're reading this in North America)... Cheese and onion, smoky bacon, prawn cocktail. (The prawn cocktail one might be contentious.)

It was hard to know which were more welcome: the visitor or the crisps.

So I'm not writing this as someone who never loved a crisp. I loved them. I'd tap the last crumbs into one corner of the bag and tip them straight into my mouth like every other child in Northern Ireland.

Then I started reading labels. And what I found wasn't on the front of the bag.

By the end of this post you'll know what's really in a bag of crisps, and why it can leave you tired, low and reaching for another one. You'll see why your "healthy" pork scratchings might be no better, and why the official advice never warned you. And you'll have a crunchy, salty snack you can eat without reading the small print first.

If you grab a packet, you might want to read the back of it as we go.

What's actually in a bag of crisps?

Potatoes, oil and salt. That's the theory.

Turn over a bag of Tayto cheese and onion, nearly everyone's stinky favourite, and the flavouring contains wheat flour. It's right there on Tayto's own website. I checked the whole Tayto range in ASDA recently, and almost every bag contained wheat. So if you're avoiding gluten, your favourite crisps are a wheat grenade.

Hold onto the name Tayto. It comes back later, and unfortunately not in a good way.

The crisps that went to court to prove they weren't crisps

In 2008, Procter & Gamble went to the High Court in London to argue that Pringles weren't potato crisps. One of its arguments was that they're only about 42% potato. The rest is flour, starch, oil and seasoning.

Why would a company argue its own best-selling crisp isn't a crisp? VAT. In the UK, crisps made from potato are taxed. Most other food isn't. Reportedly around £100 million in past tax was at stake, plus about £20 million a year.

The High Court agreed with them. The Court of Appeal didn't. In 2009 it ruled that there's more than enough potato in a Pringle to call it "made from the potato", so they're crisps, and VAT is charged on them.

So for a while, in the eyes of the law, Pringles weren't food made from potatoes. The company that sells them said so, in court, to save on tax.

Forty-two per cent potato. I presume the rest is tears and regret.

It's a funny story, but it isn't only funny. A company that will stand up in court and argue that its crisps aren't crisps, to save on tax, will argue about anything that stands between it and a profit. Including what counts as healthy food.

Keep that in mind. We'll come back to it.

Crisps and oxalate

Potatoes contain a fair amount of oxalate, and frying concentrates it. Lab-tested potato crisps come in at roughly 13 to 21 mg of oxalate per small 28 g bag, depending on the brand.

On the Trying Low Oxalates scale, that's high to very high. Anything over 15 mg a serving counts as high there, and over 20 mg as very high.

And when did you last stop at one small bag? A big 8 oz bag (about 225 g) tested at over 100 mg.

Oxalate does more than form kidney stones. In lab studies, it damages mitochondria, the power stations in your cells, cutting their energy output and ramping up oxidative stress. If you've ever wondered why you feel flat after a "harmless" snack, here's what happens when your mitochondria take a hit.

Many people tell me they've cut their dietary oxalates right back after reading about them, and now they're scared of eating vegetables in case they make things worse. Some of them are still eating crisps, because crisps don't look like a plant. And some trigger oxalate dumping from cutting their oxalates too quickly, but this isn't the place to discuss oxalate dumping as it deserves its own post.

If you're only hearing about oxalate now, you might wonder whether it's behind some of your symptoms. I didn't suspect it either, until my "healthy" diet made me ill. My green smoothie story shows how easily it creeps up on you. And if you're already cutting back, crisps are an easy place for oxalate to sneak back in, so an oxalate counter would save a lot of guesswork.

The comfort-eating loop

Your body's master antioxidant is glutathione. It mops up the damage from stress, medication and toxins, and your mitochondria depend on it. When it runs low, you feel it. Low glutathione is associated with depression and anxiety.

And what do most of us reach for when we're low and anxious? Something crunchy and salty. Or sweet. Better yet, just the perfect combination of sweet, salty, and umami. Which is why so many processed food companies spend untold amounts on research so they can hit the optimal flavour combinations. Then once you pop...

What you get is momentary consolation wrapped in foil, immediately chased by guilt.

So you open a bag.

In lab studies, wheat gliadin forces gut cells towards accumulating oxidised, exhausted glutathione. You get a dose of oxalate, which adds to the toxic load. The seed oils have been heated, and heated oils oxidise. And because potatoes are nightshades, there's a side of sly, toxic solanines thrown in.

You feel worse. You reach for another bag.

It's a loop that's very hard to escape if nobody tells you it's there.

None of this happens in isolation. Your body runs on ancient tech, and it was never built for a modern world of seed oils, refined flour and a steady trickle of man-made chemicals. Every toxicant adds to the same load. Oxalate is one.

Gadolinium from MRI contrast is another, and the two can interact. In lab experiments, Professor Brent Wagner's team at the University of New Mexico showed that oxalate can pull gadolinium out of the chemical cage that's meant to keep it safe, and the reaction still ran at the acidic pH found inside lysosomes, your cells' recycling centres.

When the load gets too heavy, some people start reacting to things they used to tolerate, from perfume to gluten to petrol fumes. Researchers call that toxicant-induced loss of tolerance. Underneath it all, your mitochondria take the strain. I explain how these pieces fit together in my ATTRACT theory.

Crisps fill you up and leave you starving

A 25 g bag of crisps has about one and a half grams of protein. That's it.

Your body needs nine essential amino acids it can't make for itself, and is better off when the other non-essential ones are topped up, too. Crisps barely register on any of them. You can eat a lot of crisps and still be malnourished. Most of us are full and underfed at the same time.

In the famous Minnesota experiment, 36 healthy young men first ate about 3,500 calories a day for three months, while walking 22 miles a week. That much food was meant to bring each man to his "ideal" weight, not fatten him up. Today, it would be called overeating.

Then, for six months, their food was cut to an average of about 1,570 calories a day, mostly potatoes and cabbage with very little meat or dairy. As they lost weight, their rations were trimmed further to keep the weight coming off. That's still more food than many modern weight-loss plans allow. Some NHS programmes use about 800 calories a day for weeks, and people on weight-loss jabs or recovering from weight-loss surgery often eat far less.

The men became obsessed with food, irritable and exhausted, and as a group their depression scores shot up. At least one in four became seriously unwell. Two were admitted to psychiatric wards. One began dreaming of "eating senile and insane people". Another lost three fingers while chopping wood, in what the researchers couldn't say was an accident. It took him two attempts to sever the fingers, which is one more than anyone in their right mind manages unintentionally. When the men were fed properly again, their minds recovered. Many people eating a "normal" modern diet show the same signs, particularly the fatigue and mood issues.

A 2024 BMJ review pulled together studies of nearly 10 million people. More ultra-processed food was linked with higher risks of heart disease deaths, type 2 diabetes, anxiety and depression. These are associations, so on their own they can't prove the food caused the harm. But we don't only have associations. When people are actually switched off processed food and refined carbohydrates, things change:

What happens when people stop eating processed food

And here's my favourite. The US Department of Agriculture's own researchers fed women who were overweight and at risk of heart disease either a diet built on the official Dietary Guidelines or a "typical American diet" for eight weeks. All the food was provided, and the menus are in the study's supplementary files. Both diets came largely out of packets and boxes: shop-bought English muffins, brown-and-serve sausages, frozen roast potatoes, tinned soup, ketchup, salted tortilla chips and fruit juice. The guidelines version swapped in whole-grain pasta, reduced-fat cheese, turkey sausage and less sugar, and still came to about 325 g of carbohydrate a day. The guidelines diet lowered blood pressure a little. But it made no difference to fasting insulin, blood sugar, glucose tolerance, insulin resistance or cholesterol compared with the typical American diet.

The typical American diet. One of the worst diets in the industrialised world, in a country with some of the worst health outcomes. And the official guidelines barely beat it.

Their one win was blood pressure. Women who followed the guidelines started at an average of 128/73 and ended at 119/71, landing exactly where the typical American diet group had been sitting all along. Is the goal the lowest blood pressure imaginable? Push it that far, and the medical term is shock.

So why does nobody warn you?

Dietary guidelines are written by experts. To become an expert, you need to do research. Research trials can cost millions. So someone with millions (or better yet billions) to spare has to pay for them.

Guess who has billions.

PepsiCo, which owns Walkers, took in about $92 billion in 2024. Nestlé took in about 91 billion Swiss francs. Remember the crisps that weren't crisps? Now picture that kind of money and legal muscle pointed at the science.

The following comes straight from Parliament. In evidence to a House of Lords committee in 2024, Public Health England's former chief nutritionist, Dr Alison Tedstone, explained how UK nutrition science is funded. The main funder, the BBSRC, makes partnership with businesses one of its key criteria. In her words, "it is hard to secure funding for nutrition research without industrial partnership." And academics who turn that funding down "risk penalisation in their careers."

She also pointed out that the same government department, DEFRA, sponsors both the research council and the food industry.

Her conclusion? Excluding experts funded this way from advisory committees would risk "lowering the quality of deliberations." The Food Standards Agency's chief scientific adviser agreed, warning against shutting out "a huge wealth of information and expertise in industry."

So the system is built to put the food industry in charge of not just the room, but of torturing the data that is allowed to enter it. Then we're surprised by what emerges.

It reminds me of something I wrote in my free e-book series about MRI dye side effects. There, I describe your doctor as a gingerbread house: a warm, reassuring front, with the witch, the system that profits, hidden behind it. Nutritionists and dietary guidelines do the same job for the food industry. They're friendly and trustworthy; they genuinely mean well, and they invite you in to eat.

When researchers looked at the 20 experts on the committee behind the 2020 US Dietary Guidelines, 95% had conflicts of interest with food or drug companies. Kellogg, Kraft and General Mills were linked to several members each.

Why would drug companies care what goes into dietary guidelines? Because they win either way. When the guidelines turn a food into a villain, they create a new "risk factor" that needs treating. And when the guidelines fail and people get heavier and sicker, there's a drug for that too, from statins to weight-loss jabs.

Weight is the obvious one. So are the things we're told are "just vanity": acne, wrinkles, skin that's lost its bounce. I don't think they're vanity at all. I think they're information. My acne was the first sign that my diet was hurting me. Skin that sags early can be a sign your connective tissue is struggling. In my ATTRACT theory, that's what happens when toxins accumulate faster than your body can clear them. And weight that won't shift often points to struggling mitochondria, hormones and insulin resistance.

So if you care how you look, there's nothing shallow about that. It can chip away at your confidence, and it's hard not to feel judged. But the shortcuts come at a price. Weight-loss jabs and surgery can leave you eating less than the starving Minnesota men, which means even less protein, fewer minerals and fewer vitamins and antioxidants. In my view they add to your toxic load, too. And rapid weight loss can leave your face gaunt and older-looking, especially when you're short of protein. Nobody signed up for that.

In the UK, Dr Zoë Harcombe went through the group Public Health England set up to advise on the Eatwell Guide. By her count, six of its eleven members came from food industry bodies, including the Food & Drink Federation and the British Retail Consortium. In 2016 she wrote in the British Journal of Sports Medicine that the guide was "designed by the food industry for wealth, not health".

Public Health England's chief nutritionist answered that it would be "irresponsible" not to engage "with those who produce and market the food we all eat".

Would it, though? I know which way I'd lean if I made crisps. And I wouldn't go out of my way to shoot myself in the foot by pointing out how badly they may harm your physical and mental health.

The committee members met federal ethics rules, apparently. I don't doubt it. But nobody needs to be wicked for this to go wrong. If your research is funded by a company that sells breakfast cereal, it's very easy to see breakfast cereal through hopeful, rose-tinted spectacles. And no company spends millions on research that sends its customers running.

I've watched Big Pharma run the same playbook: pay for the science, then sell the conclusions back to us as public health advice. Our dietary guidelines are making us malnourished, and they were written with the help of the people who sell us the food.

If that makes you angry, you're allowed to be. You might also feel foolish, or sad about the years you spent eating what you were told was good for you, and missing things you loved. Please don't turn that on yourself. I fell for the healthy-eating advice too. You trusted people whose job was to be trustworthy. You didn't fail the guidelines; they failed you.

And bodies are forgiving. Remember the Minnesota men? Once they were properly fed again, their depression lifted. Yours can respond too, once you start giving it what it needs. So let's start with something small: the snack.

And if you'd like help working out what your own body needs, that's exactly what my free 90-minute call is for. More on that at the end.

Pork scratchings vs pork rinds

So you put down the crisps and pick up a bag of pork scratchings. Pigskin and salt, surely?

Remember Tayto?

Mr Porky and Midland Snacks Traditional scratchings both list pork rind, salt, monosodium glutamate, hydrolysed soya protein, wheat rusk and dextrose. Both brands belong to the Tayto Group, whose home is Tayto Castle in Tandragee.

The same company that puts wheat in your cheese and onion puts wheat in your pork scratchings.

I give Tayto a hard time, but I don't think anyone at Tayto Castle is plotting against you. I'd bet they have no idea the vegetable oils were already oxidising before they arrived at the factory gates, that potatoes are oxalate bombs, or that wheat might be the detonator that turns a small fire into a mushroom cloud.

They're caught up in the same myths as the rest of us. Myths that span generations, cross continents, and get added to year after year. A dead customer isn't a customer, and everyone has to eat. Most people who make ultra-processed food believe a little here and there never hurts anyone. "All things in moderation." It sounds sensible. Nobody has ever proved it, or defined what moderation even is. But it tells us exactly what we want to hear.

Homemade pork rinds are pigskin and salt. Shop-bought scratchings are another story. Read the label, or make your own.

Are pork rinds a healthy snack?

Homemade ones, yes, with a couple of honest caveats.

They're naturally low in oxalate, which makes them one of the easiest low oxalate snacks there is. No flour, no starch, no sugar, no flavour enhancers. They're crunchy, salty and moreish, and they scratch (pun intended) the exact same itch as a bag of crisps.

I make mine in the oven, with no deep fat fryer and no seed oils. Here's my oven-baked pork rinds recipe.

Glorious glycine

Pork rinds are a bit like dehydrated bone broth. They're rich in glycine, proline and serine, which your body uses to build and repair connective tissue.

Glycine is one of the three amino acids you need to make glutathione. Remember that comfort-eating loop? Glycine helps, but it's not enough on its own to help you escape it. Glutathione also needs cysteine, and skin, collagen and bone broth are all low in that. For that, you need meat, fish, shellfish or organs like liver, kidney and heart. More on that catch below.

Glycine also builds skin, joints and bones. Collagen is the most abundant protein in your body, at about a third of all your protein. And glycine makes up about a third of your collagen.

One caution. Some people convert glycine and proline into oxalate inside the body, particularly when deficient in vitamin B6. If that's you, go gently with pork rinds, bone broth and collagen.

Skin's other secret: GAGs

Skin isn't just collagen. It's also packed with glycosaminoglycans, or GAGs for short. They hold water in your tissues, cushion your joints, keep you limber and young looking, and coat the inside of every blood vessel in a carbohydrate lining called the glycocalyx.

I think GAGs are seriously underrated, and I have a theory about the job they do when your body's back is against the wall. That's a whole post of its own, and it's coming soon.

Your antioxidants come from protein too

We're told about vitamin C, vitamin E, fruit and vegetables for antioxidants all the time. We hear far less about protein.

Yet your heaviest-duty antioxidant defences are enzymes, and enzymes are made from protein. Superoxide dismutase, catalase, and the peroxidases, including glutathione peroxidase, deal with the most dangerous free radicals and peroxides before they do damage. Glutathione reductase recycles used-up glutathione so it can work again.

And those enzymes need helpers. Superoxide dismutase needs copper, zinc and manganese. Catalase needs iron. Glutathione peroxidase needs selenium. Glutathione reductase runs on riboflavin (vitamin B2), and the whole recycling system is powered by niacin (vitamin B3). CoQ10, which your mitochondria use to make energy, also works as an antioxidant inside your cell membranes.

Meat, especially red meat, and organs, particularly liver and kidneys, are top sources of zinc, iron, selenium, riboflavin, niacin and CoQ10. They're also the only reliable natural source of vitamin B12. Some microbes make B12, but that doesn't mean fermented foods will give you what you need: many contain inactive look-alikes. Animal foods also give you omega 3 and 6 fats, vitamin D and retinol (active vitamin A), along with the most digestible, complete protein.

Pork rinds vs potato chips: what pork rinds can't do

Here's the catch I promised.

Skin protein is low in several amino acids. It has almost no tryptophan. You need tryptophan to make serotonin and melatonin, and melatonin isn't only your sleep hormone; it's also a major antioxidant inside your mitochondria. Good luck sleeping well if you're short of it.

It's also low in cysteine and methionine, the sulphur amino acids. You need those for glutathione, for making sulphate, for methylation and even for making taurine. And it's low in lysine.

Pork rinds are a poor source of taurine itself, too. Shellfish, especially clams, octopus and shrimp, plus fish, are the top sources.

So, pork rinds are low in some amino acids. Crisps are low in all of them.

Pork rinds and bone broth are a wonderful add-on, but they can't replace meat. Swap your meat for gelatin, collagen and pork rinds, and you'll run short of tryptophan, the sulphur amino acids and taurine.

Pork rinds vs potato chips at a glance

Make your own

Think of it as a joy snack: one you don't have to be frightened of, and one you can reach for without reading the small print first. Two ingredients, a hot oven and a cast iron pan. The skin even supplies its own cooking fat: it renders out as the rinds dry, and they crisp up in it.

Make my oven-baked pork rinds

All the crunch, none of the tears and regret.

If crisps aren't the whole story

Maybe you've been eating "well" for years and still feel exhausted, foggy or unwell, and nobody can tell you why. Book a free 90-minute video call with me. That's about six times longer than a typical GP appointment, so there's time to go through your whole story. You'll leave knowing which pieces matter most for you, whether that's oxalate, toxic load, your mitochondria or something else, and what your next steps could be. A partner or family member is welcome to join you.

Frequently asked questions

• Are crisps bad for you?

  Eaten often, most crisps are a poor snack. A small bag carries 13 to 21 mg of oxalate, which counts as high, and many flavoured crisps contain wheat flour in the seasoning. A 25 g bag has only about 1.5 g of protein, so you can eat plenty and still be underfed. Frying heats the oils, and heated oils oxidise. Large studies link diets high in ultra-processed food with heart disease, type 2 diabetes, anxiety and depression. Official guidelines rarely warn you, partly because the food industry often funds the research behind them.

• Are pork rinds a healthy snack?

  Homemade pork rinds made from just pigskin and salt are low in oxalate and high in protein, with no flour, starch, sugar or flavour enhancers. They're rich in glycine, which your body uses for collagen and glutathione. Bake them in the oven and the skin crisps up in its own rendered fat, so there are no seed oils either. The catch is that skin protein is low in tryptophan, the sulphur amino acids and lysine, so pork rinds work as a snack alongside meat, fish and organs, not instead of them. If you convert glycine to oxalate, go gently.

• What's the difference between pork scratchings and pork rinds?

  They're close cousins. British pork scratchings are usually pig skin with a layer of fat still attached, fried until hard. American-style pork rinds are skin with most of the fat removed, dried and then puffed, so they're lighter and airier. Crackling is the crisp skin on a roast. In Spain, Latin America and the Philippines, the same family of snacks is called chicharrón or chicharon. Two leading UK scratchings brands list wheat rusk and hydrolysed soya protein in their ingredients.

• Do crisps contain gluten?

  Many flavoured crisps do. Tayto cheese and onion lists wheat flour in its flavouring. Watch out for yeast extract too. Some is made from spent brewer's yeast, a by-product of beer made from barley, while some is grown on sugar beet molasses or other sugars with no grain involved. In the UK, barley has to be named on the label if it's there, but if you're unsure, ask the manufacturer.

• Are crisps high in oxalate?

  Yes. Lab-tested potato crisps contain about 13 to 21 mg of oxalate per small 28 g bag, which counts as high to very high on the Trying Low Oxalates scale. A large 225 g sharing bag tested at over 100 mg. Potatoes are naturally high in oxalate, and frying concentrates it as the water cooks off. In lab studies, oxalate damages mitochondria and raises oxidative stress, so it's worth more than a passing thought if you're tired all the time. If you're cutting back, do it gradually to avoid oxalate dumping.

• What's a good low oxalate snack instead of crisps?

  Homemade pork rinds are one of the simplest. They're crunchy and salty, with almost no oxalate, and they scratch the same itch as a bag of crisps. All you need is pigskin, salt, a hot oven, and a cast-iron pan. Shop-bought pork scratchings are often lower in oxalate than crisps too, but check the label, because two leading UK brands contain wheat rusk and hydrolysed soya. Here's my oven-baked pork rinds recipe. 

• Can pork rinds or bone broth help me make glutathione?

  Partly. Glutathione is built from three amino acids: glycine, cysteine and glutamate. Pork rinds, collagen and bone broth are rich in glycine, but they're low in cysteine. So they can only help if you're also eating good sources of cysteine: meat, fish, shellfish, eggs, or organs such as liver, kidney and heart. On their own, they won't top up your glutathione.

• Can collagen, gelatine or bone broth replace meat?

  No. Collagen is low in tryptophan, the sulphur amino acids and lysine, and it isn't a good source of most vitamins and minerals. If you swap meat for collagen, gelatine, bone broth, and pork rinds, you'll run short of protein building blocks and nutrients like zinc, iron, selenium, and vitamin B12. They can be a brilliant addition to a diet with meat, fish and organs. But they can't replace them.

• Do gummy sweets count as a source of gelatine?

  Sadly not. Sweets like Haribo do contain gelatine, but it comes wrapped in sugar and glucose syrup. A whole 100 g bag of Goldbears has under 7 g of protein, alongside 77 g of carbohydrate. If you want gelatine, bone broth, slow-cooked cuts on the bone and homemade pork rinds are far better sources.

Sources

This post is for education, not personal medical advice.