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Does anyone know of any research connecting sugar with IBS?

I just discovered yesterday in Professor John Yudkin's book 'Pure, white and Deadly' that sugar is a stomach irritant, as in if you look at the interior of the stomach when it is given a sugar solution (particularly on its own) it will make the lining turn red and it inflames the tissues, I had no idea it did this. Has anyone seen any research or heard anything about sugar's effect on the gut or a connection to IBS? Sugar is so pervasive these days you actually have to work to avoid it so I wondered how many of us might be eating it with no idea it could be contributing to/causing our IBS problems.

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Hi, my body cannot absorb Fructose or Lactose , Fructose is the natural sugar in Salads, Fruit ,Apples And Pears have the highest amount .Tomatoes and onions are a definite no go for me .I have to read the label on everything's I eat ,Tablets usually contain Lactose .I can have Dextrose ,so I only have weight watchers White bread . I have a very boring Daily diet .If I eat some thing with Fructose in I am doubled up In pain and have to dash to the loo.I had my Gallbladder out 3 years ago.I wish I had never had it out . Hope this helps .


Hi Sammy, I confess I did wonder if it might be a fructose problem. I know it's the fructose part of sucrose that causes diabetes and metabolic syndrome - it's the bad part, as it were - but I know they also recommend leaving fructose out in the FODMAPS diet. I really love my fruit so I'm loath to give it up. I've gone on a low sugar diet and hope to phase it out completely, except for fruit. I'm going to see If it helps, but I have noticed I get more colic after fruit so I'm dreading that might be the reason! It's anew thing though, I never used to have a problem with fruit, and I don't have one with milk, although I do know that A2 milk agrees with me more than ordinary - that's a protein issue though, not sugar.


I have recently given sugar up (apart from the odd minor blip) and have noticed a massive difference. My stomach is very sore, bloated and acidic after consuming anything sugary or with a high sugar content. I feel lighter, have more energy and have noticed less grey circles under my eyes and my digestive system feels less stressed in general. It is alarming how many things have added sugar but I am finding if I stick to plain meat, fish and veg that I feel a lot better.


Hi Florence - glad to hear someone else is doing the same thing! I'm on my second day 'sugar free', although I am not wholly as I am still using it in bottled sauces and diluting drinks, but I'm keeping them to a minimum and I'm not renewing them when they run out. But I've ditched all the junk foods and white breads and cereals. But man, the cravings. They've only just kicked in but I expect I'll have them at least a week or more. Serves me right! But I'd love to hear from you again further down the line with how you've got on. Have you cut all sugar, including fruit, or are you just cutting added sucrose in packaged foods?


Funny you should mention grey circles under the eyes. I have noticed that I have developed these and put it down to tiredness, even though I seem to sleep quite well. So you think it might be connected to IBS? I never thought of that.


Dark circles under the eyes are usually connected to liver problems. I know this because when I had gallstones, and was very sick with them, I developed big black bags under my eyes - hence the 'looking liverish' expression. I've also noticed, weirdly, that on TV shows about people doing weight loss it's common for obese people to have them before their diet is cleaned up, and they are often pre-diabetic, which of course is related to liver/cholesterol problems. All that said, I'm sure there are other health problems that cause them!


I find that for me (and it is all very much down to the individual) that if I eat some protein, chicken, eggs, nuts and good fat like olive oil, avocado or coconut oil (also fish, brown rice and quinoa) then I feel more satisfied. It does take time to re-train your taste buds and create different habits but the more I read about sugar the more convinced I am that this is much better and I can honestly say the difference I feel is huge. I have always struggled with lactose but a few other irritants for me include garlic, onions and spicy food so I tend to avoid things with long lists of ingredients. As long as I have a better snack to hand (current naughty fav coconut or nut butter on rice cakes) or a handful of nuts and I drink plenty of water then I don't miss biscuits - eat to make your body happy and fight disease don't feed it😋


Couldn't agree more, and I'm with you on the onions. I've never been great with them but since I developed IBS they have been a major pain - literally!


There are a few points I feel an urge to correct. I'm not sure where to start so I'm just going to take them in the order I saw them:

- there is no hard evidence that fructose causes diabetes and the patterns scientists see are probably more likely to be a reflection of the types of diets in general rather than increased fructose

- that said, fructose can be a problem for some people with IBS. I avoid rum (high in fructose) and foods containing fructans (like bread, onions and garlic) where I can. The problems with fructans (one of the oligosaccharides in the low FODMAP diet) is that humans simply cannot digest them. The problem isn't the fructose in these foods as it is the fructans themselves.

- another possible cause of IBS flare-ups from eating fruit is the polyols (sorbitol and mannitol) in fruit, which again can't be digested by humans but are digested by the bacteria leading to IBS symptoms.

- sucrose is a source of glucose and fructose but as the fructose and glucose are present in equal amounts they are absorbed into the blood stream together and so there should be none left for the bacteria. That said, I sometimes wonder whether if food is travelling too quickly through our guts, do we not have time to fully digest all the sucrose, making more of it available to the bacteria.

- while cravings can be a sign of addiction, they can also be a sign that your body needs that food. We require a lot more energy for our minds and bodies to function properly than our ancestors did millennia ago. When I am working hard at work I have sugar crashes and I carry dextrose tablets with me for a shot of glucose when I urgently need it. If you are cutting out sugars (and all sources of them) make sure you're getting sufficient energy elsewhere. Carbohydrates should take up a significant portion of your diet.

Finally, do you have a reference for that study about the stomach lining getting inflamed due to sugar? Would be interested in reading it.


Hi Patient, with respect I'm going to disagree right back at you - there is a lot of hard evidence that fructose is the problem in diabetes simply because it is fructose that causes insulin to be released (NOT as spikes, but in a long-term mechanism that I have promptly forgotten; I need to go look it up!) and therefore insulin resistance (when the body can no longer handle how much insulin is in the system) and that, in turn, causes diabetes. It is so commonly accepted as the cause that I'm a little baffled as to why you feel it is under some doubt?

You are absolutely right with the fructans and the sugar alcohols - the latter certainly give me bother and always have. I have IBS with constipation but I can always rely on sugar alcohols to go right through me! I've certainly read the theory that IBS may be caused by bacterial overgrowth in the (lower) gut, but that one is still under debate. They know the gut microbiome is affected by certain things, but it does seem to be uncontrollable, largely (hence no hard evidence that probiotics work), and there is no clear evidence as to what is actually happening, or whether it's a chicken and egg situation. I always steer clear of the gut microbiome theories because they are in their infancy and it is just depressing when there is nothing you can really do to help yourself!

Lastly, I'd love to believe my cravings for chocolate ice cream is a nutritional deficit but I just know it's not. It's very much biochemically driven and is simply an addiction caused by my brain lighting up like a Xmas tree every time that sugar/fat parcel is delivered. Unfortunately I'm a binge eater and abstinence is the only way I can get the sugar monkey off my back! I've tried for decades to 'eat like a normal person' around sugar but it can't be done. I also hate to disagree on the 'need' for carbohydrates but it simply isn't true. Your brain needs glucose as fuel, yes, but it doesn't actually need carbs to get that glucose. It can in fact burn ketones just as well. It's a bit of a myth that we need carbs, no doubt from all the food pyramid ideology that the government has churned out for years.

The reference to sugar being stomach inflammatory is in Yudkin's book. I suspect he did the study himself, but I'm not sure. I can try and find it again for you if you want? Let me know. I suspect it's also in Thomas(?) Cleave's book, which is from 1969, I believe, and a forerunner of Yudkin, I'm pretty sure he was the first doctor (ship's surgeon, I think) to observe stomach irritation from sugar. Let me know if you'd like me to try and find that reference in Yudkin.

P.S. See addendum below!


I admit you sent me looking back through my biochemistry text books and for a trawl of PubMed. Seems my knowledge is a little bit more outdated/rusty than I realised: I had overlooked one part of the pathway of fructose metabolism. All the same, I still believe that fructose taken in as part of a healthy diet isn't going to contribute to diabetes in the mainstream population.


Absolutely, fructose in the whole fruit itself is fine. It's not good on its own or as part of sucrose or as fruit juice and smoothies though. And I always feel I need to add the caveat that even whole fruit can be overdone. As low-carb diet gurus always point out, we were never meant to eat fruit all year, and modern cultivars are bigger and sweeter than wild and ancient fruits that hunter gatherers would have eaten, so yes, you probably can overeat fruit, especially if you have fructose intolerance or poor insulin resistance. But, hey, most people don't eat enough fruit so I think it's probably the least of our worries!


I just checked it I Robert Lustig's book - it's because Fructose causes fat metabolism in the liver (hence cholesterol problems in metabolic syndrome diseases). So although Fructose doesn't cause sugar spiking (that's why it used to be recommended to diabetics) it causes fatty liver disease, obesity and all the related problems leading to diabetes and beyond. Also, it would be sugar in general that causes insulin release, not Fructose on its own - all sugars cause insulin release, but it's the Fructose part of the sugar that is metabolised into fat in the liver and that's where the problems start. Roughly speaking - I'm damn sure it's a lot more complicated than that!


Not heard of this but its interested. Sugar is EVERYWHERE but I've heard repeated studies about it contributing to Alzheimers too.


Yes, Autumn, some scientists are now postulating that Alzheimer's is diabetes Type 3. My grandmother died of Alzheimer's and she was corpulent when she died (she didn't know she'd already eaten so just kept eating), but she had been overweight all her life and was married to a 'feeder' who used to bring her ice cream and lemonade every night. She was definitely a living (and dying!) advert for sugar damaging your brain in the long-term.


I did wonder about sugar, and was told to go on the candida free diet, wondering if my problem is more candida!



Yes, Myrrtle, there's quite a strong argument for SIBO (bacterial overgrowth) being the cause of IBS, but I find it depressing because it's almost impossible to treat yourself (you really need antibiotics). That said, the one thing you can do for it is starve the little mothers out. They love their sugar; take it away and you get die-off. Of course, go back to it and they'll come right back; they're tough little sods and very resilient!


I am having a terrible time at the moment, I went to see a functional practice doctor, who said I had leaky gut, which is candida over growth, with is like what you said above.

Every time I try and follow her suggested diet I get lose stools, which I just can not live with, I have to go to work and be professional, I get more anxious.

So I go back to my normal diet, which is low sugar anyway, but included sourdough for breakfast, if I follow this I get fairly normal stools. So I am stuck in a weird place!!!!


Hi Myrtle. You don't always get candida overgrowth with a leaky gut; the two things are actually separate, although one can facilitate the other. Did she actually test you for Candida, likewise leaky gut? If you do have a leaky gut your problem could be autoimmune reaction to proteins in your bloodstream, particularly wheat proteins. I think that's the basis of Non-coeliac Gluten Sensitivity, but don't quote me on that! Likewise a leaky gut can be causing allergy or inflammation. There's a theory that suggests fibromyalgia and arthritis could be linked to that, for example. But all this would be based on some kind of proof of leaky gut, which I believe is really hard to do.

Also, if her diet is giving you the runs it sounds like she may not be adhering to FODMAPS for you, which she really should be doing. What is it about her diet that makes your guts react, do you think? What's different to what you normally eat?

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So she did testing and looked at my diet and stress levels and came up with leaky gut, you are probably right about me not having candida, as think it was my stress levels and immune after the flu with knocked my gut out, not over eating on sugar, as I never did really.

So I have been having oats for breakfast with lactose free milk, I lost so much weight from almond milk and cashew milk, I was starving all the time, so went back to LF milk, but now think that might have caused problems. I brought some raw milk today, but now not sure about that - hmm all over the place.

IBS? Leaky gut? Candida?

I just know sourdough works! I makes things a bit more normal and predictable - which is rather nice. But I do not want to eat it if it is damaging my gut - you know??!?!

I am not sure what to do next? What to think? Another Drs appointment or see her again? At a cost.

I suspect my gut flora got knocked out by the flu and my stress levels at the time, but not sure what to do to repair it now.

I tried greek yogurt and was ok on that, do I try and build the probiotics back up?

Thanks xx


Probiotics are very iffy. So far all the rigorous scientific testing that's been done on them has failed to show any improvement with them. There's always the problem that the nature of the gut, to digest food and protect us from bugs, destroys any potential merit in eating a probiotic (we just digest them!) so I think they are probably a waste of your hard-earned cash.

Personally, I'd do the FODMAPS diet, if you haven't already done that. If you do it for the two months they suggest then carefully reintroduce the food groups as per their instructions ("The Complete Low Fodmap Diet" by Dr Sue Shepherd and Dr Peter Gibson) this will narrow it down for you so that you are not blundering around in the dark. One of the troubles with our omnivore's diet is we eat so many different things that it's a minefield trying to identify the culprits.

It will only cost you the price of the book and it will almost certainly improve your health simply because it is so broad base. Once you've done that you will be armed with much greater knowledge (hopefully!) of the source of your problems.

But always remember you may be one of a minority of people who may have a more serious illness like Coeliac Disease, or a skeletal problem that's affecting the gut. Have you actually been diagnosed with IBS by a GP?


I did do (and still do) the LOW FODMAPS and it worked really well, apart from some foods.

Then I tried a functional practitioner and things all changed, she said IBS was a blanket term doctors used when they did not know what was wrong. UGH!

After the flu and the stress I went back to the doctors many times and they finally said cut out dairy, and that helped, then there were other things so I went back again and she said IBS, and that was that - left in the dark there I guess. I do not know to go back, do doctors take it seriously?

So I looked on the internet and followed FODMAPS, and it worked for a bit, but still sensitive to sugar at this point and dairy obviously, so looked for a functional practitioner. And that is where I am now.

Lost, confused, and fed up.

I think I will stick to FODMAPS, which I pretty much am, basically fish, chicken, green veg, no dairy etc etc.

I just want to get better.

I find breakfast the hardest, I used to eat loads of fibre brown breads, loads of wonderful fruit, I feel robbed of my diet.

Breakfast, what can I have, no toast, not really oats, unless I have with water? The functional practitioner said I was sensitive to almonds, so no almond milk, who knows if that is right, cashew milk is too rich for me :(

If it was Coeliac Disease would I not be constipated? Rather than diarrhoea?

I think what ever I had was brought on by a really stressful time and the bad flu combined - it seemed to ruin my gut flora.


First off, hell no on Coeliac - diarrhoea is the norm for coeliac disease. In fact, they use it as the primary diagnostic. Have you never been tested for coeliac? From the way you are spelling it I guess you are in the UK, as I am? If so, your doc should have tested it for you automatically when they diagnosed IBS. Shame on them if they didn't! If you haven't had it tested that's the very first thing you must do, but you will need to eat wheat every day for 6 weeks before you have a blood test otherwise it will give a false negative.

Here's a link to Coeliac UK's assessment - it's nice and quick and easy to do and will tell you immediately if you are at risk. It also gives you a handy thing to print out and take to your doc which shows exactly why you should be tested.


You will have to register to do it but it's free. I never tell people what to do but in this case I'm going to make an exception! - you really MUST get this tested - I can't believe no-one's given you one. Lots of poor souls are walking around with IBS diagnoses when they actually have Coeliac Disease, and it's a life-threating condition. Anyway, just think, if you do prove positive for Coeliac the only thing you will have to give up is wheat (and maybe dairy, at least until your gut repairs itself!) - think what a relief that would be!

Let me know how you get on. X

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Thanks, I have a docs appointment soon, my friend is coeliac but suffered from C rather than D so I just guessed it was more C.

On the wheat thing, when I eat sourdough though everything goes back to normal, stool wise. So I am not sure it would be wheat causing trouble???

Thanks. xx


You'd think! Annoyingly, I know I've read something about why sourdough bread is more easily digested recently but I've got about 6 books on the go at the moment and I can't remember which one I read it in! If I can find it I'll give you a shout. I FEEL it was something about the fermentation in sourdough breaking down the gluten, but I could be talking rubbish. That said, I'd still get the test done; if nothing else it will put your mind at rest and it's one more thing to tick off your list. They should also test your IgA and possibly something else I've forgotten now - it's all helpful to know. I have IgA deficiency, for example, ten times more common in coeliacs, but blood tests keep coming up negative for me. I still feel I have an issue with wheat and I'm either an unlucky coeliac who keeps getting false negatives or I suffer from NCGS - which could your problem too. I should really ask for a biopsy just to check, but I'm a big coward and hate the idea of sticking something down my throat!

I think I'm right in saying you may well not get immediate symptoms on eating wheat with coeliac disease, because some coeliacs present with no gastric symptoms at all. Some get minor gastric symptoms or occasional symptoms, and others present with gut ataxia or just a rash, so I definitely wouldn't eliminate it as an idea just because your gut finds sourdough a little easier to handle.

Anyway, I'll see if I can find the bit on sourdough and get back to you. In the meantime though please do get the coeliac bloods done. They're quick and easy and fairly reliable - although not foolproof - and at least you'll know you didn't give yourself colon cancer or osteoporosis just because you didn't get a blood test done! X

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Thanks again for your advice. I will ask my dr when I have this nx appointment :)


You're welcome. Just remember to say nothing about being able to tolerate sourdough - don't give him any excuses to refuse you. As far as he is concerned, wheat doesn't agree with you, full stop! Best of luck. Let me know how you get on.

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What do you have for breakfast? Just out of interest? I used to LOVE breakfast, but can now struggle. I am post infectious lactose intolerant so porridge is usually out, I do have almond milk in tea, I used to love porridge fruit or toast, I struggle for ideas now :(


I'm really boring at breakfast! I have scrambled egg and smoked salmon every morning. I buy two packs at Aldis and split them in half so that lasts me 4 days. The other three days I alternate with (frozen) smoked haddock or salmon fillets. I used to eat it with grilled baby tomatoes but they are currently verboten because I have silent reflux/oesophagitis. But I hope to get them back eventually. If I have to eat cereal I make my own muesli or have Kallo puffed brown rice. That's nice with banana and berries, but it's light and doesn't sustain you long. The muesli is better because I put a lot of nuts and seeds in it. I used to be a dedicated cereal eater until I went on a low-carb diet. I found the protein breakfasts so much more sustaining and also easier to digest (that tells you something about grains!) so I stuck with them. I've only very recently realised, after giving up sugar (again!) and going onto FODMAPS that I haven't been eating enough for years. Ironic, given that I'm overweight. However, I realised because I've spent my whole life starving myself in one way or another that I just did it all the time and that that was driving my overeating (constant snacking, eating every hour instead of eating enough at meals). Since I stopped it and made myself eat decent sized satiating meals (full fat) I've started losing weight, Unbelievable but true!


Yes Uk. :)


As I understand it the sugar situation in IBS is explained by the Monash institute within the information for FODMAP diet. Since following FODMAP I can have some sugar without pain (so I assume that it isn't irritating my gut anymore) which is lovely.


Hi Lorna. Yes, according to the FODMAP diet it's fructose that's the problem sugar (that and sugar alcohols) but this is a different kind of thing. Yudkin was talking about sucrose. Of course, it's quite possible that it was the fructose part of sucrose that was doing the irritation but he wouldn't have known that when he wrote his book (1969). And it's also quite possible that sucrose still inflames the gut but the effect is going unnoticed because who puts a sugar solution onto human intestines and watches the effects in modern research?!


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