Sue's Blog

Diet-induced stuttering


I've started to notice when my nearly 5 year old is having a food reaction her stutter is terrible then in between times it's almost gone – Renee, facebook thread

I have an 11 year old daughter and the stuttering definitely escalates when we are not careful with her diet – Michelle, facebook thread

My son had a severe stutter for 2 years or more, it would get better for a while, then re-appear. When we started the first steps recommended on the fed-up website, his stutter disappeared within a few days and  hasn't returned. It's been 7 months now. He's 5 – Marion, facebook thread

Stuttering (also called stammering):

  • affects mostly children between the ages of 2 and 5
  • boys are more likely to stutter than girls
  • about 5% percent of all children will stutter for some period
  • about 1 percent of adults stutter

What causes stuttering – according to medical experts

  • obvious brain trauma such as a blow on the head
  • the side effect of medication such as anti-depressants anti-psychotics especially Clozapine.  Drug-induced stuttering has been reported in coeliacs (people with gluten intolerance) (Bär KJ et al, 2004)
  • they used to think anxiety could cause stuttering – but now they think that stuttering can cause anxiety (Craig A et al, 2017, 2005)
  • risk factors include a family history of stuttering, a family history of ADHD and symptoms of ADHD, (nearly 60% of school aged children with stuttering had symptoms of ADHD, Donaher et al 2012)

NO-ONE is looking at food

The only medical paper on diet and stuttering examined the effect of copper and thiamine on stuttering and found no connection (Hum et al, 2017).

4 reasons why I think stuttering is strongly diet-related

1. We have received numerous reader success stories - from parents who find that the stutter disappears when they either follow the cutting down instructions on our website - or do the full elimination diet.

Just realised my 3 year old has stopped stuttering since starting fs nearly 7 weeks ago! Another tick in the box for the one kid we thought didn't have a problem – Kylie [1246]

2. There is a strong link between ADHD symptoms and stuttering – and our readers have already seen exceptional benefits of the RPAH elimination diet on symptoms of ADHD.

With a diagnosis of ADHD, our paediatrician recommended Ritalin as a first step. I refused and taught her a bloody good lesson on the results that can be achieved with just removing food. She admitted she never thought it would work (in fact she put me down about it at the time) but because I had worked with a qualified dietician and we had an amazing change in my daughter she accepted it … – Roxanne [1472]

3. The child who stutters is not necessarily the one with ADHD – there’s a link to ADHD families.

My 7 year old son has been failsafe for a couple of years now with great results.  My 5 year old daughter has quite a bad stutter and it has just dawned on me that diet may make it worse. I have often noticed that her speech is worse when my son’s behaviour is at its worst. Her speech therapist pointed out that it may be due to diet and that his hyperactivity is the symptom but her symptom is stuttering.  Given that they both generally eat the same thing this makes sense.  I tend to be more lax with her diet though.- from [392]

4. Medications especially antidepressants and antipsychotics such as Clozapine can cause stuttering. This is not an allergy but a pharmacological reaction – in other words, the same as a food intolerance reaction.  It has been shown that children with food intolerance are slow or null metabolisers of cysteine dioxygenase which is one of the CYP450 enzymes (Breakey 2004), the same enzyme system that cause problems with psychiatric drug intolerance.  It seems that intolerance to antidepressants and food chemicals may be due to the same mechanism.
Which diet? - foods and additives that can cause stuttering

Most internet suggestions promote the GFCF (gluten free, casein free) diet, but in our experience:

  • the reason this diet works is that going GFCF removes most processed foods
  • people who improve after going GF  tend to assume the culprit had to be gluten, when it is more likely to be the propionate bread preservatives – except  coeliacs and their relatives

The diet we recommend – the RPAH elimination diet from Sydney’s Royal Prince Alfred Hospital – is much better for figuring out exactly which foods affect you or your child.


Nitrate/nitrite preservatives (249-252) in ham, bacon, hotdogs

“Our two and a half year old son had difficulty with stuttering for a few months … we removed all nitrates (preservatives 249-252) from our son's diet and within about a week the stuttering was gone. Yesterday, our son went on an outing to the zoo with my mother. Strangely, his stuttering returned full-force today … what he had for lunch and dinner yesterday? The glaring answer:  a HOTDOG.” - from [396]

Propionate bread preservatives (280-283, also hidden as cultured dextrose or cultured anything especially in organic or “healthy” bread and wraps)

Our nearly two year old twin girls both have lack of language … I started a gluten free and dairy free diet last week … Within days they had both improved very noticeably. At first I thought it couldn't work that fast but whilst reading your books I realise it might be lack of the bread preservative (propionates 280-283, also hidden as  cultured dextrose or cultured anything while claiming no artificial preservatives)”. – from [300]

Benzoate preservatives (210-218) commonly used in foods and medications

While we were doing the elimination diet, our doctor recommended daily double doses of claratyne liquid … On the second day my daughter started to talk incessantly and stutter a little … then on day 3 at daycare she became drunkish, socially withdrawn and stopped talking (this had improved on failsafe )… The claratyne liquid with sodium benzoate preservative  (211) went in the bin, we got claratyne tablets …  and the next day at daycare she was back to normal. – [394]

Sulphite preservatives  in dried apricots, instant mashed potatoes, juice, many other foods

Sulphites (preservatives 220-228) send my 17 yo into a complete ODD asshole … Since cutting out the crap that sends him loopy, from depression, out of control anger, tears and stuttering … he has gone from a failing student all his life to getting A's and B's in most subjects.. - from [1288]

Salicylates and benzoate preservatives (210-218)

My 9 year old son started stuttering when he was around 4 years old. He seemed to be sensitive to preservatives especially 211 (sodium benzoate) and I have steered clear of this preservative, but a few weeks ago his stuttering came back in full force, around the same time I had apple juice (very high in salicylates) in the house ... I now think he is intolerant to salicylates as well. I have changed all of his foods to failsafe foods, and his speech is now good … from [397]


Two hours after eating chocolate and banana (for her amine challenge, our 4 year old daughter was) defiant and oppositional again. And biggest of all, we couldn’t understand a word she said. We now know she is intolerant to amines in a huge way. – Wendy from [699]

Salicylates, amines, wheat, dairy, preservatives, colours, flavours

My son becomes hyper and stutters as a result of reactions to salicylates, amines, wheat, dairy, preservatives, colours and flavours. His older sister also stutters when reacting but she is more tolerant of foods and other reactions are milder. -  from [393]

Milk/dairy foods

We initially started my three year old son on the diet because of his hyperactivity …  I now have a list of symptoms such as stuttering … that I can link to cows milk as these have all gone since we eliminated it and its derivatives  from his diet … Since we took him off the cows milk (as well as failsafe) and got over the withdrawals my son now no longer needs speech therapy … “ - Kylie from [716]

What a speech therapist says about diet

(After seeing such a big improvement in my 4 year old daughters’s speech…) her private speech therapist has since done the diet with her own child and encourages other parents to look into diet - from [699]

My conclusion

It seems to me that the stuttering/diet connection has been overlooked. Stuttering can lead to social anxiety and poor self esteem. Children and adults with stuttering deserve every chance to explore possible causes.  Anyone who is interested in pursuing diet should be helped. A 3 week trial of diet is usually enough to find out what is going on. I would recommend:

“A simple way to start” from our website


To find out exactly what the culprits are: a 3 week trial of the RPAH elimination diet with challenges, supervised by an experienced RPAH trained dietitian from our website list

More reader stories

Our son is not stuttering anymore - he would get stuck on the first word or two of a sentence if he was overwhelmed and repeat it over and over unable to finish the sentence. It hasn't happened once since we started failsafe – from [1430]

Sue's book has been really helpful with our 2.5 year old boy. He was developing a stutter and drawn out speech impediment, but since we have changed his diet, it seems to have rectified the situation. It is alarming to learn that this was caused by foods – Ryan, from [1234]

… My five year old son’s stutter was so bad, that it would take him 3-4 minutes to get through a simple sentence. I was trying to be patient and not draw attention to it as the speech pathologist had told us, but it was not only driving me mad, but for the first time, it was really bothering him.

"Mu..Mu...Mu...Mu...Mum..... I....I ....I....I...I.... wa....wa. wa...wa..... Uh, what was I saying mum?” … 

Upon reading various fact sheets on the website, I had an epiphany! I had put dried apricots (salicylates and sulphite preservatives) in his lunchboxes for the 2 kinder days and 1 day care day a week for about the last 3-4 weeks. Just 3-4 each time, but I cut them out immediately while I kept researching.

Within 4-5 days of removing apricots [and no other changes], the stutter had improved, but was still apparent. After another week, other people started noticing the improvement.

That was the beginning. While the stutter had not vanished at this point, it was enough to make me convinced that there was something to all this 'intolerance stuff'. We got more serious, and finally started to see the gorgeous little boy that we knew was in there somewhere. The aggression all but disappeared, the frustration and the stutter were much improved but there were still times where things would go downhill again.

After hearing Sue talk, I decided to get much more serious, and undertook the complete elimination diet, including the elimination of dairy and wheat … The changes in the household were amazing. I was spending a couple of hours extra in the kitchen every day, but with the elimination of wheat [I am convinced] I had the extra energy to do it. A week in, and his stutter had all but disappeared. It was as if he had suddenly grown up an extra year or two …

We are lucky in a way, to have a son who reacts so quickly and obviously to things. It makes identifying problems a lot easier. During our salicylate challenge, he went off the chart for silliness, and the stutter got worse. During a course of antibiotics … he got aggressive, angry, and the stutter got worse. Every time we have slipped up with food, the stutter gets worse. It is our main indicator that something is amiss …  - Kylie from [991]

See more

Our Stuttering factsheet

Our stuttering story collection

Introduction to food intolerance



Mayo clinic on stuttering

Bär KJ, Häger F, Sauer H, Olanzapine- and clozapine-induced stuttering. A case series. Pharmacopsychiatry. 2004 May;37(3):131-4. Quote: Drug-induced stuttering has been described in association with several drugs, in particular antidepressants and low-potency neuroleptics. Here we describe a case series of stuttering induced by the atypical neuroleptics olanzapine and clozapine. … Seven cases of drug-induced stuttering were observed. Six patients suffered from stuttering in association with olanzapine treatment, and one received clozapine. Stuttering arose on average 2-21 days after initiation of treatment and ceased 2-5 days after discontinuation. Most patients suffered from additional diseases, such as … celiac disease …

Professor Ashley Craig, Dr Yvonne Tran, What is the relationship between stuttering and anxiety? “evidence does suggest that PWS (people with stuttering)  have higher levels of social anxiety (Craig, 2000), in which the anxiety is more likely a consequence rather than a cause of stuttering.”

Donaher J1, Richels C. Traits of attention deficit/hyperactivity disorder in school-age children who stutter. J Fluency Disord. 2012;37(4):242-52.

Breakey J, Is food intolerance due to an inborn error of metabolism? Asia Pacific Journal of Clinical Nutrition ( 2004) 13 (Suppl) S175
Quote: “… The fact that symptoms responding were in many of the body's systems meant that several possible mechanisms have been proposed but none clarified. Yet another mechanism was proposed with the use of a gluten and casein free diet in autistic children. Peptides from these proteins are absorbed and thought to act as opiates affecting brain function. However those using this diet also exclude additives, chocolate, MSG and other small molecular weight compounds … Since most of the suspect chemicals are aromatic in structure the possibility of their poor metabolism arose. This was supported by the finding that similar enzymes are involved in the metabolism of both the suspect phenolic compounds [additive colours and flavours, salicylates and the benzoate preservative] and the amines. … The numbers of slow metabolisers or null metabolisers of cysteine dioxygenase in autistics is much higher than the normal population. A study of non-autistic food intolerant patients showed similar biochemical abnormalities.”

Hum J et al, A pilot study into a possible relationship between diet and stuttering. J Fluency Disord. 2017;52:25-36