It has been a very long time since I blogged, but this has really got my goat! I recently saw a post pop up in my Facebook feed with the big bold statement ‘100% of Hashimoto’s patients should NEVER eat gluten!’ This outlandish, fearmongering statement was followed by a long post making several unsubstantiated physiological claims about what gluten does to your thyroid and immune system. This post went to the extent of saying that if you did not completely cut ALL gluten out of your diet you “will be destroying your thyroid tissue, your brain, and if left ignored your ability to walk and talk.” – Yes, this is a direct quote!! Of course, they also claimed there may be several other undisclosed food items that you will also need to eliminate, however, you will need to make an appointment with them (for a small fee of course) to find these out… As a nutritionist and someone with Hashimoto’s this made me pretty darn annoyed! The fact is, that this claim is not supported by the current body of research and unnecessarily cutting gluten out of your diet can risk inadequate intake of calcium, iron, magnesium, zinc, and vitamins, including vitamin B12, folate, and vitamin D, while also significantly reducing your fiber intake. 1 A diet low in fibre can increase your risk of constipation, haemorrhoids, diverticulitis, irritable bowel syndrome, coronary heart disease, diabetes and colon cancer. There may also be other consequences due to disruptions in gut microbiota, however, these are still under investigation. As you can see, cutting gluten containing foods from your diet is pretty serious stuff and should not be done without sufficient reason (as supported by evidence). And with out appropriate guidance from a accredited practicing dietitian. On this note, I want to take a deeper look at the evidence related to Hashimoto’s and gluten -because if you are going to make a claim (or in this case, a counter claim), you must be able to support it with evidence! The Evidence: Firstly, no scientific societies have developed comprehensive dietary recommendations for Hashimoto’s. Further to this, there is no Cochrane review that has examined gluten free diet and Hashimoto’s. (Cochrane reviews are the top dog of high-quality systematic reviews; systematic reviews aim to include all relevant scientific literature in a particular field and evaluate that literature in terms of how well each study was conducted, and thus the quality of the evidence produced) These are two big red flags that indicate the evidence to support the claim that ALL Hashimoto’s patients need to cut out gluten, just doesn’t exist. The closest I could get to a systematic review on this topic, was a review that involved a search of several databases (PubMed, Embase, and Cochrane Library databases [to March 2019]) as well as the bibliographies of key articles – This means the reviewing authors have looked pretty extensively for as many studies as they could find to evaluate, although did not necessarily consider that quality of the evidence produced. 2 From this review, the authors developed a dietary protocol that they intend to further test in an experimental study. This experimental study will be a 6-month randomised (blinded) dietary intervention (parallel groups: experimental and control) involving 100 participants – and seemingly one of the most comprehensive trials in the field. This intervention is hoped to provide substantially more information regarding dietary protocols that may be beneficial for Hashimoto’s, however, at this stage we can’t say that this diet has any benefit (despite being based on a thorough review of the literature). Even after controlling for factors related to diet quality and other lifestyle factors, as this trial intends, the results will still require the support of additional studies (larger populations, with longer follow up periods) before definitive recommendations can be drawn. While this leaves much unknown presently, the results of this trial will definitely be worth watching out for. While we wait for these results, let’s take a look at the dietary protocol they will implement. As informed by the review of the literature, this experimental trail will recommend patients with Hashimoto’s consume vegetables, calcium rich foods, fruit, wholegrains (YES WHOLEGRAINS!! – Because the evidence to say gluten free is necessary is inconsistent), animal foods rich in zinc, animal foods rich in selenium, and nuts and seeds. 2 *Note: Remember, this dietary protocol under investigation and has NOT been proven to be effective as yet. Mind you, there would be absolutely no harm in following this well balance, whole food diet. There were also some foods which the experimental trial did suggest to limit, including;
*Note: These are recommended limitation (as well informed by the literature) – and not once do they say you can NEVER have these foods, nor do they try to create fear around these foods. If you are interested in the reason why these foods are recommended to be included or limited, check out the original research – it’s an interesting read. Of course, this is only one study and we should read more widely in order to make informed decisions. As I mentioned systematic reviews were scarce. I did, however, find a general review (published 2017) on the importance of iodine, selenium, vitamin D and gluten on the autoimmunity and dietary management of Hashimoto patients. 3 This review did indicate that there may be some evidence supporting the benefit of avoiding gluten if you have Hashimoto’s, although this review was not systematic and did not in any way indicate how studies were selected to be included or excluded from the review. There was also no consideration given towards the quality of evidence reviewed. This means, this review has not produced high-quality evidence and it would be very unwise to use this to inform significant changes in dietary patterns. In terms of assessing the quality of individual studies, I have pulled apart a trial that did report benefit of a gluten free diet for Hashimoto’s so you can see why the results should be interpreted cautiously (and in consideration of the entire field of research). The Effect of Gluten-Free Diet on Thyroid Autoimmunity in Drug-Naïve Women with Hashimoto’s Thyroiditis: A Pilot Study (2019) This trial aimed to investigate whether a gluten-free diet affects thyroid autoimmunity, hypothalamic-pituitary-thyroid axis activity and thyroid function tests in women with Hashimoto’s. The study claimed that in the gluten-free group there was a reduced thyroid antibody titers. While this sounds promising, we need to remember… This trial was significantly flawed due to a small sample size (group of people who participated; bigger groups of participants give stronger evidence). It was non-randomised. All participants were told of the risks and benefits of following a gluten free diet, and then they chose which group they wanted to be in. This is a significant flaw of the study! If participants were randomised, and blinded from the treatment they were receiving, the results would be far more believable. It had a short study period (6months; so who knows what happens in the long term – particularly in terms of the risks associated with removing gluten and the other nutrients found in these foods). A food frequency questionnaire was used to determine if they ate gluten (not exactly accurate, relying on memory and honesty. There is a very good probability that the participants were dishonest because they had selected their treatment group, and probably want to look like they are following it – this is called social desirability bias). We also don’t know from this dietary monitoring method, if participants were actually successful in selecting foods that were in fact gluten free – many foods (i.e. sauces, soups, stocks) will unexpectedly contain gluten). The study did report statistically significant (within group and between group) change in TPOAb and TgAb, this sounds positive and I am no immunologist, however, we don’t know if these changes were to a clinically significant level (It appears to me, that they are still well outside what is considered the normal range). These results could have also been somewhat a result of a placebo effect (placebos are amazing!), given that the participants chose to have gluten or not, after being told benefits v risks. It was not indicated if the study participants were also taking medications or other dietary supplements. We don’t know what their gluten intake was before the trial or if they changed their diet in other ways. We also don’t know if there were any other lifestyle changes that could contribute to the results. Interactions with vitamin D and selenium seem to be important considerations. As you can see, despite these results initially sounding promising, there were some major issues with the study that make the results very questionable – I certainly would not be making any dietary decisions based on these findings, particularly when considering the other studies also available.
The big take away points I am not an immunologist, and nor do I pretend to be. I have nothing to gain from this post – no sponsorship, I am not trying to sell you anything, and I do not see patients clinically. I just want to present accurate, unbiased information so we can all make informed health decisions. This is far from a systematic review of the evidence, but I have scoured the databases and leading scientific societies to ensure I am giving you as accurate information as I can. And here it is… There is NO clear or consistent evidence that in any way supports the ALL patients with Hashimoto’s need to follow a gluten free diet. I am not saying that we should completely rule this dietary approach out – I am saying we do not have enough clinical evidence to make this call, and it is ethically and morally irresponsible to make definitive, fearmongering statements like “100% of people with Hashimoto’s disease must be on a gluten-free diet.” This type of misinformation can create distrust in medical professionals and lead to people stopping medications – and this makes me angry! We do not have enough evidence to have any clear dietary recommendations for Hashimoto’s, but with emerging evidence we may be able to start to develop a clearer picture. It is also important to remember that if you do choose to eliminate any major food groups from your diet, to do so under the guidance of an accredited practicing dietitian who can ensure you are still meeting all your nutrient requirements
1 Comment
8/9/2020 04:33:38 am
fresh foods with adequate fibers, and lots of water is the best way to keep your gi tract healthy
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AuthorNikki is a PhD qualified Nutritionist and an expert in children's eating. Categories
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