Are carbs "destroying your brain"? - Healthy Evidence

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Are carbs "destroying your brain"?


Has anyone responded to this? Why carbs are destroying your brain (£)

In his new book, neurologist David Perlmutter claims that the origin of brain disease such as dementia is predominately dietary. The result of us consuming too many carbohydrates and too few healthy fats. Can anyone contact David Permutter to Ask for Evidence?

25 Replies

Hi Emily, since the Times is subscription, can you do a bit of a summary for the rest of us?

In the mean time - here is Perlmutter talking about his book on YouTube:

He is certainly promoting his book everywhere he can - it has had a lot of coverage since its publication, but it is hard to find much discussions about the science (I am still looking)

This is a reaction from the Food Industry

in reply to JossS

Here is some extra reading - or at least it may lead to further more authoritative reading

in reply to JossS

Second that, if someone could dropbox the article that would be great!

I've just seen this and tweeted @DavidPerlmutter and @thetimes.

I expect we'll have to read his book in order to find out what research he bases most of his claims on. According to his Wikipedia page, the studies linking gluten and dairy sensitivities to headaches and Crohn's were conducted by himself and published in Case Reports in Immunology and the Integrative Medicine Journal. I have only seen this abstract, linked from Wikipedia, which is not a proper study at all but basically reports on three patients whose health improved after cutting out gluten. The Wiki article also mentions that Perlmutter is a medical advisor for the Dr Oz show.

It occurs to me that the Wikipedia article may benefit from some editing.

David Perlmutter has replied to my call for evidence via Twitter, directing me to the "science" section of his website. I've only had the briefest of glimpses so far, but let's just say it raises a lot of red flags.


Sara Stanner, Science Programme Manager at the British Nutrition Foundation has asked someone to give us a steer on this.

in reply to Emily_Jesper

I would be interested to hear what they say - my limited trawl around for research (for either side of the argument) is plagued by way too many vested interests. But then, that is not uncommon when it comes to nutrition and health, sadly.

We desperately need an independent, public orientated, database of studies that does not leave everyone swimming in the mire of self publicity and interests!

I'm not convinced that the information you will receive from the BNF will be impartial, as it is funded by companies that make processed foods and sugar. Independent peer-reviewed research data that is not influenced by commercial interest is needed here. The BNF, despite its Science Programme, is at the end of the day, a lobbying organisation for the food industry.


Due to the paywall on The Times, I am not able to look fully at the detail of this article but, more generally, I would be very cautious about any claim that suggests dementia can be wholly prevented. In fact the article starts by saying that the origin of brain disease such as dementia is predominantly dietary. Dementia itself isn't actually a disease, it is a condition caused by brain diseases but even if you look at diseases like Alzheimer's (the most common cause of dementia) - in the majority of cases research suggests that the causes are incredibly complex.

For some people with Alzheimer's and other forms of dementia such as frontotemporal dementia, the cause can be genetic and a mutation can be passed down in families which causes these diseases. Suggesting that these cases (while they are rare) can be caused by diet therefore clearly goes in the face of many years of solid genetic research.

Research into non-inherited forms of Alzheimer's suggests a complex mix of risk factors, including age, lifestyle and our genetic make-up (whether we carry any 'risk genes'). Cardiovascular risk factors such as obesity, diabetes, high blood pressure (which may be influenced by diet in some cases) do appear to be risk factors for dementia, but the contribution of lifestyle factors to our overall risk will likely differ from person to person.

In my opinion these claims, which also suggest an element of blame towards the person with the condition, are unhelpful and do not do justice to the complexity of these diseases.

Apologies that I can't comment more on the specifics.


Paraphrasing the article:

"The neurologist's eating rules by Dr David Perlmutter - author of Grain Brain

Eat plenty of... >>lists foods; some given a brief explanation as to why<<

Eat in moderation... >>lists foods; some given a brief explanation as to why<<

Avoid... all sources of gluten (including anything made with wholegrain wheat, contaminated oats)… and all forms of processed carbs, sugar and starch (including potatoes)… and all packaged foods labelled fat-free or low fat (unless naturally so) …and certain fats (including all commercial cooking oils)”

A couple of interesting responses about the evidence-base can be found on The Whole Grains Council website:

Wrote a bit about this article here:

in reply to drmatthewl

Nice article Matt - thanks for the mention.

This article seems to be a rather unsubtle piece of book promotion. There isn't the slightest reason to believe that sugar or grains "destroy your brain".

Because so little is know about diet and health (see ), people are free to make up myths and get rich by selling books that promote the latest fad.

It's true that we probably eat too much sugar because of the way it's surreptitiously added to almost everything by the food industry. But the only known problem that that causes is that it makes it very easy to take in too many calories.

Seen a couple like this in the telegraph and times the last couple of weeks. Most likely for the post-new year diet and health freaks.

Are carbs really destroying your brain?

In the article ‘Why carbs are destroying your brain’ as cited in the Times newspaper Dr Perlmutter, argues that ‘the origin of brain disease such as dementia is predominantly dietary, the result of us consuming too many carbohydrates (i.e. predominantly from wheat-based bread and pasta, as well as sugar) and too few healthy fats’. He bases this claim on the ‘latest science’, however closer inspection of the ‘science’ behind it (looking specifically at the articles highlighted in the Times piece) suggests serious weaknesses and flaws in the argument presented. The ‘evidence’ is based on two prospective cohort studies in elderly participants that investigated the role of carbohydrate in brain disease/dementia (Roberts et al. 2012; Crane et al. 2013) (observational data), as well as an editorial published in 2002 by Hadjivassiliou et al. that reported on case studies in patient cohorts with coeliac disease (again this is in observational data).

The evidence as cited in the Times article is very limited as it denotes data from observational studies. Observational studies entail observing participants in their natural state. These include cohort studies, case-control studies and cross-sectional surveys. These studies are generally more prone to bias and provide weaker evidence on the effectiveness of interventions (such as high carbohydrate consumption vs. no or low carbohydrate consumption) than randomised-controlled trials.

Furthermore, the studies cited report on ‘associations’ between carbohydrate intake and dementia. One cannot extrapolate the findings of observational research to causative mechanisms (i.e. an association does not make for causation). Also, most of the data cited appears to come from patient groups such as those with coeliac disease, with little or none carried out in healthy individuals, and if so, alongside poor dietary assessment measurements (discussed further). Clearly, studies in coeliac patients, a medical condition where individuals must exclude wheat, as well as rye and barley, cannot be extrapolated to a healthy population. Additionally, the two most recent studies were carried out in elderly population groups; any claim that carbohydrates cause brain disease needs to be investigated in healthy young populations.

The main crux of Dr Perlmutter’s argument is that the origin of brain diseases such as dementia is predominantly dietary related (i.e. a consequence of consuming too many carbohydrates and too few healthy fats). Yet, the dietary intake data of the studies cited in the Times piece is poor. For example, the prospective cohort study by Roberts et al. (2012) only measured dietary intake at baseline and failed to assess this throughout the study period (3 years). Because dietary intake can change over time the results obtained do not reflect true dietary intake data during the study period, meaning that the results are not a true reflection of what actually took place, thus leading to biased results. Furthermore, the method of dietary assessment used in this study was a food frequency questionnaire. Use of this method of dietary assessment is not without its limitations and is not considered the ‘gold standard’ (i.e. weighed food intake record) of assessment in nutrition research, making any results obtained susceptible to bias. Additionally, the second study cited (by Crane et al. 2013) did not provide any evidence of dietary intake data throughout the study duration (not even at baseline); meaning that the type of carbohydrates consumed (to influence glucose levels) is unknown. Perlmutter states that we should avoid ‘all sources of gluten’ and ‘all forms of processed carbohydrates’, yet it is clear that the evidence does not examine dietary data in any great detail to support this statement.

He also states that we should forget the idea that a low-fat, high-carb diet is good and cholesterol is bad. That we should instead follow a high-fat low-carb diet that denotes 75% fat 20% protein and 5% carbohydrates (as opposed to 60% carbohydrates, 20% protein and 20% fat). This contradicts international and national dietary guidelines that are based on sound science. Carbohydrates are key components in the diet, comprising sugars, starchy carbohydrates and dietary fibre. Starchy carbohydrates provide an important source of energy, and fibre is important for digestive health. There is also evidence to show that the type of carbohydrate consumed can affect risk of certain diseases including heart disease. Some forms of complex carbohydrates, such as pectin in fruit and beta glucan in oats, may slightly reduce the level of cholesterol in blood. These are forms of soluble fibre. There is also some evidence that resistant starch may have a slight, beneficial effect on CVD risk. Also the body’s tissues require a constant supply of glucose, which is used as a fuel. The main source of glucose is dietary carbohydrate but it can also be synthesised from protein. If the diet is low in carbohydrate (as suggested by Perlmutter), a greater percentage of dietary protein is used to provide glucose, which means less is available for the growth and repair of body tissues. Thus, carbohydrate in the diet has a protein-sparing effect. Furthermore, in contrast to Perlmutter’s claim, supporting evidence for carbohydrate consumption in the diet can be seen in results from large well cited studies such as the DASH (Dietary Approaches to Stop Hypertension), which showed a lower risk of dementia in a large cohort that consumed carbohydrate.

In terms of Perlmutter’s recommendation to increase dietary fat intake (by 75%), we all need some fat in our diet but it’s important to pay attention to the amount and type of fat we’re eating. There are two main types of fat: saturated and unsaturated. Too much saturated fat can increase the amount of cholesterol in the blood, which increases your risk of developing heart disease and stroke. Studies have shown that replacing some saturated fat with unsaturated fat in the diet reduces blood cholesterol. Public health advice is to reduce saturated fat intake and although saturated fat intake has decreased in the UK over recent decades, it is still higher than recommended. Therefore, a recommendation to increase dietary fat intake by as much as 75% of the diet is both unhelpful and unfeasible. In fact, this type of diet is only recommended in certain specific medical conditions such as drug-resistant medical epilepsy.

Overall, there is no concrete evidence that carbohydrate causes dementia. Looking at the evidence-base cited to back up the claim being made by Perlmutter it is clear that the ‘science’ is based on a small number of observational studies and on the associations obtained within these studies. Until more is known about the precise mechanisms underlying the cause of dementia it is premature at best to make statements of this kind.

For more information on healthy living please see


•The Times (2014) Why carbs are destroying your brain. Available at: (accessed 22nd January, 2014).

•Roberts RO, Roberts LA, Geda YE, et al. (2012) Relative intake of macronutrients impacts risk of mild cognitive impairment or dementia. Journal of Alzheimer’s Disease, 32:329-339.

•Crane PK, Walker R, Hubbard RA, et al. (2013) Glucose levels and risk of dementia. New England Journal of Medicine, 369:540-548.

•Hadjivassiliou M, Grunewald RA, Davies-Jones GA. (2002) Gluten sensitivity as a neurological illness. Journal of Neurology Neurosurgery & Psychiatry, 72:560-563.

What it requires is for you to change your paradigm. Is lowering cholesterol a good thing for example?

Much of the evidence base for international dietary guidelines is based on observational/epidemiological studies. As you wrote, they can identify associations, but not cause and effect.

Dr. Robert Lustig has examined the biochemistry of fructose, determining that it is a toxin that stimulates appetite, has to be metabolised by the liver, and consequently contributes to non-alcoholic fatty liver disease and insulin-resistance. Combined with high-insulin producing foods, such as many starchy carbohydrates, it forms a toxic cocktail of appetite stimulation, fat-deposition, hyperinsulinaemia, and hypertriglyceridaemia.

Before it was down-graded, the Food Standards Agency identified that the population are eating closer to 'Eatwell Plate' guidelines than ever before. Obesity and diabetes continue to escalate; this epidemiological association continues to be ignored.

The BNF has a pro-carb agenda, it is funded and governed by food processing companies. As is the Wholegrain Council. As other responses on here have already noted, there are too many vested interests in the nutrition business (and it is a business) for the public to be able to have clear untainted advice. Sadly, the government seems blind to the biases in the organisations like BNF that it listens to. That perhaps may explain the growing blight of obesity and diabetes on the nation's health.

You are so out of touch with reality, but it's no surprise as all we hear from the majority of the medical profession is this tired old dogma!! Go look at your sources again. There is no medical evidence that eating saturated fat raises cholesterol, nor that cholesterol causes CVD. On the other hand more and more evidence, a lot of it anecdotal because Big Pharma won't support studies that may reveal results that will shoot their own profits in the foot, that eating carbohydrates, refined or otherwise, (in many, possibly the majority, but not all individuals) cause elevated glucose levels in the blood that over prolonged periods of time will exacerbate the tendency to develop conditions such as metablic syndrome, and DT2, but also Alzheimers and some forms of cancer. Begin by reading Yudkin! Forget Keys.

PS Check out: Dr. Dominic D’Agostino from the Universtiy of Florida, on starving cancer! Fascinating.


Thanks for analysing Perlmutter's argument. This sort of thing is really helpful.

Yes - thank you very much


A double page spread has been published in today’s Sun (the highest circulating national at approx. 3 million) promoting David Perlmutter’s book Grain Brain



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I want to add here one more thing and that is autistic children are also fed GF/ CF (Gluten free/ Casein free) diet mainly carbohydrate by their parents because of this reason. The diet with gluten are found allergic and low immunogeneic to make the autistic child's weak immune system more weak.

Actually it makes the autoimmune disorder, as gluten is considered as a foreign in-digesting protein so, few people's immune system make antibodies against these gluten proteins and attacks the lower intestine which causes inflammation.

That's why there is another way of diet is found for the patients or children with neurological disorder like autism. This article may help to know better

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