Carbs are bad news for the brain

Alzheimer’s disease (a form of dementia) is characterized by the build-up in the brain of a protein known as ‘amyloid-beta’. Not surprisingly, amyloid-beta has been ‘targeted’ by drug companies, including Eli Lilli who produced the drug Semagacestat which did a nice job of retarding amyloid-beta synthesis. However, in trials, Semagacestat accelerated decline in brain function in those who took it.

I learned this fact today reading a review from the European Journal of Internal Medicine entitled Nutrition and Alzheimer’s disease: The detrimental role of a high carbohydrate diet [1]. The review is dense with information, and I might extract its information over more than one blog. But for starters, I thought I would pull out at least some of the interest insights this paper contains.

One of the major points made in the paper is this: cholesterol and fat is really important to the brain. It points out that although the brain is only about 2 per cent of body weight, it contains about a quarter of the total cholesterol in the body. The authors point out several roles for cholesterol in the brain, including the synapse – the ‘gap’ where one cell can communicate with another. Communication here is via what are known as ‘neurotransmitters’, which are released by one nerve cell and float across the synaptic gap to exert the effect on the nerve adjacent to it. The authors summarise the importance of cholesterol in the brain like this:

Cholesterol is required everywhere in the brain as an antioxidant, an electrical insulator (in order to prevent ion leakage), as a structural scaffold for the neural network, and a functional component of all membranes. Cholesterol is also utilized in the wrapping and synaptic delivery of the neurotransmitters. It also plays an important role in the formation and functioning of synapses in the brain.

It’s also true that the brain actively takes up cholesterol (in the form of LDL cholesterol). This in itself suggests that cholesterol is desired in the brain and does something useful. Interestingly, a gene defect which leads to impaired cholesterol uptake by the brain is also associated with an enhanced risk of Alzheimer’s disease.

The authors of this review also point out that the fluid that circulates in and around the brain and spinal column (the cerebrospinal fluid) in individuals with Alzheimer’s disease is low in cholesterol and other fats compared to individuals without this disease. Also, those who run low cholesterol levels are found to be at increased risk of dementia.

What this got to do with carbohydrate, though? As the reviewers point out, carbohydrates raised blood sugar levels, and sugar (either in the form of glucose or fructose) can damage tissues through the formation of ‘advanced glycation end-products’ (AGEs). AGE damage can affect LDL cholesterol, and impair its uptake into the brain.

The authors of the review note also that individuals with type 2 diabetes (who tend to run raised blood sugar levels) have a 2- to 5-fold enhanced risk of Alzheimer’s disease. It’s been suggested that the fundamental problem here is impaired cholesterol availability by the brain.

What we’ve learned from this is:

  1. our brains need cholesterol
  2. a high-carbohydrate diet is likely to stop our braining getting enough cholesterol

Now, do we have any takers for a low-fat, low-cholesterol, high-carbohydrate diet?


1. Seneff A, et al. Nutrition and Alzheimer’s disease: The detrimental role of a high carbohydrate diet Eur J Int Med 2011;22:134-140

40 Responses to Carbs are bad news for the brain

  1. Nigel Kinbrum 29 March 2011 at 7:16 am #

    Dear John,

    Despite providing mum’s nursing home with a low-carb diet sheet for her Lewy Body Dementia (blobs of alpha-synuclein), I found her with a plate of biscuits one morning. The carer who gave them to her (a very good one, as it happens) told me that old people should “eat whatever they like”. Jeez!

    Cheers, Nige.

    P.S. Do you ever give lectures at small establishments? (hint!)

  2. Reijo Laatikainen 29 March 2011 at 7:16 am #

    Well spotted. What do you think of the effect of saturated fat on dementia?

  3. MrWeetabix 29 March 2011 at 11:27 am #

    Just for people in doubt of a carbohydrate based diet on weight

  4. fredt 29 March 2011 at 3:47 pm #

    What Neal D. Barnard, M.D. really shows is that a well designed vegetarian diet with whole food and nuts outperforms a poorly designed ominvore and sugar diet.

    Note that it was not tested against a meat and vegetable style diet.

    but what do I know.

  5. MrWeetabix 29 March 2011 at 4:20 pm #

    Meat isn’t even sustainable considering rising populations…

    Prices will also skyrocket.. what is wroong with grains…it isn’t like have a bowl of rice and you will suffers from a slow painful death.

  6. kateryna 29 March 2011 at 4:31 pm #

    The Neal Barnard study article was published in 2005 and focuses on weight loss and the cutting out of meat and fat (cholesterol). Now what does it have to do with this particular article that shows how the brain needs fat/cholesterol for proper functioning and on what diminishes the uptake of the cholestorol to the brain? Nice try MrWeetabix.

  7. MrWeetabix 29 March 2011 at 6:57 pm #

    You can get cholesteral from eggs, which at least doesn’t kill the animal…

    It is more sustainable also.

    Are you saying all vegetarians end up demented?

  8. MrWeetabix 29 March 2011 at 6:58 pm #

    Sorry I mean alzehmer sufferers! don’t kno why I thought dementia!

  9. MrWeetabix 29 March 2011 at 6:59 pm #

    And no I ain’t got it! haha…I’m contradicting myself…I forgot about the above article..and I’m vegetarian!

  10. John Briffa 29 March 2011 at 7:45 pm #


    As the title of this blog post says: carbs are bad news for the brain…

  11. Lori 30 March 2011 at 12:38 am #


  12. MrWeetabix 30 March 2011 at 4:53 pm #


    Dr Briffa, do you ever eat grains? at all

  13. John Briffa 30 March 2011 at 4:59 pm #

    Mr Weetabix

    Rarely, and usually in very limited quantities when I do. Why do you ask? Do you think I’m somehow missing out on something?

  14. MrWeetabix 30 March 2011 at 5:18 pm #

    Not at all.

    It just I tried to eat vegetables today, Broccoli, cauliflower and carrots and found they were very bulky and not energy dense.

    I find it easier to get calories via grains..

    But I’m not sure how you manage to get enough energy through your Primal Diet? I am not against it, I’m rather interested.

    Is it also important to use food scales? I’ve never done this before….but I feel somehow trapped by relying on pre-packed food which have the nutritional information printed…This is why I’m interested in your research!

    Would you perhaps be able to give me some time aside? I have tried to contact you via email but with no reply…I understand you may be busy aswell.

  15. MrWeetabix 30 March 2011 at 5:21 pm #

    BTW you can address me as Sam. My username probably winds you up! 🙂

  16. John Briffa 31 March 2011 at 6:08 am #


    I don’t give a second thought to the quantity of calories I consume. I do, however, focus on the quality of those calories. I look for nutrient-dense, sustaining foods which, in my case, include meat, fish and nuts.

    Your username – MrWeetabix – does not ‘wind me up’, but Weetabix does a bit. It’s an example, in my opinion, of rubbish food (fodder, actually) given a healthy reputation by its manufacturers which is then perpetuated by many health professionals and health agencies,

  17. MrWeetabix 31 March 2011 at 7:36 am #


    What would you advocate to a vegetarian, who doesn’t do well with eggs?

    B: 80g wheat ( fortified) MD: 80G wheat

    AS: Punnet of plums D: 81G rolled oats.

    That is what I am currently consuming, however as you have stated my B.M.I is very low. How would one improve? As surely if replace with vegetable foods they would equate to less despite being larger in volume and more nutritious.

    Dietitians on the NHS are no use…it is like they are brainwashed into this eatwell plate, like it must be accurate and no arguing is to be done…but I disagree…and I’m sure you would to?

  18. John Briffa 31 March 2011 at 8:48 am #


    I can’t give you personalised advice. However, what is most notable about your diet is (in my view) the absence of good quality protein and fat.

    My suggestion is that you seek advice from a nutritionist or naturopath, though their ability to help you will be somewhat constrained by the fact that you are vegetarian.

  19. Paul Anderson 31 March 2011 at 12:06 pm #


    A good source of calories might be coconut oil. Cocunut might also supply a limited amount of protein.

    Adding butter to vegetables would provide energy and also make fat soluable vitamins more easily absorbed. Butter from grass fed cow’s probably best option.

    Cheese of course is a very good source of calories and complete proteins.


  20. Kirsty 1 April 2011 at 10:09 am #

    I doubt there are studies into this but the sustainability arguments for vegetarianism don’t sit well with me. There are two main reasons. The first, based on my own experience and others who blog about paleo eating is that cutting out grains completely leads to consuming less food overall. I eat way less than my veggie sister. my diet is mostly fresh veg and meat. Secondly, veggie diets rely heavily on industrially processed foods from wheat and other grains to quorn, soy and similar non-foods. What is the overall environmental impact of growing, processing and transporting these industrial foods compared with eating local, unprocessed veg and meat?

  21. John Briffa 1 April 2011 at 10:47 am #

    Hi Kirsty

    Thanks for your comments. I occurs to me that sometimes livestock farming is painted as inherently wasteful (and wrong) and agriculture as something benign (and good) in comparison. It’s clearly not quite like this, as you allude to.

    If you haven’t read it already, can I recommend ‘The Vegetarian Myth’ by Lierre Keith?

  22. NSAHPT 1 April 2011 at 11:44 am #

    Add statins to a high carb diet, as recommended by the various national heart associations and one further perfects the phenomena that you report.

  23. MrWeetabix 1 April 2011 at 2:18 pm #

    On a large scale, vegetarianism would have less of an impact overall.

    As it is not possible for everyone to source to ‘local’ meat and vegetables, which ultmately leads to factory meat and foreign or long distance veg, which consumes much more energy.

    I personally do not consume Quorn, as why would you immitate something which you’re against?it just seems counter-productive in my opinion.

    Plus grains come in the form of groats etc in their natural form…Not all grains are in the form on crepes and croissonts!

    And meat requires processing, e.g. cleansing, checking for contamination etc…

  24. MrWeetabix 1 April 2011 at 2:19 pm #

    Also test the average body mass of a vegan/vegetarian against that of a ‘omnivore’ and see if carbs really are this obese potion you suggest it is…

  25. Kirsty 1 April 2011 at 5:32 pm #

    The two fattest people I know are vegetarians and have been for 20+ years.

    Meat processing can be done by hand if necessary, unlike grains. I don’t know anyone who eats groats or other unprocessed grains and who knows where flour sold in the UK originates. I certainly haven’t seen any rice, quinoa or corn fields in the UK. There may be a healthy way to be a vegetarian without eating industrial fats and grains but I doubt it. How is it moral to encourage others to eat things that damage their health and ultimately kill them?

  26. Kirsty 1 April 2011 at 5:34 pm #

    Also, you’d need to compare body mass against paleo eaters, not omnivores who eat grains.

  27. Galina L. 1 April 2011 at 6:55 pm #

    If you check Wikipedia article about Dr.Neal Barnard you will find that he is the animal right activist(“Up until 2005, Barnard also sat on the board of the Foundation to Support Animal Protection (the PETA Foundation)… Barnard also writes a medical column for Animal Times, PETA’s magazine.”) who advises to diabetics to go on the low-fat vegetarian diet because it suits his ideology.

  28. kate 1 April 2011 at 7:23 pm #

    ‘As the reviewers point out, carbohydrates raised blood sugar levels, and sugar (either in the form of glucose or fructose) can damage tissues through the formation of ‘advanced glycation end-products’ (AGEs). AGE damage can affect LDL cholesterol, and impair its uptake into the brain.’

    When I looked at the study abstract, the mere mention of AGEs gave me pause. These are produced by cooking meat, also. Carbs have nothing to do with it. If they do, then throw in the whole category of meat – which is eaten cooked, not raw (as many carbs as there are are, many are eaten raw). There’s your culprit.

    Also, look to the carb-heavy diet: vegetarianism, for starters, and show that eating that many carbs inexorably leads to Alzheimer’s. I don’t believe it does.

  29. Brian 1 April 2011 at 8:03 pm #

    What are your thoughts on lactaid milk (2% or whole) mixed with chocolate syrup to make chocolate milk? I don’t add too much chocolate but have heard that chocolate milk is a good post workout fuel and have been doing it in place of protein shakes for about a week.

  30. Alan 1 April 2011 at 9:02 pm #

    Mr Weetabix

    Out of interest can you name an ancient population that did not eat meat whose descendants are still alive today?

    Also, is it right that our planet earth does not have the space and resources to support upwards of 7 billion people?

    Do you think If the top 2% wealthiest people on earth did not own 50% global riches there may not be this problem of “sustainability”.

    What are your thoughts guys?

  31. John Briffa 2 April 2011 at 7:11 am #


    In reference to advanced glycation end-products (AGEs) you state:

    Carbs have nothing to do with it.

    Really?! Would you also have us believe that the AGE-related damage seen in diabetes also has nothing to do with carbs?

  32. Kirsty 2 April 2011 at 9:52 am #

    Kate – Most of the carbs in the standard recommended diet are certainly not eaten raw. The high-carb foods in particular can’t be consumed raw (wheat, rice, potatoes etc) and it’s useful guidance for paleo eating to avoid plants that cannot be eaten raw. Eating non-foods that require industrial processing – there’s your culprit.

  33. Riedel Caroline 5 April 2011 at 12:02 pm #

    This very well expressed and documented explanation gives me the reasoning behind what my doctor has tried to tell me (in the few minutes my insurance allots him). I follow some of the more seemingly educated medical sites online in order to be able to try and find more information which will help me to help myself in things regarding health. It is not easy to find a doctor who can or is willing to work WITH his/her patients! And it is my cynical reaction to our diminishing medical support system (here in Germany – where it was better in the past) that tells me, most doctors and the drug industry are working hand in hand to grab the last pennies we can fork up…………HEALING anything is at the end of their menue. I want to do, within reason, what I can to promote my health without meds as much as I can.

  34. Feona 9 April 2011 at 9:02 am #

    It may be too late to add to this debate, but the arguments for and against high protein/low carb diet continue to confuse me. I have osteoporosis and both my mother and her mother were diagnosed with Alzheimer’s in their 8os.There is currently considerable interest in the acid/alkaline balance diet to combat osteoporosis and even reverse it. Most animal protein is considered to be acid-producing in this context and should therefore only constitute only 20 per cent of the diet. The other 80 per cent is mostly vegetables, fruits and certain grains – quinoa, rye, oats (I think). It all get very complicated, but, from this blog and the ensuing discussion, it appears that my choice is between strong bones and possibly Alzheimer’s, or a weak skeletal system and less chance of Alzheimer’s. What am I supposed to do!

  35. Bill 3 May 2011 at 3:57 pm #

    Dear MrWeetabix,

    It’s not that meat isn’t sustainable, it’s that the rising population isn’t sustainable.

  36. Elenor 25 May 2011 at 12:23 pm #

    Bill says: “It’s not that meat isn’t sustainable, it’s that the rising population isn’t sustainable.”

    Oh BRAVO Bill! Superb! I’m gonna steal that and use it in my urging folks to go paleo (or at least low carb or at least non-grains)!

    Well said! ( er… written…)

  37. David 1 June 2011 at 4:14 pm #

    What a fallacious account of the article. Yes, I’ll stay with a high-carbohydrate diet. I just won’t eat processed foods with their processed sugars and tons of fat. Which is what the so-called “high-carbohydrate” diet that the authors are talking about is. Check the article: Their characterization of high-carbohydrate diet: “A diet high in processed carbohydrates and low in fats results in a rapid rise in blood glucose levels following meals…. Fructose, a sugar increasingly in use in processed foods, also because of economical constraints, is estimated to be ten times more reactive than glucose in inducing glycation [34].With the widespread availability of high fructose corn syrup as a sweetening agent, the Western diet is associated with much higher risk of AGE damage to proteins.”

    Do you know anyone recommending that kind of diet as a high-carbohydrate diet? Let’s name the big names in “high-carbohydrate” diet, the ones you’re implicitly deriding: McDougall, Esselstyn, Fuhrman, Ornish, Barnard, Campbell, Pritikin. So: Do any of them recommend a diet that is high-simple-sugars and processed foods-based?

    Do the authors of the study give any support for the consumption of the non-nutrient cholesterol? None.

    Then AGEs: In fact, sugar is low in AGEs and AGE formation compared to meat. Not just a little lower: Orders of magnitude lower. High AGEs are found in the diet in meats and cheeses and cooked high-fat nuts. Not in carbohydrate foods like potatoes, beans, green vegetables, and even including sugars.


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