High starch diets associated with increased risk of type 2 diabetes

Last week one of my blogs focused on story regarding the spiralling costs of medication for diabetes. I suggested that one reason for this is that many diabetics are advised to eat a diet rich in starchy carbohydrate, yet these foods generally are very disruptive to blood sugar levels. Yes, that’s right – diabetics who by definition tend to run high blood sugar levels are often advised to eat plenty of foods that cause high blood sugar.

In that blog post I cited a study which showed that low carbohydrate eating allowed more than 95 per cent of type 2 diabetics to reduce or eliminate their medication. This, by the way, does mirror what I see in practice. Low-carb eating is not a sure-fire way of controlling blood sugar in every individual with diabetes, but one thing I know for sure is that by an large this is a highly effective strategy (and for quite obvious reasons too, I think).

Could low-carb eating have some value in the prevention of type 2 diabetes? In theory, yes. And here’s why:

As distinct from type 1 diabetes (in which the pancreas produces little or no insulin), many individuals with type 2 diabetes make lots of insulin, it’s just not doing its job properly. This situation is described as ‘insulin resistance’, and the more insulin one secretes over the course of one’s life, the more likely one is to become insulin resistant. Eating less blood sugar-disruptive carb could, therefore, lead to generally lower levels of insulin and less risk of insulin resistance.

Some type 2 diabetics are suffering from a degree of ‘beta-cell exhaustion’. It is the beta cells in the pancreas that make insulin. The harder these cells are worked during our lifetime the more likely they are to get exhausted. Now we have the potential of low levels of insulin. The risk here is that some people can end up secreting low levels of not-very-effective insulin.

Anyway, one doesn’t need a PhD to realise that eating a lower carb diet will generally lower insulin levels and make less demands on the pancreas. In short, common sense dictates that a carb-controlled diet should help prevent type 2 diabetes.

The best way to confirm or refute this concept would be to randomise people to a high- or low-carb diet, follow them up over time (preferably, several years) and see if the lower-carb dieters had lower risk of type 2 diabetes compared to the higher-carb eaters. I can’t find such a study in the scientific literature, and have a hunch such a study is unlikely ever to be done.

The next best thing is to look at populations (preferably large ones) and see if, over time, there is any relationship between carbohydrate intake and risk of type 2 diabetes. This is precisely what a group of researchers from the Netherlands did recently, and their findings were published on-line this week in the American Journal of Clinical Nutrition.

In this study, almost 38,000 adults were followed for an average of 10 years. The researchers looked at the relationship between not just carb intake and type 2 diabetes, but also the tendency of those carbs to disrupt blood sugar. Specifically, the researchers assessed the relationship between the glycaemic index (GI) and glycaemic load (GL). The glycaemic index is a measure of the speed an extent to which a standard weight of food releases glucose into the bloodstream. The glycaemic load takes into account the amount of carbohydrate eaten too, and therefore generally gives a better indication of the overall amount of blood sugar disruption that comes from food.

In some of their analyses the researchers took account of factors that might affect diabetes risk including age, sex, levels of physical activity and other dietary factors. In these analyses it was found that:

Higher carbohydrate was associated with a 20 per cent increased risk of type 2 diabetes

Higher dietary GI was associated with an 8 per cent increased risk of type 2 diabetes

Higher dietary GL was associated with a 27 per cent increased risk of type 2 diabetes

Higher sugar consumption was not associated with a statistically significant increase in risk of type 2 diabetes

Higher starch consumption was, however, associated with a 23 per cent increased risk of type 2 diabetes

The authors also quote other studies that have attempted to discern what, if any, dietary GI or GL has with diabetes risk. While not all studies show a link, six do (and therefore are consistent with the findings of this latest study). So, by my calculations that’s now seven studies we have linking high GI and/or GL with enhanced diabetes risk.

Now, I know there will be some that claim that the evidence is ‘inconclusive’ here, but that’s a matter of opinion. To my mind, science, and of course common sense, support the idea that if we’re keen on doing what we can to protect ourselves from type 2 diabetes, we need to be a bit careful with those carbs, and not swallow whole without thinking the conventional advice that tells us we can safely and happily have our fill of them.

References:

1. Sluijs I, et al. Carbohydrate quantity and quality and risk of type 2 diabetes in the European Prospective Investigation into Cancer and Nutrition–Netherlands (EPIC-NL) study. Am J Clin Nutr 4 August 2010 [epub ahead of print]

17 Responses to High starch diets associated with increased risk of type 2 diabetes

  1. Stef 6 August 2010 at 10:13 am #

    Hello Dr. John

    Reading this in the context of the link to your July 2010 blog, and the Jan 2009 and 2008 blog (about Diabetes UK advice) is great input – thank you.
    Best wishes
    Stef
    PS I like the new web presence :)

  2. Neil Fiertel 6 August 2010 at 10:35 am #

    I stopped eating carbs other than what is found in modest amounts of legumes six months ago. I also lost 21 kg in that period of time. My blood glucose dropped from pre-diabetic to well into the normal range. Further, triglycerides dropped dramatically, HDL went up and LDL went down. What can I say but, Dr. Briffa, it was your advice that I used to set up my eating regime. I was told completely conflicting dietary information by several “experts” in nutrition. It is as if these folks do not have a clue about scientific research and are going by presumption made in 1880! Tens of millions are being made sick by terrible nutritional advice. If it were not for my two weeks of internet study and several research papers published on this blog I would likely still be overweight and would be heading directly to diabetes II. I thank you Doctor for your research and insight and can only recommend this approach to eating which is high protein, high fiber and reasonable amounts of fruit as well ( 5 or so portions) and normal amounts of fats included animal and olive oil. I eat 2.5% yoghurt, In other words as all the super low animal fat advice is nonsense. My blood lipids dropped like a stone and yet I eat sausages when I wish and the main change in my eating is NO sugar. NO Carbs. I am my own control. I will stick with this easy diet forever. I have NO insatiable hunger and the chocolate bars in my kitchen are just getting stale as I have no desire to eat sweets any longer. I am amazed by it. I can only say, try this approach and I suggest you can succeed losing weight and improving your health.,

  3. dennis 6 August 2010 at 12:13 pm #

    Type 2 diabetes is not due to carbs – it is due to malnutrition as 90 % of the calories in the western diet comes from nutrition poor processed foods – I suggest you read Paul Clayton’s ‘Health Defence’ and Joel Fuhrman’s ‘Eat to Live’ for explanation. Also diabetes type 2 can be avoided and reversed with diets which are not obsessively low in carbs, provided that they are high in nutrients (loads of fresn veg, fruit, nuts, seeds etc) but avoid added fat and excessive animal food consumption – in addition to the above books see Neal Barnard’s ‘Reverse Diabetes Diet’ and Gabriel Cousens ‘There is a Cure for Diabetes’. Transport of glucose through the bloodstream under control of insulin is an absolutely normal human biological process and is done without problem and without risk to health in a normally healthy body – if one cannot eat carbs, the body is not working properly.

  4. Stan 6 August 2010 at 12:49 pm #

    Hi John, Like Neil Fiertel, I was actually diagnosed as T2D just 4 years ago, was given the ‘normal’ diet advice, ie. low-fat, starchy carbs. etc.
    Luckily for me I came across Barry Groves nutrional website, and like yourself,advises the low-carb,high fat way of eating.
    Needless to say, I dropped 2 1/2 stone, Have gradually dropped from hab1ac of 7.5 to 6.5, then 6.2 and earlier this year 5.5. Trigycerides from 2.7 now 1.1, Chlorestrol from 6.5 now 4.8. Blood pressure 160/99+ to now 135/85 – 140/85.
    And all this with a good fried breakfast every morning, fatty meat, cheeses, cream in coffee,fish, prawns, offal etc. BUT no bread, cakes, sweets, no fruit, few veges occasionally. Feel fine at 76 of age. Even then my diabetic nurse, said be careful with this diet! And because I am not on drugs for diabetes, cannot have prescribed test strips etc. I do use these for my own peace of mind, but not cheap.
    Anyway, keep up the pressure on the ‘system’ and a little sorry to mention your ‘competition’ Barry, but you know what mean. Thanks again. Stan

  5. andy 6 August 2010 at 5:07 pm #

    This study was done by food frequency questeionairre, which is not the most acurate method. This method ask how often do you consumer certain food so you can imagine the accuracy.
    Also this study found too that dietary fibre was negatively assocaited with diabetes.

    And also ppl ussually consume junk carbs, cereals , which called whole grains, so no wonder, whole grains are associacted with diabetes.

  6. Stan 7 August 2010 at 12:18 pm #

    Surely Dennis, although you sound basically right, even on a low-carb

    (note, NOT no-carb) diet where I avoid the obvious rubbish, ie. Bread, cakes, cereals, sweets, pasta etc. I am consuming a quite sumptious diet compared to the average person.
    It’s hard to see where consuming, cheeses, eggs, fish, prawns, shellfish, all forms of fresh meats, chicken, offal, cream can lead to malnutrition. One can live entirely on meat alone providing the fat is eaten, and some offal occasionally, it’s just logical. If your not diabetic, fine, you eat my forbidden items as extra foods, but not at the expense of the basic vital foods.
    Unfortunately the populace generally is scared to eat any fat, cheeses, kids are frightened to drink milk, no way will most children, indeed most young adults, eat bacon, and more than two eggs a week, well thats suicide.

  7. dennis 7 August 2010 at 5:31 pm #

    Stan,

    I just wanted to pojnt out that low carb, moderate protein, high fat is not the only solution to managing diabetes – also that carbs are not the problem. The results Dr John quotes are evidently the way they are because the starch referred to is refined and processed and most of it comes form wheat. The references I quoted are by practising nutritionists with various degrees of vegan extremism (Fuhrman the least, Cousens the most) but there is no question that these diets are effective in treating type 2 diabetes and even type 1 in some cases. I think there is some conflict between high fat and high carb because there is some evidence that some types of fat reduce the response of cells to insulin. So a low carb, high fat diet may be a solution because it enables poor insulin response to be tolerated but does not reverse the diabetes like a low fat diet does. Personally I am drawn more to the low fat side rather than the low carb side , to some degree because I find eating large amounts of fat to be nauseous (remember we are not all the same in our metabolism – Jack Sprat could eat no fat his wife could eat no lean). I think the diet needs to be highly nutritious and that all foods eaten should show some nutritional benefit – this basically means whole foods rather than refined and processed food. I think one should eat large amounts of fresh veg and fruit, sufficient high quality protein – sea fish, wild game, grass fed venison, lamb and beef, offal, some poultry (though this is so intensively farmed I wonder whether it is healthy) and eggs, natural unsalted nuts and seeds, a variety of herbs and spices, some legumes and whole grains other than wheat (ie oats, brown rice, millet, rye and spelt) + minimal added fats such as extra virgin olive oil and New Zealand butter. I generally draw the line at modern wheat and dairy because they are so intensively farmed, there has been a lot of anecdotal evidence against them, and I doubt if they are healthy. I agree that one needs to consume sufficient fat in order to digest protein but I do not see any point in consuming substantial amounts of added fats as they are very poor from a nutritional perspective. Also I do not see any point in consuming bacon, sausages or cheese as these are just highly processed, non-paleo, versions of more healthy fresh pork and milk (though I don’t think modern milk is particularly healthy). I note your hint that one may be able to live on animal foods alone, as our ancestors did, but I wonder if this is true today as our modern meats are so different from what they ate – I think the only truly paleo food is sea fish.

  8. Stan 7 August 2010 at 7:34 pm #

    Hi Dennis, Thanks for your detailed response, I get your drift now. Luckily, I do not suffer any adverse effects from any amount of fat. Also never been a lover of too many vegies, so in that respect it suits me fine. But it took me to approx. 72 years of age to find a weight loss diet that works, ie low-carb. I am completely free of ‘heartburn’ that I suffered from over the years, always being told by various Doctors to cut down on fat and possibly Dairy foods. Never did anyone mention to reduce carbs and sugar intake, in fact they still don’t.
    Having been in the Consruction industry, I always notice the men in the various canteens, cafes etc. always had a
    good hearty meal of eggs,bacon,beans etc, toast with real butter, Steak pies for dinner. Never ever see anyone ask for a bowl of Mueseli or low fat cheese etc.
    You watch a farmer and his family eat, Fresh fatty meat, eggs galore, cream, full fat milk, and they never retired like today.
    Cannot imagine King Henry VIII sitting down to a Bean salad and fruit juice, what would he toss over his shoulder.

    But I can see the problem today, too much choice, too easy access to quick foods. Hey Ho! Anyway there’s always more than one side to problem, Cheers Stan

  9. dennis 8 August 2010 at 11:35 am #

    Thanks Stan, Yes I agree there are different solutions. I was an office worker and drank and ate loads of carbs until I was 50. I was overweight and felt generally unfit and probably on the way to T2D of which I had some probably related symptoms. I stopped boozing at 50 and improved a bit but it was not until five years ago when I was 59 that I discovered high nutrient eating – I lost weight , and am now at ideal BMI, but astonishingly almost all my minor ailments cleared up. During this time I reviewed more than 200 nutrition books ranging form T. Colin Campbell’s China Study to Barry Groves’ Trick and Treat / Natural Health and Weight Loss with so many shades of opinion in between – the extremes of diet seemed to have nothing in common until the realisation that they were all effectively saying to avoid refined. processed (and intensively farmed) foods. I would not say that the diet I decided on is low carb but is it not high carb either – I have no desire to obsess on filling up with carbs like I used to, presumably because the very wide range of different foods that I eat provides all the nutrients I need. Incidentally, as insurance I also take a balanced range of dietary supplements along the line recommended in Paul Claytons’ Health Defence – one of my favourite books along with Joel Fuhrman’s books and Dr John’s True You Diet ! The bottom line is that humans can survive well on a huge range of different diets provided that they avoid empty calorie refined and processed foods – a point that Weston A Price realised as long ago as 1936 in his famous book on Nutrition and Physical generation ! Good luck.

  10. Daniel 10 August 2010 at 11:05 pm #

    Humans have been eating starch for a very long time. There are very healthy populations (e.g., kitava) where people get 70% of their calories from starch. Also, on the population level, one could cite Peru and Asia where generally there are lower levels of diabetes but much higher starch intakes. It wouldn’t surprise me if the results are hopelessly confounded in the US. Perhaps the people who consume the most starch also consume the most polyunsaturated fat (i.e., the “heart healthy” crowd that does exactly the opposite of what is actually heart healthy). Or possible, once beta cells are damaged initially (oxidation/inflammation from PUFA imbalance/fructose overload), glucose toxicity plays a role — but only at a fairly advanced stage of pre-diabetes. I just don’t buy it that starch causes disease.

  11. Dennis 12 August 2010 at 9:45 pm #

    I was recently sent by my wife to buy some ‘healthy’ coleslaw in a local supermarket for a dinner party. When I perused the pack I was considering purchasing, I worked out that no less than 93% of calories would be from refined vegetable oil ! – I thought it would be unethical to feed this to our guests and refused to buy it. Seriously though – I think refined vegetable oils are an even greater threat to our health than refined starches. So I agree with you Daniel.

  12. Catherine Dignan 17 August 2010 at 1:37 am #

    I think it important to stress that “low-carb” does not mean “no-carb”. Twice in the last year I have become ill from eating a diet with a high protein/relative to carb content – I can only assume the high protein was taxing the kidneys, making my blood too acidic and increasing levels of joint pain forced me to return to a more balanced regime. Eating a little protein with each meal is however a sensible approach to insulin control.

    In the 21st century, it’s not too easy to obtain your grub by shooting a passing wild boar, catching fish in the local stream, and plucking some berries from the odd blueberry bush growing in the forest. But there is an easier way of eating healthily: eat foods as close to their natural state as possible, which have not been messed around or processed by technology and, if possible, produced locally. So lean meat, game, fish, eggs, fresh fruit and steamed vegetables, olive oil, butter, whole milk, real bread, etc – the list gives plenty of scope. In practice, this just means avoiding aisle upon aisle of supermarket junk. Easy.

    Admittedly, the cattle providing the meat and milk will have been stuffed full of hormones, the fruit and veg cultivated into perfect shapes and sprayed to eliminate the real taste of such items, but at least you will be avoiding the worst of refined food poison, which, there is increasingly good evidence to show, disrupts your gut bacteria, leading to obesity, reduced immune function and poor digestion, or even gut-brain behavioural/cognitive spectrum disorders.

  13. Alain Cordier 21 August 2011 at 2:11 pm #

    I totally agree with your aricle,mister.I am diabetic.My biggest food addiction was: wheat!It’s not of course a bad food,except when that becomes an addiction.It’s so easy to get wheat in our societies,it smells so good when it has been cooked in so many different brands and kinds…Nostalgia.But how incredible it is,when you stop it,to discover and taste so many other kinds of (good)foods:green vegetables,raw vegetables(crudités),rice,boiled potatoes,buckwheat,quinoa(…),fruits and even…fish!.Weird fact:with these latter foods,overeating decreases!Highly.Weight too.

  14. Raymond Neville 11 December 2013 at 9:37 pm #

    At 64 yrs I completely reversed my Diabetes Type 2 by:

    1 Stop eating foods with “Trans Fats”.

    2 Eat a fistful of Walnuts per day to replace the accumulated buildup of trans fats in your cell fat membranes and restore them to normal so that your insulin can work as intended. Walnuts are a very good source of essential natural fats.

    3 Do for 7 months … my Diabetes Type 2 completely reversed.

    Wrote a short eBooklet (10 pages) free on Kindle Prime called

    “The Walnut Cure for Diabetes Type2″

    Hope it helps someone.

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