How to Minimize Hyperglycemic Toxicity

In my reply to Jimmy Moore’s safe starches symposium (see Jimmy Moore’s seminar on “safe starches”: My reply, Oct 12), I didn’t quite have time to fully address the issue of hyperglycemic toxicity.

As J Stanton commented, it would have been good to note that we recommend consuming “safe starches” as parts of meals, not as isolated snacks, and to discuss how meal design mitigates risk of hyperglycemic toxicity:

I’ve written entire articles on the fact that fat content is the primary driver of glycemic index. It’s silly to demonize white potatoes due to high GI when a couple pats of butter – or simply consuming it as part of a PHD-compliant high-fat meal – will drop it far more than substituting a sweet potato.

I thought I’d delve into the factors affecting blood glucose response to meals, and how to minimize the rise in blood sugar. It’s a topic of general interest, since hyperglycemia might have a mild detrimental health effect in nearly everyone; but of special importance to diabetics, since controlling blood sugar is so crucial to their health.

Glycemic Index of Safe Starches

The glycemic index (GI) is “defined as the area under the two hour blood glucose response curve (AUC) following the ingestion of a fixed portion of carbohydrate (usually 50 g).” Pure glucose in water is used as the reference and defines a GI of 100.

Our recommended “safe starches” are significantly lower in GI than glucose.

White rice is typically listed with a GI of 70 or 72, but it varies by strain: Bangladeshi rice has a GI of 37, American brown rice of 50, Japonica (a white short-grained rice) of 48, Basmati rice of 58, Chinese vermicelli of 58, American long-grain rice of 61, risotto rice of 69, American white rice is 72, short-grain white rice is 83, and jasmine rice 89 (source).

Potatoes are a high-GI food but again the GI is highly variable. Baked white potatoes with the skin have a GI of 69, peeled their GI is 98. Yams have GI of 35 to 77 depending on how they are prepared, sweet potatoes of 44 to 94 (source).

With some foods the GI varies strongly with ripeness. Plaintains when unripe have a GI of 40 but when ripe the GI can reach 90 (source).

Taro has a GI of 48 to 56. That’s similar to many fruits, such as bananas which have a GI of 47 to 62. Tapioca has a GI of 70 if steamed, but can exceed 80 if boiled (source).

Gentle Cooking Lowers the Glycemic Index

As a rule, gentle cooking of starchy plants leads to a lower glycemic index and high cooking temperatures lead to a higher glycemic index.

In general, industrially processed foods, which are often processed at very high temperatures to speed them through factories, have high GIs. A study in the American Journal of Clinical Nutrition [1] compared home-cooked corn, rice, and potato with processed foods based on them (instant rice, Rice Bubbles, corn chips, Cornflakes, instant potato, and potato crisps), and the processed foods had consistently higher GIs:

Another study in the British Journal of Nutrition [2] looked at 14 starchy plants prepared in different ways and found that roasting and baking raised the GI:

GI value of some of the roasted and baked foods were significantly higher than foods boiled or fried (P<0.05). The results indicate that foods processed by roasting or baking may result in higher GI. Conversely, boiling of foods may contribute to a lower GI diet.

Perhaps cooking methods that dry out the plant increase the GI.

Meals Have Lower GI

GI is calculated by eating a single food and only that food.

But what happens when you eat a meal? You’re no longer eating one food, but a mixture of foods. The baked potato may come with meat and vegetables, and with butter on top.

You might think that a weighted average of the GI of the various foods might give a good indication of the GI of the meal. Then, since fat, meat, and vegetables have a low GI, you’d expect GI of the meal to be much lower.

It turns out that the GI of meals is low – in fact, it is even lower than the average GI of the foods composing the meal.

That is the result of a new study in the American Journal of Clinical Nutrition [3]. Three meals were prepared combining a starch (potato, rice, or spaghetti) that digested to 50 g (200 calories) glucose with vegetables, sauce, and pan-fried chicken. The GIs of the meals were consistently lower than the values predicted using a weighted average of GIs of the meal components:

Meal Actual GI Predicted GI
Potato 53 63
Rice 38 51
Spaghetti 38 54

So eating a starch as part of a meal reduces GI to the range 38 to 53 – below the levels of many fruits and berries.

Fat Reduces GI

J Stanton has noted that adding a little fat to a starch is very effective in lowering its GI. In a post titled “Fat and Glycemic Index: The Myth of Complex Carbohydrates,” JS states that:

  • Flour tortillas have a GI of 30, compared to a GI of 72 for wheat bread, because tortillas are made with lard.
  • Butter reduces the glycemic index of French bread from 95 to 65.
  • A Pizza Hut Super Supreme Pizza has a GI of 30, whereas a Vegetarian Supreme has a GI of 49.

JS suggests that the reason fat does this is that it lowers the gastric emptying rate, and cites a study which showed that adding fat to starches could increase the gastric emptying time – the time for food to leave the stomach – by 50%. [4]

What’s interesting to me here is that what we really care about is not the glycemic index, but the peak blood glucose level attained after a meal. It is blood glucose levels above 140 mg/dl only that are harmful, and the harm is proportional to how high blood glucose levels rise above 140 mg/dl. So it’s the spikes we want to avoid.

But another paper shows that gastric emptying rate is even more closely tied to peak blood glucose level than it is to glycemic index. From [5]:

So combining a starch with fat may reduce peak blood glucose levels even more than it reduces the glycemic index; which is a good thing.

Dairy reduces GI

Dairy is effective at reducing GI:

[D]airy products significantly reduced the GI of white rice when consumed together, prior to or after a carbohydrate meal. [6]

It is not likely that dairy fat alone was responsible, because whole milk worked better than butter. However, low-fat milk only reduced the GI of rice by 16%, while whole milk reduced it by 41%. So clearly dairy fats are part of the recipe, but not the whole story; whey protein may also matter.

Fiber Reduces GI

Fiber is another meal element that reduces the rise in blood sugar after eating.

Removing fiber from starchy foods increases their glycemic index [7]; adding fiber decreases it. For instance, adding a polysaccharide fiber to cornstarch reduced its GI from 83 to 58; to rice reduced its GI from 82 to 45; to yogurt from 44 to 38. [8]

So it’s good to eat starches with vegetables – the foods richest in fiber.

Acids, Especially Vinegar, Reduce GI

Traditional cuisines usually make sauces by combining a fat with an acid. Frequently used sauce acids are vinegars and citric acid from lemons, limes, or other citrus fruits.

It turns that sauce acids can substantially reduce the GI of meals. The best attested is vinegar. From a study in the European Journal of Clinical Nutrition [6]:

In the current study, the addition of vinegar and vinegared foods to white rice reduced the GI of white rice. The acetic acid in vinegar was thought to be responsible for the antihyperglycemic effect. The amount of acetic acid to be effective could be as low as that found in sushi (estimated to be about 0.2–1.5 g/100 g). The antihyperglycemic effect of vinegar is consistent with other studies performed earlier (Brighenti et al, 1995; Liljeberg & Bjorck, 1998). Although vinegar could lower GI vales, the mechanism has rarely been reported. Most studies accounted the mechanism to be due to a delay in gastric emptying. In animal studies, Fushimi (Fushimi et al, 2001) showed that acetic acid could activate gluconeogenesis and induce glycogenesis in the liver after a fasting state. It could also inhibit glycolysis in muscles. [6]

Other acids also work. Pickled foods, which are sour due to lactic acid released by bacteria, reduce the glycemic index of rice by 27% if eaten before the rice and by 25% if eaten alongside the rice [6].

Wines, especially red wines, are somewhat acidic. I haven’t seen a study of how drinking wine with a meal affects glycemic index, but it is known observationally that wine drinkers have better glycemic control and, often, long lives. [9]

So What’s the Healthiest Way to Eat “Safe Starches”?

One way to limit the likelihood of reaching dangerous blood sugar levels after a meal is by eating a relatively “low carb” diet. We recommend that sedentary people eat about 400 to 600 carb calories per day. This limits the amount eaten at any one sitting to about 200 calories / 50 g, which is the amount of a typical glucose tolerance test. It is an amount the body is well able to handle.

But the manner in which carbs are eaten may be just as important as the amount.

Let’s look again at the Perfect Health Diet Food Plate:

The design of a PHD meal is found in the body of the apple. Assuming two meals a day, the recipe is to combine:

  • A safe starch (roughly ½ pound, which translates to 150 to 300 carb calories);
  • A meat, fish, or egg (¼ to ½ pound);
  • A sauce made up of fats and acids such as lemon juice or vinegar;
  • Vegetables, preferably including fermented vegetables with their healthy acids;
  • (Optionally) some dairy or a glass of wine.

This is precisely the recipe which science has found minimizes the elevation of blood glucose after meals.

It seems reasonable to expect that a meal designed in this fashion will have a glycemic index around 30. The odds of 200 carb calories with a glycemic index of 30 generating blood sugar levels that are dangerous – 140 mg/dl or higher – in healthy people is very low. Even in diabetics, it may be uncommon.

So, yes, Virginia. There is a Santa Claus, and you can eat safe starches and avoid hyperglycemia too!


[1] Brand JC et al. Food processing and the glycemic index. Am J Clin Nutr. 1985 Dec;42(6):1192-6.

[2] Bahado-Singh PS et al. Food processing methods influence the glycaemic indices of some commonly eaten West Indian carbohydrate-rich foods. Br J Nutr. 2006 Sep;96(3):476-81.

[3] Dodd H et al. Calculating meal glycemic index by using measured and published food values compared with directly measured meal glycemic index. Am J Clin Nutr. 2011 Oct;94(4):992-6.

[4] Thouvenot P et al. Fat and starch gastric emptying rate in humans: a reproducibility study of a double-isotopic technique. Am J Clin Nutr 1994;59(suppl):781S.

[5] Mourot J et al. Relationship between the rate of gastric emptying and glucose and insulin responses to starchy foods in young healthy adults. Am J Clin Nutr. 1988 Oct;48(4):1035-40.

[6] Sugiyama M et al. Glycemic index of single and mixed meal foods among common Japanese foods with white rice as a reference food. Eur J Clin Nutr. 2003 Jun;57(6):743-52. Full text:

[7] Benini L et al. Gastric emptying of a solid meal is accelerated by the removal of dietary fibre naturally present in food. Gut. 1995 Jun;36(6):825-30.

[8] Jenkins AL et al. Effect of adding the novel fiber, PGX®, to commonly consumed foods on glycemic response, glycemic index and GRIP: a simple and effective strategy for reducing post prandial blood glucose levels–a randomized, controlled trial. Nutr J. 2010 Nov 22;9:58.

[9] Perissinotto E et al. Alcohol consumption and cardiovascular risk factors in older lifelong wine drinkers: the Italian Longitudinal Study on Aging. Nutr Metab Cardiovasc Dis. 2010 Nov;20(9):647-55.


Leave a comment ?


  1. Hi Paul,
    I had a question regarding eating starch/carbs in the morning. Many people advocate that no carbs should be included in breakfast because you are less insulin sensitive in the morning. What is your opinion on this? I noticed you don’t shy away from advocating breakfasts with fruit/rice/potatoes.

  2. Thanks for the detailed info!

    I have a question about tapioca/cassava – isn’t it dangerous since it contains high amounts of cyanogenic glycosides? How can we know if the tapioca we buy at the store has been processed correctly to remove this dangerous compound? I don’t want to poison myself!

    Thanks again and let me know,

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  5. Regarding gastric emptying, I actually think that I may have naturally-slow gastric emptying
    — which is made even slower by cinnamon, vinegar, and other things that are supposed to naturally moderate blood sugar spikes —
    and this makes the GERD/acid reflux that I have (due to a hiatal hernia which was due to an unavoidable accident) worse, because some meals that I am eating are staying in my stomach for so long that I will still burp up gas from them and get acidic splashes at the back of my mouth from them 6-8 hours after I have stopped all eating for the day (whether I have stayed upright and awake all those hours or have gone to sleep after the first 3 hours of not ingesting anything – 3 hours is the minimum time I put between eating and lying down, to ward off acid reflux when I’m sleeping).

    Since I was an infant, and I’m 5 decades from that now, I have had constipation that did not really respond to the various typical remedies (most of them are counterproductive for me), and I wonder if I have slow motility, disregulated migrating motor complex, delayed gastric emptying.

    I had always heard that cinnamon was healthy (in moderation) and helped prevent diabetes, so I’d add it where I could, but last year when I learned that the way cinnamon actually lowers blood sugar is to delay gastric emptying (which is not what I want to do), I stopped using much cinnamon, and I think I could even tell that my digestion started to go a tiny bit faster (though maybe that was just wishful thinking).

    I am of a healthy weight, good BMI, have good blood sugar readings and regulation as far as I know (I get general blood tests a lot, due to other health issues), so I am wondering what things/foods might speed up my gastric emptying and my digestion process generally?

    I always try to add some protein to every meal, not have too much in the way of sugars, and have a moderate amount of carbs, but sometimes it feels as if I am dipping into lowish blood sugar, especially after I take my supplements at a midday meal, and I don’t know if this could be because my gastric emptying does not go very quickly for food, but maybe it goes faster for supplements or things that can go directly into the bloodstream from the stomach without proceeding down the digestive system (I don’t know much about biology, so I’m guessing)?

    To lessen my acid reflux from supplements, I take them right in the middle of a meal, not before, not after, but halfway in. I have to do this even with supplements that say it’s best to take them on an empty stomach, all except for glutamine, which I take every morning on an empty stomach and it doesn’t bug me at all.

    Paul, do you recommend the daily vinegar only to slow down people’s gastric emptying in order to level out their blood sugar, or does it have other effects on the health?

    My tum and my acid reflux do not like having vinegar in water (or straight), but I try to use a vinegar and olive oil salad dressing when I have a salad (or anything else that goes well with such a dressing – sometimes I put it on warm boiled potatoes, etc.)

    I’ve tried so many kinds of probiotics over the years, and none of them seemed to help my constipation,
    except one which I resisted trying for a while since it’s patented and sold by a massive FMCG (fast moving consumer goods) company (I’m not sure why, but I just would rather not encourage them), it’s relatively expensive, and it’s just a single strain (for various reasons that stretch back to my mom’s pregnancy and state of health, plus my childhood, illnesses, antibiotics use and so forth, I expect that I don’t have a native population of enough of a number of the healthier strains).
    It actually does seem to help me have more frequent BMs — taking it every day, I’ve gone from one or two BMs a week to about five a week. Which is a pretty major improvement for a typically-mildly-constipated person!
    It’s Align bifidobacterium longum subsp. longum 35624 ™.
    For a few weeks, I tried to take this probiotic at one meal of the day, and at my other main meal of the day, to take a different probiotic that has more strains (other bifidos like infantis, and some acidophilus types like rhamnosus), but even taken 6 hours apart, they seemed to counteract each other and I stopped having the regular BMs, so I went back to just the Align.
    I’m not sure what the mechanism is for this specific probiotic to help my BMs be more regular, softer, quicker, and more comfortable.

    I wonder what it is doing – ? From my continued acid reflux and burping, the Align does not seem to be making my gastric emptying go any more quickly.

    I don’t think it’s increasing my serotonin, at least the serotonin in my brain, which I guess some probiotics do? – plus I don’t know if a little more serotonin would help me or maybe have the opposite effect, but I feel a bit more depressed now while I’m taking the Align than I think that I did before I started taking it. (I’ve taken it for about 4 months, and I don’t have a seasonal type of variation in moods so it’s probably not due to the fact that it’s winter now.)

    I happened to have oatmeal the other day for the first time in a few months (since last summer, I’ve experimented with mainly avoiding grains, except for white rice), and I had it with some almonds, full-fat unsweetened plain Greek yogurt, a really tiny bit of brown dried-cane-juice organic sugar, and ample butter, and it was wild – it was like a happy drug – starting one hour after eating it, and lasting for only about one hour, I felt optimistic and found myself spontaneously planning future things in my thoughts, and I felt motivated. And then that went away. It was the eveningtime, and I went to bed 3 hours after I ate, so about 1 hour after the little happy spell ended. The next day I thought, “Wow, what was that? How can I experience that great mood again?” Unfortunately, that day and for a couple of days after that, my joints and tendons were aching like they did last summer before I decided that I might have a problem with gluten, and nothing else had changed in my diet or life, so it seemed that the aching was due to the oatmeal (it was “gluten free” oats, but of course there is the avenin in oats which some people respond to, and there are possible gluten cross-reactions and such). From past experience when I ate oatmeal about once a month, oatmeal does not seem to affect my blood sugar as much as it affects some people’s, so I think I digest it pretty steadily. And I’m from a northern UK/Scandinavian/German ancestry, according to 23andMe – I don’t know if the Scandinavians/Germans ate many oats, but of course the Scottish did. If anyone has any thoughts about what it was in the oats that caused the unusual and so welcome, but short, burst of good mood and motivation that seemed to come directly from that meal, and how I could recreate that without having the probably-oat-related joint and tendon aching for several days afterwards, please comment below.

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