How to Reduce the Glycemic Impact of Potatoes

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Broccoli, vinegar, and lemon juice are put to the test to blunt the glycemic index of white potatoes.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

White potatoes have a high glycemic index, and consumption of high glycemic impact foods may increase the risk of diabetes. Normally after a meal, we’d like our blood sugars to just gently, naturally rise and fall. But with high glycemic foods like potatoes, you get an exaggerated blood sugar spike, which leads your body to over-compensate with insulin, forcing your blood sugars lower than when you started, which results in negative metabolic consequences––such as a rise in triglyceride fats in the blood. However, potatoes are a good source of potassium, vitamin C, and polyphenols, which may counterbalance the glycemic impact. This may explain why potatoes appear to have a neutral effect when it comes to lifespan, unlike other whole plant foods that have been associated with actively living longer.

In my last video, I detailed my nip-and-nuke method, where the act of chilling potatoes can dramatically lower their glycemic index, even if you then reheat them in a microwave. How else might we reduce the glycemic impact of white potatoes? The answer is the same way you make anything better in your nutritional life—add broccoli. The co-consumption of two servings of cooked broccoli with your mashed potatoes would certainly do it, immediately cutting the insulin demand by nearly 40 percent. In contrast, adding chicken breast makes things worse, and adding tuna fish makes things even worse still, nearly doubling the amount of insulin your body has to pump out.

Why does plant protein make things better, but animal protein make things worse? Because decreased consumption of branched-chain amino acids improves metabolic health.  I cover this in my book How Not to Diet as well as my video on the topic.

Speaking of How Not to Diet, remember the section on vinegar? Here are the blood sugar and insulin spikes someone with prediabetes can get from eating a bagel. Eat that same bagel with a tablespoon or so of apple cider vinegar diluted in about a quarter cup of water, though; the impact is significantly less. Does it work for potatoes too?

Simply chilling potatoes may cut down on the blood sugar and insulin spikes, but to get significant drops in both, you just have to add about a tablespoon of vinegar to drop levels by 30 to 40 percent. And that was just plain white distilled vinegar.

Is it the vinegar itself, or would any acidy condiment do? In a test tube, lemon juice appeared to have a remarkable starch-blocking effect, but you can’t know if it works in people, until you put it to the test. And indeed, lemon juice reduces the glycemic responses to bread. And not just by a little, but by like 30 percent. Now, the subjects were drinking a half cup of lemon juice, but that makes it even more remarkable that it helped, because that added an extra half teaspoon of sugar, and yet they still had a better blood sugar response. Vinegar is more potent, though. Just one to two tablespoons a day of vinegar diluted in water can significantly improve both short- and long-term blood sugar control in diabetics, which is why clinicians may want to incorporate vinegar consumption as part of their dietary advice for patients with diabetes.

Please consider volunteering to help out on the site.

Motion graphics by Avo Media

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

White potatoes have a high glycemic index, and consumption of high glycemic impact foods may increase the risk of diabetes. Normally after a meal, we’d like our blood sugars to just gently, naturally rise and fall. But with high glycemic foods like potatoes, you get an exaggerated blood sugar spike, which leads your body to over-compensate with insulin, forcing your blood sugars lower than when you started, which results in negative metabolic consequences––such as a rise in triglyceride fats in the blood. However, potatoes are a good source of potassium, vitamin C, and polyphenols, which may counterbalance the glycemic impact. This may explain why potatoes appear to have a neutral effect when it comes to lifespan, unlike other whole plant foods that have been associated with actively living longer.

In my last video, I detailed my nip-and-nuke method, where the act of chilling potatoes can dramatically lower their glycemic index, even if you then reheat them in a microwave. How else might we reduce the glycemic impact of white potatoes? The answer is the same way you make anything better in your nutritional life—add broccoli. The co-consumption of two servings of cooked broccoli with your mashed potatoes would certainly do it, immediately cutting the insulin demand by nearly 40 percent. In contrast, adding chicken breast makes things worse, and adding tuna fish makes things even worse still, nearly doubling the amount of insulin your body has to pump out.

Why does plant protein make things better, but animal protein make things worse? Because decreased consumption of branched-chain amino acids improves metabolic health.  I cover this in my book How Not to Diet as well as my video on the topic.

Speaking of How Not to Diet, remember the section on vinegar? Here are the blood sugar and insulin spikes someone with prediabetes can get from eating a bagel. Eat that same bagel with a tablespoon or so of apple cider vinegar diluted in about a quarter cup of water, though; the impact is significantly less. Does it work for potatoes too?

Simply chilling potatoes may cut down on the blood sugar and insulin spikes, but to get significant drops in both, you just have to add about a tablespoon of vinegar to drop levels by 30 to 40 percent. And that was just plain white distilled vinegar.

Is it the vinegar itself, or would any acidy condiment do? In a test tube, lemon juice appeared to have a remarkable starch-blocking effect, but you can’t know if it works in people, until you put it to the test. And indeed, lemon juice reduces the glycemic responses to bread. And not just by a little, but by like 30 percent. Now, the subjects were drinking a half cup of lemon juice, but that makes it even more remarkable that it helped, because that added an extra half teaspoon of sugar, and yet they still had a better blood sugar response. Vinegar is more potent, though. Just one to two tablespoons a day of vinegar diluted in water can significantly improve both short- and long-term blood sugar control in diabetics, which is why clinicians may want to incorporate vinegar consumption as part of their dietary advice for patients with diabetes.

Please consider volunteering to help out on the site.

Motion graphics by Avo Media

Doctor's Note

This is the fourth video in a five-part video series on potatoes. Missed the first three? See:

 What about the glycoalkaloid toxins in potatoes? I cover that and discuss the best kind of potato in my upcoming final video in the series: The Healthiest Type of Potato.

If you haven’t yet, you can subscribe to my videos for free by clicking here.

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