Are yellow-fleshed potatoes healthier than white? And, what about the glycoalkaloid toxins?
The Healthiest Type of Potato
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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.
The high glycemic impact of potatoes may increase the risk of type 2 diabetes, perhaps by chronically overstimulating the insulin-producing cells in the pancreas. In my last two videos, I explained how you can decrease the glycemic impact of white potatoes by eating them cold, or chilling then reheating them, or adding broccoli, lemon juice, or vinegar. What else can we do?
Well, if you remember, I had a video a few years back that showed how the pigments in brightly colored berries can act as starch blockers. So, if you’re going to eat a high glycemic food, you may be able to moderate its impact by spreading raspberries on your toast, for example, or adding strawberries to your cornflakes, or sprinkling blueberries in your pancakes. No, I’m not saying you have to put blackberries in your baked potato, but given that the natural color compounds in fruits can slow down starch digestion, what about pigmented potatoes?
Even just yellow potatoes like Yukon gold may be preferable to white, but the best may be purple potatoes: not just purple-skinned potatoes, but purple-fleshed potatoes. If you’ve never seen purple potatoes, they are remarkable; they have almost a neon blue glow. And not only do they look cool, but purple potatoes cause less of an insulin and blood sugar spike compared to even the yellow-fleshed potatoes, suggesting that switching from yellow or white to purple could have a large potential public health benefit.
How do we know it’s the pigments themselves that are responsible, rather than other differences between the different potato varieties? The researchers tried adding a control comprised of berries in a potato starch jelly, but that would seem to add even more variables. In a test tube, extracts of purple- and red-fleshed potatoes can act as starch blockers; so hey, if you can extract and purify out the purple potato pigments—say that five times fast—you could remove any other effects of the different potato varieties by adding the purple pigments to yellow potatoes. And lo and behold, compared to just plain yellow potatoes, you can get a suppression of the blood sugar and insulin spikes. This way, you don’t get that overshoot reaction where your blood sugars can actually drop below fasting like you might get otherwise; instead, you get the gentler up and down in blood sugars you’d expect from a lower glycemic food.
The authors suggest purple potato extracts could be produced to make into supplements or fancy functional foods, but these health-promoting compounds may be more cost-effectively received from consuming purple potatoes themselves.
If you were paying attention, you may have caught in the title as it flashed by that the purple potato pigments may also affect inflammation. The Potato Association of America likes to paint potatoes as an anti-inflammatory food, but what they don’t tell you is that this benefit may be limited to pigmented potatoes. If you randomize people to eat a small white potato every day for six weeks versus a yellow- or purple-fleshed potato, the purple potato group achieved significantly lower levels of inflammation compared to the white potato group, measuring both c-reactive protein and interleukin-6.
Pigmented potato consumption also alters oxidative stress. Within hours of eating a large purple potato, you get a nice 60 percent bump in the antioxidant power of your bloodstream, and this translates into less free radical DNA damage. If you compare the antioxidant activity of white potatoes, yellow potatoes, and purple potatoes, Yukon gold has about twice the antioxidant power as white, but purple has twenty times the antioxidants. This is comparable to what you might see in berries. A half of a purple potato has about the same polyphenol antioxidant complement as a half cup of blueberries.
Purple potatoes can increase the antioxidant capacity of our bloodstream, whereas straight white potato starch can act as a pro-oxidant and decrease it. Eat a purple potato, and over the next eight hours the antioxidant capacity of your blood stream goes up. In contrast, if you eat white potato starch devoid of any pigment, you can end up worse off than where you started. Okay, but does this translate into different physiological effects?
Yes indeed. Have people eat either purple potatoes or white potatoes for two weeks, and the purple potatoes improved a measure of arterial stiffness, whereas the white potato did not. And this translates into a drop in blood pressure, even in those already taking high blood pressure drugs, suggesting purple potatoes are an effective blood pressure lowering agent.
But what about the toxic glycoalkaloid compounds in potatoes? The toxic human dose starts around 2-5 mg/kg of body weight, and the lethal dose is not too far behind. But the average amount of total glycoalkaloids in most potatoes, however, is less than 100 mg/kg. So, at the average American weight of 180 pounds, a toxic dose is like four to nine pounds of potatoes. What happens when you approach that? It’s possible you can get nausea, vomiting, or diarrhea that could be easily confused with something like gastroenteritis or food poisoning. Some people can start to get sick at just 1.25 mg/kg of body weight, or even 1 mg/kg. That would only be about two pounds of potatoes at the average American weight. It’s also possible they could start accumulating if you eat them day in and day out. But what about those people who go on a fad potato diet and eat three or four pounds a day? They can do that without risking getting sick only if they peel their potatoes, which removes nearly all of the glycoalkaloids.
Please consider volunteering to help out on the site.
- Bidel Z, Teymoori F, Davari SJ, Nazarzadeh M. Potato consumption and risk of type 2 diabetes: A dose-response meta-analysis of cohort studies. Clin Nutr ESPEN. 2018;27:86-91.
- Grussu D, Stewart D, McDougall GJ. Berry polyphenols inhibit α-amylase in vitro: identifying active components in rowanberry and raspberry. J Agric Food Chem. 2011;59(6):2324-31.
- Ramdath DD, Padhi E, Hawke A, Sivaramalingam T, Tsao R. The glycemic index of pigmented potatoes is related to their polyphenol content. Food Funct. 2014;5(5):909-15.
- Linderborg KM, Salo JE, Kalpio M, et al. Comparison of the postprandial effects of purple-fleshed and yellow-fleshed potatoes in healthy males with chemical characterization of the potato meals. Int J Food Sci Nutr. 2015;67(5):581-91.
- holiday moussaka by torbakhopper : purple and gold, potatoes. Flickr. November 24, 2015.
- Ramdath DD, Padhi E, Hawke A, Sivaramalingam T, Tsao R. The glycemic index of pigmented potatoes is related to their polyphenol content. Food Funct. 2014;5(5):909-15.
- Extraction and purification of anthocyanins from purple-fleshed potato. Food Bioprod Process. 2016;99:136-46.
- Anthocyanin-rich extract from purple potatoes decreases postprandial glycemic response and affects inflammation markers in healthy men. Food Chem. 2020;310:125797.
- Reddivari L, Wang T, Wu B, Li S. Potato: an anti-inflammatory food. Am J Potato Res. 2019;96(2):164-9.
- Kaspar KL, Park JS, Brown CR, Mathison BD, Navarre DA, Chew BP. Pigmented potato consumption alters oxidative stress and inflammatory damage in men. J Nutr. 2011;141(1):108-11.
- Madiwale GP, Reddivari L, Stone M, Holm DG, Vanamala J. Combined effects of storage and processing on the bioactive compounds and pro-apoptotic properties of color-fleshed potatoes in human colon cancer cells. J Agric Food Chem. 2012;60(44):11088-96.
- Vinson JA, Demkosky CA, Navarre DA, Smyda MA. High-antioxidant potatoes: acute in vivo antioxidant source and hypotensive agent in humans after supplementation to hypertensive subjects. J Agric Food Chem. 2012;60(27):6749-54.
- Tsang C, Smail NF, Almoosawi S, McDougall GJM, Al-Dujaili E a. S. Antioxidant rich potato improves arterial stiffness in healthy adults. Plant Foods Hum Nutr. 2018;73(3):203-8.
- Changes in glycoalkaloids content of potatoes destined for consumption. Food Chem. 2008;106(2):706-11.
- Friedman M. Potato glycoalkaloids and metabolites: roles in the plant and in the diet. J Agric Food Chem. 2006;54(23):8655-81.
- Mensinga TT, Sips AJAM, Rompelberg CJM, et al. Potato glycoalkaloids and adverse effects in humans: an ascending dose study. Regul Toxicol Pharmacol. 2005;41(1):66-72.
- Hellenäs KE, Nyman A, Slanina P, Lööf L, Gabrielsson J. Determination of potato glycoalkaloids and their aglycone in blood serum by high-performance liquid chromatography. Application to pharmacokinetic studies in humans. J Chromatogr. 1992;573(1):69-78.
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.
The high glycemic impact of potatoes may increase the risk of type 2 diabetes, perhaps by chronically overstimulating the insulin-producing cells in the pancreas. In my last two videos, I explained how you can decrease the glycemic impact of white potatoes by eating them cold, or chilling then reheating them, or adding broccoli, lemon juice, or vinegar. What else can we do?
Well, if you remember, I had a video a few years back that showed how the pigments in brightly colored berries can act as starch blockers. So, if you’re going to eat a high glycemic food, you may be able to moderate its impact by spreading raspberries on your toast, for example, or adding strawberries to your cornflakes, or sprinkling blueberries in your pancakes. No, I’m not saying you have to put blackberries in your baked potato, but given that the natural color compounds in fruits can slow down starch digestion, what about pigmented potatoes?
Even just yellow potatoes like Yukon gold may be preferable to white, but the best may be purple potatoes: not just purple-skinned potatoes, but purple-fleshed potatoes. If you’ve never seen purple potatoes, they are remarkable; they have almost a neon blue glow. And not only do they look cool, but purple potatoes cause less of an insulin and blood sugar spike compared to even the yellow-fleshed potatoes, suggesting that switching from yellow or white to purple could have a large potential public health benefit.
How do we know it’s the pigments themselves that are responsible, rather than other differences between the different potato varieties? The researchers tried adding a control comprised of berries in a potato starch jelly, but that would seem to add even more variables. In a test tube, extracts of purple- and red-fleshed potatoes can act as starch blockers; so hey, if you can extract and purify out the purple potato pigments—say that five times fast—you could remove any other effects of the different potato varieties by adding the purple pigments to yellow potatoes. And lo and behold, compared to just plain yellow potatoes, you can get a suppression of the blood sugar and insulin spikes. This way, you don’t get that overshoot reaction where your blood sugars can actually drop below fasting like you might get otherwise; instead, you get the gentler up and down in blood sugars you’d expect from a lower glycemic food.
The authors suggest purple potato extracts could be produced to make into supplements or fancy functional foods, but these health-promoting compounds may be more cost-effectively received from consuming purple potatoes themselves.
If you were paying attention, you may have caught in the title as it flashed by that the purple potato pigments may also affect inflammation. The Potato Association of America likes to paint potatoes as an anti-inflammatory food, but what they don’t tell you is that this benefit may be limited to pigmented potatoes. If you randomize people to eat a small white potato every day for six weeks versus a yellow- or purple-fleshed potato, the purple potato group achieved significantly lower levels of inflammation compared to the white potato group, measuring both c-reactive protein and interleukin-6.
Pigmented potato consumption also alters oxidative stress. Within hours of eating a large purple potato, you get a nice 60 percent bump in the antioxidant power of your bloodstream, and this translates into less free radical DNA damage. If you compare the antioxidant activity of white potatoes, yellow potatoes, and purple potatoes, Yukon gold has about twice the antioxidant power as white, but purple has twenty times the antioxidants. This is comparable to what you might see in berries. A half of a purple potato has about the same polyphenol antioxidant complement as a half cup of blueberries.
Purple potatoes can increase the antioxidant capacity of our bloodstream, whereas straight white potato starch can act as a pro-oxidant and decrease it. Eat a purple potato, and over the next eight hours the antioxidant capacity of your blood stream goes up. In contrast, if you eat white potato starch devoid of any pigment, you can end up worse off than where you started. Okay, but does this translate into different physiological effects?
Yes indeed. Have people eat either purple potatoes or white potatoes for two weeks, and the purple potatoes improved a measure of arterial stiffness, whereas the white potato did not. And this translates into a drop in blood pressure, even in those already taking high blood pressure drugs, suggesting purple potatoes are an effective blood pressure lowering agent.
But what about the toxic glycoalkaloid compounds in potatoes? The toxic human dose starts around 2-5 mg/kg of body weight, and the lethal dose is not too far behind. But the average amount of total glycoalkaloids in most potatoes, however, is less than 100 mg/kg. So, at the average American weight of 180 pounds, a toxic dose is like four to nine pounds of potatoes. What happens when you approach that? It’s possible you can get nausea, vomiting, or diarrhea that could be easily confused with something like gastroenteritis or food poisoning. Some people can start to get sick at just 1.25 mg/kg of body weight, or even 1 mg/kg. That would only be about two pounds of potatoes at the average American weight. It’s also possible they could start accumulating if you eat them day in and day out. But what about those people who go on a fad potato diet and eat three or four pounds a day? They can do that without risking getting sick only if they peel their potatoes, which removes nearly all of the glycoalkaloids.
Please consider volunteering to help out on the site.
- Bidel Z, Teymoori F, Davari SJ, Nazarzadeh M. Potato consumption and risk of type 2 diabetes: A dose-response meta-analysis of cohort studies. Clin Nutr ESPEN. 2018;27:86-91.
- Grussu D, Stewart D, McDougall GJ. Berry polyphenols inhibit α-amylase in vitro: identifying active components in rowanberry and raspberry. J Agric Food Chem. 2011;59(6):2324-31.
- Ramdath DD, Padhi E, Hawke A, Sivaramalingam T, Tsao R. The glycemic index of pigmented potatoes is related to their polyphenol content. Food Funct. 2014;5(5):909-15.
- Linderborg KM, Salo JE, Kalpio M, et al. Comparison of the postprandial effects of purple-fleshed and yellow-fleshed potatoes in healthy males with chemical characterization of the potato meals. Int J Food Sci Nutr. 2015;67(5):581-91.
- holiday moussaka by torbakhopper : purple and gold, potatoes. Flickr. November 24, 2015.
- Ramdath DD, Padhi E, Hawke A, Sivaramalingam T, Tsao R. The glycemic index of pigmented potatoes is related to their polyphenol content. Food Funct. 2014;5(5):909-15.
- Extraction and purification of anthocyanins from purple-fleshed potato. Food Bioprod Process. 2016;99:136-46.
- Anthocyanin-rich extract from purple potatoes decreases postprandial glycemic response and affects inflammation markers in healthy men. Food Chem. 2020;310:125797.
- Reddivari L, Wang T, Wu B, Li S. Potato: an anti-inflammatory food. Am J Potato Res. 2019;96(2):164-9.
- Kaspar KL, Park JS, Brown CR, Mathison BD, Navarre DA, Chew BP. Pigmented potato consumption alters oxidative stress and inflammatory damage in men. J Nutr. 2011;141(1):108-11.
- Madiwale GP, Reddivari L, Stone M, Holm DG, Vanamala J. Combined effects of storage and processing on the bioactive compounds and pro-apoptotic properties of color-fleshed potatoes in human colon cancer cells. J Agric Food Chem. 2012;60(44):11088-96.
- Vinson JA, Demkosky CA, Navarre DA, Smyda MA. High-antioxidant potatoes: acute in vivo antioxidant source and hypotensive agent in humans after supplementation to hypertensive subjects. J Agric Food Chem. 2012;60(27):6749-54.
- Tsang C, Smail NF, Almoosawi S, McDougall GJM, Al-Dujaili E a. S. Antioxidant rich potato improves arterial stiffness in healthy adults. Plant Foods Hum Nutr. 2018;73(3):203-8.
- Changes in glycoalkaloids content of potatoes destined for consumption. Food Chem. 2008;106(2):706-11.
- Friedman M. Potato glycoalkaloids and metabolites: roles in the plant and in the diet. J Agric Food Chem. 2006;54(23):8655-81.
- Mensinga TT, Sips AJAM, Rompelberg CJM, et al. Potato glycoalkaloids and adverse effects in humans: an ascending dose study. Regul Toxicol Pharmacol. 2005;41(1):66-72.
- Hellenäs KE, Nyman A, Slanina P, Lööf L, Gabrielsson J. Determination of potato glycoalkaloids and their aglycone in blood serum by high-performance liquid chromatography. Application to pharmacokinetic studies in humans. J Chromatogr. 1992;573(1):69-78.
Motion graphics by Avo Media
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Title
The Healthiest Type of Potato
LicenseCreative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Content URLDoctor's Note
This is the last in a five-video series on potatoes. If you missed any of the others, see:
- Do Potatoes Increase the Risk of Diabetes?
- Do Potatoes Increase the Risk of High Blood Pressure and Death?
- Glycemic Index of Potatoes: Why You Should Chill and Reheat Them
- How to Reduce the Glycemic Impact of Potatoes
I previously highlighted purple potatoes in Anti-Inflammatory Effects of Purple Potatoes.
You may also be interested in The Best Way to Cook Sweet Potatoes.
The video on berries I mentioned is Getting Starch to Take the Path of Most Resistance.
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