Can raw potatoes make me sick

Can raw potatoes make me sick?

Pawel Malczewski
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Short summary

Potatoes can make you sick in a number of ways: from indigestible starch, also called resistant starch, that in raw potatoes can cause stomach upset, from the contamination of bacteria present in the soil and from toxins present in some potatoes. For a quick answer click here.

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Explanation

Indigestible Starches (1)Sajilata MG, Singhal RS, Kulkarni PR. Resistant starch – a review. Comprehensive Reviews in Food Science and Food Safety. Volume 5, Issue 1, pages 1–17, January 2006. Available here.

Starchy foods, such as raw potatoes, unripe (green) bananas, plantains, and some legumes contain large amounts of resistant starch – a type of starch that is very slowly or incompletely digested in the small intestine.

By eating raw/uncooked potatoes, green bananas or uncooked plantains, large amounts of indigestible starches pass through the small intestine almost intact. When they reach the large intestine, colon bacteria feed on it producing gas.

Please note that while the resistant starches have shown to exert various health benefits when used in small a mounts as supplements (2)Birt DF, Boylston T, Hendrich S, Jane JL, Hollis J, Li L, McClelland J, et al. Resistant Starch: Promise for Improving Human Health. Adv Nutr November 2013 Adv Nutr vol. 4: 587-601, 2013. Available here., the amounts of resistant starch of over 30g may cause gastrointestinal symptoms such as abdominal pain, discomfort, bloating, flatulence and cramps. (3)Nugent AP. Health properties of resistant starch. TOC Volume 30, Issue 1 March 2005 Pages 27–54. Available here.

Cooking potatoes and plantains and ripening bananas breaks down the cellular walls of these resistant starches, making them digestible.

Bacteria (4)Selma MV, Allende A, Lopez-Galvez F, Elizaquivel P, Aznar R, Gil MI. Potential microbial risk factors related to soil amendments and irrigation water of potato crops. Article first published online: 4 AUG 2007. Available here.

Bacteria such as Listeria, E. coli and Salmonella are found in water and soil. Potatoes may absorb some of these bacteria while growing, as well as during harvest or packaging. Cooking the potatoes destroys the bacteria. Eating the potato raw may cause abdominal cramps, diarrhea, fever and an upset stomach.

Toxins

Two toxic chemicals (steroidal glycoalkaloids) solanine and chaconine are naturally present in potatoes and are important components of their resistance against pests and pathogens. They can be, however, toxic to humans when taken at high levels. When subjected to stress (sunlight, incorrect handling or bruised, sprouted or damaged in any way) potatoes release these toxins in potentially harmful amounts that can be deadly. Any form of cooking does not reduce the amount of these toxins, and only up to 30% is removed by peeling them. (read more..)

What about juicing potatoes?

As long as the potato does not contain harmful doses of glycoalkaloids, juicing fresh, peeled potatoes removes most of the resistant starches and is considered safe, at least there are no studies showing otherwise. It is even claimed to be beneficial for the digestive tract by many natural medicine practitioners.

Conclusion

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Provided that the potatoes are fresh and not damaged (read more..), the only safe and beneficial way of having raw potatoes is to juice them.

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References   [ + ]

1. Sajilata MG, Singhal RS, Kulkarni PR. Resistant starch – a review. Comprehensive Reviews in Food Science and Food Safety. Volume 5, Issue 1, pages 1–17, January 2006. Available here.
2. Birt DF, Boylston T, Hendrich S, Jane JL, Hollis J, Li L, McClelland J, et al. Resistant Starch: Promise for Improving Human Health. Adv Nutr November 2013 Adv Nutr vol. 4: 587-601, 2013. Available here.
3. Nugent AP. Health properties of resistant starch. TOC Volume 30, Issue 1 March 2005 Pages 27–54. Available here.
4. Selma MV, Allende A, Lopez-Galvez F, Elizaquivel P, Aznar R, Gil MI. Potential microbial risk factors related to soil amendments and irrigation water of potato crops. Article first published online: 4 AUG 2007. Available here.

Comment

  1. Liz says:

    Perhaps you should read up on the benefits of resistant starch before you knock it. If someone has a reaction to it, it’s because their gut is messed up and the treatment is resistant starch.

    1. Thanks for your comment Liz.

      This article refers to eating raw/uncooked potatoes rather than adding some resistant starches to our diet for a therapeutic purpose.
      The resistant starches that exist in raw potatoes (specifically ungelatinised resistant granules with B-type crystallinity, classified as RS2), indeed provide some health benefits (such as improvement in gastrointestinal function or lowering blood insulin and glucose).

      The amounts, however, need to be small. Preferably you should start with small amounts and increase gradually since if you are not accustomed to resistant starch, the described symptoms may occur.

      Studies on humans usually use up to 30g of resistant starches which don’t seem to cause adverse symptoms.(1,2,3)

      Amounts of over 30g of resistant starches may cause diarrhea, and have other unpleasant symptoms such as flatulence, belching, bloating and stomach aches. (4)

      Raw potatoes are considered very high in resistant starch.
      Total starch content in raw potatoes is 15.29g/100g.
      75% of the total starch is resistant starch.

      This means that a large raw potato of 369g will contain 42g of resistant starch and hence will most likely cause the above-mentioned symptoms. (5)

      So, in conclusion, while it is fine to take resistant starch supplements, eating uncooked potatoes may cause unpleasant symptoms. You might consider shredding uncooked potatoes into your food as a therapeutic supplement but you need to take into consideration other safety issues as described in this article.

      Thanks for your comment again and please note that I added a clarifying comment to the article.

  2. Matthew says:

    Yes, raw potatoes can be dangerous. Especially if they’ve sat around for a while. I once made potato salad from undercooked potatoes that had been in storage for several months. I wound up with bloody diarrhea, and was seriously concerned I might die. My guess is most raw potatoes are fine. Most people don’t have potatoes that have sat in storage for 6 months or longer. But if you do, WATCH OUT! They may look and taste fine, but they can kill you.

  3. Although they can be eaten raw, their starchy texture and slight bitterness are unappealing to most.

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