Are Potatoes Making You Sick?

By Jennifer Ide, R.BIE, CNP

Potatoes are a decent source of vitamin C, potassium and fiber. They also have a longer shelf life than most types of produce, which makes them an ideal item to pick up at the grocery store during these times of heightened uncertainty. Storing raw potatoes in the right conditions can allow them to last anywhere between 2-4 months.

When we talk about the impact of foods on our health, we often talk about WHAT we are eating. Rarely do we consider how the handling of food may influence our health. Everything from how food is stored, prepared and cooked, can alter the food’s chemistry, therefore, it will have specific effects on our bodies when it is consumed.

Refrigerating raw potatoes can increase sugar content and lead to the formation of a cancer-causing substance once cooked

Storing potatoes in the fridge before you cook them can have negative health consequences. We usually think that storing food at a cooler temperature will extend its shelf life. This is true in most cases. However, when it comes to potatoes, although it is best to store them at lower temperatures, the refrigerator may not be the best place (it’s too low of a temperature).

When potatoes are stored in the fridge, they can undergo a process called “cold-induced sweetening,” where the starches in the potato convert to reducing sugars (i.e. glucose and fructose) (1, 2). When these cold potatoes are cooked at a high heat (roasting, baking, or frying), the reducing sugars react with free amino acids in the potato, forming a byproduct called acrylamide, a carcinogen and neurotoxin (3, 4, 5). This chemical reaction is known as the Maillard reaction.

Exposure to light can increase the levels of a neurotoxic substance in raw potatoes

It is important to keep your raw potatoes away from light. Exposure to light can increase the levels of chemical compounds called glycoalkaloids. The main types of glycoalkaloids in potatoes are a-solanine and a-chaconine. These chemical compounds can be toxic to humans, where they can disrupt nerve impulseswithin the body (6). In addition, they can cause headaches, fatigue and digestive issues (nausea, vomiting, abdominal pain and diarrhea) (6).

One way to gauge the levels of glycoalkaloids in the potatoes would be to see how much green there is on the potato. The longer the exposure to light, the greener the potato becomes (7). If the potato has only a small portion of green, you can remove the green part without much worry.

Eat potatoes that have been cooked and cooled to increase your intake of resistant starch

Something interesting happens when you cook potatoes and then place them in the fridge. Cooking and cooling the potatoes increases the formation of resistant starch , which is a type of carbohydrate that cannot be broken down by the body.

The main benefits of resistant starches include the following:

1. Lowers the glycemic index (GI), which helps to reduce blood sugar spikes after eating. This could be good for those that have issues with balancing blood sugar. Cooking and cooling potatoes can reduce the GI by about 25% (8).

2. Improves gut health , where the resistant starch serves as food for the good bacteria (probiotics) within your gut. Keeping the good gut bacteria happy and thriving help them do their job. They are key players in producing substances like short-chain fatty acids, which help to maintain the integrity of the gut lining, making you less prone to leaky gut syndrome (9, 10, 11).

Key take away points:

1. Store your raw potatoes in a cool place, but not in the refrigerator or freezer. Some good places can include your basement or inside a cabinet. The ideal temperature to store them at is between 42°-55°F (7). This will help to prevent the accumulation of acrylamide in your potatoes. Also, make sure that the potatoes are well ventilated. Do not put them into a non-perforated bag. This will shorten their shelf life.

2. Keep your raw potatoes away from light. This will decrease the levels of toxic glycoalkaloids in your potatoes. If your potatoes are green, toss them out.

3. Eat potatoes that have been cooked and cooled to increase your intake of resistant starch. The ideal length of time for the potatoes to cool in the fridge would be between 1-3 days.

We look forward to connecting with you soon! In the meantime, eat well and fill your body with nutrient dense foods. This will help to maintain overall health and support your immune system.

References

1. Alamar, M.C. et al. 2017. Assuring Potato Tuber Quality during Storage: A Future Perspective. Frontiers in Plant Science . 8, 2034.

2. Sowokinos, J.R. 2001. Biochemical and molecular control of cold-induced sweetening in potatoes. American Journal of Potato Research . 78, 221–236.

3. Mottram, D.S. et al. 2002. Acrylamide is formed in the Maillard reaction. Nature. 419, 448-449.

4. Pruser, K.N. and Flynn, N.E. 2011. Acrylamide in health and disease. Frontiers in Bioscience (Scholar edition) . 3, 41-51.

5. Shepard, L.V.T. et al. 2010. Variation in acrylamide producing potential in potato: Segregation of the trait in a breeding population. Food Chemistry. 123, 568-573.

6. Cantwell, M. 1996. A Review of Important Facts about Potato Glycoalkaloids. Perishables Handling Newsletter. 87, 26-27.

7. University of Idaho Extension. 2009. Options for Storing Potatoes at Home. https://www.extension.uidaho.edu/publishing/pdf/cis/cis1153.pdf . Accessed March 30, 2020.

8. Tahvonen , R. et al. 2006. Influence of different processing methods on the glycemic index of potato (Nicola). Journal of Food Composition and Analysis . 19, 372-378.

9. Clifton, P.M. and Topping, D.L. 2001. Short-chain fatty acids and human colonic function: roles of resistant starch and non-starch polysaccharides. Physiology Reviews. 81, 1031-1064.

10. Wong, J.M. et al. 2006. Colonic health: fermentation and short chain fatty acids. Journal of Clinical Gastroenterology . 40, 235-243.

11. Bird, A.R. et al. 2010. Resistant starch, large bowel fermentation and a broader perspective of prebiotics and probiotics. Beneficial Microbes. 1, 423-431.

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