Why do sweet potatoes get "superfood" status while regular potatoes are vilified? Here's why both tubers deserve a place on your plate.
It's time to set the record straight on spuds.
In recent years, and in certain "healthy eating" circles, the sweet potato has been crowned a "superfood" while the regular potato has been treated like the bad guy.
High carb, high glycemic index, loaded with antinutrients? Is the plain old potato really so bad?
Here's the real deal: Both regular potatoes and sweet potatoes deserve a place in your diet. You can eat both as part of a well-balanced, whole food diet and still have a lean and healthy body.
But as usual, there is a catch or two. Here's what you need to know.
In defense of starchy carbohydrates
Have you been warned by diet gurus to stay away from "starchy carbs"?
Moderating your carbohydrate intake (or timing your consumption of carbs around your exercise program) may be a good thing, depending on your goals, body type, and activity levels.
But there's a difference between high-carb processed foods and whole foods that contain resistant starch.
Resistant starch refers to complex starch molecules that we can't digest. To break these molecules down, the gut bacteria in our large intestine need to go to work. That breakdown process takes time and effort.
Both regular potatoes and sweet potatoes contain starch, some of which is resistant starch. That's one of the reasons why they're considered "slow-burning" -- they make you feel full for hours because it takes your body longer to process them. That provides energy and satiation -- a satisfied, full feeling that is especially important if you're trying to eat less.
Resistant starch is one of the reasons why you shouldn't lump potatoes together with high-carb processed foods. Because a plain baked potato is going to behave differently in your body than a bag of chips or a donut.
Don't be mislead by the glycemic index
Maybe you've heard of the glycemic index, and the benefit of eating "low glycemic" foods.
The glycemic index (GI) maps how quickly a food converts to glucose. This is often compared with how much a food converts to glucose (which is known as the glycemic load, aka GL).
The idea is to avoid foods with a high GI and/or GL, lest they cause a blood sugar spike, and contribute to fat gain. People following this approach will usually choose sweet potatoes over regular potatoes.
But there's a problem with ranking food this way.
For one thing, GI changes with food type. And potatoes vary by variety, so floury potatoes will wind up somewhere different on the glycemic scale than waxy potatoes.
For another, GI changes when other foods are introduced. We don't usually grab a plain baked potato and start gnawing on it. We generally eat both potatoes and sweet potatoes as part of meals.
Finally, and perhaps most striking, GI changes with food preparation. Boiling usually results in a lower GI, since starch can bind with water. The dry heat of baking, on the other hand, lowers moisture and concentrates sugars. Cutting up potatoes and sweet potatoes helps preserve their starchiness, while cooking them whole results in more sugariness.
So, for example, a baked sweet potato actually has a higher GI than a boiled white potato.
Bottom line: The glycemic index misses a lot of important information. If you take into consideration all the variables, it's also incredibly complicated. Good luck trying to hack your way through that potato matrix.
Antinutrients aren't so scary
What about antinutrients? Don't worry, they're not as scary as they sound.
Antinutrients are substances that either interfere with nutrient absorption, or act as toxins in the body. Almost all plant foods contain antinutrients as natural defenses against pests, diseases, and environmental threats. Tubers are no exception.
For instance, most tubers are relatively toxic when uncooked. In fact, green potatoes are poisonous (so cut off the green bits or toss green potatoes altogether).
Potatoes contain proteins such as patatins and lectins, which can be allergenic, particularly if if eaten raw. However, most of these are problems only for people with existing allergies, intolerances, and autoimmune disorders. If you eat potatoes and feel fine, don't worry about it.
Sweet potatoes also contain some antinutrients. But as with regular potatoes, cooking decreases or removes most of them. And sweet potato allergy or intolerance is quite rare.
In the end, both potatoes and sweet potatoes -- like nearly all other plant foods -- have some antinutrients. But these occur in very low levels, and most of the time our bodies are perfectly able to process them.
The good stuff
Now that I've debunked some nasty myths about potatoes, here are some feel-good reasons you should eat them.
Sometimes we get so caught up in talking about macronutrients (proteins, fats and carbs) we forget about the small-but-mighty micronutrients (aka our vitamins and minerals). So let's get micro for a minute.
Sweet potatoes and potatoes of various varieties contain antioxidants, substances that help control oxidative damage in the body. They also offer other nutrients like carotenoids (vitamin A precursors), ascorbic acid (vitamin C), and tocopherols (vitamin E). Plus, they're packed with potentially helpful phytonutrients, including polyphenols, alpha-lipoic acid, selenium, lycopene, and many more.
All these great vitamins, minerals and powerful little plant chemicals may offer some great health benefits. On that basis, sweet potatoes or colored potatoes (e.g., yellow, orange, and purple-fleshed varieties) do offer some extra benefit. In fact, red-fleshed or purple-fleshed potatoes are comparable to Brussels sprouts, blueberries or spinach!
Eat potatoes, not "potatoes"
The most important question you should really be asking about potatoes is: "How am I eating them?"
Is that a plain baked potato on your plate, next to a serving of grassfed steak or wild salmon and some steamed kale?
Or is it a pile of French fries, slathered in ketchup, accompanying your fast food burger?
Did your potato come from the ground... or out of a bag or box?
The reality is, most people in the western world consume potatoes in some processed form -- as French fries, tater tots, or potato chips.
Then we layer all kinds of stuff on top of those treats. Fries get ketchup or gravy. Chips get dip. Even baked potatoes get "loaded" with sour cream and bacon.
The sweet potato doesn't get a free pass either. In North America -- especially in the Southern U.S. -- the phrase "sweet potato" is often followed by "pie." (Cue the mini-marshmallows.)
Let's get real with ourselves. Something that ends in the word "pie" probably doesn't count as a vegetable.
Here's how to get the best from your regular and sweet potatoes:
Prepare them properly. First, make sure they're cooked. Baking, boiling, or roasting potatoes and sweet potatoes is generally healthier than frying them. When fried, the starch can create harmful acrylamides.
Eat them as part of a healthy meal. Next to your lean protein and some other veggies, potatoes have their place. Just go easy on the condiments or toppings. A little bit of healthy fat (like a small pat of butter or a drizzle of olive oil) can help your potatoes taste great, and it will even help you absorb the vitamin A in your sweet potatoes.
Mind your portions. In general, a baseline of 1 to 2 cupped handfuls of starchy carbs per meal is reasonable. Potatoes and sweet potatoes count, but so do beans and lentils, fruit, and whole minimally processed grains. You can adjust your carb choices based on your goals and your body's needs -- and have some fun with variety, too.
Potatoes are great... in their natural form, properly cooked, and as part of a healthy meal.
So if you want to eat potatoes, eat potatoes.
Hold the fries.
Want some help finding the best diet for you? Download this free guide: Paleo, vegan, intermittent fasting... Here's how to choose the best diet for you.
About the author.
John Berardi, Ph.D. is a founder of Precision Nutrition, the world's largest online nutrition coaching company. He also sits on the health and performance advisory boards of Nike, Titleist and Equinox.
Dr. Berardi was recently selected as one of the 20 smartest coaches in the world by livestrong.com, the internet's most popular fitness site.
In the last five years, Dr. Berardi and his team have personally helped over 30,000 people improve their eating, lose weight, and boost their health through their renowned Precision Nutrition Coaching program.
Allen, Jonathan C. et al. Glycemic index of sweet potato as affected by cooking methods. Open Nutrition Journal 6 (2012).
Andre, Christelle, et al. Andean potato cultivars (Solanum tuberosum L.) as a source of antioxidant and mineral micronutrients. Journal of Agricultural and Food Chemistry 55 no.2 (2007): 366-378.
Atkinson, Fiona, et al. International tables of glycemic index and glycemic load values: 2008. Diabetes Care 31 no.12 (December 2008): 2281-2283.
Bahado-Singh, Perceval S., et al. Relationship between processing method and the glycemic indices of ten sweet potato (Ipomoea batatas) cultivars commonly consumed in Jamaica. Journal of Nutrition and Metabolism 2011.
Beausoleil, Janet L., et al. Anaphylaxis to raw potato. Annals of Allergy, Asthma & Immunology 86 no.1 (January 2001): 68-70.
Bouis, Howarth and Yassir Islam. Delivering nutrients widely through biofortification: Building on orange sweet potato. International Food Policy Research Institute (IFPRI) Brief 11 (June 2012).
Brown, C.R. Antioxidants in potato. American Journal of Potato Research 82 no.2 (March-April 2005): 163-172.
Burlingame, Barbara, et al. Nutrients, bioactive non-nutrients and anti-nutrients in potatoes. Journal of Food Composition and Analysis 22, no. 6 (September 2009): 494-502.
Burri, Betty J. Evaluating sweet potato as an intervention food to prevent Vitamin A deficiency. Comprehensive Reviews in Food Science and Food Safety 10 (2011).
De Swert, L.F.A., et al. Diagnosis and natural course of allergy to cooked potatoes in children. Allergy 62 no.7 (July 2007): 750-757.
Denham, Tim. Ancient and historic dispersals of sweet potato in Oceania. PNAS 110 no.6 (February 5, 2013): 1982-1983.
Huang GJ, et al. Defensin protein from sweet potato (Ipomoea batatas [L.] Lam 'Tainong 57′) storage roots exhibits antioxidant activities in vitro and ex vivo. Food Chem 135 no.3 (Dec 2012): 861-7.
Huang, Dong-Jiann, et al. Antioxidant and antiproliferative activities of sweet potato constituents. Bot. Bull. Acad. Sin. 45 (2004): 179-186.
Jeffery J, et al. Physical barriers to carotenoid bioaccessibility: Ultrastructure survey of chromoplast and cell wall morphology in nine carotenoid-containing fruits and vegetables. Journal of Science, Food, & Agriculture 92 no.13 (Oct 2012): 2594-602.
Jiao, Yuzhi, et al. Study on chemical constituents and antioxidant activity of anthocyanins from purple sweet potato (Ipomoea batatas L.). International Journal of Food Engineering 8 no.2 (June 2012).
Jung, Joong-Keun, et al. Distribution of phenolic compounds and antioxidative activities in parts of sweet potato (Ipomoea batata L.) plants and in home processed roots. Journal of Food Composition and Analysis 24, no.1 (February 2011): 29-37.
Kim SH, et al. Cloning and characterization of an Orange gene that increases carotenoid accumulation and salt stress tolerance in transgenic sweetpotato cultures. Plant Physiology and Biochemistry 70 (September 2013):445-54.
Lachman, J., et al. Red and purple coloured potatoes as a significant antioxidant source in human nutrition - a review. Plant, Soil and Environment - UZPI (Nov 2005).
Landon, S. et al. The Resistant Starch Report: An Australian update on health benefits, measurement and dietary intakes. Food Australia 2012.
Low, Jan, et al. The introduction of orange-fleshed sweet potato in Mozambican diets: A marginal change to make a major difference. In Diversifying Food and Diets: Using Agricultural Biodiversity to Improve Nutrition and Health. Routledge, 2013: 283-290.
Low JW, et al. A food-based approach introducing orange-fleshed sweet potatoes increased vitamin A intake and serum retinol concentrations in young children in rural Mozambique. Journal of Nutrition 137 no.5 (May 2007): 1320-1327.
Ludvik B, Hanefeld M, Pacini G. Improved metabolic control by Ipomoea batatas (Caiapo) is associated with increased adiponectin and decreased fibrinogen levels in type 2 diabetic subjects. Diabetes Obes Metab. 10 no.7 (July 2008): 586-92.
Ludvik, Bernhard, et al. Efficacy of Ipomoea batatas (Caiapo) on diabetes control in Type 2 diabetic subjects treated with diet. Diabetes Care 27 no.2 (February 2004): 436-440.
Mehr, Sam. Food protein-induced enterocolitis syndrome: 16-year experience. Pediatrics 123 no. 3 (March 2009): e459 - e464.
Monti, G. et al. A case of severe allergic reaction to cooked potato. Acta Paediatrica 100 no.11 (November 2011): 236-238.
Nassar, Atef M.K., et al. Some Canadian-grown potato cultivars contribute to a substantial content of essential dietary minerals. Journal of Agicultural and Food Chemistry 60 no.18 (2012): 4688-4696.
Ooi CP, Loke SC. Sweet potato for type 2 diabetes mellitus. Cochrane Database Systematic Reviews 9 (September 2013): CD009128.
Pramod, S.N., et al. Potato lectin activates basophils and mast cells of atopic subjects by its interaction with core chitobiose of cell-bound non-speciﬁc immunoglobulin E. Clinical and Experimental Immunology 148 (2007): 391-401.
Rose, Ingabire Marie and Hilda Vasanthakaalam. Comparison of the nutrient composition of four sweet potato varieties cultivated in Rwanda. American Journal of Food & Nutrition 1 no.1 (2011): 34-38.
Roullier, Caroline, et al. Disentangling the origins of cultivated sweet potato (Ipomoea batatas (L.) Lam.). PLoS 1 8 no.5 (May 2013).
Roullier, Caroline, et al. Historical collections reveal patterns of diffusion of sweet potato in Oceania obscured by modern plant movements and recombination. PNAS 110 no.6 (February 5, 2013): 2205-2210.
Schmidt, Mirko, et al. Evaluation of patatin as a major cross-reactive allergen in latex-induced potato allergy, Annals of Allergy, Asthma & Immunology 89 no.6 (December 2002): 613-618.
Senthilkumar R, Yeh KW. Multiple biological functions of sporamin related to stress tolerance in sweet potato (Ipomoea batatas Lam). Biotechnology Advances 30 no.6 (Nov-Dec 2012): 1309-17.
Shewry, Peter. Plant storage proteins. Annals of Botany 91 no.7 (2003): 755-769.
Tanumihardjo SA, Palacios N, Pixley KV. Provitamin A carotenoid bioavailability: What really matters? International Journal of Vitamin & Nutrition Research 80 no.4-5 (October 2010): 336-50.
Teow, Choong C. Antioxidant activities, phenolic and b-carotene contents of sweet potato genotypes with varying ﬂesh colours. Food Chemistry 103 (2007): 829-838.
Tomlins, Keith, et al. Relationship among the carotenoid content, dry matter content and sensory attributes of sweet potato. Food Chemistry, 131 no.1 (2012): 14-21.
Trinidad, Trinidad P., et al. Sweet potato and cassava can modify cholesterol profile in humans with moderately raised serum cholesterol levels. Food & Nutrition Sciences 4 (2013): 491-495.
Tumuhimbise GA, Namutebi A, Muyonga JH. Microstructure and in vitro beta carotene bioaccessibility of heat processed orange fleshed sweet potato. Plant Foods in Human Nutrition 64 no.4 (December 2009): 312-8.
Velloso, A., et al. Anaphylaxis caused by Ipomoea Batatas. Journal of Allergy and Clinical Immunology 113 no.2 (February 2004): S242.
Wahl R., et al. IgE-mediated allergic reactions to potatoes. International Archives of Allergy & Immunology 92 (1990): 168-174.