Sweet potato vs. normal fries
by T J Waterfall
25 July 2018
We asked TJ Waterfall, a plant-based human biologist (BSc), psychologist (BSc), and nutritionist (MSc) for an in-depth analysis of whether sweet potato fries are any better for you than regular spuds
Hit up your favourite burger joint and you can bet your bottom dollar that you’ll find sweet potato fries on the menu. A quick scroll through instagram and you can’t get away from those vibrant orange dream sticks.
And this is great, because there’s a growing number of us who would rather opt for a healthier alternative to the old-fashioned potato fry. Many of us have been there: “no, I’m being good at the moment, I’ll order the sweet potato fries instead please”.
But what really are the health benefits of sweet potato fries over normal fries? Let’s firstly take a look at some of the most noticeable nutritional differences between the two tubers:
Sweet potatoes are much higher in beta carotene, the pigment that gives the red / orange colour in many fresh fruits and vegetables. Beta carotene is an antioxidant and is converted in the body to vitamin A, so it’s an important nutrient necessary for maintaining healthy skin, eyes, and immune systems, and can help protect against cancer. Sweet potatoes are also higher in fibre, something most of us are lacking in our western diet (1) which is really important for digestion and keeping our guts healthy.
So far, so good.
However, regular potatoes contain much more vitamin C, which as we all know is important for our immune systems, but is also an antioxidant, and is involved in the synthesis of collagen which is required for the normal structure and function of connective tissues such as skin, cartilage and bones. Regular potatoes are also much higher in potassium, essential for water and electrolyte balance and the normal functioning of cells, including nerves. In fact, many of us don’t meet the suggested intake of potassium and instead we eat too much sodium (salt), and this high sodium-to-potassium ratio is putting us at higher risk of cardiovascular disease (2,3).
Sweet potatoes and regular potatoes are roughly on a par for most other nutrients. Both provide a little bit of protein, some B-vitamins, and small amounts of some minerals such as copper, manganese and iron. It’s important to remember however that most of the nutrients are found in the skin of both varieties, so whether we’re ordering out or making some at home, it’s best to go for the skin-on options where possible.
What about the calories? Many of us choose to order sweet potato fries because we’re watching our waistline, but sweet potatoes are in fact slightly more calorific than regular potatoes due to their higher sugar content!
Now, it’s all very well nit-picking about the nutritional content of sweet potatoes and regular potatoes. To be fair, both contain some important nutrients. But there’s one aspect which is probably the most significant point of all with regards to our health; how the fries are cooked. When we order either type at a restaurant, the chances are they’re deep fried. So let’s take a look at some important nutritional points to consider when we order anything that’s deep fried:
Oils used for deep-frying (like vegetable and sunflower oils) are high in omega-6. While this is an essential fatty acid, in the western world we tend to eat far too much of it, while typically consuming too little omega-3 (found in leafy vegetables, walnuts and flaxseeds). A high intake of omega-6 relative to omega-3 leads to a pro-inflammatory state within our bodies, which is linked with many chronic inflammatory diseases (4). Therefore, we should try to reduce our intake of anything deep fried and up our intakes of those healthy omega-3 sources, which incidentally come with an array of other health benefits.
The combination of high temperatures, and the oils used in deep frying, can lead to the formation of acrylamide in starchy foods like potatoes and sweet potatoes, a chemical that has the potential to increase risk of cancer (5,6). The lipids in common cooking oils, such as sunflower oil, also degrade over time at high temperatures, forming various oxidative products known as aldehydes, some of which are also known to be carcinogenic (7,8).
Frying either type of potato significantly increases its calorific density because of the extra fat content that’s absorbed by the fries. Both sweet potato and regular fries typically come in at well over 400 calories per regular-sized serving. That’s 20% of your recommended daily caloric intake in just a side order.
If you’re trying to be healthy, ordering sweet potato fries probably isn’t the answer. While they’re higher in some nutrients, regular potato fries are in fact higher in others, and they’re just as calorific. Plus they’re still deep-fried, and probably covered in salt, which pretty much offsets any of the health benefits anyway. So the boring answer would be: don’t order either – go for a side of veggies or salad instead.
However, the practical answer, and the mantra I live by, would be to keep things in moderation. Go for whichever fries you like every once in a while. Include them as part of a healthy balanced diet that contains plenty of fruit, vegetables, whole grains, pulses, nuts and seeds. It’s easy to get bogged down by focusing too much on the macro- or micro-nutrient content of our foods, rather than eating food for the enjoyment of it. If you prefer them, then fine, but ordering sweet potato fries when you don’t actually like them as much, to me defies the point of eating out altogether. We eat every day of our lives, so having a healthy relationship with our food, enjoying what we eat, and savouring that pleasure is something we should all try to embrace more.
"TJ Waterfall is a registered nutritionist specialising in plant-based nutrition, and founder of meatfreefitness.co.uk. He's debunking the myths surrounding getting fit and healthy on a plant-based diet, using science-based evidence. He also provides tailored nutrition guides to vegan and vegetarian clients to help them reach their weight, fitness and health goals. Check out his website, Instagram, Twitter and Facebook pages"
1. Public Health England publishes latest data on nation’s diet: https://www.gov.uk/government/news/phe-publishes-latest-data-on-nations-diet (accessed 03.07.2018)
2. Powles, J., Fahimi, S., Micha, R., et al. (2013). Global, regional and national sodium intakes in 1990 and 2010: A systematic analysis of 24 h urinary sodium excretion and dietary surveys worldwide. BMJ Open, 3(12), E003733.
3. World Health Organisation issues new guidance on dietary salt and potassium: http://www.who.int/mediacentre/news/notes/2013/salt_potassium_20130131/en/ (accessed 03.07.2018)
4. Patterson, E., Wall, R., Fitzgerald, G., Ross, R., & Stanton, C. (2012). Health Implications of High Dietary Omega-6 Polyunsaturated Fatty Acids. Journal of Nutrition and Metabolism, 2012(11), 16
5. Lim, P., Jinap, S., Sanny, M., Tan, C., & Khatib, A. (2014). The Influence of Deep Frying Using Various Vegetable Oils on Acrylamide Formation in Sweet Potato ( Ipomoea batatas L. Lam) Chips. Journal of Food Science, 79(1), T115-T121.
6. Food Standards Agency: Information on the risks of acylamide and how you an reduce the chances of being harmed by it: https://www.food.gov.uk/safety-hygiene/acrylamide (accessed 03.07.2018)
7. Katragadda, Fullana, Sidhu, & Carbonell-Barrachina. (2010). Emissions of volatile aldehydes from heated cooking oils. Food Chemistry, 120(1), 59-65.
8. Peng, Lan, Lin, & Kuo. (2017). Effects of cooking method, cooking oil, and food type on aldehyde emissions in cooking oil fumes. Journal of Hazardous Materials, 324(PB), 160-167.