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All About the Humble Spud

July 14, 2017

So yesterday was apparently International Fries day, and as a happy coincidence this is what I plated up for dinner. 

 

I must say its not something I'd regularly cook, but last night I was really craving some tater-y goodness. These fries are a far cry from the ones you would get at Maccas, but they were delicious just the same.

 

Now, white potatoes have taken a beating in the media over the last few years and many people now avoid them because they are concerned about the carbohydrates, the high glycaemic index and the potato glycoalkaloids (alko-what now? More on this later) ...but is it justified? Lets take a look.

 

 

Potato Nutrition

Originating in South America, potatoes are a starchy, tuberous crop from the nightshade family and have been a dietary staple for thousands of years.

 

Lets take a look at the nutrition of a small white potato (150 g):

  • 420 kJ (100 calories)

  • 3.5 g protein

  • Very low in fat, with less than half a gram

  • 3.5 g of fibre 

  • Cholesterol free

  • Low in salt

  • 31.5 mg of Vitamin C (70% of RDI)

  • 645 mg of Potassium ( 23% of RDI for women, 17% of RDI for men)

  • 0.2 mg of Vitamin B6 (15 % of RDI)

That's not too shabby. So a small potato contains more potassium than a banana, and more vitamin C than an orange! Potassium is a very important nutrient that can help decrease your blood pressure and reduce your chance of stroke, and unfortunately most of us aren't eating enough. 

 

Potatoes also score very highly on the satiety index, meaning they fill you up and keep you full. In fact potatoes score almost 2.5 times higher than other carbohydrate sources like rice and pasta. This means potatoes could have a key role in weight management by helping control our appetite.

 

 

But here's the problem 

The devil is in the detail. How you prepare a potato can either turn this food into a nutritious and delicious dinner OR turn it into a health disaster. If you load your potatoes up with salt, oil, sour cream or bacon bits all the potassium in the world isn't going to save you. Additionally processed potato products do not have the same satiety - you can easily overeat. Let's take a look at the difference in fat content, depending on cooking method:

 

When you consume potato chips (crisps) a whopping 58% of your calories are coming from fat.
 

What about GI?

The average white potato is generally considered to be a high GI food, although this is very dependent on the variety and cooking method, for example baked potatoes tend to have a higher GI than boiled. Not all potatoes fall into the high GI category and recently some potato varieties have been developed to have a low glycaemic index. If you cook and then cool your potatoes before consuming you also increase the amount of Resistant Starch in your taters, which will lower the GI. Resistant starch may also deliver other health benefits like improved digestion, increased satiety, lower cholesterol and improved immunity. I would like to add however, if you are Diabetic and struggle greatly with controlling your blood sugars I usually recommend moderating (NOTE - note completely avoiding!) your intake of white potato and other carbohydrates that score highly in terms of glycaemic load, and focusing more on legumes as your major source of carbohydrate, but more on that another time. 

 

 

Glycoalkaloids

Glycoalkaloids are nitrogen-containing compounds which potatoes produce as a natural insecticide.  When humans consume them in excess they can cause disruption to cell membranes and neurotransmitters. Yikes! The amount of glycoalkaloids found in potatoes is influenced by growing conditions, physiological stress to the potato (bruising, cuts etc), climate, insect attacks and exposure to artificial light or sunlight. Have you ever noticed your potatoes developing a green hue when left in sunlight? When this happens.- don't eat them. This is solanine, one of the most common glycoalkaloids found in potatoes. Likewise if the potato is damaged or bruised it is best to err on the side of caution and opt for a better looking spud. It is important to always store your potatoes in a cool, dry and dark place. If you are still worried about glycoalkaloids removing the skin can reduce amounts by up to 50%.

 

In Australia there is no standard for glycoalkaloid levels in potatoes, although a safety limit of 200 mg/kg fresh weight is widely accepted. In previous government testing no potatoes have exceeded the safety limit, with most having between 43-103 mg/kg, showing that potatoes pose minimal risk for glycoalkaloid toxicity. Deep frying potatoes that still have their peels however, can allow glycoalkaloids to move into the cooking fat. If that oil is reused repeatedly before changing, it can increase the glycoalkaloid concentration by up to three times. Another good reason to avoid chips! 

 

 

Would you like fries with that? Well your tastebuds might, but your body definitely would not. 

 

 

Acrylamide

Deep frying your potato can also significantly increase the amount of acrylamide. Acrylamide can form in starchy foods when they are cooked at high temperatures. Frying, baking and roasting are more likely to create acrylamide, whilst steaming, boiling, or microwaving appears less likely to do so.  The International Agency for Research on Cancer (IARC) classifies acrylamide as a “probable human carcinogen”. So best not to leave your potatoes to char or crisp up too much in the oven. 

 

 

Take Home Message

Potatoes are a good source of some key nutrients and are quite satiating when cooked appropriately. Potatoes do contain some naturally occurring toxins (as do many other foods!) but when eaten in moderate amounts these substances pose minimal risk to health. Store your potatoes correctly to minimise any risk. When cooked with minimal processing, potatoes can play a part in a healthy diet, and as an added bonus they have a low environmental footprint! If you have no desire to incorporate potatoes into your diet then that's completely fine, however if you can't imagine your life without the odd mashed potato, steamed spud or oven bake, please enjoy your meal and ditch the guilt.