Spud Sunday: What?s In A Spud?

I’ve been called many things in my time, though “Guardian … of the Spud” was a new one.

That title was kindly bestowed by Aoife McElwain (she of I Can Has Cook) in her brand new Foodie News column in the Irish Independent weekend magazine. Needless to remark, it is a moniker that I will wear with pride (and perhaps even, as suggested by some, with an accompanying superhero-style cape).

So, as Guardian (not to mention Promoter) o’ the Spud, it seemed as good a time as any for a no-holds-barred, down ‘n’ dirty nutritional profile of what is, after all, the world’s most widely cultivated vegetable. So brace yourselves, folks, you’re about to find out that there’s a whole lot more to this tuber than starch. Let the facts begin.

For one thing, there’s water, and lots of it. H2O accounts for about 80% of a typical potato tuber, though this percentage can vary significantly depending on the type of potato. Waxy varieties will have a higher water content, floury types, less.


The rest of the potato is mostly starch, though I’m guessing you knew that already. Your average potato also contains small amounts of simple sugars, which are important for developing the golden-brown colour of fried and roasted potatoes. Overall, a potato has a lower carbohydrate content than other roots and tubers and a plain boiled potato has less calories than the equivalent weight of plain boiled rice, pasta or bread. Honest.


Over time, some of a potato’s starch will convert to sugars when stored below about 10°C, and markedly so at 6°C and below. So it’s best not to store your spuds in the fridge, unless uncharacteristically sweet potatoes are what you’re after.


While only 2% of a potato is protein, the protein is high-quality and the potato boasts a good carbohydrate to protein ratio. When compared with rice and cereals, it has a higher lysine content and lower concentrations of other amino acids such as cysteine. For those not averse to a bit of carb-on-carb action, this means that putting rice or pasta on your plate alongside potatoes will actually provide a better quality protein than either one or the other. Who’d-a-thunk-it?


Fat content is very low, as is, consequently, the occurrence of fat-soluble vitamins. If your spuds are fried or roasted, however, that’s a fatter matter entirely.


Both the flesh and the skin of a potato contain dietary fibre, though (unsurprisingly) there’s a greater concentration in the skin. The skin also prevents or reduces the leaching of vitamins and minerals into cooking water when boiling, so it is better (nutritionally) to peel after boiling, if you’re going to peel at all.



It’s said that when men were dying from scurvy during the Klondike Gold Rush, potatoes were sold for their weight in gold. This had everything to do with the fact that potatoes were, and are, a very good source of vitamin C. 100g of freshly harvested spuds, boiled in their skins, gives about 50% of an adult’s typical recommended daily intake. Long term storage (which is increasingly common) and cooking, especially if potatoes are peeled beforehand, will, however, deplete vitamin C levels.


Spuds have much else in their nutritional vitamin arsenal, being well-equipped with B complex vitamins, especially B1, B6 and niacin.


There’s a goodly array of minerals, such as magnesium and phosphorous, residing spudside too. They’re particularly rich in potassium, the consumption of which, if this recent article is to be believed, may predispose a woman to conceive male children. Many’s the royal spouse who could, no doubt, have done with that information.


Sodium quantity is low, which is good for those who need, or want, to avoid excessive amounts in their diet.


You’ll find a host of trace elements in a potato, from aluminium to zinc, and its iron content can contribute significantly to daily requirements.



Highly-coloured potato varieties – those with blue, purple, red or even just yellow flesh – are rich in antioxidants, though specific concentrations will vary with different varieties. Recent research has shown that their consumption may lower susceptibility to certain chronic diseases, when compared with eating white-fleshed potatoes.


Overall, potatoes are an alkaline food source, with high levels of potash and alkaline salts. This makes them a good thing to eat if you’ve got a hangover, when acidity levels in the body are elevated.


While the focus of the book Potatoes, Not Prozac is about managing biochemical imbalances brought about by sugar sensitivity, consuming complex carbohydrates, such as potatoes and their skins, is part of its dietary solution for mental health and well-being.


All potatoes contain glycoalkaloids, which can be toxic if present in large quantities. Whilst levels are safe in our cultivated varieties, concentrations will increase with exposure to light. This exposure also results in greening of the potato and, although it’s a separate process, it acts as a useful indicator of increased glycoalkaloid content. What I’m trying to say is, don’t eat the green bits, ok?


Finally, If you’ve eaten potatoes for long enough, you’ve probably come across those that show browning or a hollow at the heart of the spud (which occurs due to abrupt changes in growing conditions). These browned centres are known in Irish as cuasán (pronounced coo-a-sawn). My father’s mother’s mother, I’m told, regarded it as a delicacy, while my mother’s father’s father maintained that the best part of the potato was that found around the cuasán. All I can say is that, if it was good enough for them, it’s plenty good enough for me.