Potato Advice for Diabetics (and Non-Diabetics)

Everybody likes potatoes. They are by far the most consumed vegetable in the UK and the solid backbone of the majority of our favourite dishes. More often than not cooked in oil and covered in salt or piled high and mashed with butter potatoes can be hugely unhealthy – and off-limits for diabetics. However, this doesn’t need to be the case. Here is some advice for both diabetics and non-diabetics on the most beneficial way to consume potatoes.

POTATOES AND ROOT VEGETABLES

Why you may need to cut back on potatoes

Potatoes are an important part of many people’s main meal of the day, but a serving of mashed potato will raise blood glucose levels quickly. This is because potatoes are very high in the type of starch that gets digested very quickly.

The GI value of potatoes varies according to variety and type of cooking. The highest GI value is in potatoes that are freshly cooked, mashed or baked. Pre-cooking and reheating or eating cold cooked potato (for example, in potato salad) has been shown to reduce the glycaemic response by as much as a third. White potatoes and waxy potatoes contain lesser amounts of carbohydrate than red-skinned varieties. Small new potatoes are a better choice because, the younger they are when picked, the lower the carbohydrate content (and this is true of all fruit and all vegetables).

Should people with Type 2 diabetes give up potatoes?

Well, a large daily portion of mashed potato is probably not a good idea. But rather than giving up potatoes, the types of potato and the way they are eaten can be altered. Instead of cooking big starchy potatoes, small potatoes can be cooked in their skins, cooled and then reheated. And mashed potato does not have to totally disappear – it can become a mixed mash. A medium potato can be left unpeeled, cut into chunks and boiled while a similar quantity of broccoli or cauliflower is steamed on top. The two can then be mashed together. Generous amounts of spinach or kale can be included in a potato mash, or equal amounts of potato and beans mashed together – these are all ways of reducing the glycaemic response to big starchy potatoes. And don’t forget bubble and squeak – a medium potato cooked with a generous number of sprouts, mashed and then fried and served with a poached egg on top is a quick supper. As always, a moderate portion rather than a mountain of mash is key. Cooking potatoes like this may seem fiddly and time-consuming but, in theory, it reduces the glycaemic response that mashed potato alone will elicit. Rightly or wrongly (no research evidence here), it makes us feel able to eat small portions of mashed potato without feeling guilty or anxious. Unfortunately, the same cannot be said of baked potatoes or chips – there is no way they can be turned into a low- or even medium-GL food.

But remember – the skins are good for you Potato skins contain a lot of fibre. They also contain high levels of potassium and vitamin C as well as other beneficial substances. It is known that potassium is linked to a lower risk of heart disease and stroke, but only if the potassium comes from natural food. As supplements taken in pill-form do not confer this benefit it makes sense to cook potatoes in their skins whenever possible. Roast potatoes are the only ones that really need to be peeled.

Potato crisps

These have a medium GI but are likely to contain a lot of salt – between 0.5–1g of salt for every small (30g) packet.

Sweet potatoes

These are not members of the potato family. They have a medium GI value but are considered nutritious because they contain high amounts of beta-carotene – the substance that makes carrots orange. Sweet potatoes take the place of ordinary potatoes in many low-GI recipes.

Parsnips

Parsnips have a GI of 97, almost as high as glucose. But, as parsnips have a medium GL of 12, a small portion of parsnip should not have the same undesirable effect on blood glucose that a small portion of mashed potato has.

In short, simply lessen the amount of potato that is on your plate, keep the skins, and substitute a sweet potato every so often. There is no reason why the potato should stop being the cornerstone of your cooking – rethought and re-approached it can continue be a source of enjoyment and nutrition.