Sweet potatoes: Not Just For Thanksgiving

After seeing my recent blog post about the hazards of rice-eating, a dispirited reader wrote to ask whether there were any safe starches left that he could eat to fuel his morning workouts. After giving up gluten-containing grains, rice had been his standby, but if he cut down on that – what was left?

My immediate answer: sweet potatoes!

They’re not only a slow-releasing source of energy perfectly suited to athletes need; they also contain a wide range of important nutrients.

For one, they are packed with antioxidant carotenoids and, in the case of purple sweet potatoes, anti-inflammatory anthocyanins which – surprisingly – are found not only in the skins of the potatoes, but also in their flesh. These can protect our cells against free-radical attacks that can lead to cancer.

Various color pigments in sweet potatoes are also thought to reduce inflammation, which is another cancer driver. In animal studies, consumption of either sweet potato or its color-containing extracts has been shown to reduce the activation of various inflammatory factors and reduce inflammation in brain tissue and nerve tissue throughout the body (2).

Unlike most other starchy tubers, sweet potatoes also have a gentle effect on our blood glucose. In addition to a moderate glycemic index ranking, they help to increase blood levels of a hormone called adiponectin that’s produced by our fat cells and helps to regulate our blood-sugar metabolism, making our cells more sensitive to the effects of insulin (3).

Last bit of good news: sweet potatoes are not members of the deadly nightshade family, so even people who cannot tolerate these (they include potatoes, peppers, tomatoes, chilies) can safely eat sweet potatoes.

For those who aren’t used to cooking with sweet potatoes, it’s easy!

First, choose potatoes whose flesh is colored orange or purple as these contain more antioxidants than the white-fleshed varieties. Make sure they are firm and don’t have any cracks or soft spots.

The most basic preparation is simply to peel the potatoes, cut them into cubes of roughly 1 by 1 inch and steam them until soft. They soften faster than white potatoes – about 15 minutes of gentle steaming should to the trick. Then mash them with a potato masher, adding olive oil, coconut oil or butter (added fats increase the absorption of the carotenoids in the potatoes), spices such as cinnamon, ginger or cardamom, top with chopped walnuts or hazelnuts and raisins or chopped apricots, and, if you like, a tiny drizzle of maple syrup. A delicious warm and sweet breakfast alternative to oatmeal!

If you prefer savory sweet potatoes, mash them with a little salt and pepper and olive oil and top with caramelized onions as a scrumptious side dish. They are delicious too roasted in the oven, split in half and eaten with a small pat of butter or a drizzle of fresh olive oil and a little salt.

And if you are the kind of person who batch-cooks to save time, simply make a large portion of sweet potato mash without adding anything, freeze it in small portions and pull them out of the freezer whenever needed, seasoned as you see fit. For people on the go, like our athletic reader above, a small portion of sweet-potato mash can, for instance, be added to a morning smoothie for added thickness, sweetness and muscle fuel.

One of my favorite ways of eating sweet potatoes is this (from Zest for Life, The Mediterranean Anti-Cancer Diet):

Sweet Potato Flan

A great way to wean your taste buds off sugar, this moist and spicy flan is deliciously sweet without containing any added sweetener. It can be enjoyed warm or cold, as a dessert (with Coconut cream, below, if you want to push the boat out), for breakfast or as a sweet snack. Makes one 9-inch/23-cm flan (gluten-free).

1¾ lb/800g sweet potatoes (orange-fleshed), peeled and cubed

2 tbsp lightly toasted grated coconut

2oz/4 tbsp/60g butter or coconut oil

4 eggs

grated zest of ½ lemon (untreated)

½ tsp powdered ginger

1 tsp cinnamon

1 tsp natural vanilla extract

pinch of nutmeg

2 tbsp potato starch

1 tsp baking powder

2oz/ heaped 1/3 cup/60g raisins or dried cranberries

pinch of salt

Preheat oven to 350°F/180°C. Line the bottom of a round cake tin (9-inch/23-cm diameter) with greaseproof paper and lightly rub the sides with butter.

Steam sweet potatoes for 15-20 minutes; remove from heat.

Meanwhile, warm a dry frying pan on medium heat and toast grated coconut until it turns a light golden color. Tip onto a plate to cool.

Tip soft potatoes into mixing bowl and beat into a soft puree with an electric whisk. Add butter or coconut oil (whichever using) and whisk again to melt. Add eggs, lemon zest, ginger, spices, potato starch, baking powder, dried fruit and salt and whisk thoroughly.

Pour into prepared cake tin and place in preheated oven. Bake for 30-40 minutes, ensuring the top doesn’t brown too much; loosely cover with foil if it does. The flan is done when a knife tip inserted in its center comes out clean.

Remove flan from oven and leave to cool. Transfer to a cake plate and sprinkle with lightly toasted grated coconut before serving.

References

(1)    Zhang ZF, Fan SH, Zheng YL, Lu J, Wu DM, Shan Q, Hu B. Purple sweet potato color attenuates oxidative stress and inflammatory response induced by d-galactose in mouse liver. Food Chem Toxicol. 2009 Feb;47(2):496-501. Epub 2008 Dec 13.

(2)    Wang YJ, Zheng YL, Lu J, Chen GQ, Wang XH, Feng J, Ruan J, Sun X, Li CX, Sun QJ. Purple sweet potato color suppresses lipopolysaccharide-induced acute inflammatory response in mouse brain. Neurochem Int. 2010 Feb;56(3):424-30. Epub 2009 Nov 24.

(3)    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. 2008 Jul;10(7):586-92. Epub 2007 Jul 21.