The highs and lows of sweet potato
We thought that it was time to see if we could sort some of the confusion about sweet potatoes. This handy vegetable has been GI-tested on a number of occasions at various labs around the world (Canada, New Zealand and Australia), and like potato, the results have been varied: sometimes high, sometimes moderate and sometimes low, What we haven’t always been able to tell from some of the earlier tests which variety was tested. So, Fiona Atkinson at SUGiRS set to and has been cooking up a storm over the past few months. What did she find? Like potatoes, it comes down to variety.
Copper-coloured skin, orange flesh
(boiled) GI 61
Purple skin, creamy flesh
(boiled) GI 75
Sweet potatoes (Ipomoea batatas), commonly called a yam in the US and Canada aren’t a ‘potato’ at all. They aren’t actually yams either, botanically speaking. They are the sweetish tasting tuberous roots of a vine from the sprawling morning glory family. They have a smooth skin which can be red, purple, copper-coloured, brown and white depending on variety and white, yellow, orange, and purple flesh. They are rich in nutrients including beta-carotene, vitamin C and fibre plus vitamin E, thiamin and folate. A big advantage over potatoes is that the skin does not develop green patches (making them inedible) when exposed to light.
What do these new values mean if you are trying to lower the GI of your diet? Well, first of all look for the lower GI varieties. Secondly, remember that not everything you eat has to have a low GI. Enjoy the higher GI varieties in season, but in moderation. And remember that serving them with a vinaigrette dressing or mashing them with legumes (pulses) will also lower the GI. And above all keep in mind that we don’t want anyone to use the GI in isolation when creating a healthy eating plan. It’s important to eat a wide variety of foods. Sweet potatoes are nutritious and filling and fat free (when steamed or boiled). A serving is about 120 grams (4 oz).
The latest North American values
Tested by Glycemic Index laboratories, Toronto
When that meal needed to be on the table 5 minutes ago, super convenience is what you need, even though it may cost a little more. Here are 9 pouch products from Uncle Ben’s Ready range with a low GI. All you do is pop the pouch in the microwave and it heats in 90 seconds.
Uncle Ben’s Ready Rice
Original Long Grain GI 48
Long Grain and Wild GI 49
Roasted Chicken Flavoured GI 51
Spanish Style GI 51
Uncle Ben’s Ready Whole Grain
Brown Rice GI 48
Chicken Flavored Brown Rice GI 46
Uncle Ben’s Ready Whole Grain Medley
Santa Fe GI 48
Vegetable Harvest GI 48
Brown and Wild GI 45
You can find details of the ingredients in each product and nutrition information on Uncle Ben’s website. But for those who need to consider carbohydrate quantity, a one-cup serving contains from 37–46 grams of carbohydrate.
Where can I get more information on GI testing?
Dr Alexandra Jenkins
Glycemic Index Laboratories
36 Lombard Street, Suite 100
Toronto, Ontario M5C 2X3 Canada
Phone +1 416 861 0506
Research Manager, Sydney University Glycemic Index Research Service (SUGiRS)
Human Nutrition Unit, School of Molecular and Microbial Biosciences
NSW 2006 Australia
Phone + 61 2 9351 6018
Fax: + 61 2 9351 6022
Dr Tracy Perry
The Glycemic Research Group, Dept of Human Nutrition
University of Otago
PO Box 56 Dunedin New Zealand
Phone +64 3 479 7508
Where can I get more information on the GI symbol program?
Acting CEO, Glycemic Index Ltd
Phone: +61 2 9785 1037
Fax: +61 2 9785 1037