Excerpt from Mendosa
What could possibly cause such tremendous variation? According to Professor Brand-Miller, for rice one of the most important considerations is the ratio of amylose to amylopectin. She says that "the only whole (intact) grain food with a high G.I. factor is low amylose rice, such as Calrose rice...However, some varieties of rice (Basmati, a long grain fragrant rice, and Doongara, a new Australian variety of rice [which is not available in the United States] have intermediate G.I. factors because they have a higher amylose content than normal rice."
Wallace Yokoyama, a research chemist working for the U.S. Department of Agriculture in Albany, California, gave me a comprehensive explanation. There are, says this noted rice specialist, four types of rice: long-grain, medium-grain, short-grain, and sweet rice. Sweet rice is also known as sticky or waxy rice. It makes the best sauces and gravies, and is usually used in Asian restaurants. Sweet rice has no amylose, Yokoyama says. In other words, it is the rice that has the highest glycemic index. The three other types of rice have lower glycemic indexes.
Of course, each of these three types of rice may be brown or white. Brown rice has a lower glycemic index than white rice, everything else being equal. Therefore brown long-grain rice—or if you can find it—brown Basmati rice—will probably have a lower glycemic index. White Basmati rice had a glycemic index of 83 in one study. Brown Basmati rice can be expected to have a somewhat lower index, but we don't know precisely what it is, because the studies haven't been done yet.
In fact, however, Uncle Ben's Converted Rice is the lowest glycemic rice you can get. This is white rice. Jennie Brand-Miller has indicated to me that this company may use a secret process.
Richard Jackson maintains in e-mail to me that my statement that there are three basic types of rice is "somewhat incorrect." He says that there is also a sweet rice used in oriental cooking. "It is not only very much stickier than standard Asian milled rice (such as Kokuro Rose Brand)," he writes, "but is perceptibly sweeter when eaten. It is typically fermented prior to cooking, whereas standard Japanese-style milled rice is not. I think if more research is done into this factor, the data may prove that the difference between sweet rice and regular Asian-style rice is different on the scale of caloric values as pertains to ingestion by diabetics."
Among potatoes, new and some white potatoes have the lowest indexes. The reason that new potatoes have a lower GI is probably because most of the amylopectin is less branched—it is more like amylose at this immature stage.
