Rice: choosing the right tool for the jobby Bill Willis, PhD on December 1, 2012
December 2012: Rice: choosing the right tool for the job
As a staple food for over half of the world’s population, rice is arguably one of the world’s most important foods. It is also one of the most versatile foods in the pantry of any hard training athlete. Most of us who are serious about training and nutrition will utilize it at some point in our nutrition plan. After all, it’s a great, low fat source of complex carbs. Like most people, in the past I have not put a whole lot of thought into the type of rice that I used in my diet. (rice is rice, right?) The differences between different types of rice were limited to taste and texture (I personally like Basmati), as far as I was concerned. Originally, that was going to be the whole message of this article… it’s all good. After looking into rice a bit more,I was reassured that it is all good, but it also became clear that different types of rice are better under different circumstances. There is definitely a science to rice, and it’s not only important for rice growers. For those of us who demand more precision in our nutritional approach, a little rice knowledge will go a long way, helping to choose the right tool for the job.
Rice is actually a seed, from the plants Oryza sativa (Asian rice) or Oryza Glaberrima (African rice). Asian rice varieties are the most common, usually referred to in English as rice. There are actually two subspecies of O. sativa, called Japonica and Indica. Indica rice is typically longer-grain, making it fluffier and less sticky after cooking. Indica grows best in hot, tropical climates, so most varieties are produced in Southern Asia. Japonica rice, on the other hand, tends to be grown in more temperate climates, including Australia, California, Egypt, and parts of China and Japan. Japonica rice grains tend to be shorter and rounder, and are also more sticky and moist after cooking.
Different types of rice
White rice vs. brown rice:
When only the outermost “husk” layer of a rice grain is removed, brown rice is produced. Just like whole-wheat bread, brown rice is more nutritious than its white counterpart; it is a whole, natural grain. Brown rice usually has a mild nutty flavor, and is chewier and more nutritious than white rice. Brown rice has a shorter shelf life than white rice, which is a disadvantage when there are long-term requirements for storage. Brown rice spoils more quickly because the germ layer, which is removed to make white rice, contains fatty acids than can become rancid. To make white rice, the bran layer and germ layer are also removed, leaving only the starchy endosperm. This changes the flavor, texture, and appearance of the rice, also extending the shelf life. After removal of the husk, bran, and germ layers, white rice is usually polished, giving it a shiny white appearance.
As far as macronutrients go, brown rice and white rice are pretty much the same, containing similar amounts of calories and carbs. The main difference is in the way they are processed, and their micronutrient content. With white rice, removal of the bran and germ layers, along with the polishing process causes loss of several vitamins, minerals, fatty acids and fiber. To compensate for nutrient loss, rice is often enriched. The FDA requires that rice produced in the US is enriched with some of these lost nutrients, including vitamin B1, vitamin B3, and iron. One mineral that is not added back to white rice is magnesium however: one cup of long grain brown rice contains 84mg of magnesium compared to 19mg in white rice. The bran layer of rice also contains an oil, which may help lower LDL cholesterol (1). Because brown rice is less processed, it has more dietary fiber and fatty acids than white rice, causing it to be digested much slower. (Brown rice has a glycemic index of around 50, compared to white rice, which has a glycemic index of around 89).
There may also be some general health benefits to brown rice in addition to the potential cholesterol lowering effect. A study that came out in 2010 suggests that brown rice may also reduce the risk of developing type II diabetes. The researchers in this study report that eating two or more servings of brown rice weekly seems to be associated with a lower risk of developing type II diabetes, while five or more servings of white rice per week is associated with increased risk (2). This study needs to be interpreted with a degree of caution, however. Large scale, epidemiological studies such as this one do not show causation, only association. While consuming refined carb sources such as white rice no doubt contributes to the development of diabetes in otherwise sedentary people, studies like this can be misleading. White rice absolutely has healthy applications, which I will discuss below.
Technically speaking, wild rice isn’t actually “rice” at all. It’s the nutty tasting seed of a long-grain marsh grass. Also called “Canada rice”,” Indian rice”, or “water oats”, wild rice is a member of a species of grasses from the genus Zizania. Wild rice is the only grain native to North America, and grows best in the shallow waters of the Great lakes region of the U.S . Wild rice is almost always sold as the dried whole grain, making it relatively high in protein (particularly the amino acid lysine). Like brown rice, wild rice is also tends to be high in dietary fiber, and is a great source of certain micronutrients. 1 cup cooked wild rice provides 5% or greater for the daily value (dv) of thiamin, riboflavin, iron, and potassium. It also provides 10% or more of the dv for niacin, B6, folate, magnesium and phosphorus; 15% dv for zinc; 20% dv for manganese.
Rice grain size: long vs. medium vs. short
The grain size of rice is determined by how long the rice grain is relative to its width. Long grain rice is 3x longer than it is wide, while medium grain rice is less than 3x longer than it is wide. Technically speaking, short grain rice has grains that are less than 2x as long as they are wide, but this term is typically used interchangeably with medium grain. Most medium-and short grain rice are considered to be in the same category. The difference in grain size isn’t just cosmetic. The major carbohydrate source in rice (and in all plants, for that matter) is starch, which consists of two different types of carbohydrate molecules. The first is Amylose, which is a linear glucose polymer. Because of its tightly packed structure, amylose is digested more slowly. A picture of the molecular structure of amylose is shown below.
The second type of carbohydrate is amylopectin, which is a branched glucose polymer. (Glycogen, which is the form of glucose storage for humans and animals, is a more branched version of amylopectin). The branched structure of amylopectin causes it to be packed less tightly at the molecular level, providing easier access to digestive enzymes. This causes amylopectin to be broken down and digested more quickly than amylose. A picture of the more branched molecular structure of amylopectin is shown below.
Long grain rice:
Long grain rice tends to have a lower glycemic index than shorter-grained rice. Now we know why; the starch in long grain rice tends to have a higher amylose content, and lower amylopectin content. Because of the linear structure of amylose, it is packed more tightly into the rice grain, making it slower to break down during digestion. For this reason, the starch in long grain rice tends to be lower glycemic index. This also increases the tendency of the rice grain to remain intact after cooking, which is why long grained rice tends to be less “sticky” after cooking than shorter grained rice. Usually, long grain rice is simply labeled “long grain”, but some other common varieties of long grain rice that you may have seen in the grocery store isle include Basmati, Carolina, Jasmine, and Texmati.
Medium/short grain rice:
The starch in medium/short grain rice tends to have higher amylopectin content, which makes medium grain rice stickier after cooking. Because of the highly branched nature of amylopectin polymers, starch from medium grain rice tends to be digested more quickly than long grain rice, raising the glycemic index. Common varieties of medium grain rice that you might come across include Bomba, Carnaroli, Arborie, Vialone, Valencia, or Thai sticky rice.
Wrap-up: Choosing the tool for the job
Whole, natural foods with all their nutrients and enzymes are generally better than refined foods, but the point of this article is not to suggest that you should always eat brown/ long grain or wild rice. It is best to choose the right tool for the job. White rice has gotten some bad press, especially in studies where it has been compared to brown rice. In defense of these studies, white rice is higher glycemic index, and has also had some of its nutrients stripped away by the refining process. That is not to say, however, that white rice isn’t totally appropriate at particular times. Far from being the element of dietary destruction that it is often made out to be, white rice is an excellent carb source where high glycemic carbs are required. White rice is an ideal carb source pre-or post workout, when you want a relatively fast carb source to increase blood glucose and insulin levels quickly. The insulin response during training can be very helpful to maximize protein synthesis, decrease protein breakdown, and increase cell volume /muscle fullness. If you are one who incorporates high GI carbs into your precontest carb-up strategy (there are many ways to skin a cat), white rice or cream of rice can also be an excellent carb source here.
On the other hand, it is generally advantageous to keep insulin levels on the low side outside of the periworkout period. While insulin is the most anabolic hormone in the body, insulin signaling also has negative feedback on lipolysis and fat oxidation. Keeping insulin levels generally low helps to keep you lean. This also helps to maximize insulin sensitivity when you need it most, during the peri-workout period. Because of this, long grain brown rice or wild rice is a better choice as a general carb source outside of the peri workout period. Unlike white rice, which is highly processed and relatively light on nutritional value, both brown rice and wild rice are minimally processed and nutrient dense.
- Most MM, Tulley R, Morales S, Lefevre M. Rice bran oil, not fiber, lowers cholesterol in humans. Am J Clin Nutr 2005;81:64-8.
- Sun Q, Spiegelman D, van Dam RM, Holmes MD, Malik VS, Willett WC, et al. White rice, brown rice, and risk of type 2 diabetes in US men and women. Arch Intern Med 2010;170:961-9.