Magical Rice Preparation?

My wife brought and interesting article in the Washington post to my attention. An undergraduate researcher and his mentor at the College of Chemical Sciences in Sri Lanka report that they have found a way to reduce the calories in rice.

This is the process as stated in the article.

  1. Bring the water to a boil
  2. Add an amount of coconut oil equivalent to 3% the weight of the rice being cooked
  3. Add the rice and cook until complete
  4. Cool and store the rice under refrigeration for 12 hours
  5. Enjoy! (ok, I added this step)

According to the article, this cooking process converts some of the starch in the rice to resistant starch. This is important because resistant starches cannot be broken down by the human digestive tract. Because of this there would be a decrease in calories from carbohydrate. Sounds pretty good, right?

The article suggests that this process could reduce the calories in a given amount of rice by as much as 50%, but then goes on to say this:

So far they have only measured the chemical outcome of the most effective cooking method for the least healthful of the 38 varieties. But that variety still produced a 10 to 12 percent reduction in calories. “With the better kind, we expect to reduce the calories by as much as 50 to 60 percent,”

So, I see some pretty big issues here:

  1. So, lets say you want to make a cup of rice. You need about 56g of dry rice, That’s going to be about 204 Calories. A 10-12% reduction in Calories saves you about 20 to 25 Calories. Ok, but you’ve also added about 3% of the weight of the rice as coconut oil, 1.68 grams at 9 calories a gram for a total of a little over 15 calories. Your net calorie reduction is somewhere between 5 and 10 calories, or somewhere between 2-5% reduction.
  2. They’ve tested 38 varieties of rice but only have results for one, which seems a little odd. Where does the claim for up to 50-60% reduction come from then? Why did they lead with the least healthy?
  3. Let’s say there’s some support for the the 50-60% claim. Would you want to consume rice that was made up of 50-60% resistant starch? My guess is “Maybe”. Just because you can’t digest the resistant starch doesn’t mean the bacteria in your gut can’t. This would be a field day for them. Assuming the same portion as in 1), that would be about an ounce of resistant starch bacteria chow in your gut. A recent study showed a “mild but significant”(1) increase in flatulence in test subjects receiving 40 grams of resistant starch as part of a test protocol. That said, a number of recent papers have shown health benefits for consumption of resistant starch, so maybe a little extra flatulence will turn out to be worth it.
  4. Some may argue that any reduction in the glycemic index of the rice would be a benefit, but a better route to reducing the glycemic index of starchy foods is to make sure you consume them with fat or protein.

So the short version of all this is that the researchers are promising a lot, but what they’ve measured so far is pretty small. 5-10 Calories isn’t particularly significant in terms of an entire day, or even a meal. You’d be better off having more vegetables and less rice the next time you make a dish involving rice.  Maybe the increase in resistant starch would be beneficial, but it seems pretty modest as well.  Focus on bananas, oats, and legumes until they  prove their claims.

1. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3987287/