Monday, October 3, 2011

More Than You Wanted to Know About Rice

I happen to be Asian. And you may have noticed that in many Asian cultures, life revolves around rice. Go to Thailand or China or Cambodia, and one of the most common greetings you’ll hear is “Have you eaten rice yet today?” (I’m not joking.)

In our household, the answer to that question was almost always “yes,” no matter what time of day it was asked. I suppose this isn’t entirely surprising, given that my paternal grandfather – before immigrating to the U.S. – was a rice farmer in southern China. (My mom’s side of the family, on the other hand, sold Froot Loops and Icees to their fellow residents in the poorest town in America.) Throughout my childhood, there was always an enormous 20-pound sack of rice in our pantry, and it never lasted long. I loved scarfing down bowl after bowl of the stuff. (Preferably doused with soy sauce.)

As an adult, I lost interest in packing my belly with rice, but it still made frequent appearances in our meals. Following common wisdom, we transitioned from white rice to the “healthier” brown variety, and patted ourselves on the back for doing so.

And then I went Paleo and abruptly cut out rice entirely. I went cold turkey, refusing to touch anything made with rice: noodles, dim sum dumpling wrappers, gluten-free (but not rice-free) treats. It wasn’t easy; when I’d politely turn down a big bowl of white rice at family gatherings or turn down an invitation to a Saturday morning dim sum orgy, I got quizzical looks, as if I’d just stood up on a table and publicly renounced my heritage.

But is rice really so bad? Or was I too knee-jerk about it when I jumped onto the Paleo bandwagon?

Let’s start with the basics -- after the jump...

What's Rice?

Rice is a cereal grain, and the seed of plants in the genus Oryza. There are dozens of varieties of rice, but the stuff most of us eat belongs to two cultivated species: Sativa (Asian rice) and Glaberrima (African rice). Rice is likely the oldest domesticated grain and remains the staple food for over two-and-a-half billion people -- mostly in Asia and the Middle East. In Asia, it accounts for a whopping 50 to 80 percent of people’s daily intake. It’s pretty damn popular elsewhere too, accounting for 20 percent of the calories consumed by humans worldwide. It's the second-most cultivated plant in the world, after corn (of course).

After the seeds of the rice plant are harvested, they’re milled using a rice huller to remove the outer husks of the grain. The result: Brown rice.

But if the milling continues, removing the inner husk and the germ (a.k.a., the husk), we end up with white rice. White rice can also be: (1) “buffed with glucose or talc powder” to create “polished” rice; (2) par-boiled, and (3) enriched with nutrients lost in the milling process (e.g., thiamin, riboflavin, niacin, folic acid, iron), usually by coating the rice with a “water insoluble substance” so the vitamin-y goodness won’t get rinsed off.

What's Wrong With Rice?

In spreading the good word about Paleo eating, it’s just easier to tell people to avoid all cereal grains (among other things). It’s become almost automatic for us to reel off the evils of grains: lectins and phytates and gluten, oh my! Gluten-containing grains are particularly nasty, and by now, we all know to steer clear of them. (Right?) So it’s natural, I suppose, for people to lump rice together with wheat, oats and the rest.

But will eating rice wreck you just as much as eating wheat bread?

The short answer: Nope.

Rice doesn’t contain gluten, for one. And while it does contain anti-nutrients, most of them are located in the hull and bran of the rice seed, and can be lost or neutralized through milling and cooking processes.

Here are the key anti-nutrients found in whole (pre-milled) rice:
  • Phytin / Phytate
This stuff binds itself to minerals and keep them from being absorbed by those who eat it. As Mark Sisson puts it, “rats can break through the phytate and get at the minerals fairly well, but they evolved that ability – we did not. Heat does little to phytate, but since it’s located in the bran, physically removing the bran removes the phytate. That’s why brown rice eaters tend to have poorer mineral balances than white rice eaters.”
  • Trypsin Inhibitor
Trypsin is an enzyme produced in the pancreas, and its job is to cleave protein peptide chains into amino acids for easy absorption in the digestive process. If trypsin is blocked – say, by the trypsin inhibitor found in rice – we can’t effectively digest the protein we eat with it.

  • Haemagglutinin-lectin
Haemagglutinin-lectin is a lectin that binds to certain carbohydrate receptor sites in the cells of the gut lining and thus blocks the absorption of nutrients. But it’s located in rice bran only, and once it’s cooked above 100 degrees Celsius, it loses its toxicity.
  • Oryzacystatin
Like trypsin, cysteine proteases are enzymes that degrade polypeptides, and in humans, they’re responsible for a host of biological processes, from apoptosis (necessary programmed cell death) to certain immune responses. Oryzacystatin, a cysteine protease inhibitor, messes with these processes. Unlike trypsin, however, oryzacystatin doesn’t get milled away or neutralized through cooking. “Oryzacystatin remains 100% active after at least 30 minutes of boiling.
  • Allergens
Although rare, rice allergies have popped up – particularly in societies that consume large amounts of rice. As Don Matesz (before he famously bid farewell to Paleo) pointed out, rice “contains an allergenic protein that occurs primarily in the milled rice, not the bran, and remains stable (60%) even after boiling for 60 minutes at 100 C (212 F).” Sisson has also raised some concerns about rice allergies:
Wheat-sensitive individuals and others with food-related autoimmune disorders seem more susceptible to rice allergy, too (big surprise there), and allergic reactions generally manifest as atopic dermatitis, eczema, gastrointestinal distress, or asthma. If you’re sensitive to food in general and grains in particular, rice could pose a problem. And even if it doesn’t cause an immediate reaction, there remains the question of latent, hidden damage.
So Should We Eat It Or Avoid It?

Knowing what we now know, should we swear off rice forever?

Not necessarily. As discussed above, if you stick with white rice (which doesn’t contain the phytate and trypsin inhibitor content of the less-milled brown rice) and you cook it properly (which neutralizes the haemagglutinin-lectin), you don’t have much to worry about from an anti-nutrient perspective. (Yes, that’s right: Brown rice is worse for you than white rice. Read more about it here.)

But just because white rice won’t destroy you doesn’t mean that it’s some kind of super-food. “White, milled, polished rice is basically pure starch… It is essentially a blank slate, nothing all that bad about it, but nothing all that great, either.” Rice can be tasty, but it’s really nothing more than empty, starchy calories.

Here’s the deal:
  • If you’re insulin resistant, looking to lose some bodyfat and relatively sedentary, rice is not for you. For all the reasons stated here, you’ll do better with diet that’s more nutrient-dense and lower in carbohydrate content.
  • On the other hand, it you’re insulin sensitive, lean and regularly engaging in physical activity, go ahead and eat some carbs – especially post-workout. Personally, I’d go with a starch that’s more nutrient dense than white rice (think sweet potatoes), but white rice definitely beats carbo-loading on whole wheat pasta. And so if you find yourself craving some of your mom’s special paella or a bowl of phở bò, go ahead and partake. Unless you have a rice allergy, it won’t wreck you like a wheat bagel would.
Last point: Some Paleo nudniks would also argue that rice should be avoided simply because cavemen didn’t eat it. But again, I don’t believe in Paleo as historical reenactment. Besides, as Raj Ganpath sagely pointed out, cavemen didn’t eat broccoli, crap in toilets or “read” Playboy, either.

Me? I'm going to stay mostly rice-free 'til I next hit a sushi joint. Until then: M's recipe for cauliflower fried "rice" hits the spot.

[Additional reading: Paul & Shou-Ching Jaminet's post on rice's role in the Perfect Health Diet.]