Want to sneak a few satisfying starches into your anti-cancer diet– say some hot, mushy sweet potatoes ?
Cook the foods in water, refrigerate them overnight, then indulge–either cold or reheated.
When it comes to starches, the soft, hot, just-cooked ones may thrill your taste buds, but they’re the worst kind on your blood sugar.
Heat plus moisture (added in the cooking process and inherent in many foods) cause the starch granules to swell and become gelatinous, making it easier for your body to absorb the carbs. Hence, your blood sugar rises.
In fact, mush the carbs–as in make some hummus or mashed potatoes–and they’re even more readily absorbed.
But thank the Buddha for retrogradation!
When you refrigerate a gelatinous starch, the starch changes its structure and becomes less digestible. (That’s”retrogradation” in food science.) Thus, it’s less absorbable by your body—even if you reheat the food the next day. In fact, continual cooling and reheating causes starches to retrograde progressively.
The process works best for foods high in a type of starch called amylose –beans, for example, and to a slightly lesser degree, grains and root vegetables. Most corn and tubers (potatoes and sweet potatoes) are lower in amylose and higher in a type of starch called amylopectin, meaning they retrograde less. But they still do it, as long as some amylose is present. In fact, one study found that boiled red potatoes, eaten cold, had a 40 percent lower effect on blood sugar than those hot off the stove.
If potatoes are your starch of choice every, every so often, find some of those small, fingerlike new potatoes fresh from the farm. (Storage can also increase the starch’s effects on your blood sugar.) And add some vinegar to your day-old potato salad–another trick for minimizing the effects of starch.
Your initial cooking method may also affect how well the starch retrogrades. Because boiling adds more water than baking and roasting, it’s likely to result in more gelatinization and retrogradation, suggest the authors of a study on sweet potatoes (a suggestion–not necessarily proof).
Those researchers also found that boiled sweet potatoes right off the stove were better on your blood sugar than baked and roasted. But consider this: The same differences in the effects of cooking methods on fresh hot foods were not found in that study on white potatoes. A possible reason? Dry heat from baking or roasting concentrates the sugars in vegetables, and as your test buds will tell you, sweet potatoes are sweeter than white ones.
Speaking of sugars, this brings us to an important nuance–Starches retrograde; sugars don’t. The peach pie filling you’re about to eat straight from the fridge will not be better for your blood sugar just because it’s been cooled.
The final trick for slipping some starchy carbs into your diet: To slow down digestion and hence their effects on blood sugar, eat them with protein, fat and lots of fiber*--including the skins of those starchy vegetables. Don’t peel your carrots, etc.
Confused yet by all these nuances?
Here’s the Bottom Line seemingly Best Practice: Opt for higher amylose starches (beans, grains, root vegetables), cook them unpeeled (and if they’re sweetish, perhaps boil them), then cool them in the fridge and engorge on leftovers, hot or cold, for days and days. Sounds like a perfect formula for making soups, right?
● Dr. Alexandra L. Jenkins, PhD, Director of Research, Glycemic Index Laboratories, Toronto, http://gilabs.com/
●”The Factors That Modify Glycemic Indexes” (from the website of Michel Montignac) and interviews with staff
●“Starches, Sugars and Obesity” and interview with author Erik Aller, PhD student, Maastricht University, Netherlands
*Another Anti-Cancer Nuance: When it comes to controlling blood sugar, soluble fiber–which dissolves in water and forms a gel–beats its insoluble sister; we’ll tackle that one soon.