The Scientist: Julie Miller Jones, Ph.D., a licensed nutritionist and member of the scientific advisory board of the Grain Foods Foundation
The Answer: We’re all told that you want to eat fewer simple carbohydrates and more whole grains, but the fact of the matter is, it’s not just a simple equation of one versus the other. Some fibers, particularly the viscous ones in some whole grains such as oats or barley, do slow the absorption of carbs into the bloodstream, helping to stave off a spike in blood sugar, but that doesn’t mean you can cancel out a bunch of carbs by eating a bunch of fiber. And it also doesn’t mean that whole grains are much lower-carb.Interestingly, it is often the texture of the carb-heavy food in question that impacts blood glucose response.
The airy, porous nature of bread—white, wheat or otherwise—means that there is a lot of surface area for quick and direct contact with the enzymes in your digestive tract that break down carbs into glucose. This helps explain why a pillowy soft baguette has a glycemic index—a measure of the body’s insulin and blood glucose response—of 95, while a dense wheat tortilla clocks in at 30. (Glycemic index is out of 100; the lower the better.) The same logic applies to pasta, which is generally more compact than bread, and accordingly, has a significantly lower glycemic index, usually between 30 and 50.
Your best bet with bread is to go for one that’s more dense and also contains whole bits of grains, kernels and seeds, which not only give you beneficial phytonutrients, but also are a source of resistant starch that acts as dietary fiber and does not raise blood sugar. Even better, dip your bread in butter, or olive oil and vinegar. The fats from butter or oil will create a physical barrier that slows the action of digestive enzymes. And since those enzymes function optimally in a neutral pH, the vinegar helps by increasing the acidity in your mouth, thereby dampening the enzymes’ efficacy and slowing glucose release into the bloodstream.
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