Eating Corn-Based Foods on a Low-Carb Diet

Carbs and blood sugar info for foods like cornmeal, grits, polenta, and popcorn

Corn
Corn Harvest. Photo: Don Farrall/Getty Images

Foods derived from corn, like popcorn, cornmeal, polenta, grits and masa flour, which is made from dried and ground corn kernels, vary in carb counts. The jury is still out on whether corn-based foods are good to include in a low-carb diet. Popcorn is low in carbs, but also low on nutritional content. Cornmeal is higher in carbs but is a decent source of minerals. The key is always moderation.

The corn plant is a grass, and corn can be considered a grain when used for its kernels.

Carb information about fresh, frozen or canned corn as a vegetable is different than dried corn.

Cornmeal, grits, polenta, and corn flour all have very similar amounts of carbohydrates. They seem to vary more by brand than by type.

Corn-based foodCarbs, fiber, and calorie counts
1/4 cup raw cornmeal (about one ounce)21 grams of net carbs, 2 grams fiber, 111 calories
1/2 cup cooked grits18 grams net carbs, 1 gram fiber, 87 calories
1 cup air-popped popcorn5 grams net carbs, 1 gram fiber, 31 calories
1 cup oil-popped popcorn5 grams net carbs, 1 gram fiber, 55 calories
1-ounce tortilla chips18 grams net carbs, 1 gram fiber, 138 calories

Glycemic Index and Glycemic Load for Cornmeal and Popcorn

The glycemic index of a food is an indicator of how much and how fast a food raises your blood sugar. Two studies of cornmeal had an average glycemic index of 68.

The glycemic load of a food is related to the glycemic index but takes serving size into account.

A glycemic load of one is the equivalent of eating 1 gram of glucose. 

Glycemic load of cornmeal and popcorn
1/4 cup raw cornmeal (about one ounce): 13
1/2 cup cooked grits: 11
1 cup popped popcorn: 3
1-ounce tortilla chips: 1

Health Benefits of Corn-Based Foods

Whole grain cornmeal is a fair source of thiamin and magnesium.

Cornmeal products made from dried corn, such as grits, polenta, and masa flour are also a good source of vitamin B6 and folate. 

Selecting Corn-Based Foods

Most corn-based products are prepackaged as they are derived from dried corn. You would be hard pressed to find corn kernels to pick yourself. Getting the best corn meal is all about where it came from and whether it is stoneground or de-germinated. Stoneground is less processed and therefore has more nutrients and a richer taste than de-germinated corn meal. However, some de-germinated corn meal is enriched with added vitamins and minerals that give it a nutritional boost.

Storing Corn-Based Foods

Stone-ground cornmeal should be refrigerated no longer than four months, but de-germinated cornmeal can be kept in the cabinet in a cool dry area for up to eight months. Cornmeal can also be frozen and last up to two years.

Polenta, a cooked cornmeal dish famous in Italy can be cooked into a porridge much like grits, or it can be fried, baked or grilled and turned into firm wedges and used as bread or as a side dish to accompany fish, meat or stews.

Grits, like regular cornmeal, can be kept in a cool dry place, however, once grits are opened they should be transferred to an airtight container or the entire package should be added to an airtight zip-closing bag to prevent spoilage.

How Do Other Food Groups Stack Up Carb-Wise?

Some choices are wiser than others in terms of selecting low-carb food options. Leafy ​vegetables and nuts and seeds seem to fare the best. Bringing up the rear are most fruits, grains and some legumes and milk and dairy products.

Sources:

Leroux, MarcusFoster-Powell, Kaye, Holt, Susanna and Brand-Miller, Janette. "International table of glycemic index and glycemic load values: 2002." American Journal of Clinical Nutrition. Vol. 76, No. 1, 5-56, (2002).

USDA National Nutrient Database for Standard Reference, Release 21.

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