Sweet corn generally has a moderate glycemic index, commonly tested in the high 40s to low 60s, lower than many people assume for a starchy vegetable. It's often mistakenly grouped with high-GI starches like white rice or potatoes, but its fiber content keeps the number more moderate, though portion still matters since corn is one of the starchier vegetables.
The numbers
Published GI values for boiled sweet corn range from about 48 (Australian testing) to the low 60s (some U.S. and South African testing), which reflects real variation by corn variety and growing region, not an error in any one study. A reasonable working figure is the mid-50s, solidly in the moderate range.
| Corn or product | Typical GI | Why |
|---|---|---|
| Corn on the cob, boiled | Moderate (about 48 to 62, varies by study and variety) | Kernel structure and fiber slow digestion more than a milled starch would |
| Creamed corn or corn canned in syrup | Higher than plain kernels | Processing and added sugar raise the effective impact |
A cup of corn kernels has roughly 25 grams of available carbohydrate: using GI 55 as a working midpoint, 55 × 25 ÷ 100 ≈ 14, a medium glycemic load, similar to a slice of bread.
Why corn isn't as bad as its reputation
Corn gets lumped in with white rice and potatoes as a generic "starchy carb," but it tests meaningfully lower than either on average. The kernel's outer layer and fiber content slow digestion more than the processed starch in rice or mashed potatoes does. That doesn't make corn a free food, it's still one of the starchier vegetables and a large portion adds up, but the plain, whole-kernel form (corn on the cob, or plain frozen or canned kernels) is a more moderate choice than its reputation suggests.
Corn on the cob or plain kernels (fresh, frozen, or canned without added sugar) are the steadier choices. Creamed corn and corn-based processed snacks, like corn chips, are milled and often fried, which pushes them meaningfully higher than the whole kernel.
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