A medium ear of corn on the cob contains about 75 calories, making it one of the lighter starchy sides you can put on your plate. Beyond its modest calorie count, corn delivers a surprisingly broad mix of vitamins, minerals, fiber, and protective plant compounds.
Calories, Carbs, and Protein
That medium ear gives you roughly 75 calories and just one gram of fat. Most of the energy comes from carbohydrates, primarily natural sugars and starch, with a solid contribution of dietary fiber. You also get a meaningful amount of protein for a vegetable, making corn more filling than many other sides in its calorie range.
Corn is often lumped in with potatoes and rice as a “starchy” food, but its glycemic index tells a more nuanced story. Sweet corn scores a 52 on the glycemic index, which puts it in the low-GI category (anything under 55). A medium ear has a glycemic load of 15, meaning it raises blood sugar moderately. For comparison, cornflakes score 81 and popcorn lands at 65. So eating corn on the cob is a very different metabolic experience from eating processed corn products.
Key Vitamins and Minerals
A large ear of raw sweet corn provides about 386 milligrams of potassium, which is comparable to a small banana. That’s a useful contribution toward the daily target of around 2,600 to 3,400 milligrams. Potassium helps regulate fluid balance and supports normal blood pressure.
Corn is also a decent source of magnesium, with a large ear supplying roughly 53 milligrams. Most adults need between 310 and 420 milligrams daily, so one ear covers about 13 to 17 percent of that. Magnesium plays a role in muscle function, nerve signaling, and blood sugar regulation.
Folate is another standout. A large ear contains about 66 micrograms, roughly 16 percent of the daily recommendation for most adults. Folate is essential for cell division and DNA synthesis, which is why it’s especially important during pregnancy. Corn also provides small amounts of B6 and other B vitamins that support energy metabolism.
Yellow vs. White Corn
If you’ve ever wondered whether the color of your corn matters nutritionally, it does, at least in one important way. Yellow corn gets its color from carotenoids, including beta-carotene, which your body converts into vitamin A. White corn contains essentially no vitamin A. The deeper the yellow or orange color of the kernels, the higher the carotenoid content tends to be, though color alone isn’t a perfect predictor. For everyday nutrition, yellow corn gives you a small but real vitamin A advantage over white varieties.
Lutein, Zeaxanthin, and Eye Health
Sweet corn is one of the better vegetable sources of lutein and zeaxanthin, two pigments that concentrate in the retina and help protect against age-related damage from light exposure. A cup of frozen corn kernels (boiled and drained) contains about 1,129 micrograms of combined lutein and zeaxanthin. Canned corn retains even more, with vacuum-packed corn reaching about 2,194 micrograms per cup. These aren’t massive amounts compared to leafy greens like kale or spinach, but corn is an easy, palatable way to add these compounds to your diet regularly.
How Cooking Affects the Nutrition
Cooking corn changes its nutritional profile, and the method matters more than you might expect. Heat breaks down certain antioxidant compounds, including ferulic acid and other phenolics that are naturally abundant in corn. Research on cooked corn found that boiling cut kernels caused the largest drop in antioxidant activity, around 57 percent. Boiling whole ears fared somewhat better, with a 46 percent decline. Steaming preserved the most: steaming whole ears reduced antioxidant activity by only about 20 percent.
The practical takeaway is simple. If you want to preserve the most antioxidants, steam your corn on the cob rather than boiling it, and keep the ear whole rather than cutting the kernels off first. Boiling loose kernels creates the most surface area for nutrients to leach into the water. That said, cooking also makes corn easier to digest and can improve the availability of certain other nutrients, so raw isn’t necessarily better overall.
Where Corn Fits in Your Diet
Corn sometimes gets dismissed as “empty” calories or criticized for being too starchy. The numbers don’t support that. At 75 calories per ear with fiber, potassium, magnesium, folate, and eye-protective pigments, corn on the cob holds its own against most vegetables. Its low glycemic index means it won’t spike blood sugar the way refined corn products do. And because it’s naturally sweet and satisfying, it can easily replace higher-calorie sides without feeling like a sacrifice.
One ear won’t single-handedly meet your daily needs for any nutrient, but that’s true of almost every whole food. Corn’s real value is in the breadth of what it delivers for so few calories, especially when you choose yellow varieties and cook them gently.