Sweet corn

← EncyclopediaFoods A-Z

By the Nutriveda editorial team · Updated 5 November 2026

Sweet corn (Zea mays) is maize picked young, while the kernels are still soft, juicy and sweet, and eaten as a vegetable: on the cob, as loose kernels, frozen or canned. One medium boiled ear (103 g) has about 99 kcal, 22 g of carbohydrate, 2.5 g of fibre and 3.5 g of protein, and its glycemic index is 52 ± 5. It gives modest amounts of potassium, magnesium and B vitamins, and corn is one of the main dietary sources of zeaxanthin, a yellow carotenoid. Dried corn, ground into whole grain cornmeal or popped as popcorn, counts as a whole grain rather than a vegetable.

Sweet corn nutrition per 100 g and per portion

Nutrient	Raw, 100 g	Boiled, 100 g	Portion: 1 medium ear, boiled (103 g)
Energy	86 kcal	96 kcal	99 kcal
Protein	3.3 g	3.4 g	3.5 g
Fat	1.4 g	1.5 g	1.5 g
Carbohydrate	18.7 g	21.0 g	21.6 g
of which sugars	6.3 g	4.5 g	4.7 g
Fibre	2.0 g	2.4 g	2.5 g
Potassium	270 mg	218 mg	225 mg
Magnesium	37 mg	26 mg	27 mg
Phosphorus	89 mg	77 mg	79 mg
Thiamin (vitamin B1)	0.16 mg	0.09 mg	0.10 mg
Niacin (vitamin B3)	1.77 mg	1.68 mg	1.73 mg
Folate	42 µg	23 µg	24 µg
Vitamin C	6.8 mg	5.5 mg	5.7 mg
Sodium	15 mg	253 mg	261 mg

Source: USDA FoodData Central, SR Legacy: “Corn, sweet, yellow, raw” (FDC 169998) and “Corn, sweet, yellow, cooked, boiled, drained, with salt” (FDC 168525), checked 5 November 2026. The portion column is calculated from the boiled record’s measure “1 ear medium” = 103 g; the record also gives 1 cup of kernels = 149 g (about 143 kcal and 31 g of carbohydrate). Values rounded. The boiled record was cooked with salt, which explains the sodium; corn cooked in unsalted water stays close to the raw value. The two records were analysed separately, so sugars and some vitamins do not line up exactly.

About three quarters of fresh corn is water, so an ear of corn is filling for under 100 kcal. Most of its carbohydrate is starch, not sugar.

Glycemic index

Sweet corn has a glycemic index of 52 ± 5 (glucose = 100) in the international GI tables (Atkinson 2008). The same table lists corn products separately: corn tortilla 46 ± 4, popcorn 65 ± 5 and cornflakes 81 ± 6. Processed corn foods can behave very differently from the fresh vegetable. GI says how fast, not how much: a medium ear carries about 22 g of carbohydrate, a full cup of kernels about 31 g. For how GI works and why the whole meal matters, see What is the glycemic index.

Health benefits: what the evidence says

• A vegetable that also counts as starch. The USDA MyPlate guide puts corn in the starchy vegetables subgroup, next to green peas and potatoes. It lists popcorn and whole grain cornmeal as whole grains, while corn grits, corn flakes and cornbread count as refined grains.
• Fibre. A cup of boiled kernels gives about 3.6 g of fibre. EFSA considers 25 g of fibre a day adequate for normal bowel function in adults, so corn is a useful contributor, especially together with beans and whole grains.
• Zeaxanthin. In an analysis of fruits, vegetables, corn and egg products, Perry and colleagues (2009) found corn and corn products to be major contributors of dietary zeaxanthin, while green leafy vegetables were the main source of lutein. Both carotenoids are studied for eye health, but the AREDS2 trial tested supplements in people who already had age-related macular degeneration, not corn as a food, so it does not show that eating corn protects your eyes.
• Potassium and magnesium. A cup of boiled kernels has about 325 mg of potassium and 39 mg of magnesium. NIH sets the adequate intake for potassium at 3,400 mg a day for men and 2,600 mg for women and notes that higher potassium intakes may help lower blood pressure.
• Naturally gluten-free. NIDDK lists flour made from corn among the gluten-free foods that people with coeliac disease can eat. Processed corn foods can still pick up gluten during production, so check the label.

How to eat sweet corn

• Buy it fresh and cold: Utah State University Extension notes that standard sweet corn loses half of its sugar within 24 hours when kept above 30 °C, and only about 8% a day near 0 °C. Extra sweet and supersweet varieties stay sweet longer. Keep ears in the fridge and eat them within a day or two.
• On the cob: boil in unsalted water for a few minutes or grill in the husk. A brush of olive oil, lime and chilli is an alternative to butter and salt.
• Kernels: stand the ear upright and slice down the sides with a sharp knife. Add the kernels to salads with kidney beans, tomatoes and peppers, to soups, omelettes and grain bowls with quinoa or brown rice.
• Frozen and canned: frozen kernels are plain corn and handy all year. Canned corn often contains added salt and sometimes sugar; choose versions without them or rinse the kernels.
• Corn as a grain: polenta, corn tortillas and air-popped popcorn are the dried-grain side of the same plant. Popcorn made at home with little oil and salt is a whole grain snack.

Who should be careful

• Diabetes. Corn is a starchy food. Count a cob or a cup of kernels as part of the meal’s carbohydrate, the same way you would count potatoes or rice, and follow your care team’s advice.
• Salt. Corn boiled in salted water had 253 mg of sodium per 100 g in the USDA record, against 15 mg in raw corn. Salted water, butter and salt on top, or canned corn add up quickly if you watch your blood pressure.
• Coeliac disease. Plain corn is gluten-free, but NIDDK warns that cross-contact with gluten can happen when foods are grown, processed, stored or prepared. Choose corn products labelled gluten-free.

Traditional view (Ayurveda)

In Usha and Vasant Lad’s food guidelines fresh corn is on the list to avoid for Vata and Pitta, marked as fine occasionally, and favourable for Kapha. This is a traditional view, not a clinical finding.

Related entries and articles

• Peas – the other sweet, starchy vegetable on MyPlate’s list
• Potatoes and sweet potato – starchy vegetables to compare portions with
• Kidney beans – the classic partner for corn in salads and chilli
• Bell peppers – for colour and vitamin C in corn salads
• Quinoa – another naturally gluten-free base for grain bowls
• What is the glycemic index (with food table)
• Plant-based meals for weight loss

FAQ

Is corn a vegetable or a grain?

Both, depending on how it is eaten. USDA MyPlate counts sweet corn as a starchy vegetable, while dried corn products such as popcorn and whole grain cornmeal count as whole grains, and corn flakes and grits as refined grains.

Is sweet corn high in sugar?

Less than its taste suggests. 100 g of boiled sweet corn has about 4.5 g of sugars and 21 g of carbohydrate in total, mostly starch, and its glycemic index is 52 ± 5 (Atkinson 2008). Portion size matters more than the sugar: one ear is about 22 g of carbohydrate.

Is corn gluten-free?

Yes, plain corn is naturally gluten-free, and NIDDK lists corn flour among gluten-free options for people with coeliac disease. Processed products such as cereals, tortillas and snacks can be contaminated with gluten during production, so look for a gluten-free label.

Sources

1. USDA FoodData Central, SR Legacy: Corn, sweet, yellow, raw (FDC 169998). fdc.nal.usda.gov
2. USDA FoodData Central, SR Legacy: Corn, sweet, yellow, cooked, boiled, drained, with salt (FDC 168525). fdc.nal.usda.gov
3. Atkinson FS, Foster-Powell K, Brand-Miller JC. International Tables of Glycemic Index and Glycemic Load Values: 2008. Diabetes Care 2008;31(12):2281-2283. PMC
4. USDA MyPlate: Vegetables. myplate.gov
5. USDA MyPlate: Grains. myplate.gov
6. EFSA NDA Panel (2010). Scientific Opinion on Dietary Reference Values for carbohydrates and dietary fibre. EFSA Journal 8(3):1462. efsa.europa.eu
7. Perry A, Rasmussen H, Johnson EJ. Xanthophyll (lutein, zeaxanthin) content in fruits, vegetables and corn and egg products. Journal of Food Composition and Analysis 2009;22(1):9-15. doi.org
8. National Eye Institute: About AREDS and AREDS2. nei.nih.gov
9. NIH Office of Dietary Supplements: Potassium, Fact Sheet for Health Professionals. ods.od.nih.gov
10. NIDDK: Eating, diet and nutrition for celiac disease. niddk.nih.gov
11. Utah State University Extension: Sweet corn, harvest and handling (Utah Vegetable Production Guide). extension.usu.edu
12. Lad U, Lad V. Food Guidelines for Basic Constitutional Types, from Ayurvedic Cooking for Self-Healing, 2nd ed. The Ayurvedic Institute. ayurveda.com

This page is for information only and is not medical or dietary advice.