Sweet corn: less sugar than it tastes, more in the can

In a small randomized crossover trial from 1986, six healthy volunteers had a lower blood glucose rise when they swallowed sweetcorn without chewing than when they chewed it well, and the abstract gives no size for the gap. That is about the whole of the human research on sweet corn and blood sugar. We found no trial of any health outcome from eating it. The composition is plainer than the taste suggests. Per 100 g, raw kernels in UK tables give 60 calories, 5.9 g starch, 2.0 g sugars and 260 mg potassium, from a UK sample whose sugar falls fast after harvest. Canned kernels in water read 7.5 g sugars and 78 calories, against 2.5 g and 67 calories for kernels boiled on the cob, from different varieties and processing.

The numbers, per 3.5 oz (100 g)

How much is actually in it

• Per 100 g, raw sweetcorn kernels give 60 calories, 3.4 g protein, 5.9 g starch and 2.0 g sugars, with 260 mg potassium and 41 ug folate. — CoFID 2021 record 13-622 Sweetcorn, kernels, raw (n = 1 CoFID record) Evidence E source
  60 calories, protein 3.4 g, fat 1.8 g, carbohydrate 8.1 g, starch 5.9 g, sugars 2.0 g, potassium 260 mg, folate 41 ug, vitamin C 8 mg, carotene 23 ug
• Canned sweetcorn kernels in water carry 7.5 g sugars and 78 calories per 3.5 oz (100 g), against 2.5 g sugars and 67 calories for kernels boiled on the cob. — CoFID 2021 records 13-529 Sweetcorn kernels, canned in water, drained and 13-508 Sweetcorn, kernels, boiled on the cob (n = 2 CoFID records) Evidence E source
  Canned: 78 calories, sugars 7.5 g, vitamin C 24 mg, folate 45 ug, sodium 1 mg. Boiled on cob: 67 calories, sugars 2.5 g, AOAC fiber 5.1 g, potassium 333 mg, vitamin C 4 mg, folate 24 ug
• Across 8 US samples of fresh sweet corn kernels, dietary fiber ranged from 1.62 to 3.8 g per 3.5 oz (100 g), while potassium stayed between 222 and 265 mg. — USDA FoodData Central Foundation Foods, Corn, sweet, yellow and white kernels, fresh, raw, 8 samples (n = 8 samples) Evidence E source
  Fiber 2.43 g (1.62-3.8); potassium 237 mg (222-265); starch 4.08 g (3.56-4.58); protein 2.79 g (2.44-3.13); water 80.3 g (78.1-82.6)

What a real portion looks like

• The US food survey counts one regular ear of corn as 3.7 oz (105 g) of kernels and one cup as 150 g. — USDA FNDDS 2021-2023, Corn, raw (75109600) (n = 1 FNDDS record) Evidence E source
  1 regular ear 105 g; 1 cup 150 g; quantity not specified 75 g

What your body absorbs

• In a small randomized trial where each food was eaten by 6 volunteers, swallowing sweetcorn without chewing gave a lower blood glucose response than chewing it well. — Healthy volunteers, six per food (sweetcorn, white rice, apple, potato), two test meals each (n = 6 per food) Evidence B source
  Lower postprandial glycemic response without chewing; magnitude not in abstract
• In 29 adults eating lutein-rich fruit or vegetables including sweet corn for four weeks, serum lutein rose by 37%. — Twenty-nine healthy normolipemic adults aged 45-65, 1.8 mg lutein/day, vegetable arm 180 g/day of green beans, pumpkin and sweet corn (n = 29) Evidence C source
  Serum lutein +37%; lutein/HDL-cholesterol +29%; no change in macular pigment

What cooking and storage change

• By the USDA retention table for vegetables boiled in covering water and drained, 65% of folate and 75% of vitamin C remain. — USDA Retention Factors Release 6, Vegetables and Vegetable Products, VEG, OTHER, boiled, water cover, drained (Retn_Code 3775) (n = 1 method row) Evidence E source
  Folate 65%, vitamin C 75%, thiamin 80%, niacin 85%, B6 85%, potassium 90%, iron 95%

Safety, limits and interactions

• Among 33 adults with confirmed food allergy at one Turkish clinic, sweet corn was the trigger in 2 (6.1%). — 33 adults with confirmed food allergy, Ankara, 2019-2024 (n = 33) Evidence C source
  Sweet corn 2 of 33 (6.1%); anaphylaxis was the most common presentation overall (72.7%)
• A case report confirms botulinum neurotoxin in both a patient's serum and the home-canned corn he had eaten days before. — One 60-year-old man (n = 1) Evidence D source
  Foodborne botulism with intubation; toxin confirmed in serum and home-canned corn
• In the 2008 Canadian total diet study, canned corn had the second highest bisphenol A level of all food composites, 83.7 ng/g, after canned fish at 106 ng/g. — 154 food composite samples, Quebec City 2008 (n = 154 samples) Evidence D source
  Canned corn 83.7 ng/g BPA; canned fish 106 ng/g, the highest

Who this works differently for

• In an RCT of 74 children aged 3-6, ten minutes with a vegetable app built around carrot and sweetcorn raised how much vegetable they then ate, relative to a control app. — Seventy-four children aged 3-6 years, single 10-minute play session (n = 74) Evidence B source
  Significantly more vegetables eaten and higher liking after the app; short-term only
• In an RCT of 155 children aged 7-10, how much sweetcorn they ate after a story was predicted mainly by how much they liked it before (beta 0.28). — 155 children aged 7-10 years, one story session (n = 155) Evidence B source
  Sweetcorn intake linked to prior liking and intake, smallest beta 0.28; lower after the carrot enjoyment story, beta -0.17
• In hereditary fructose intolerance, a case report advised more vegetables but avoiding carrots, onions, leeks and tinned sweet corn. — One 17-year-old male with hereditary fructose intolerance (n = 1) Evidence D source
  Dietary advice to avoid tinned sweet corn among higher-fructose vegetables

What is still unknown

• A review of Australian food composition data found iron in sweet corn fell by 30-50% between measured time points, though methods differed too much to be sure. — 34 articles and six Australian food composition databases, 1930s to 2021 (n = 40 sources) Evidence D source
  Iron decrease of 30-50% for sweet corn; no definitive conclusion

The bottom line

Across 8 US samples of fresh kernels, fiber ran from 1.62 to 3.8 g per 3.5 oz (100 g) while potassium held between 222 and 265 mg. The US survey counts one regular ear as 3.7 oz (105 g) of kernels and a cup as 150 g, from a record named plain corn, since none is named sweet corn. Boiling in water that is then drained keeps about 65 percent of folate and 75 percent of vitamin C by a USDA group factor for vegetables, dated 1975 and never measured on sweet corn. In 29 adults aged 45 to 65 who ate 1.8 mg of lutein a day from food for four weeks, serum lutein rose 37 percent. The vegetable group got it from 180 g a day of green beans, pumpkin and sweet corn together, the groups were set by season and not randomized, and macular pigment did not change. An Australian review saw iron in sweet corn fall by 30 to 50 percent between time points, and its authors reached no conclusion because methods changed across the decades. In children, sweet corn mostly appears as a test vegetable. In a randomized trial in 74 children aged 3 to 6, ten minutes with a vegetable maths app built around carrot and sweetcorn raised how much vegetable they ate straight afterward. In 155 children aged 7 to 10, how much sweetcorn they ate after a story tracked how much they liked it beforehand (beta 0.28). Who should be careful. Sweet corn caused 2 of 33 confirmed food allergies in adults at one Turkish clinic, a very small count. A single case report confirmed botulinum toxin in a man and in the home-canned corn he ate days earlier. It is a single case with no measure of risk, and we have no card on how corn can be canned safely at home, so this page gives no canning method. In 2008 Canadian samples, canned corn had 83.7 ng/g bisphenol A, second highest of all foods tested, and can linings may have changed since. In one case report of hereditary fructose intolerance, clinicians advised avoiding tinned sweet corn. We have no card on pregnancy or medicines.

Sources

1. swc8-daily-r8-01 · reference dataset
   CoFID 13-622 Sweetcorn, kernels, raw: Energy 60 kcal, Protein 3.4 g, Fat 1.8 g, Carbohydrate 8.1 g, Starch 5.9 g, Total sugars 2.0 g, Potassium 260 mg, Folate 41 ug, Vitamin C 8 mg, Carotene 23 ug per 100 g
   CoFID 2021, Public Health England / OGL v3.0 · checked 2026-09-29
2. swc8-daily-r8-02 · reference dataset
   CoFID 13-529 Sweetcorn kernels, canned in water, drained: Energy 78 kcal, Total sugars 7.5 g, Sodium 1 mg, Folate 45 ug, Vitamin C 24 mg per 100 g. CoFID 13-508 Sweetcorn, kernels, boiled 'on the cob' in unsalted water: Energy 67 kcal, Total sugars 2.5 g, AOAC fibre 5.1 g, Potassium 333 mg, Folate 24 ug, Vitamin C 4 mg per 100 g
   CoFID 2021, Public Health England / OGL v3.0 · checked 2026-09-29
3. swc8-daily-r8-03 · reference dataset
   Corn, sweet, yellow and white kernels, fresh, raw: Fiber, total dietary 2.428 G range 1.62-3.8, 8 samples; Potassium, K 237.0 MG range 222.0-265.0, 8 samples; Starch 4.078 G range 3.56-4.58, 8 samples; Protein 2.789375 G range 2.4375-3.125
   USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-09-29
4. swc8-daily-r8-04 · reference dataset
   FNDDS 2709783 Corn, raw, code 75109600 - 1 cup 150 g, 1 regular ear 105 g, Quantity not specified 75 g
   USDA FNDDS 2021-2023 · checked 2026-09-29
5. swc8-daily-r8-06 · randomized crossover trial
   Subjects ate meals of sweetcorn, white rice, diced apple or potato on two occasions; on one occasion they chewed the food thoroughly, on the other occasion they swallowed each mouthful without chewing it. ... Swallowing without chewing reduced the glycaemic response to each food,
   Br J Nutr, 1986 · checked 2026-09-29
6. swc8-daily-r8-07 · dietary intervention study
   Twenty-nine healthy normolipemic subjects, aged 45-65 y, consumed 1.8 mg lutein/day supplied from fruits (14 subjects, 500 g/day of oranges, kiwi and avocados) or vegetables (15 subjects, 180 g/day of green beans, pumpkin, and sweet corn) for four weeks. Serum lutein concentration increased by 37%.
   Nutrients, 2021 · checked 2026-09-29
7. swc8-daily-r8-05 · reference dataset
   USDA-RETN-R6:3775 VEG,OTHER,BLD,WATER COVER,DRAINED: folate_total_ug 65%, vitamin_c_mg 75%, thiamin_mg 80%, niacin_mg 85%, vitamin_b6_mg 85%, potassium_mg 90%, iron_mg 95%
   USDA Table of Nutrient Retention Factors, Release 6, 2007 · checked 2026-09-29
8. swc8-daily-r8-11 · retrospective study
   The primary allergens identified included hen's egg (n = 6, 18.2%), fish and shellfish (n = 4, 12.1%), and various nuts such as peanuts (n = 2, 6.1%), hazelnut (n = 1, 3.0%), and almond (n = 1, 3.0%) as well as seeds like sesame (n = 2, 6.1%) and sweet corn (n = 2, 6.1%)
   Allergol Immunopathol (Madr), 2025 · checked 2026-09-29
9. swc8-daily-r8-12 · case report
   The patient then revealed that he consumed home-canned corn several days prior to admission. On hospital day 8, botulinum neurotoxin was confirmed in the patient's serum and the home-canned corn.
   Ann Pharmacother, 2013 · checked 2026-09-29
10. swc8-daily-r8-13 · total diet study
    High concentrations of BPA were found mostly in the composite samples containing canned foods, with the highest BPA level being observed in canned fish (106 ng g(-1)), followed by canned corn (83.7 ng g(-1)),
    Food Addit Contam Part A Chem Anal Control Expo Risk Assess, 2011 · checked 2026-09-29
11. swc8-daily-r8-09 · randomized controlled trial
    Liking and acceptance of the vegetables used in Vegetable Maths Masters (carrot and sweetcorn) and other vegetables which were not used in the game (yellow pepper and tomato) were measured pre- and post-play in both groups. ... Children who played with the Vegetable Maths Masters app consumed significantly more vegetables after playing with the app and reported significant increases in their liking of vegetables, relative to the control group.
    Appetite, 2019 · checked 2026-09-29
12. swc8-daily-r8-10 · randomized controlled trial
    Sweetcorn liking and intake after a story were associated with pre-story sweetcorn liking and intake (smallest β = 0.28, p < 0.01), and sweetcorn intake was lower following the story modelling carrot enjoyment compared to the stories not modelling enjoyment (β = -0.17, p = 0.04).
    Appetite, 2019 · checked 2026-09-29
13. swc8-daily-r8-14 · case report
    A change in diet associated with a supplementation in vitamin C was advised, with an increase in vegetable intake, principally avoiding carrots, onions, leaks and tinned sweet-corn.
    Ann Endocrinol (Paris), 2007 · checked 2026-09-29
14. swc8-daily-r8-08 · scoping review of composition data
    The majority of vegetables had similar iron content between two or more timepoints but decreases of 30-50% were noted for sweet corn, red-skinned potatoes, cauliflower and green beans ... Due to limited data and variations in sampling and analytical techniques, no definitive conclusions could be established.
    Foods, 2021 · checked 2026-09-29