Sweetcorn

Food · Vegetable · Food, Typed Supps

A vegetable that is really a grain, and one of the few good sources of the pigment that concentrates in the back of the eye.

Stage by stage

Intake (Mouth): The kernel's tough cellulose skin resists chewing; how thoroughly it is broken determines how much starch is released.
Stomach (Stomach): The endosperm is digested normally while the intact pericarp passes through unchanged.
Small intestine (Small intestine): Starch, folate and niacin are absorbed; lutein requires dietary fat for micellar uptake.
Eye (Macula): Lutein and zeaxanthin deposit selectively in the macula, where they filter blue light.

Time to effect

Months: Blood glucose responds within the hour, but measurable increases in macular pigment density take several months of regular intake.

Allergens

None of the fourteen major allergens. Derived from what this food is, not from a product label.

Eating patterns

Fits: Vegan, Vegetarian, Pescatarian, Halal, Kosher, Gluten-free.

In season

July to September in the northern hemisphere, January to March in the southern.

Satiety

183 on the satiety index, where white bread is 100 — high. Modelled from the Holt et al. (1995) measurements.

Environmental footprint

0.5 kg CO2e and 108 litres of freshwater per kg, matched to "Other vegetables" in Poore & Nemecek (2018), Science 360.

Cost band

Cheap — roughly £2.5 per kg, as a band midpoint rather than a price.

Key nutrients

Lutein
Dietary fibre
Potassium

Nutrition per 100g

Calories: 98
Protein: 4g
Carbohydrate: 13.9g
of which sugars: 6g
Fat: 2g
of which saturated: 0.5g
Fibre: 4.7g
Sodium: 21mg

Food vs. supplement

Lutein supplements are the better-evidenced option for people with established age-related macular degeneration, where trial doses far exceed anything a plate of corn provides. For everyone else, dietary lutein from corn, leafy greens and egg yolk is the sensible route: the doses are lower, but so is the evidence base for supplementing in the absence of disease.

Kitchen tip

Grill or barbecue on the cob rather than boiling — dry heat concentrates the lutein and the sugars instead of leaching them into water that gets poured away. A little butter or oil is not indulgence here; without fat present, carotenoid absorption drops sharply.

Common myth

"Corn passes straight through, so there is no point eating it." In reality: Only the cellulose skin of the kernel survives digestion. The starch, protein, folate and lutein inside are absorbed normally — the visible husk in stool is the wrapper, not the contents.