Cornmeal

Food · Grain · Food, Typed Supps

Cooking polenta does not change what is in it much — it mostly adds water.

Stage by stage

Intake (Cooked and softened): Boiling in water gelatinises the starch granules, which is what makes cornmeal digestible at all.
Digestion (Amylase attacks the starch): Amylase breaks the gelatinised starch into sugars, quickly, since there is little viscous fibre to slow it.
Absorption (Glucose to the bloodstream): Glucose is absorbed rapidly; grind size, more than anything else, determines how fast.
Fermentation (Colon and short-chain fatty acids): Starch that recrystallised on cooling resists digestion and is fermented by gut bacteria in the colon.

Time to effect

Under an hour: Blood glucose rises within roughly 30 to 60 minutes of a cooked serve.

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. Depends on the product: Low-FODMAP.

Satiety

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

Environmental footprint

1.7 kg CO2e and 216 litres of freshwater per kg, matched to "Maize" in Poore & Nemecek (2018), Science 360.

Cost band

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

Key nutrients

Starch
Magnesium
Selenium

Nutrition per 100g

Calories: 340
Protein: 8.5g
Carbohydrate: 70g
of which sugars: 0.7g
Fat: 1.7g
of which saturated: 0.2g
Fibre: 3g
Sodium: 0mg

Food vs. supplement

No supplement competes here; cornmeal is a staple starch. Its historical footnote is worth keeping: maize niacin is chemically bound and poorly absorbed, which caused widespread pellagra wherever maize became the dominant food without the lime-soaking step that releases it.

Kitchen tip

Cook coarse polenta rather than instant, then set it in a tray and chill it before grilling. Both steps — the coarser grind and the cooling — reduce how fast the starch digests.

Common myth

"Polenta is a rustic wholegrain." In reality: Most polenta is degermed maize with the bran and germ milled out, which puts it closer to white rice than to whole wheat. Wholegrain or stoneground cornmeal exists and is a different product, but the fibre figure on the packet is the way to tell them apart.