Black Beans

Food · Legume · Food, Typed Supps

A type of starch that reaches your colon mostly intact — which is the whole point.

Stage by stage

Intake (Cooking is essential): Cooking is essential to soften their structure and improve digestibility.
Stomach (Some starch resists digestion): Protein and starch digestion begins, though a portion of their starch resists digestion entirely.
Small intestine (Iron & protein absorbed): Non-heme iron and protein are absorbed; resistant starch passes through largely undigested.
Colon (Fermented by gut bacteria): Resistant starch reaches the colon intact, where gut bacteria ferment it into compounds studied for colon health.

Timing

Pairing with a vitamin C source improves non-heme iron absorption.

Time to effect

Weeks: Regular intake contributes to iron and fibre-related gut health markers.

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.

Satiety

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

Environmental footprint

1 kg CO2e and 397 litres of freshwater per kg, matched to "Peas" in Poore & Nemecek (2018), Science 360.

Cost band

Cheap — roughly £2.2 per kg, as a band midpoint rather than a price.

Key nutrients

Resistant starch
Non-heme iron
Plant protein
Fiber

Nutrition per 100g

Calories: 132
Protein: 8.9g
Carbohydrate: 23.7g
of which sugars: 0.3g
Fat: 0.5g
of which saturated: 0.1g
Fibre: 8.7g
Sodium: 1mg

Food vs. supplement

Resistant starch behaves more like fibre than a typical digestible carbohydrate — a fibre supplement can provide bulk, but doesn’t replicate the specific fermentation byproducts gut bacteria produce from black beans’ particular starch structure.

Kitchen tip

Rinsing canned beans removes a meaningful share of the added sodium without losing much fibre or protein.

Common myth

“All carbohydrates in beans digest and absorb the same way.” In reality: A meaningful portion is resistant starch, which passes to the colon largely undigested and feeds gut bacteria instead of being absorbed as sugar.