Clams

Food · Protein · Food, Typed Supps

Clams pack more vitamin B12 into a few bites than almost any other food on Earth, plus a big dose of iron.

Stage by stage

Chewing & Breakdown (Mouth): Chewing breaks down clam tissue and releases protein-bound vitamin B12, iron, and other nutrients for digestion.
Acid Digestion (Stomach): Stomach acid and pepsin free B12 from its protein carrier so it can bind to a transport protein for the next stage of absorption.
Nutrient Absorption (Small Intestine): In the small intestine, B12 binds intrinsic factor for absorption in the terminal ileum, while heme iron, zinc, and selenium are absorbed separately in the upper small intestine.
Circulation & Use (Bloodstream): Absorbed nutrients enter the bloodstream, where B12 supports red blood cell formation and nerve maintenance while iron is built into haemoglobin.

Timing

Clams don't require special timing -- they're typically eaten as part of a meal, and pairing them with vitamin-C-rich foods can help absorb their non-heme iron content.

Time to effect

Weeks: For someone with mild B12 or iron insufficiency, regular clam consumption can help restore blood levels and ease related fatigue over several weeks of consistent intake; correcting a diagnosed deficiency takes longer and should be guided by a clinician.

Allergens

Contains: Molluscs. Derived from what this food is, not from a product label.

Eating patterns

Fits: Pescatarian, Keto, Gluten-free. Depends on the product: Halal, Low-FODMAP.

Satiety

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

Environmental footprint

13.6 kg CO2e and 3691 litres of freshwater per kg, matched to "Fish (farmed)" in Poore & Nemecek (2018), Science 360.

Cost band

Mid — roughly £11 per kg, as a band midpoint rather than a price.

Key nutrients

Nutrition per 100g

Calories: 86
Protein: 14.7g
Carbohydrate: 3.6g
of which sugars: 0g
Fat: 1g
of which saturated: 0.2g
Fibre: 0g
Sodium: 601mg

Food vs. supplement

Clams deliver vitamin B12 together with heme iron, zinc, and selenium in one whole-food package, while a standalone B12 supplement provides only that single nutrient in isolated form.

Kitchen tip

Purge live clams in cold salted water before cooking, discard any that won't close when tapped or fail to open after steaming, and cook them thoroughly -- heat kills Vibrio bacteria, though it won't neutralize algal biotoxins from an unsafe harvest area.

Common myth

"Clams and other shellfish are bad for your heart because they're loaded with cholesterol." In reality: Clams are low in saturated fat, and the 2015-2020 Dietary Guidelines for Americans dropped the longstanding 300 mg/day dietary cholesterol cap after evidence showed dietary cholesterol has a limited direct effect on blood cholesterol for most people; saturated fat, which clams contain very little of, is the more significant dietary driver of LDL cholesterol.

Recipes that use it

Clams with Linguine