Fish
Food · Protein · Food, Typed Supps
How oily a fish is, and what is wrapped around it, matters far more than the word on the packet.
Stage by stage
- Intake (Flesh broken up): Chewing breaks the muscle structure and releases oil held between the fibres.
- Digestion (Protein and fat separated): Protein digestion begins in the stomach; fat passes on largely intact.
- Absorption (Fats carried by bile): Bile emulsifies the fat, carrying omega-3 and vitamins A and D across the gut wall.
- Use (Built into membranes): EPA and DHA are incorporated into cell membranes, including heart and brain tissue.
Time to effect
- Weeks: Regular oily fish intake shifts cell membrane fatty acid composition over roughly four to eight weeks.
Allergens
Contains: Fish. Derived from what this food is, not from a product label.
Eating patterns
Fits: Pescatarian, Kosher, Keto, Low-FODMAP, Gluten-free. Depends on the product: Halal.
Satiety
136 on the satiety index, where white bread is 100 — moderate. 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: 178
- Protein: 18.4g
- Carbohydrate: 0g
- of which sugars: 0g
- Fat: 11.7g
- of which saturated: 2.4g
- Fibre: 0g
- Sodium: 51mg
Food vs. supplement
An oily fish like eel supplies EPA and DHA already in the form the body uses, plus vitamin D, vitamin A and protein that a fish oil capsule does not carry. The reverse also holds: a capsule is a reasonable way to get EPA and DHA if oily fish is not something you will eat, but it does nothing for the coated frozen fillets in this family, which were never an omega-3 source to begin with.
Kitchen tip
Eel is fatty enough to grill, smoke or roast without added oil, and its fat renders as it cooks — a rack or grill lets it drain. For frozen crumbed or battered fillets, baking on a wire rack rather than a solid tray keeps the underside from steaming in its own released oil, which is the difference between crisp and soggy but does not change the nutrition much.
Common myth
“Fish fingers count as eating fish.” In reality: They count as protein, but the fish inside is typically a lean white species with little omega-3, and a substantial share of the energy comes from the crumb or batter and the oil it holds. They do not substitute for oily fish.
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