Swordfish
Food · Protein · Food, Typed Supps
Swordfish gives you a lot of protein and vitamin D in one meal -- but it's also on the short list of fish doctors say to skip if you're pregnant or feeding young kids.
Stage by stage
- Chewing (Mouth): Chewing breaks down swordfish's dense, low-fat muscle fibres into a bolus ready for digestion.
- Protein Breakdown (Stomach): Stomach acid and pepsin begin breaking the fish's complete protein into peptides while releasing the fat-soluble vitamin D and omega-3 fats bound in its tissue.
- Nutrient Absorption (Small Intestine): The small intestine absorbs amino acids, selenium, vitamin B12, and vitamin D into the bloodstream.
- Muscle & Tissue Use (Muscle & Cells): Amino acids support muscle repair and growth while selenium and vitamin D are used in antioxidant defense, immune function, and bone metabolism.
Timing
Eating swordfish alongside some dietary fat helps absorb its fat-soluble vitamin D, and its satiating protein load makes it well suited to a main meal rather than a snack.
Time to effect
- Hours to weeks: Protein satiety and amino acid uptake occur within a couple of hours of eating, while measurable improvements in vitamin D or selenium status from regular consumption take several weeks.
Allergens
Contains: Fish. 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
161 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
Pricey — roughly £20 per kg, as a band midpoint rather than a price.
Key nutrients
Nutrition per 100g
- Calories: 144
- Protein: 19.7g
- Carbohydrate: 0g
- of which sugars: 0g
- Fat: 6.7g
- of which saturated: 1.8g
- Fibre: 0g
- Sodium: 90mg
Food vs. supplement
Swordfish delivers a rare combination of complete protein, vitamin D, and selenium in one food, but its mercury content means it can't be treated as a routine, high-frequency protein source the way a supplement or a lower-mercury fish can.
Kitchen tip
Cook swordfish just to opaque and flaking (about 145°F/63°C internal) rather than well-done, since its dense, low-fat flesh dries out and toughens quickly with overcooking.
Common myth
"Swordfish is a safe, everyday lean-protein fish, no different from salmon or tuna." In reality: Because swordfish is a long-lived apex predator, it bioaccumulates methylmercury to levels that put it on the FDA/EPA list of fish to avoid entirely during pregnancy, breastfeeding, and childhood, and to limit even for other adults -- unlike lower-mercury choices such as salmon, cod, or shrimp.
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