The amounts in the reference foods
USDA’s final SR Legacy 2018 release reports atlantic cod, cooked dry heat: 42 mg per 100 g; farmed atlantic salmon, cooked dry heat: 30 mg per 100 g; farmed rainbow trout, cooked dry heat: 30 mg per 100 g; light tuna canned in water, drained: 23 mg per 100 g. These are named historical reference foods, not measurements of a current package or meal. [1]
What changes the interpretation
The cod record gives 42 mg per 100 g, salmon and trout 30 mg, and drained light tuna 23 mg. These four entries do not cover every fish species or preparation. A fish with less magnesium may differ in other nutrients; the smallest magnesium number should not be relabeled the worst fish. Species, preparation and edible weight must remain attached to the comparison. [1]
A hypothetical portion comparison
For hypothetical 85 g portions, the magnesium estimates are 35.7 mg for cod,25.5 mg for salmon or trout and 19.55 mg for light tuna. A larger serving can change the amount per plate even when the per 100 g ordering stays the same. The table uses the explicitly chosen edible weights. Scale a matching per-100-g value by the grams eaten divided by 100; a count of pieces or an unspecified spoonful is not the same denominator. [1]
| Food | Chosen portion | Nutrient estimate |
|---|---|---|
| Atlantic cod, cooked dry heat | 85 g | 35.7 mg |
| Farmed Atlantic salmon, cooked dry heat | 85 g | 25.5 mg |
| Farmed rainbow trout, cooked dry heat | 85 g | 25.5 mg |
| Light tuna canned in water, drained | 85 g | 19.55 mg |
Sources for this article
- USDA FoodData Central — SR Legacy April 2018 composition and portion tables
Source consulted: 2026-09-20. This is a reference resource, not a claim that we conducted the studies or tested a product.