Salmon and trout: close cousins, different fat

In a 2-week trial in 32 adults, cooked salmon and algal-oil capsules giving 600 mg of DHA a day raised DHA in plasma phospholipids by about 80% in both groups, in a short, small, open-label study. Between the two fish the difference is mostly fat. UK tables put baked farmed salmon at 232 calories, 14.6 g of fat and 3.10 g of omega-3 fat per 3.5 oz (100 g), and baked rainbow trout at 150 calories, 6.1 g of fat and 1.72 g of omega-3, from single UK sample sets where farm feed changes the omega-3. On protein (25.2 and 23.8 g), vitamin D (7.3 and 8.2 mcg) and selenium (20 and 23 mcg) per 3.5 oz (100 g) the two are close. Portions differ: the US dietary survey counts a regular grilled salmon fillet as 140 g and a trout fillet as 90 g. In an autumn trial in 120 Polish women aged 20 to 25, a salmon sausage slowed the seasonal drop in blood vitamin D (minus 4.3 against minus 15.0 nmol/L in controls), and smoked salmon made no significant difference, though both supplied about 5 mcg of vitamin D a day.

How much is actually in it

• Per 100 g, baked farmed salmon has 232 calories, 14.6 g fat and 3.10 g omega-3 fat, versus 150 calories, 6.1 g fat and 1.72 g omega-3 in baked rainbow trout. — UK composition data, cooked flesh only Evidence E source
  Salmon about 1.5x the energy and 1.8x the omega-3 of trout
• Per 100 g, baked farmed salmon and baked rainbow trout give similar vitamin D (7.3 vs 8.2 ug) and selenium (20 vs 23 ug), and similar protein (25.2 vs 23.8 g). — UK composition data, cooked flesh only Evidence E source
  Vitamin D 7.3 vs 8.2 ug; selenium 20 vs 23 ug; protein 25.2 vs 23.8 g

What a real portion looks like

• In the US dietary survey, a regular grilled salmon fillet is counted as 140 g while a regular grilled trout fillet is 90 g. — US FNDDS portion weights Evidence E source
  Salmon fillet 140 g (large 210 g); trout fillet 90 g (large 135 g, whole fish 270 g)

What your body absorbs

• In a crossover trial in 13 women, eating intact salmon gave higher blood EPA and DHA over 6 hours than the same salmon minced or defatted with oil added back. — Healthy women, single meals, 6-hour postprandial sampling (n = 13) Evidence B source
  Plasma EPA and DHA significantly higher after intact salmon (p < 0.001)
• In a 2-week RCT in 32 adults, 600 mg DHA a day from algal-oil capsules raised blood DHA as much as cooked salmon, about 80% in plasma phospholipids. — Healthy men and women aged 20 to 65, 2 weeks (n = 32) Evidence B source
  Plasma phospholipid DHA +80%, erythrocyte DHA +25% in both groups
• In an 8-week autumn RCT in 120 young women, salmon sausage slowed the fall in blood vitamin D (minus 4.3 vs minus 15.0 nmol/L) but smoked salmon did not. — Non-obese women aged 20 to 25 in Poland, 8 weeks in autumn (n = 120) Evidence B source
  25(OH)D change -4.3 vs -15.0 nmol/L (salmon sausage vs control); smoked salmon not different

Safety, limits and interactions

• US FDA and EPA list both salmon and trout as Best Choices, advising 2 to 3 servings of 4 ounces a week in pregnancy and breastfeeding. — People who are or might become pregnant, breastfeeding, and children Evidence E source
  2 to 3 servings a week of 4 oz

What people believe that the data does not support

• In an 8-week RCT in 38 young women with excess weight, 7.1 oz (200 g) of smoked farmed salmon a week lowered LDL by 8.2 mg/dL while it rose 9.5 mg/dL in controls. — Women aged 18 to 30 with BMI 25 or more, 8 weeks (n = 38) Evidence B source
  LDL change -8.2 vs +9.5 mg/dL (p = 0.011); no difference in end values
• The EU did not authorize a claim that a salmon oil supplement supports normal blood cholesterol. — EU food labeling Evidence E source
  Claim non-authorized

Who this works differently for

• In a 16-week RCT in 205 preschool children, salmon meals three times a week raised EPA and DHA but did not change IQ scale scores versus meat meals. — Children aged 4 to 6 in Norway, 16 weeks (n = 205) Evidence B source
  No difference in WPPSI-III scale scores; 2 of 8 raw subtest scores better
• In an RCT in 123 pregnant women, two 5.3 oz (150 g) portions of farmed salmon a week from week 20 did not change maternal gut bacteria or gut immune markers. — Pregnant women who rarely ate oily fish, week 20 to delivery (n = 123) Evidence B source
  No effect on maternal fecal microbiota, sIgA or calprotectin

What is still unknown

• USDA lab samples show raw farmed Atlantic salmon at 0.585 g DHA per 3.5 oz (100 g) (range 0.488 to 0.739) versus 0.326 g in wild sockeye (range 0.214 to 0.48), and trout has no such sample data. — USDA Foundation Foods, 8 samples each Evidence E source
  DHA farmed 0.585 g vs wild sockeye 0.326 g per 3.5 oz (100 g) raw; spread 43% vs 82%

The bottom line

How the fish reaches you may matter. In a crossover trial in 13 women, intact salmon gave higher blood EPA and DHA over the 6 hours after the meal than the comparison meals, a single-meal result in a small group. USDA lab samples of raw salmon put DHA at 0.585 g per 3.5 oz (100 g) in farmed Atlantic (range 0.488 to 0.739) and 0.326 g in wild sockeye (range 0.214 to 0.48). Trout has no sample data of this kind, so we cannot say how much its DHA varies. The cholesterol evidence is thin. In 38 women aged 18 to 30 with a BMI of 25 or more, 7.1 oz (200 g) of smoked farmed salmon a week for 8 weeks lowered LDL by 8.2 mg/dL while it rose 9.5 mg/dL in controls, yet LDL at the end of the study did not differ between the groups. The EU did not authorize a claim that a salmon oil capsule supports normal blood cholesterol, a ruling about a supplement product. The safety section of this page holds one card, the FDA and EPA fish advice. FDA and EPA put both salmon and trout on their Best Choices list for people who are or may become pregnant, breastfeeding mothers and children, advising 2 to 3 servings a week, and that ranking is built on mercury and does not weigh nutrient differences. We have no card on fish allergy, on medicines or on upper amounts for these fish. In 123 pregnant women who rarely ate oily fish, two 5.3 oz (150 g) portions of farmed salmon a week from week 20 did not change their gut bacteria or gut immune markers, measured in a subset of 75 mothers. In 205 Norwegian children aged 4 to 6, farmed salmon meals three times a week for 16 weeks gave no difference in IQ scale scores compared with meat meals. We did not find a study that compared salmon with trout directly, so every comparison on this page is between composition tables.

Sources

1. slt-r5-01 · food composition table
   Salmon, farmed, flesh only, baked (CoFID 2021, code 16-359): Energy 232 kcal; Fat 14.6 g; n-3 poly 3.10 g per 100 g. Trout, rainbow, flesh only, baked (code 16-396): Energy 150 kcal; Fat 6.1 g; n-3 poly 1.72 g per 100 g
   CoFID 2021 (Public Health England), codes 16-359 and 16-396 · checked 2026-10-02
2. slt-r5-02 · food composition table
   Salmon, farmed, flesh only, baked (CoFID 2021, code 16-359): Protein 25.2 g; Selenium 20 ug; Vitamin D 7.3 ug per 100 g. Trout, rainbow, flesh only, baked (code 16-396): Protein 23.8 g; Selenium 23 ug; Vitamin D 8.2 ug per 100 g
   CoFID 2021 (Public Health England), codes 16-359 and 16-396 · checked 2026-10-02
3. slt-r5-04 · portion dataset
   Fish, salmon, grilled (FNDDS 26137123, fdc_id 2706287): 1 small/regular fillet 140 g; 1 large fillet 210 g. Fish, trout, grilled (FNDDS 26151123, fdc_id 2706304): 1 small/regular fillet 90 g; 1 large fillet 135 g; 1 whole fish 270 g
   USDA FNDDS, Fish salmon grilled (26137123) and Fish trout grilled (26151123) · checked 2026-10-02
4. slt-r5-05 · RCT
   Healthy female participants (n = 13) consumed the meals in a postprandial crossover study and blood was collected at regular time points for 6 h post meal consumption. ... Results: showed that plasma concentration of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were significantly higher after participants consumed intact salmon compared to the other meals (covariate analysis p < 0.001).
   Food Funct, 2021 · checked 2026-10-02
5. slt-r5-06 · RCT
   DHA levels increased by approximately 80% in plasma phospholipids and by approximately 25% in erythrocytes in both groups. Changes in DHA levels in plasma phospholipids and erythrocytes were similar between groups.
   J Am Diet Assoc, 2008 · checked 2026-10-02
6. slt-r5-07 · RCT
   While all groups experienced a decrease in 25(OH)D serum concentrations, the decrease was significantly smaller in the salmon sausage group compared to the control group (-4.3 vs. -15.0 nmol/L, p < 0.05), and no significant difference was observed between the smoked salmon and control group after 8 weeks (p > 0.05).
   Nutrients, 2024 · checked 2026-10-02
7. slt-r5-12 · agency advice
   Eat 2 to 3 servings a week from the "Best Choices" list
   FDA/EPA Advice about Eating Fish · checked 2026-10-02
8. slt-r5-10 · RCT
   However, differences in the change of the LDL concentration were noted, with a decrease of 8.2 ± 20.7 mg/dL in the intervention group compared to an increase of 9.5 ± 20.0 mg/dL in the control group (p = 0.011)
   Nutrients, 2024 · checked 2026-10-02
9. slt-r5-11 · EU claim register
   POL-HC-7853 Pure salmon oil 500 mg. D alpha tocopherol10 mg.-cps Supports the normal level of blood cholesterol. Non-authorised
   EU Register on nutrition and health claims, claim POL-HC-7853, snapshot 2026-09-21 · checked 2026-10-02
10. slt-r5-08 · RCT
    Children (n = 205, age 4-6 years) in this trial were individually randomized to eating meals containing farmed Atlantic salmon or meat three times weekly for 16 weeks. ... In general linear models no significant differences between the intervention groups were found in the scale scores of the WPPSI-III tests and the 9-HPT.
    Clin Nutr, 2019 · checked 2026-10-02
11. slt-r5-09 · RCT
    Women (n 123) who rarely ate oily fish were randomly assigned to continue consuming their habitual diet or to consume two 150 g portions of farmed salmon per week from 20 weeks of pregnancy to delivery. ... There was no effect of salmon consumption on maternal faecal microbiota or on maternal or infant faecal sIgA and calprotectin concentrations.
    Br J Nutr, 2014 · checked 2026-10-02
12. slt-r5-03 · food composition dataset
    Fish, salmon, Atlantic, farm raised, raw: PUFA 22:6 n-3 (DHA) 0.585 g, range 0.488-0.739, 8 samples, spread 43%. Fish, salmon, sockeye, wild caught, raw: PUFA 22:6 n-3 (DHA) 0.326 g, range 0.214-0.48, 8 samples, spread 82% (USDA Foundation Foods, release 2026-04-30)
    USDA FoodData Central, Foundation Foods, release 2026-04-30 · checked 2026-10-02