Fish soup: a light, salty bowl rarely studied as such

In a 1-year randomized trial in 200 adults with overweight or obesity on a calorie-restricted diet, two daily servings of low energy-dense soup led to 16 lb (7.2 kg) weight loss against 11 lb (4.8 kg) with two servings of high energy-dense snack foods. The group given no special food lost 18 lb (8.1 kg), so adding soup did not bring more weight loss than the diet alone. That soup was not fish soup, and we found no trial on fish soup itself, so the firmest numbers here come from soup in general. A one-cup bowl of fish or shrimp soup, 245 g in the US survey database, gives about 74 calories and 6 g protein with 620 mg sodium. That is one standard recipe, and creamy chowders and home versions differ. USDA records for a homemade fish soup and a fish stock run from 2.26 to 7.4 g protein per 3.5 oz (100 g).

The numbers, per 3.5 oz (100 g)

What a real portion looks like

• A one-cup serving of fish or shrimp soup (245 g) in the US survey database gives about 74 calories and 6 g protein but 620 mg sodium. — USDA FNDDS 2021-2023 food code 28355480, Soup, fish or shrimp (n = -) Evidence E source
  Per 100 g: 30 calories, protein 2.58 g, fat 0.47 g, sodium 253 mg; 1 cup 245 g: 73.5 calories, 6.3 g protein, 620 mg sodium

What your body absorbs

• Fish allergens are absorbed within 10 minutes of eating cod, and in people with fish allergy poorly digested fish triggered reactions at 10- to 30-fold lower doses. — healthy volunteers (open challenge) and patients with diagnosed codfish allergy (titrated DBPCFC) Evidence C source
  Absorbed allergens detectable after 10 min, peak 1-2 h; fish digested at pH 3.0 reacted at 10-30 fold lower cumulative doses than at pH 2.0

What cooking and storage change

• The FDA warns that histamine in poorly chilled fish cannot be removed by washing, freezing or heating, so cooking fish into soup does not make spoiled fish safe. — US fish and fishery products (n = -) Evidence E source
  Histamine heat-stable; FDA action level 200 ppm (Compliance Policy Guide, November 2024)

What it does to your health

• In a 1-year randomized trial in 200 adults on a calorie-restricted diet, two daily servings of low energy-dense soup led to 16 lb (7.2 kg) weight loss versus 11 lb (4.8 kg) with two servings of high energy-dense snacks. — 200 overweight and obese women and men, energy-restricted diet, 1 year (n = 200) Evidence B source
  Weight loss at 1 year: two-soup 7.2 +/- 0.9 kg vs two-snack 4.8 +/- 0.7 kg (50% greater); comparison 18 lb (8.1 kg)
• In a randomized crossover trial in 32 lean men, a higher-energy soup preload raised blood glucose more than a lower-energy one, and total daily energy intake did not differ. — 32 healthy lean males (mean age 28.9 years, mean BMI 22.1) (n = 32) Evidence B source
  HED preloads larger glucose spike (p < 0.001); total daily energy intake no difference (p >= 0.214)
• In a randomized crossover trial in 68 women with overweight or obesity, 6.8 fl oz (200 ml) of vegetable soup with added MSG before lunch lowered energy eaten at that lunch compared with the same soup without it. — sixty-eight overweight and obese women (BMI 25.0-39.9) (n = 68) Evidence B source
  Lower lunch energy intake with MSG soup (size not in abstract); fewer high-fat savory foods; afternoon snack no significant difference

Safety, limits and interactions

• A review of 103 histamine poisoning incidents found a mean of 1107 mg/kg histamine in the implicated food, mostly tuna and marlin-type fish. — 55 reports, 103 histamine poisoning incidents, 1959-2013 (n = 103 incidents) Evidence C source
  Mean histamine 1107.21 mg/kg (95% CI 422.62 to 2900.78); I2 100%

Who this works differently for

• A case report describes a 4-year-old with fish allergy who had anaphylaxis to many fish preparations, including fish soup and even cooking vapours. — one 4-year-old boy with fish allergy (n = 1) Evidence D source
  Anaphylaxis to cod, tuna, salmon, trout, eel, fish soup and fish-contaminated chopsticks

What is still unknown

• USDA reference records for fish soup differ about threefold in protein, from 2.26 g in fish stock to 7.4 g in an Alaska Native homemade fish soup per 3.5 oz (100 g). — USDA SR Legacy: Soup, fish, homemade (Alaska Native) FDC 168027 and Soup, stock, fish, home-prepared (n = -) Evidence E source
  Protein 2.26-7.4 g, niacin 1.19-2.64 mg, phosphorus 56-112 mg per 3.5 oz (100 g); Foundation samples 0; no CoFID record

The bottom line

Two shorter trials show what a bowl does at one meal. In 32 lean men, a higher energy soup preload raised blood glucose more than a low energy broth, and total energy eaten over the day did not differ. In 68 women with overweight or obesity, 6.8 fl oz (200 ml) of vegetable soup with added MSG before lunch lowered the energy eaten at that lunch compared with the same soup without it. The abstract gives no size, and the afternoon snack showed no significant difference. The real cautions with fish soup are fish allergy and spoiled fish. In a challenge study, cod allergens reached the blood of people without allergy within 10 minutes and peaked at 1 to 2 hours. In patients with cod allergy, fish digested at a less acidic pH 3.0 triggered reactions at 10 to 30 times lower doses. A case report describes a 4-year-old boy with fish allergy who had anaphylaxis to fish soup, several fish, chopsticks touched by fish and the vapours of fish cooking. The FDA says histamine, once it forms in poorly chilled fish, cannot be removed by washing, freezing or heating. Simmering spoiled fish into soup does not make it safe. Across 103 histamine poisoning incidents, the implicated food held a mean of 1107 mg/kg histamine (95% CI 423 to 2901), mostly tuna and marlin-type fish, with very uneven results between reports. We found no data on mercury in soup or on calcium from bones in broth.

Sources

1. fsp-r7-01 · reference dataset
   Soup, fish or shrimp (FNDDS 28355480, fdc_id 2707143): Energy 30 KCAL, Protein 2.58 G, Total lipid (fat) 0.47 G, Sodium 253 MG per 100 g; 1 cup 245 g
   USDA FNDDS 2021-2023 · checked 2026-10-02
2. fsp-r7-06 · controlled clinical trial
   Ingestion experiments in subjects without allergy revealed absorption of biologically active fish allergens only 10 minutes after ingestion with maximal serum levels after 1 to 2 hours. ... Fish digested at pH 3.0 revealed comparable reactivity patterns as undigested extracts. Moreover, these test materials triggered reactions at 10-fold to 30-fold lower cumulated challenge doses in patients with allergy.
   J Allergy Clin Immunol, 2007 · checked 2026-10-02
3. fsp-r7-08 · agency guidance
   Unless fish are properly chilled, histamine can accumulate and once formed, cannot be removed by washing, freezing, or heating.
   US FDA, FDA Issues Final Compliance Policy Guide on Scombrotoxin (Histamine)-Forming Fish and Fishery Products, 2024 · checked 2026-10-02
4. fsp-r7-03 · RCT
   Additionally, subjects were randomized to consume daily either one or two servings of low energy-dense soup, two servings of high energy-dense snack foods, or no special food (comparison group). ... At 1 year, weight loss in the comparison (8.1+/-1.1 kg) and two-soup (7.2+/-0.9 kg) groups was significantly greater than that in the two-snack group (4.8+/-0.7 kg)
   Obes Res, 2005 · checked 2026-10-02
5. fsp-r7-04 · RCT
   Energy compensation and postprandial blood glucose response were measured in 32 healthy lean males (mean age = 28.9 years, mean BMI = 22.1 kg/m²). ... Energy intake at subsequent meals and total daily energy intake did not differ between the four treatments (both p ≥ 0.214). Consumption of HED preloads resulted in a larger spike in postprandial blood glucose response compared with LED preloads, irrespective of taste quality (p < 0.001).
   Nutrients, 2018 · checked 2026-10-02
6. fsp-r7-05 · RCT
   A fixed portion (200 ml) of control vegetable soup or the same soup with added MSG (0·5 g/100 ml) was provided 10 min before an ad libitum lunch and an ad libitum snack in the mid-afternoon. ... The soup with MSG in comparison with the control soup resulted in significantly lower consumption of energy at lunch.
   Br J Nutr, 2016 · checked 2026-10-02
7. fsp-r7-07 · meta-analysis of outbreak reports
   Fifty-five (55) reports were included, these studies reported 103 incidents. All pooled analyses were based on random effect model; histamine mean concentration in poisoning samples was 1107.21 mg/kg with confidence interval for the meta-mean of 422.62-2900.78 mg/kg ... Fish involved in histamine poisoning was mainly tuna or Istiophoridae species.
   Crit Rev Food Sci Nutr, 2018 · checked 2026-10-02
8. fsp-r7-09 · case report
   Many fish preparations caused these episodes including several different kinds of fish (cod, tuna, salmon, trout, eel...), fish soup, chopsticks contaminated with fish preparations and canned fish. ... Avoidance of fish may need to include both ingestion and inhalation of cooking vapors.
   Zhonghua Min Guo Xiao Er Ke Yi Xue Hui Za Zhi, 1998 · checked 2026-10-02
9. fsp-r7-02 · reference dataset
   Soup, fish, homemade (Alaska Native) (FDC 168027, sr_legacy): protein 7.4 g, niacin 2.64 mg, phosphorus 112 mg per 100 g; Soup, stock, fish, home-prepared: protein 2.26 g, niacin 1.186 mg, phosphorus 56 mg; Foundation samples 0
   USDA FoodData Central SR Legacy · checked 2026-10-02