Sushi roll: salty rice, a little seaweed and the raw fish question

The strongest trial evidence near a sushi roll is about its wrapper. A meta-analysis of 29 randomized trials in 1583 adults found that edible algae lowered systolic blood pressure by 2.05 mmHg (95% CI 0.31 to 3.80). Heterogeneity was high, the biggest effects came from spirulina, and a roll holds far less seaweed than most of those trials used. We found no study of sushi rolls as a dish on any health outcome. What the numbers do show is salt. Across seven US survey codes, rolls carry 342 to 428 mg of sodium per 3.5 oz (100 g), about 100 to 130 mg in every 1.1 oz (30 g) piece, and that is before any soy sauce. A piece of California roll in the same data has about 28 calories, 5.5 g of carbohydrate and under 1 g of protein, recalculated from the 100 g values of one standard recipe. An unspecified serving is coded as 180 g.

As people eat it, per 3.5 oz (100 g)

How much is actually in it

• Across seven US survey sushi roll codes sodium runs from 342 to 428 mg per 3.5 oz (100 g), about 100 to 130 mg in each 1.1 oz (30 g) piece before any soy sauce. — US household measures, FNDDS, 7 sushi roll codes (n = 7 food codes) Evidence E source
  Sodium mg/100 g: tuna 342, eel 343, salmon 350, shrimp 358, avocado 361, vegetable 361, California 428

What a real portion looks like

• US survey data count a piece of California roll as 30 g, with about 28 calories, 5.5 g carbohydrate and 0.9 g protein per piece. — US household measures, FNDDS food code 58151180 (n = 1 food code) Evidence E source
  Per 100 g: 94 calories, carbohydrate 18.39 g, protein 2.92 g; per 30 g piece 28.2 calories, 5.5 g, 0.9 g; unspecified quantity 180 g

What your body absorbs

• In a randomized trial in 30 vegetarians, 5 g of nori a day for four weeks raised serum vitamin B12 by 59 pmol/L versus no nori, with the effect appearing to plateau at that dose. — 30 vegetarians aged 20-60 not using B12 supplements, Taiwan, 4 weeks (n = 30) Evidence B source
  Serum B12 +59 pmol/L (95% CI 25 to 93); holoTC +28.2 pmol/L; homocysteine -3.7 umol/L vs control
• In a randomized stable-isotope study in 35 men, selenium from trout was absorbed as well as selenate and retained better, and cooking did not change it. — 35 male volunteers aged 18-50, UK and Netherlands, labeled trout eaten in four meals over two days (n = 35) Evidence B source
  Fish selenium absorption similar to selenate; retention significantly higher (P<0.001); no difference between processing methods

What cooking and storage change

• FDA guidance says parasites in fish meant to be eaten raw are killed by freezing at -20°C (-4°F) or below for 7 days, or at -35°C (-31°F) until solid and then 15 hours, and that heating fish enough to kill bacteria also kills parasites. — fish intended to be eaten raw or undercooked (US seafood industry guidance) Evidence E source
  -4 °F (-20°C) for 7 days, or -31 °F (-35°C) until solid plus 15 hours at -31 °F (-35°C), or plus 24 hours at -4 °F (-20°C), kills parasites

What it does to your health

• A meta-analysis of 29 randomized trials with 1583 adults found edible algae lowered systolic blood pressure by 2.05 mmHg, with larger effects above 3 g a day. — 1583 adults, healthy or with cardiometabolic conditions, interventions of at least 4 weeks (n = 1583) Evidence A source
  SBP -2.05 mmHg (95% CI -3.80 to -0.31); DBP -1.87 mmHg (95% CI -3.10 to -0.64); >3 g/day SBP -3.71 mmHg
• In a school intervention with 4 to 5 year olds, 1.76 g of roasted nori a day for 10 weeks lowered diastolic pressure by 6.77 mmHg in boys versus 0.05 in controls, with no effect in girls. — 81 preschool children aged 4-5 in Japan, classes randomized, 10 weeks (n = 81) Evidence B source
  Boys DBP -6.77 vs -0.05 mmHg (P=0.031); SBP -8.29 vs +0.50 mmHg (P=0.051); no difference in girls

Safety, limits and interactions

• In a randomized dinner study in nine adults, a sushi meal raised urinary iodine and a newly harvested seaweed salad on the side pushed it up 385%, with serum TSH up 150% on day 2 and back by day 3. — 9 euthyroid adults, single halibut maki meal with or without seaweed salad, followed one week (n = 9) Evidence B source
  Urinary iodine +385% (fresh Greenlandic seaweed), +59% (no salad), +43% (store salad); serum TSH +150% on day 2, back by day 3
• Japanese national data for 2013 to 2023 count 2009 cases of Kudoa septempunctata food poisoning, 99% of them traced to flounder eaten as sashimi or sushi. — reported food poisoning cases, Japan, 2013-2023 (n = 2009) Evidence C source
  2009 cases; peak 429 in 2014; flounder sashimi and sushi implicated in 99%
• In a 2024 hepatitis A outbreak in Curitiba, Brazil, eating raw fish was linked to 2.54 times higher odds of infection in a case-control study of 242 people. — 121 cases and 121 controls aged 16 and over, Curitiba, 2023-2024 (n = 242) Evidence C source
  Raw fish consumption aOR 2.54 (95% CI 1.39 to 4.64)

What people believe that the data does not support

• In a double-blind randomized taste test, 40 Japanese adults did not prefer sushi from never-frozen mackerel over once-frozen mackerel (odds ratio 0.86 for choosing unfrozen as tasting better). — 40 healthy adult medical students and residents in Kobe, 120 paired tastings each of mackerel and squid sushi (n = 40) Evidence B source
  Mackerel: unfrozen preferred 42.5%, frozen 49.2%, OR 0.86 (95% CI 0.59 to 1.26); squid OR 1.38 (95% CI 0.93 to 2.05)

Who this works differently for

• FDA lists raw or smoked fish and other seafood among foods that can carry Listeria. Pregnant women are about 10 times more likely to get listeriosis than other healthy adults, and it is life-threatening for unborn and newborn children, adults over 65 and people with weakened immune systems. — Pregnant women, unborn and newborn children, adults over 65, people with weakened immune systems (n = -) Evidence E source
  Raw or smoked fish and other seafood listed as Listeria sources, pregnant women about 10 times more likely to get listeriosis
• Pooling 14,496 samples, a meta-analysis found Listeria monocytogenes in 5.8% of raw fish and 14.5% of ready-to-eat fish products. — fish, fish products and processing environments worldwide, 14,496 samples (n = 14496) Evidence C source
  L. monocytogenes prevalence raw fish 5.8% (95% CI 4.7 to 6.9); ready-to-eat products 14.5% (95% CI 11.1 to 18.0)
• FDA and EPA advise fish during pregnancy for the baby's cognitive development, while listing bigeye tuna, swordfish, king mackerel and other species as choices to avoid for mercury. — people who are or might become pregnant, breastfeeding, and young children, United States Evidence E source
  Fish intake in pregnancy recommended; highest-mercury species to avoid include bigeye tuna, swordfish, king mackerel, marlin, orange roughy, shark, Gulf tilefish

The bottom line

Nori does deliver something measurable, in amounts bigger than a roll. In an open-label randomized trial in 30 vegetarians in Taiwan, 5 g of nori a day for four weeks raised serum vitamin B12 by 59 pmol/L (95% CI 25 to 93) against no nori, and the effect appeared to plateau at that dose. In 81 Japanese preschool children, where three classes were randomized, 1.76 g of unsalted roasted nori a day for 10 weeks lowered diastolic pressure by 6.77 mmHg in boys against 0.05 in controls, with no difference in girls. Selenium from fish is well used by the body. In a stable isotope trial in 35 men eating trout, fish selenium was highly bioavailable and cooking did not change its absorption or retention. A common belief is that frozen fish makes worse sushi. This was tested. In a double-blind randomized taste trial, 40 adults in Kobe did not prefer mackerel sushi that had never been frozen over fish frozen at minus 40 C for a week (odds ratio 0.86, 95% CI 0.59 to 1.26). For squid the result leaned toward unfrozen without reaching significance (odds ratio 1.38, 95% CI 0.93 to 2.05). That trial measured taste and nothing else. It says nothing on whether freezing makes raw fish safer, and we hold no card on freezing as a step against parasites, so this is not a safety result. Who should be careful. Raw fish carries infections. In Japan, 2009 cases of Kudoa septempunctata food poisoning were reported from 2013 to 2023, and flounder eaten as sashimi or sushi was implicated in 99 percent of them. During one 2024 hepatitis A outbreak in Curitiba, Brazil, a case-control study of 242 people linked eating raw fish to 2.54 times higher odds of infection (95% CI 1.39 to 4.64), an association in one outbreak. Pooling 14,496 samples, a meta-analysis found Listeria monocytogenes in 5.8 percent of raw fish and 14.5 percent of ready-to-eat fish products, which measures contamination in samples rather than the chance of falling ill. FDA and EPA recommend fish in pregnancy for the baby's cognitive development and list the highest-mercury species as choices to avoid. That advice is about mercury. It does not address sushi, raw fish or the Listeria figures above, and the tuna in a roll can be of different species. This page holds no card that clears raw fish in pregnancy. If you are pregnant, treat the Listeria numbers above as unresolved for you and ask your doctor or midwife before eating raw fish. Seaweed adds iodine. In nine adults with normal thyroid function, one maki dinner raised urinary iodine by 59 percent, and a side of freshly harvested Greenlandic seaweed salad raised it by 385 percent. Serum TSH rose 150 percent on day 2 and was back by day 3. Nobody has tested regular eating or people with thyroid disease in that design. We hold no card on an upper limit for iodine, so the nori amounts in the trials above are study doses rather than amounts to copy, least of all for children or anyone with thyroid disease. We also found no glycemic data for vinegared sushi rice.

Sources

1. srl-r8-02 · reference dataset
   FNDDS Sodium mg/100 g: Sushi roll tuna 342 · eel 343 · salmon 350 · shrimp 358 · avocado 361 · vegetable 361 · California 428 (1 piece 30 g = 128.4 mg)
   USDA FNDDS 2021-2023 · checked 2026-09-29
2. srl-r8-01 · reference dataset
   FNDDS 2708961 Sushi roll, California: 1 piece 30 g · 1 cup 150 g · Quantity not specified 180 g · Energy 94 kcal/100 g, 1 piece 28.2 kcal · Carbohydrate 18.39 g/100 g, 1 piece 5.5 g · Protein 2.92 g/100 g, 1 piece 0.9 g
   USDA FNDDS 2021-2023 · checked 2026-09-29
3. srl-r8-03 · randomized controlled trial
   Vitamin B12 status appeared to plateau at low dose (5 g of nori), which compared with control group, improved serum vitamin B12 (lease square mean [95% CI] = + 59 [25, 93] pmol/L, P = 0.0014); holoTC (+ 28.2 [10.1, 46.3] pmol/L, P = 0.0035); Hcy (-3.7 [-6.8, -0.6] µmol/L, p = 0.0226); and 4cB12 score (+ 0.67 [0.24, 1.09], p = 0.0036).
   Eur J Nutr, 2024 · checked 2026-09-29
4. srl-r8-05 · randomized controlled trial
   Fish selenium is a highly bioavailable source of dietary selenium. Cooking did not affect selenium apparent absorption or retention from fish.
   Eur J Clin Nutr, 2004 · checked 2026-09-29
5. sf-fpf-r1-7 · agency advice
   Freezing and storing at an ambient temperature of -4°F (-20°C) or below for 7 days (total time), or freezing at an ambient temperature of -31°F (-35°C) or below until solid and storing at an ambient temperature of -31°F (-35°C) or below for 15 hours, or freezing at an ambient temperature of -31°F (-35°C) or below until solid and storing at an ambient temperature of -4°F (-20°C) or below for 24 hours are sufficient to kill parasites. ... The process of heating raw fish sufficiently to kill bacterial pathogens is also sufficient to kill parasites.
   FDA, Fish and Fishery Products Hazards and Controls Guidance, Chapter 5: Parasites · checked 2026-10-08
6. srl-r8-07 · meta-analysis of RCTs
   Twenty-nine RCTs encompassing 1583 participants were included. Edible algae intake significantly reduced systolic BP (SBP: -2.05 mmHg; 95% CI: -3.80, -0.31; p = 0.022) and diastolic BP (DBP: -1.87 mmHg; 95% CI: -3.10, -0.64; p = 0.001).
   J Hum Nutr Diet, 2025 · checked 2026-09-29
7. srl-r8-08 · cluster-randomized trial
   Changes in DBP were -6.77 mm Hg in the intervention group and -0.05 mm Hg in the control group (P = 0.031). In girls, no difference in blood pressure changes was found between the intervention and control groups.
   J Epidemiol, 2021 · checked 2026-09-29
8. srl-r8-06 · randomized trial
   UIE rose (p < 0.001) by 385%, 59% and 43% for groups A, B, and C, peaked in the 6-h spot urine sample at 393, 120, and 109 µg/g, and was down to pre-meal values by day 2. Serum TSH rose (p = 0.012) 150% on day 2 and was down to pre-meal values by day 3.
   J Endocrinol Invest, 2020 · checked 2026-09-29
9. srl-r8-10 · retrospective surveillance study
   Reported cases totaled 2009, reaching a peak in 2014 (429 cases) then declining to < 100 cases during the COVID-19 pandemic. October had the highest number of monthly reports. Flounder, particularly sashimi and sushi, were implicated in 99% of cases.
   Sci Rep, 2026 · checked 2026-09-29
10. srl-r8-11 · case-control study
    In the adjusted multivariate model, hepatitis A infection maintained a significant association with raw fish consumption (aOR 2.54; 95%CI 1.39; 4,64; p-value 0.002) and with MSM (aOR 2.38; 95%CI 1.10; 4,85; p-value 0.027).
    Epidemiol Serv Saude, 2026 · checked 2026-09-29
11. srl-r8-04 · randomized double-blind trial
    The odds ratio for selecting unfrozen sushi as "tastes better" over frozen sushi was 0.86 (95% confidence interval [CI], .59-1.26; P = .45).
    Clin Infect Dis, 2015 · checked 2026-09-29
12. sf-lrs-r3-4 · agency advice
    You can get listeriosis by eating raw, unpasteurized milk ... raw or smoked fish and other seafood. ... Pregnant women are about 10 times more likely to get listeriosis than other healthy adults. ... Listeriosis is a life-threatening disease, especially for unborn or newborn children, adults over the age of 65, and those with weakened immune systems.
    US FDA, Listeria (Food Safety for Moms-to-Be) · checked 2026-10-08
13. srl-r8-09 · meta-analysis of prevalence studies
    Pooled prevalence of L. monocytogenes and Listeria sp. in raw fish was 5.8 % (95 % CI: 4.7-6.9) and 12.2 % (95 % CI: 8.9-15.5) respectively. Significantly higher results were observed for ready-to-eat products, occurrence of L. monocytogenes and Listeria sp. was 14.5 % (95 % CI: 11.1-18.0) and 21.7 % (95 % CI: 11.8-31.6) respectively.
    Sci Total Environ, 2024 · checked 2026-09-29
14. srl-r8-12 · agency advice
    Fish intake during pregnancy is recommended because moderate scientific evidence shows it can help your baby's cognitive development. ... Choice to Avoid: HIGHEST MERCURY LEVELS
    FDA and EPA, Advice about Eating Fish · checked 2026-09-29