Know2eat

Nori

Pyropia spp.

What nori has been studied for

2 associations assessed — 1 with at least some human evidence behind it. Strongest first.

  • 1 Limited
  • 1 Insufficient
3 things to know first — allergies, interactions and intake limits

About nori

Red algae of the genera Pyropia and Porphyra, best known pressed into the thin sheets used for sushi. Welsh laverbread is the same group of species cooked to a purée.

Also known as Laver, Gim, Purple laver, Zicai

Gut & Digestive HealthHeart Health

The evidence in depth

Best supported: Limited

What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how impressive the food is. How we rate evidence.

Gut microbiome

Gut & Digestive Health
Limited evidence

Porphyran, the characteristic sulphated polysaccharide of nori, can only be broken down by bacteria carrying specific enzymes, and Japanese gut microbiomes appear to have acquired those genes from marine bacteria. It is a striking finding about microbial adaptation; it is not evidence that eating nori improves anyone's health.

Limited evidence. Early human work, or mostly lab and animal research.

1 source

Deep research mode adds each paper’s own conclusion and stated limitations.

Cardiovascular risk markers

Heart Health
Insufficient evidence

Cohort studies in Japan and Korea associate higher seaweed intake with lower cardiovascular risk, but seaweed intake tracks with an entire dietary pattern. Nothing has been tested in a trial.

Insufficient evidence. Not enough human research to say anything useful yet.

No source is attached to this association yet, so it is rated insufficient by default. It is listed because people commonly ask about it — not because there is evidence for it.

Ask about Nori

Ask about Nori

Answers are written only from the entries on this page — the same nutrients, compounds, claims and citations you can read above. Nothing is added from outside the database, and every answer lists what it was built from.

AI explanations are not switched on for this site, so there is nothing to ask here. Everything above is read straight from the database and does not need them.

Key nutrients

Nutrient content per 100 grams
NutrientAmount% DV
Macronutrients
Calories35 kcal2%
Protein5.81 g12%
Total fat0.28 g0%
Carbohydrate5.11 g2%
Fibre0.3 g1%
Total sugars0.49 g—
Water85 g—
Fats
Saturated fat0.061 g0%
Monounsaturated fat0.025 g—
Polyunsaturated fat0.11 g—
Cholesterol0 mg0%
EPA (omega-3)0.08 g—
DHA (omega-3)0 g—
DPA (omega-3)0 g—
Linoleic acid (omega-6)0.0040 g—
Vitamins
Vitamin A260 µg29%
Vitamin C39 mg43%
Vitamin D0 µg0%
Vitamin E1 mg7%
Vitamin K4 µg3%
Thiamin (B1)0.098 mg8%
Riboflavin (B2)0.446 mg34%
Niacin (B3)1.47 mg9%
Pantothenic acid (B5)0.521 mg10%
Vitamin B60.159 mg9%
Folate146 µg37%
Vitamin B120 µg0%
Choline10.4 mg2%
Minerals
Calcium70 mg5%
Iron1.8 mg10%
Magnesium2 mg0%
Phosphorus58 mg5%
Potassium356 mg8%
Sodium48 mg2%
Zinc1.05 mg10%
Copper0.264 mg29%
Manganese0.988 mg43%
Selenium0.7 µg1%
Other measured compounds
Beta-carotene3121 µg—
Alpha-carotene0 µg—
Lycopene0 µg—
Lutein + zeaxanthin0 µg—
Caffeine0 mg—
Ash3.77 g—

Nutrient values are per 100 g of the USDA reference entry named on this page and vary with variety, growing conditions, storage and preparation.

Source record: Seaweed, laver, raw (USDA FoodData Central, FDC ID 168458).

% DV uses the FDA Daily Values for adults and children aged 4 and over. A dash means no Daily Value has been established for that nutrient.

Bioactive compounds

Compounds present in meaningful amounts. Presence is banded rather than quantified, because whole-food levels vary enormously with variety, growing conditions, storage and preparation.

How preparation changes things

Only effects with real support are listed. If a preparation method is missing, it is because nothing dependable is documented — not because it makes no difference.

Nothing dependable is recorded about how preparation changes this food’s nutritional properties. Rather than guess, this section stays empty.

Things to know

Allergies, interactions and intake concerns. Every food gets this section — a reference where everything is uniformly good is not a reference.

  • Worth knowing

    Not a dependable vitamin B12 source

    Nori contains compounds measured as vitamin B12, and some of it does appear to be the active form, but results vary enormously between samples and species and much of what is detected is inactive analogue. Some analogues may even block B12 metabolism. Anyone on a vegan diet needs a supplement or fortified food, not nori.

  • Worth knowing

    Iodine and arsenic

    Nori is much lower in iodine than kelp or wakame, which makes it the least concerning seaweed on that front, but heavy daily consumption still adds up. Red algae also accumulate arsenic, with levels depending on origin.

  • Worth knowing

    Seasoned snack sheets

    Roasted seasoned nori snacks are prepared with oil and salt. They are a reasonable snack but they are not the plain seaweed this record describes.