By the Nutriveda editorial team · Updated 5 November 2026
Nori is a thin red seaweed of the genera Porphyra and Pyropia, best known as the dark, dried sheets wrapped around sushi; in Britain and Ireland the same seaweed is called laver, and in Wales it is cooked into laverbread. Laver, sometimes called purple seaweed, and nori are one and the same: “nori” is the Japanese word, now used in English for Porphyra and Pyropia in general. Fresh laver has 35 kcal per 100 g and gives vitamin C, folate and beta-carotene. Among edible seaweeds, nori has one of the lowest iodine ranges, 10-400 µg per gram dried, far below kelp or kombu. It is not a source of vitamin B12: the USDA record lists none.
Nori (laver) nutrition per 100 g and per portion
| Nutrient | Laver, raw, 100 g | Portion: 10 g (2 tablespoons) |
|---|---|---|
| Energy | 35 kcal | 4 kcal |
| Protein | 5.8 g | 0.6 g |
| Fat | 0.3 g | under 0.1 g |
| Carbohydrate | 5.1 g | 0.5 g |
| of which sugars | 0.5 g | under 0.1 g |
| Fibre | 0.3 g | under 0.1 g |
| Vitamin C | 39 mg | 3.9 mg |
| Vitamin A (RAE) | 260 µg | 26 µg |
| Beta-carotene | 3,120 µg | 312 µg |
| Folate | 146 µg | 15 µg |
| Riboflavin (B2) | 0.45 mg | 0.04 mg |
| Manganese | 0.99 mg | 0.10 mg |
| Potassium | 356 mg | 36 mg |
| Iron | 1.8 mg | 0.2 mg |
| Calcium | 70 mg | 7 mg |
| Sodium | 48 mg | 5 mg |
| Vitamin B12 | 0 µg | 0 µg |
| Iodine | no data in this record | no data |
Source: USDA FoodData Central, SR Legacy: “Seaweed, laver, raw” (FDC 168458), checked 5 November 2026. The 10 g measure (2 tablespoons) is a USDA portion; the portion column is calculated. The record also lists 0.08 g of the omega-3 fat EPA per 100 g, out of 0.3 g of fat. Values rounded. The record has no iodine value; iodine is covered below from NIH and the BfR.
This is fresh laver, with 85% water. The dried nori sheets sold in shops contain far less water, so per gram they are more concentrated; we had no USDA record for dried nori, so we give no numbers for it. Per 100 g, fresh laver covers about 73% of the EU reference intake for folate (200 µg), about half for vitamin C (80 mg) and manganese (2 mg), and a third for vitamin A (800 µg) and riboflavin (1.4 mg).
Iodine in nori
NIH lists 2 tablespoons of flaked dried nori (5 g) at 116 µg of iodine, 77% of the daily value. The BfR gives a range of 10-400 µg per gram of dried nori, against 1,500-8,000 µg per gram for kombu. By that range, the same 5 g could carry from 50 to 2,000 µg, so the product matters. Adults need 150 µg a day, and EFSA’s upper limit for adults is 600 µg a day from all foods.
Glycemic index
Nori is not listed in the international GI tables (Atkinson 2008). With 5.1 g of carbohydrate per 100 g fresh, and a few grams per serving, it has almost no effect on blood sugar. With sushi or onigiri, the rice decides the GI of the meal. More in What is the glycemic index? (with food table).
Health benefits: what the evidence says
- A moderate source of iodine. Under EU rules, iodine contributes to the normal production of thyroid hormones and normal thyroid function (Regulation (EU) No 432/2012). Of the seaweeds in the BfR table, nori has the lowest range, which makes it the easiest seaweed to fit into a diet without going far over the limit.
- Vitamin C, folate and beta-carotene. Per 100 g, fresh laver gives 39 mg of vitamin C, 146 µg of folate and 3,120 µg of beta-carotene (USDA). Under EU rules folate contributes to normal blood formation and to maternal tissue growth during pregnancy (Regulation 432/2012).
- Low in inorganic arsenic in testing. The Canadian Food Inspection Agency reports that samples of nori, kombu and dulse tested low for inorganic arsenic, unlike hijiki.
- Not a vitamin B12 source. Nori is often mentioned as a B12 food for vegans, but the USDA record lists 0 µg. NIH states that plant foods do not naturally contain vitamin B12, so vegans should not count on nori for it.
How to eat it
- Sushi and rolls: wrap rice, avocado, tofu or fish in a sheet; place the shiny side out.
- As a topping: cut toasted nori into strips or crumble it over rice, soups, eggs or salads, with a few sesame seeds.
- Toasting: pass a dry sheet briefly over a gas flame or a hot dry pan until it turns crisp.
- Laverbread: in Wales laver is cooked into laverbread, a dark seaweed purée sold fresh and in tins. Spread it on toast or warm it in a pan as a side.
- Snacks: seasoned nori snacks are handy, but compare the salt and oil on the label.
- Storage: keep sheets sealed and dry; once open, they soften quickly in humid air.
Who should be careful
- Thyroid conditions. Nori is lower in iodine than kelp, but it still adds iodine. NIH notes that people with autoimmune thyroid disease may react to intakes that are safe for others, and the BfR also names autonomous thyroid nodules and Graves’ disease. If you have a thyroid condition, ask your doctor how much seaweed is right for you.
- Pregnancy, breastfeeding and children. The BfR counts these groups as vulnerable to high iodine. EFSA’s upper limits for children are 200 µg a day at ages 1-3, rising to 500 µg at 15-17.
- Thyroid medicines. NIH warns that high iodine intakes with antithyroid drugs such as methimazole can add up and cause hypothyroidism.
- Many seaweeds in one day. Iodine adds up. Nori on sushi, wakame in miso soup and kombu in the stock can together go well past 600 µg.
Traditional view (Ayurveda)
Nori is not named in Usha and Vasant Lad’s food guidelines. Seaweed in general is listed as favourable for Vata and okay in moderation for Pitta and Kapha. This is a traditional system, not clinical evidence.
Related entries and articles
- Seaweed – brown, red and green seaweeds compared, with iodine per type
- Kelp – the brown seaweed with the most iodine
- Wakame
- Spirulina – another product sold as a B12 food that is not one
- Brown rice – for wholegrain sushi and rice bowls
- What is a vegan diet: benefits and risks
FAQ
Are laver and nori the same thing?
Yes. Both names refer to thin red seaweeds of the genera Porphyra and Pyropia. “Laver” is the traditional British and Irish name, and “nori” is the Japanese name that is now used for the dried sheets everywhere.
How much iodine is in nori?
It depends on the product. NIH lists 116 µg for 2 tablespoons (5 g) of flaked dried nori, and the BfR gives a range of 10-400 µg per gram. That is low for a seaweed, but a few sheets a day still add up against EFSA’s adult limit of 600 µg.
Is nori a good source of vitamin B12 for vegans?
No. The USDA record for laver lists 0 µg of vitamin B12, and NIH states that plant foods do not naturally contain it. Vegans need fortified foods or a B12 supplement.
Sources
- USDA FoodData Central, SR Legacy: Seaweed, laver, raw (FDC 168458). fdc.nal.usda.gov
- Guiry MD: Porphyra umbilicalis Kützing, seaweed.ie (common names laver and nori; laverbread). seaweed.ie
- NIH Office of Dietary Supplements: Iodine, Fact Sheet for Health Professionals (updated 5 November 2024). ods.od.nih.gov
- German Federal Institute for Risk Assessment (BfR): Binding maximum iodine levels in edible seaweeds may help reduce health-relevant intake levels. Opinion No. 044/2026. doi:10.17590/20260921-134034-0. bfr.bund.de
- NIH Office of Dietary Supplements: Vitamin B12, Fact Sheet for Health Professionals. ods.od.nih.gov
- Canadian Food Inspection Agency: Inorganic arsenic and hijiki seaweed consumption. inspection.gc.ca
- Regulation (EU) No 432/2012, authorised health claims (iodine, folate). legislation.gov.uk
- Regulation (EU) No 1169/2011, Annex XIII (reference intakes). legislation.gov.uk
- Atkinson FS, Foster-Powell K, Brand-Miller JC. International Tables of Glycemic Index and Glycemic Load Values: 2008. Diabetes Care 2008;31(12):2281-2283. PMC
- Lad U, Lad V. Food Guidelines for Basic Constitutional Types, from Ayurvedic Cooking for Self-Healing, 2nd ed. The Ayurvedic Institute. ayurveda.com
This page is for information only and is not medical or dietary advice.