Calories in seaweed: 43 kcal per 100 g

What’s in an 80 g portion

More than half of a portion is fibre.

1.3 gFat

5.7 gProtein

47 gFibre

10.2 gWater

15.9 gMinerals and the rest

1.3 gFat
5.7 gProtein
47 gFibre
10.2 gWater
15.9 gMinerals and the rest

Below average for vegetables

Seaweed is 43 kcal per 100 g. The 240 vegetables in this database average 59.9.

Seaweed43

Vegetables average59.9

High in fibre

58.7 g of fibre per 100 g; the UK “high fibre” line is 6 g.

Fibre, per portion47 g

Protein, per portion5.7 g

Vitamins and minerals in seaweed

Nine of the 17 reach the “high in” level, led by iodine.

235024 %

Iodine

353 mg in an 80 g portion

1st of 99 vegetables

Iodine contributes to normal cognitive function and to normal thyroid function.

Magnesium488 mg130 %

Calcium720 mg90 %

Vitamin B120.00224 mg90 %

Iron10.2 mg73 %

Copper0.52 mg52 %

Also high in

A source of

None recorded

Vitamin D

Show all 17 with amounts

Iodine353 mg, 235024 %

Magnesium488 mg, 130 %

Calcium720 mg, 90 %

Vitamin B120.00224 mg, 90 %

Iron10.2 mg, 73 %

Copper0.52 mg, 52 %

Zinc5 mg, 50 %

Manganese0.8 mg, 40 %

Phosphorus168 mg, 24 %

Potassium360 mg, 18 %

Riboflavin (vitamin B2)0.21 mg, 15 %

Vitamin C10.4 mg, 13 %

Vitamin A0.0456 mg, 5.7 %

Thiamin (vitamin B1)0.06 mg, 5.1 %

Selenium0.0016 mg, 2.9 %

Vitamin B60.01 mg, 0.6 %

Vitamin Dnone recorded

Badges use the UK legal thresholds per 100 g: 15 % of the reference intake for “source of”, 30 % for “high in”.

What seaweed doesn’t give you. And where to find it.

No recorded vitamin D, and only 3.6 % of the selenium reference intake and 0.7 % of the vitamin B6 reference intake per 100 g.

Vitamin D

0mgin seaweed

Find it inBloater, grilled500 % per 100 g

Selenium

3.6%in seaweed, per 100 g

Find it inKidney, pig, fried491 % per 100 g

Vitamin B6

0.7%in seaweed, per 100 g

Find it inWheatgerm184 % per 100 g

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100 mgVitamin C, 125 %

0.075 mgSelenium, 136 %

0.00125 mgVitamin D, 25 %

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Made in the UK since 1998, with every nutrient and its declared amount listed on the label.

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Questions about seaweed

What the numbers say to the questions people actually search.

How many calories are in a portion of seaweed?

A typical portion (80 g, one of your five a day) gives 34 kcal. Per 100 g the figure is 43 kcal.

Is seaweed high in iodine?

Yes. Seaweed, kombu, dried, raw has 441 mg iodine per 100 g, 293780 % of the NRV, above the 30 % threshold for a “high in” claim.

Which vitamins and minerals does seaweed have most of?

By share of the daily reference intake: iodine (441 mg, 293780 %), magnesium (610 mg, 163 %) and calcium (900 mg, 113 %) per 100 g.

Is seaweed a good source of protein?

Seaweed, kombu, dried, raw has 7.1 g protein per 100 g, 18 % of the energy, which meets the UK threshold for “source of protein”.

How these numbers were made

Every figure comes from the UK Composition of Foods Integrated Dataset (CoFID), 2021 edition, record 13-339, Seaweed, kombu, dried, raw, published by Public Health England under the Open Government Licence v3.0. Main data references: Vegetables, Herbs and Spices Supplement, 1991. Values are per 100 g of the edible part; a portion is 80 g, one of your five a day, the usual UK portion for vegetables. Reference intakes follow Regulation (EU) 1169/2011 Annex XIII as retained in GB law; “source of”, “high in” and “low” follow Regulation (EC) 1924/2006, assessed per 100 g. Function lines are the authorised wording from the GB register of nutrition and health claims, credited to the nutrient. Energy is rounded to the whole kcal and kJ; other amounts to one decimal, or two below 1. A trace is shown as “trace” and never gets a figure or a badge; a nutrient never analysed is left off the page. We start from the dataset’s 2,887 records and keep 2,322: records weighed with bone, shell or skin, alcoholic drinks, infant foods, brand-named products, records with fewer than eight measured vitamins and minerals and near-identical variants are left out. Group context uses the 240 vegetables kept from the dataset; a rank counts only the foods with a measured figure for that nutrient. Food images are illustrations from Ingredient Atlas, released under CC0; they show the food, not the measured sample, and where no illustration of the exact food exists the nearest one is shown (here: Irishmoss Seaweed). Checked 5 October 2026. Contains public sector information licensed under the Open Government Licence v3.0.