Seaweed (Kelp, Kombu, Wakame)

Can babies have seaweed?

It depends on the type. Nori, the thin sheet used for sushi and snacks, is low in iodine and fine in small amounts from 6 months. Brown seaweeds like kelp, kombu, wakame and arame are different. A single gram of dried kelp can have more than a thousand micrograms of iodine. There’s no upper limit set for babies under 1, and the limit for children aged 1 to 3 is 200 µg a day. So brown seaweeds wait until 12 months, and then only in small amounts, about once a week.^[1][2][3]

The same goes for foods made from them. Keep kombu dashi as an occasional broth rather than an everyday base, skip kelp powder and kelp supplements, and don’t make kelp noodles a regular food. Blanching brown seaweed for five minutes and throwing away the water removes much of the iodine, so from 12 months a small bowl of miso or seaweed soup once a week is fine.^[3][4]

Hijiki, the black shredded seaweed served in Japanese side dishes, is the one to avoid at any age. It has far more inorganic arsenic than other seaweeds, and food regulators in Canada, the UK and Australia advise against eating it.^[5][6]

Choking risk

Brown seaweed is a moderate choking risk - dried strips of kelp or wakame are tough until fully rehydrated, and cooked wakame is slippery and stringy in a way that can be hard for a new chewer to manage.

Soak and simmer until soft, then chop fine for a toddler's bowl. See how to serve for age-by-age prep.

Allergens

Seaweed is not a common food allergen, so a true allergy to it is rare.^[7]

Two label notes: dashi and seaweed salad often contain fish (bonito flakes), sesame or soy, and seaweed is harvested and dried alongside shellfish, so "may contain" warnings are common on packs. If your baby has a fish or shellfish allergy, choose plain dried seaweed from a brand that labels clearly.

Start with a small amount and watch for a reaction.

If baby refuses

Wakame's slippery texture is usually the issue rather than the taste. Chop it very fine into a soup or stir a little through rice so it's a flavor rather than a strand, and come back to it in a few weeks. Toasted nori is the easier way to build a taste for seaweed in the meantime.

Food safety

Iodine is the main limit. A small amount keeps the thyroid working, but too much over time can push it the other way, and babies are the most sensitive. Breastfed newborns have developed underactive thyroids when their mothers ate seaweed soup every day.^[1] The iodine in seaweed varies hugely by type and batch, from a few micrograms to nearly 3,000 per gram. That’s why Australia’s food regulator advises children to have brown seaweed no more than once a week, and why families should never use kelp as an iodine supplement.^[2][3] In the US, rules for special dietary foods limit iodine from kelp to 45 µg a day for infants, a fraction of what kelp powder contains.^[4]

Hijiki is the arsenic concern. Canadian testing found far more inorganic arsenic in it than in other seaweeds, Australia tests every imported batch, and the advice is simply not to eat it. Nori, kombu, wakame and arame aren’t covered by that advice.^[5][6]

Salt is the last thing to watch. Ready-made seaweed salad is dressed with plenty of soy sauce and sugar, and dashi powders and seasoning sachets are mostly salt and flavor enhancers. Babies shouldn’t have added salt in the first year, so make your child’s portion from plain dried seaweed and season the adults’ bowls at the table.^[8]