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Kelp

Saccharina japonica (Laminaria japonica) · 昆布

Sea Moss & Algae. Chinese Medicine and Modern nutrition.

Also called Kombu, Sea kelp, Kun bu, Haidai

Pinyin: Kūn Bù

Spanish: Kombu

Iodine overload risk

A large brown seaweed rich in iodine, used to flavor broths and sold as a supplement.

Did you know? Iodine was discovered in 1811 by Bernard Courtois while he was working with seaweed ash.

What it may help, and how strong the proof is

Thyroid. Iodine is needed for thyroid hormones, and kelp can supply it. Its iodine content varies so much that it can also cause thyroid problems.
Early proof
Cholesterol. Seaweed fibers may lower cholesterol in lab work. Human trials on kelp itself are few.
Traditional proof
Weight. Sold for weight loss. No good human evidence supports this.
Not supported

Parts of the body

Thyroid, Heart & vessels, Liver, Energy & metabolism

Traditional use

In Chinese medicine, kelp (kun bu) was used to clear phlegm and soften hard lumps, including goiter. In Japan, kombu has flavored dashi broth for centuries.

How it is classified

Herbal actions: Nutritive, Diuretic. Energy: cooling.
Chinese medicine: 昆布 Transform phlegm & stop cough. Nature: cold. Flavour: salty. Enters the Liver, Stomach and Kidney channels.

How people take it

Eaten as kombu in broths or salads. Supplements vary too much in iodine, so ask a clinician before taking them for iodine.

Food, decoction, capsule and powder.

Where to get it

Grows on cold ocean rocks along the coasts of Japan, Korea, China and the North Atlantic and North Pacific. Sold dried as sheets, flakes, powder and capsules, often from farmed seaweed.

Be careful

Too much iodine can cause thyroid problems, in both directions. Some seaweeds carry arsenic and other metals, so choose tested products. Heavy or long-term use should be checked by a clinician.

Avoid if: thyroid disease; pregnancy.

Mixing with other things

Works well together
Both are used in Japanese broths and miso soup.
Use caution
Thyroid medicine (levothyroxine (Synthroid))
Iodine can change how thyroid medicine works and shift thyroid levels.

Adds up with others that carry iodine: , , , , , .

The honest take

Kelp is a healthy food in moderate amounts. Its iodine content is very uneven, and a small 2004 trial found thyroid hormone changes in healthy people taking kelp. Claims that kelp helps weight loss or detoxes the body are not supported.