What is kelp? What is it used for?
Kelp is a type of seaweed found in coastal regions where the water is
shallow enough for light to penetrate to the sea floor. It is the largest
type of seaweed in the world, with some varieties growing to 30 meters
or more in length.
Kelp beds usually grow in forests which are highly productive ecological
systems similar to tropical rain forests. Like rain forests, they form
canopies under which many other species live, including fish, snails,
shrimps and sponges.
Although kelp has no medicinal properties, it is an important source
of food for fish and other marine animals. For humans, it is a vital source
of several minerals, including iodine (a vital ingredient involved in
the creation of thyroid hormones), magnesium, calcium and iron.
How much kelp should I take?
While there is no recommended daily allowance for kelp, many practitioners
in the U.S. suggest a maximum of 150 micrograms per day. Because of its
high iodine content, however, daily kelp intake should be monitored closely.
What forms of kelp are available?
Although it can be eaten raw, many specialty stores and Asian markets
prefer to sell dried kelp leaves, either individually or in bulk. Kelp
is also available in capsule or tincture form. Trace elements of it are
also found in many multivitamin supplements.
What can happen if I take too much kelp?
Are there any interactions I should be aware of? What precautions should
Several case studies have suggested that high kelp intake could provide
too much iodine, thus interfering with the normal function of the thyroid
gland. Patients with hyperthyroidism, or who are taking medication to
combat hyperthyroidism, should avoid all supplements that contain kelp.
- de Smet PA, Stricker BH, Wilderink F, Wiersinga WM.
Hyperthyroidism during treatment with kelp tablets. Ned Tijdschr
Geneeskd 1990;134:10589 [in Dutch].
- Eliason BC. Transient hyperthyroidism in a patient
taking dietary supplements containing kelp. J Am Board Fam Pract 1998;11:47880.
- Kim JY, Kim KR. Dietary iodine intake and urinary
iodine excretion in patients with thyroid diseases. Yonsei Med J
- Kupper FC, Kloareg B, Guern J, Potin P. Oligoguluronates
elicit an oxidative burst in the brown algal kelp laminaria digitata.
Plant Physiol Jan 2001;125(1):278-291.
- van Netten C, Hoption Cann SA, Morley DR, van Netten
JP. Elemental and radioactive analysis of commercially available seaweed.
Sci Total Environ Jun 2000;8:255(1-3):169-75.