The site is rich with information, but I'll just c&p the section on iodine in sea vegetables.

Sea Vegetation (http://www.envirohealthtech.com/sea_vegetation.htm#What%20about%20Iodine)

What about Iodine?
Dr. Ryan Drum, noted herbalist and sea vegetable gatherer, states in Therapeutic Use of Seaweeds (Proceedings of the 2001 Pacific Northwest Herbal Symposium) "Seaweeds, eaten regularly, are the best natural food sources of biomolecular dietary iodine... no land plants are reliable sources of dietary iodine."

For comparison, you would have to eat about 40 lb. of fresh vegetables and/or fruits to get as much iodine as you would from 1 gram of our whole leaf kelp.

Iodine is the main component of the hormone produced by the thyroid gland, which regulates our metabolism - thyroid hormone accelerates cellular reactions, increases oxygen consumption and basal metabolism, and influences growth and development, energy metabolism, differentiation and protein synthesis.

Dr. Linda Rector Page, author and herbalist, writes in Healthy Healing, p.205: "Iodine is essential to life... it is an important element of alertness, and rapid brain activity, and a prime deterrent to arterial plaque. Iodine is also a key factor in the control and prevention of many endocrine deficiency conditions prevalent today, such as breast and uterine fibroids, tumors, prostate inflammation, adrenal exhaustion, and toxic liver and kidney states."

Unfortunately, not all iodine is good for us and the human thyroid cannot distinguish between life sustaining iodine-127 and radioactive iodine-131. On this subject Ryan Drum further warns, "The real reason for making sure that iodine consumption is at the high end is to insure a full body complement of iodine at all times as preventative medicine against the next nuclear disasters [whether from intentional radioactive pollution as the result of armed conflict or terrorism, nuclear power plant failures, or industrial contamination]. A full body load of iodine 127 from seaweeds (or any source) will tend to allow the body to reject topical and air and food-source iodine 131, particularly from fresh milk."

In general, brown sea vegetables (kelps) offer more bio-available organic iodine than red sea vegetables (dulse, laver, and nori). Whole leaf kelp (Laminaria longicruris) has approximately 450 mcg. (micrograms or parts per million) iodine per gram. Our milled kelp (Laminaria digitata), sold in bulk and has even higher amounts, about 5000 mcg. In comparison, Dulse contains 50 mcg per gram. These amounts are approximations as there is variation depending on season of harvest and the age of plant.

Finally, a cautionary note about getting too much of a good thing. We all need between 150 and 1,100 micrograms in our daily diets to keep our thyroids healthy and prevent uptake of radioactive Iodine. Healthy thyroids will "spill" unneeded iodine. But some people with sensitive thyroids, particularly nursing mothers, postmenopausal women, or anyone with an unusual thyroid dysfunction may have adverse reactions to excess dietary iodine (most often if you decrease the intake of dietary iodine the condition goes away.) Please consult with your health care practitioner if you have any questions about your consumption of iodine.

WHFoods: Are sea vegetables a good source of iodine? (http://www.whfoods.com/genpage.php?tname=george&dbid=98)

Are sea vegetables a good source of iodine?

No food group serves as a better iodine source than sea vegetables. According to the Institute of Medicine at the National Academy of Sciences, adults need 150 mcg (micrograms) of iodine each day to meet their health needs. Depending upon the specific type of sea vegetable, this guideline can be met by 1-2 grams of sea vegetable-the amount contained in about to 2/3 - 1 teaspoon.

Kelps, including bladderwrack (Fucus vesiculosus), usually contain between 100-200 micrograms of iodine per gram (meeting daily iodine needs with a serving of about 2/3 - 1 teaspoon). Kelps are particularly interesting with respect to iodine because some studies suggest that between 5-35% of the iodine contained in some varieties of kelp is actually stored in the same forms in which iodine is found in our thyroid hormones. In these organic forms, iodine is hooked together with the amino acid tyrosine. Tyrosine connected with one iodine atom (mono-iodotyrosine), two iodine atoms (di-iodo-tyrosine) and three iodine atoms (tri-iodo-tyrosine) appears to be found within some kelps. These iodine-tyrosine combinations are primary constituents of our thyroid hormones, T3 (which contains 3 iodine atoms) and T4 (which contains 4 iodine atoms). In keeping with these observations, some research has also suggested lower rates of thyroid-related problems in countries where sea vegetables are consumed regularly.

Compared to ordinary table salt, sea vegetables have a slightly higher iodine content. A gram of iodized table salt typically contains about 65 micrograms of iodine. For sea vegetables, the range is 79-300 micrograms (see table below).
Sea Vegetable Amount Iodine Content
kelps 1 gram 100-200 micrograms
wakame 1 gram 79 micrograms
dulse 1 gram 150-300 micrograms

Compared with
iodized table salt 1 gram 65 micrograms

It is important to note that sea vegetables vary greatly in their iodine content, depending on the circumstances in which they grow. Even state-of-the-art databases, like Food Processor for Windows Database Version 7.60, ESHA Research, Salem, Oregon, do not provide iodine values for sea vegetables.

The reason is simple: the iodine content of most sea vegetables is just too variable.

Variations in sea vegetables' iodine content are due to two factors. First, the iodine content of marine water undergoes much greater natural change than the iodine content of soil. And secondly, unlike other minerals, which usually get hooked onto other substances in sea vegetables, iodine does not hook onto other substances very readily but tends to stay in its free, water-soluble form. In studies of Pacific sea vegetables, for example, about 10% of the total iodine content is hooked onto other substances (usually parts of protein, called amino acids) while the other 90% remains in its free, water-soluble form. Since most of the iodine remains water-soluble, even when it's inside the sea vegetable, it can easily move back and forth between the ocean and the plant. This constant movement of iodine in its water-soluble form means that some sea vegetables can increase or decrease their iodine content by as much as 10-fold depending on ocean conditions. For this reason, it's best to think of sea vegetables as providing a high amount of iodine that falls within a general range, rather than a specific, pinpoint amount.

References:

Arasaki, S. & Arasaki, T. (1983). Vegetables from the sea. Japan Publ. Inc.Tokyo.

Haug, A. & Jensen, A. (1954). Seasonal variations in the chemical composition of Alaria esculenta, Laminaria saccharina, Laminaria hyperborea and Laminaria digitata from northern Norway. Rep. Norw. Inst. Of Seaweed Res. No 4. Trondheim: Institutt for bioteknologi, NTH.

Chlorella and iodine content -

Chlorella Nutritional Analysis (http://www.naturalways.com/chlorella-nutritional-analysis.htm)

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*Daily intake of 3 gm chlorella provides 4 mcg of vitamin B-12, 70% of the U.S. RDA.

great info Sue. Thank you