Thyroid, Iodine and Seagreens®

by Dr Craig Rose PhD. The Seaweed Health Foundation. Oct 2012.

We need iodine to maintain a healthy thyroid, yet more than half the UK population has iodine insufficiency. This leads to a range of health problems, commonly put down to 'middle-age'. One of the best natural sources is seaweed, especially if it follows Seagreens® processing standards to retain the highest levels of nutrients.

The need for iodine 

Iodine is an essential mineral for normal thyroid function, mammary gland development, and foetal and infant neurological growth. Despite this, iodine deficiency is epidemic in developing countries, parts of Europe and the United States (1). This deficiency is largely responsible for an epidemic of hypothyroid-linked illnesses and breast cancer. Such illnesses are being successfully treated with high dosages of iodine equivalent to the Japanese daily intake, which are particularly high as a consequence of a diet of seafood and seaweeds. These levels of iodine intake are 50-fold greater in Japan than in the US (2). 

Iodine deficiencies in the developed world are increasing, and to epidemic proportions in the UK, with 76% of school aged girls (3) and 66% of adult women (4) being iodine deficient. 

The cost of iodine deficiencies can be significant with, for example, Germany spending one billion dollars annually in both healthcare expenditures and lost work time as a result of iodine deficiency and resultant thyroid disease (5). 

Sources of iodine 

The oceans are the worldwide repository of iodine, and very little of the earth’s iodine is actually found in soil, and therefore within terrestrial foods.

The main sources are eggs, milk (although not so much in organic milk as supplements are not given to cows) and fish. Other sources are processed foods with iodised salt added, which is an artificial way of supplementing foods with iodine, and is common practice in some countries particularly with severe deficiencies. 

By far the richest natural source of iodine is from seaweeds, which are widely consumed in Asian cultures. 

Iodine in seaweeds 

Depending on the species, seaweeds can have 10–100 times higher mineral content, such as iodine, than land-based vegetables (6), (7). 

The species of seaweed used in Napiers Hebridean Seagreens® Organic Kelp Capsuleshas relatively moderate and highly beneficial levels of iodine in their naturally occurring forms. This species is Ascophyllum nodosum (common name being Egg or Knotted Wrack), which is sustainably harvested off the coast of the Scottish Outer Hebrides using proprietary methods of production.

Following from the requirements and health benefits of iodine discussed here, research has demonstrated that Japanese women who consume a traditional high-seaweed diet also have a low incidence of benign and malignant breast disease (8), (9). On the contrary, Japanese women who consume a Western diet low in seaweed or who emigrate to the United States lose this protective advantage and gain the same risk for fibrocystic breast disease and breast cancer as their Western counterparts (10), (11). Furthermore, Japan also has a low incidence of iodine-deficiency goiter and autoimmune thyroiditis (12). Consequently, it has been hypothesized, the amount of iodine in the Japanese diet has a protective effect for breast and thyroid disease (13).

This antioxidant effect of iodine may explain the therapeutic effects of seaweed baths or iodine-rich solutions known as thalassotherapy used historically to treat ocular diseases, thyroid disease, diabetes, cardiac and respiratory disease, and arteriosclerosis (14). 

Napiers has been leading a research project with the Medical School at Glasgow University investigating the use of its products for iodine supplementation. Initial results are extremely positive, and we anticipate a full publication in a scientific journal in the near future. 

Overall, seaweeds form an essential source of natural iodine, being described as an ideal food-safe natural source of the mineral iodine (15). Iodine is proven to be highly beneficial in the diet, and significantly deficient in western diets.   


Also read Safe Iodine Levels in Napiers Seaweed Products