One of the most common deficiencies in vegan diets is Iodine deficiency. How come? Nobody knows exactly, but here are some assumptions. Firstly, Iodine deficiency is common among the general population. Nearly two billion people do not have an adequate intake of this micronutrient! Secondly, vegans can be restrictive in their diet more often, meaning that they don’t only exclude foods of animal origins from their diet but also other food groups, such as bread. Bread is a major source of Iodine in many countries as bread flour is often enriched with iodized salt.
How to ensure you get enough Iodine from your diet? One of the easiest solutions is to regularly eat small quantities of seaweed. Seaweed is the richest organic source of Iodine on our planet.
Recognized leaders in the consumption of algae are the Japanese. An average consumption of seaweed in Japan is about 10 g (dry weight) per person per day. Among European countries, the leader of algae consumption is France. The French consume 10 g of (dried) seaweed per person per year. Which makes it about 365 times less than in Japan…
Algae can be green, purple, brown… All types of algae are a great source of the trace mineral Iodine, but brown algae are the richest source of this mineral compared to all the other seaweed types. Kelp or laminaria are examples of edible brown algae. Edible brown seaweed contains 1% of iodine on average, which is 30.000 times greater than the concentration of iodine in seawater. Thus, in one kilogram of kelp, iodine content equals to that of 100.000 litres of seawater!
Why do we need iodine?
Iodine deficiency is a serious health problem in the world, according to the World Health Organization. As of 2003, at least 54 countries are affected by Iodine deficiency, and nearly 2 billion people lack adequate iodine intake. This is about one quarter of Earth population!
Iodine is present in the body in small amounts (15-20 mg), almost exclusively in the thyroid gland. Thyroid hormones regulate metabolism in most cells and play a crucial role in the early growth and development of most organs, especially the brain. In humans, much of the growth and brain development occurs during the foetal period and during the first three years of life. A significant lack of Iodine during this critical period may cause hypothyroidism (low thyroid hormone level) and brain damage. The clinical consequence would be an irreversible mental retardation. Forty three million people worldwide suffer from mental retardation, which developed because of Iodine deficiency. Deficiency of Iodine in any period of life, including adulthood can cause the development of goitre with mechanical complications and / or failure of the thyroid gland.
How much Iodine do we need and where do we find it?
The recommended daily allowance of Iodine depends on age and physiological state and varies from 90 to 250 micrograms.
Iodine intake should be regular. But if you just rush to take Iodine supplements or consume handfuls of iodized salt, you can encounter undesirable results. It is best to consume Iodine from sea derived foods, the most important of which is seaweed.
Edible seaweed has an extremely large amount of Iodine, varying from 1.600 to 8.000 micrograms per 100 grams of dried weight.
The content of Iodine in sea-fish and shellfish is 100-500 mcg per 100 g. Other, non-marine, foods contain non-essential amounts of Iodine.
In my home country, Belarus, pretty much all the salt you can buy at a supermarket is enriched with iodine. This measure is a consequence of the Chernobyl disaster and it is simply absolutely necessary to ensure adequate Iodine intake in the country (if there is a deficiency of iodine in the body, it tends to compensate for it by absorbing radioactive iodine, which is abundant on the territories suffering from the Chernobyl explosion).
In many countries (including the Netherlands where I live now) Iodine is always added to bread salt, which is used by bakeries to make bread. If bread is not an essential part of your diet, and if you do not use iodized salt on a regular basis, the chance that you might be deficient in Iodine is pretty high.
Other health benefits of seaweed
Besides Iodine, algae are a source of vitamins B1, B5, B11, B12, C, D and E, as well as minerals calcium, phosphorus, and potassium. However, the bioavailability (how efficiently they are absorbed by the body) of those elements is not clear.
All types of seaweed are extremely low in calories. It has between 10-25 calories per 100 g, and therefore is an excellent dietary product. It satiates greatly and prevents overeating and associated problems. Several placebo-controlled intervention trials in humans have shown consumption of algae derived products to significantly impact appetite and food intake.
Some seaweed-derived fibers such as alginate, carrageenan, and agar are a great substitute for animal agents. They have been used for decades for their emulsifying, stabilizing, and thickening characteristics to improve the sensory properties of food.
It is not clear how much heavy metals algae absorbs from the waters where it grows. Too much Iodine is as harmful as too little. Taking these two points into consideration, my advice is: use seaweed regularly but sparingly and vary between different sorts.