Iodine is essential to proper thyroid function. It is necessary for the production of thyroid hormones, which help regulate the growth and development of the body and the maturation of the reproductive system. Thyroid conditions are often the result of an iodine deficiency. Roughly 80% of the body's iodine is found in the thyroid.

Iodine deficiency can cause physical symptoms including unusual weight gain, goiters, decreased fertility, fatigue, dry scaly skin, and constipation. Iodine deficiency can also cause mental health issues, such as depression, anxiety, frustration, and can even decrease one's IQ by as much as 15 points.

Chronic iodine toxicity can develop when intake is greater than 2 mg per day. People who previously suffered from iodine deficiency become particularly prone to hyperthyroidism. Toxicity may impair the creation of thyroid hormones, thereby causing some of the same symptoms as a deficiency, such as goiter or hypothyroidism. It can also lead to ulcers on the skin, sometimes called "kelp acne" due to high levels of iodine in seaweed.

Most natural iodine is found in seawater, but a small amount enters the atmosphere and is deposited through rain on soil near the sea. In the western world, most people consume iodized salt, making deficiency very rare. Health enthusiasts who choose not to consume regular table salt should be sure to find an alternative source of iodine.

US Recommended Daily Allowance: 150 mcg

Health Benefits of Iodine

Concentration/Learning Iodine deficiency can reduce IQ and is the leading cause of mental retardation worldwide.
Fertility Iodine deficiency can cause infertility, stillbirth, growth abnormalities, and mental retardation.
Mood Iodine deficiency can cause feelings of frustration, anxiety, and depression.
Pregnancy/Postnatal Iodine deficiency can cause infertility, stillbirth, growth abnormalities, and mental retardation. Iodine plays an important role in the maturation of the reproductive system.
Thyroid Critical to normal functioning of the thyroid and to production of thyroid hormones.
Weight Loss Helps prevent excess fat storage. Helps the body efficiently burn calories.

Food Sources of Iodine

Coconut (Mature) N/A N/A
Hemp N/A N/A
Kelp N/A N/A Has relatively consistent levels of iodine compared to other some sea vegetables.
Strawberries N/A N/A
Watercress N/A N/A One of the very few non-oceanic plants containing iodine.