Iodine In Your Diet

Why is iodine in your diet important? How much iodine do we need and what is the maximum upper limit?

Are you getting enough iodine in your diet? I will show you on this page why we all need dietary iodine, how much we need, why we need it, what can happen if you do not get enough, and what the maximum upper limit is for this very important mineral.

WHAT IS IODINE?

Your body contains around 20 - 30 mg's of iodine, and is mostly stored in the thyroid gland which is located in the front of the neck, just under the voice box.

WHY DO WE NEED IT?

Iodine is a component of the bodies' hormones called thyroxin and triiodotyrosine, both of which are secreted by the thyroid gland. The thyroid gland affects the metabolic rate as well as the growth and the development of the body and is absorbed through the foods we eat and excreted in the urine.

You need iodine in your diet because if you do not get enough, it can lead to an enlarged thyroid gland (goiter) or other iodine deficiency disorders such as hypothyroidism, hyperthyroidism and thyroid cancer. It is very important that children get enough iodine in their diets as iodine deficiency in children can cause mental retardation.

The thyroid hormones are needed for normal growth and development of tissues, such as the central nervous system, as well as playing a broader role in the development of the body as a whole. They are also important for energy production and oxygen consumption in cells, helping to maintain the body’s metabolic rate.

HOW MUCH IODINE IN YOUR DIET DO YOU NEED?

0 - 6 months - 110 micrograms per day

7 - 12 months - 130 mcg per day

1 - 3 years - 90 mcg per day

4 - 8 years - 90 mcg per day

9 - 13 years - 120 mcg per day

Males age 14 and older - 150 mcg per day

Females age 14 and older - 150 mcg per day

*The Food and Nutrition Board at the Institute of Medicine


CAN YOU TAKE TOO MUCH IODINE?

Yes. You need iodine in your diet but it is important not to take too much of it in the form of foods or supplements. We actually only need a teaspoon of iodine in a lifetime, but the thyroid gland cannot store this amount so we must consume small amounts regularly. Excessive iodine in your diet has a complicated disruptive effect on the thyroid and may cause either hypothyroidism (underactive thyroid gland) or hyperthyroidism (overactive thyroid gland). Too much iodine in your diet can also increase the risk of thyroid cancer.

Hypothyroidism is where there is too little thyroid hormone in the bloodstream. This causes inadequate stimulation of cells and organs in the body due to low levels of thyroid hormone. Symptoms of hypothyroidism include tiredness, mental fatigue, inability to tolerate cold and constipation.

Hyperthyroidism is when there is too much thyroid hormone in the bloodstream, producing symptoms that include rapid heart beat, extreme fatigue, weight loss, nervousness and an inability to tolerate heat.

WHERE CAN VEGANS GET THEIR DIETARY IODINE FROM?

Some countries, including the US, contain foods that are fortified with iodine. You can also get iodised salt in the UK from most supermarkets.

Iodine is found in seawater so any type of seafood provides a rich source of iodine, particularly seaweed (kelp). As iodine is not readily available in a lot of foods, non vegetarians get their dietary intake from fish. However, most dieticians will tell you to limit your fish intake because of the high levels of mercury.

If you use salt in cooking, then try and use salt that is iodised to help get iodine in your diet. One teaspoon of iodised salt contains around 400 mcg's of iodine, therefore this is more than enough for your daily requirement. However, it is best that you do not start eating salt purely to get iodine in your diet.

Fruits and vegetables can contain iodine but this is dependent on soil content. Eg - how much iodine is in the soil.

Fruits and vegetables grown by the seas are likely to contain more iodine than fruits and vegetables which are grown inland.

Seaweed is one of the richest sources of iodine and you only need to consume a small amount for your daily requirements.

Just one gram of dried brown algae provides from 500-8,000 mcg's of iodine and even the green and red algae (such as the purple nori that is used in Japanese cuisine) provides 100-300 mcg's in a single gram.

Or around half a cup of kelp would give around 900 mcg's of iodine.

Further information. Please note that a µg = a mcg.

UPPER INTAKE LEVELS

Excessive iodine intake may cause goiter (enlargement of the thyroid gland), hypothyroidism, thyroid cancer and/or iodermia (a serious skin condition).

Overdose of iodine from medications or supplements in amounts exceeding one gram may cause vomiting, dirarrhea, nausea and stomach pains. In extreme cases, it can cause coma.

Therefore, the Institute of Medicine recommends the following Tolerable Upper Intake Levels for iodine:

1-3 years - 900 mcg

4-8 years - 300 mcg

9-13 years - 600 mcg

14-18 years - 900 mcg

19 years and older - 1,100 mcg

Pregnant women 14-18 years - 900 mcg

Pregnant women 19 years and older - 1,100 mcg

Lactating women 14-18 years - 900 mcg

Lactating women 19 years and older - 1,100 mcg

*The Food and Nutrition Board at the Institute of Medicine



So if you do not use iodised salt or eat seaweed on a regular basis, you may consider taking an iodine supplement. Remember, for optimal thyroid function, you musn't take too much iodine in your diet. If you do choose to take iodine supplements, take an amount of around 100-200 mcg's per day, depending on whether your food provides an iodine source.

If you have any concerns about whether you are getting enough iodine in your diet, consult your doctor as she/he can do a simple blood test which will clarify whether you need to supplement/include more iodine rich foods in your diet.

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