Iodine deficiency in Irish people

Iodine, necessary for proper functioning of our thyroid gland, is found in a range of foods, most notably fish and dairy products.

The thyroid gland – the small butterfly-shaped gland in the neck located just in front of the windpipe – produces thyroid hormones, which help to regulate the body’s metabolism (the process that turns food into energy).

Many people are still getting too little iodine in their diet, however, according to UK research being highlighted here by our National Dairy Council (NDC).

The NDC is currently stressing the importance of iodine, particularly for pregnant women, after a British Journal of Nutrition international study found that 77% of Irish women of childbearing age are not getting the required amount of iodine necessary during pregnancy. This is putting their babies at risk of developmental problems related to IQ, speech, hearing, growth and reading ability.

Teenage girls may also not be getting quite enough iodine in their diets either, going by recent research, the NDC says.

The thyroid gland doesn’t get enough attention, according to Dr Sinead Beirne, well-known for her Ireland AM and Doctor in the House TV appearances.

“It’s one of the important organs that does a lot, and we tend to not really think about it. This study is particularly concerning in that it shows that almost 80% of Irish women are not meeting their requirement for iodine during pregnancy. Young girls are not getting quite enough either.

“I don’t think any pregnant woman thinks enough about iodine or the fact that it’s important to have a bowl of cereal in the morning with milk that’s going to naturally have iodine in it.”

CONCERNED ABOUT MOVE TO ALTERNATIVES

Dr Beirne believes that there is a lot to be said for having a good balanced diet, but she is concerned about the move to dairy alternatives. “There is a big trend for all the dairy alternatives. You see it everywhere: soya and almond, for example. They have almost become trendy,” she says.

Dr Beirne stresses that it is important for women to realize that these drinks don’t have all the nutrients they need. “It is better to view those things just as cordials. It is fluid. It looks like milk, but it’s important that people realize that these are not nutritionally complete. You’re not getting iodine or the correct amount of calcium or vitamin D as well.

“Milk is really a food. People who choose these alternative drinks need to be aware of what they are lacking and think about where they are going to get those nutrients in their diet,” she advises.

Upping one’s intake of white fish is therefore vital if you’re pregnant and not eating enough dairy foods, she says.

“Unfortunately Irish people are not great fish eaters. It doesn’t seem to be a cultural Irish thing to do, unfortunately, so it’s very important for pregnant women or women of child-bearing years to know that dairy is important.”

Dr Beirne has some sobering information around the consequences for babies of iodine deficiency in the mother. “What’s scary is that a lot of people aren’t aware that iodine deficiency is one of the most prevalent reasons for brain damage (among babies).

“If you’re severely deficient in iodine, you’re also at risk of your child having speech and hearing problems. If you’re slightly deficient in iodine, it has been linked with lower IQ in the child, so I think that’s kind of shocking,” the doctor warns.

On the positive front, most of us do drink milk, she says. “I think the figure is 97% of Irish adults, and our iodine, about 45% of it, comes from the dairy foods we eat. This is reassuring, but there are groups – like pregnant women – who need a bit more iodine. They should be aware that eliminating dairy from their diet can have serious consequences.”

OVERACTIVE AND UNDERACTIVE THYROID

The most common cause of goitres worldwide is a lack of iodine in the diet. However, in developed countries, a goitre is usually caused by an autoimmune disease.

While hyperthyroidism (overactive thyroid) is less common, underactive thyroid or hypothyroidism can cause symptoms like weight gain, tiredness, hair loss, dry skin, depression and intolerance to cold, Dr Beirne says. Young girls not getting enough iodine in their diet could be at risk of this.

“Hyperthyroidism – overactive thyroid – can include symptoms like tremor and anxiety and can make the person feel ill very quickly.”

Too much of a good thing

High intakes of iodine can cause some of the same symptoms as iodine deficiency – including goitre, elevated thyroid stimulating hormone (TSH) levels, and hypothyroidism – Dr Beirne says. “That’s because excess iodine in susceptible individuals inhibits thyroid hormone synthesis and thereby increases TSH stimulation, which can produce goitre.

Iodine-induced hyperthyroidism can also result from high iodine intakes, usually when iodine is administered to treat iodine deficiency. Studies have also shown that excessive iodine intakes cause thyroiditis and thyroid papillary cancer. Cases of acute iodine poisoning are rare and are usually caused by doses of many grams.”

Dr Beirne thinks that it would be impossible to prove that either of these conditions were due to iodine excess in the diet. “Particularly as we don’t have a way of checking iodine levels in a patient’s blood in practice at present. We check the TSH levels in the blood, but we have no way of proving if it is due to an excess of iodine.”

The causes of hypothyroidism include autoimmune disease, treatment for hyperthyroidism, thyroid surgery, radiation therapy and medications.

Less often, hypothyroidism may result from congenital disease, a pituitary disorder, pregnancy and iodine deficiency. The causes of hyperthyroidism (overactive thyroid), she says, include autoimmune disease, a thyroid tumour or inflammation of the thyroid gland.

Little awareness among doctors

She believes that there is very poor awareness overall among health professionals about iodine. “We’ll check thyroid function tests as part of a blood test, but as clinicians we can’t actually check the amount of iodine that someone has in their blood.

“It would make sense to do that, because a person could be deficient in iodine and be about to develop a problem with their thyroid function but it might not be seen in the thyroid blood test for a while. In a way, the thyroid function test is an indicator of a person’s iodine status because you need iodine to make the thyroid hormones.”

Iodine important for mood stability

Iodine in one’s diet is also important for keeping the mood stable, she adds. “Hypothyroidism can make you feel depressed, so iodine is very important in mood regulation.”

The heel-prick test done on newborn infants checks for congenital underactive thyroid (congenital hypothyroidism), she points out. “Even though congenital hypothyroidism is a rare condition, when it is picked up it can be treated with medication.”

No iodine supplements in pregnancy Taking iodine supplements in pregnancy is not recommended, however, because studies have found no evidence of a beneficial effect of supplemental iodine in pregnancy and there are some indications of negative effects of supplements on behaviour outcomes in children of mothers with a low iodine intake from food, according to Abel et al in the Journal of Nutrition.

COWS’ MILK ALLERGY

Dr Sinead Beirne acknowledges that some babies can be allergic to cows’ milk, making alternative foods necessary. “There is a little bit of emergence of cows’ milk allergy among babies – about one to two percent – but thankfully they grow out of it when they get over one year of age.

“Even for those kids, it’s important that you have dietetic input (advice from a registered dietitian) so that the child is getting adequate calcium and vitamin D supplements. That’s because when you have to use things like soya and almond, they are not nutritionally complete for a kid.” CL

>> Iodine facts