Iodine is a mineral found in specific foods. It’s an important micronutrient needed to control thyroid hormone regulation. Iodine deficiencies are on the rise. This is a decades-old problem, that was first discovered in the 1830s. This issue had improved by supplementing iodine in the diet, through the invention of iodized salt. This salt was and is still used to today as table salt, for seasoning home cooked food. A recently published Nutrients research article identifies that increases in iodine deficiency have stemmed from a change in eating habits, such as eating out more and at home less.

What is Iodine?

It plays a major role in the regulation of the thyroid, as it is a key component of thyroid hormones thyroxine (T4) and triiodothyronine (T3). T3 and T4 have a lot of functions, including the regulation of metabolism, digestive system, mood, body temperature, and bone health. T3 and T4 are also important for regulating other thyroid hormones such as thyroid stimulating hormone (TSH).

TSH is responsible for stimulating the thyroid gland to produce thyroid hormones if the blood level dips too low. If the blood level of T3 and T4 is too high, it inhibits the release of TSH via negative feedback loops. Without this regulation, TSH continues to stimulate the thyroid gland, causing the overproduction of thyroid hormones.

Effects of Iodine Deficiency

A variety of effects are associated with Iodine deficiency. This includes the overproduction of thyroid hormones. Which can result in hyperthyroidism and can cause growth effects on thyroid follicular cells. This causes the enlargement of the thyroid, often referred to as a ‘goitre’, which presents as a lump in the front of the neck. Hyperthyroidism can also increase the risk of serious health conditions, including atrial fabulation and stroke.

Thyroxine (T4) is crucial in the early stage of foetal life and is fundamental throughout pregnancy and even for fertility. Iodine deficiencies have various detrimental effects on foetal growth and development, especially brain development. It is the most common cause of preventable brain damage in the world.

Sources of Iodine

The body does not produce iodine. Therefore, one of the only ways to get it is through food. However, iodine dietary sources are limited. These include seaweed, seafood, and dairy. Iodine content in dairy can vary as it’s not a natural source. The sanitation process of milk produces iodine.  Other sources include dietary supplements or iodized table salt.

Iodine Deficiency in Canada

Iodine deficiency is still an ongoing issue in 25 countries. This includes Cambodia, Israel, Bulgaria, Estonia, Mali, and more. Globally, it affects 683 million people. And it could even affect many more.

Vegetarianism and veganism diets becoming more popular could be influencing iodine deficiency. These diets cut out food which are a key source of iodine such as dairy products and fish. In addition, other changes in diet, such as consuming more processed food, could also be to blame. These foods are usually high in salt, but not iodized salt.

McMaster University researchers quantified and measured iodine levels in urine samples collected from 800 participants in Canada. The researchers identified an interesting variation in iodine concentrations between regions in Canada. They identified that residents in Hamilton and Ottawa had sufficient iodine levels. However, many more residents in Vancouver and Quebec City had iodine deficiencies. The study suggested that greater exposure to iodine uptake inhibitors such as nitrate and thiocyanate could be the cause of this.

Increased consumption of nitrate-rich food, including processed meat, fruit and vegetables was suggested to cause the variation between areas. Increased tobacco smoking in these areas was also thought to contribute to this difference, as as thiocyanate exposure is associated with smoking tobacco.

Iodine uptake inhibitors such as thiocyanate prevent the sufficient uptake of iodine in the body. Natural sources of this include food products such as cabbage, kale, and broccoli. In addition, nitrates are also in various leafy greens and vegetables, including carrots. This is an issue for vegans and vegetarians as they are more likely to consume increased amounts of these foods. In addition, they are not able to eat key sources of iodine including fish and dairy products.

How to Tackle Iodine Deficiency

The variation in iodine dietary uptake in different regions in Canada is important. It highlights that there could be gaps in iodine deficiency research, which could unknowingly be affecting a larger population. This study highlights that diet and lifestyle changes throughout the years can directly affect our nutrition. Researchers agreed that greater public awareness of the importance of iodine is needed. Especially as  healthier diets excluding salt and animal products become more popular.

This could be in the form of health guidelines that demonstrate optimal sodium and iodine intake. Solutions to this problem could also include expanding the use of iodized salt in those with vegetarian or vegan diets. This could include iodized bread or even the use of more produce rich in iodine, such as seaweed.

Nutrients are committed to providing peer-reviewed research on different aspects of human nutrition. Including research on iodine and the effects of iodine deficiency. If you want to contribute to Nutrients, take a look at our author’s page.