Mum and Baby: How Much Iodine Should We Have?
Iodine is one of those minerals we don’t really talk about in everyday life. Where do we find it? How much do we need? Is it even important? The answer to the latter is….yes!
Here we will be discussing just why iodine is so important (especially during pregnancy), and where we can get it from in the diet.
The importance of iodine:
Iodine is a mineral that is needed to make thyroid hormones. These thyroid hormones support a variety of important body processes such as growth, regulating metabolism and, during pregnancy and early life, the development of a baby’s brain. During pregnancy the baby’s brain is developing rapidly and numerous studies have shown the importance of iodine on brain development. In addition to this, studies have shown that a lack of iodine could contribute towards neurological or behaviour disorders such as ADHD or a lower IQ.
Iodine is an essential micronutrient meaning it can only be obtained exclusively through the diet or via supplementation or fortification. Therefore, it is recommended that we achieve the correct amount of iodine through a variety of food sources in our diet to help keep our body healthy.
Too much or too little iodine can be dangerous:
Iodine deficiency (when we have an insufficient supply of iodine in the body) may cause the thyroid to work overtime and this can result in an enlarged thyroid gland causing a swelling in neck. This is the body’s attempt at ‘trapping’ any iodine available – in the UK however, this is actually fairly rare.
More commonly, low levels of thyroid hormones can cause symptoms such as tiredness, dry skin, muscle aches and loss of libido.
Similarly, too much iodine over a long period of time can change the way your thyroid gland works, and this should be avoided.
How much iodine do I need during pregnancy?
Iodine is especially important when it comes pregnancy. In fact, the British Dietetic Association suggests that women of childbearing age (or those planning a pregnancy) should be aiming to meet iodine requirements several months before their pregnancy even begins.
This is to allow a person’s body to build up stores of iodine in the thyroid, which then will go to support the development of a growing baby from conception.
During pregnancy the requirements of iodine increase and the British Dietetic Association recommended the amounts shown in the table below:
Table 1: BDA recommendations for iodine:
The BDA table above is based on European Food Safety Authority recommendations, however, The Department of Health also suggest iodine recommendations for adults which differ slightly from those in the table above at 140 mcg per day.
Why do pregnant women need more iodine?
The reason for the increase in required iodine during pregnancy and breastfeeding is because a new mum needs to create and supply enough thyroid hormones and iodine to support the growth and development of a baby’s brain. This supply occurs via the placenta during pregnancy and directly via breast milk during breastfeeding.
In fact, according to Dr Sarah Bath (a leading researcher in iodine), there is around a 50% surge in thyroid hormone production that occurs during the early stages of pregnancy. Since the unborn baby cannot yet make their own thyroid hormones, meeting the increased thyroid needs is vital for baby’s health.
How much iodine does my baby need?
Government Dietary Requirements produced by Public Health England offer a recommendation for the intake of iodine. Below you can see the requirements for children between 1 and 6 years of age.
Tip: you may see the units for iodine mcg or ug used interchangeably – don’t worry, these are the same value.
Table 2: Recommendations for iodine requirements in young children
Where can I get iodine from?
Iodine is found in the diet in a fairly limited number of foods so if you don’t consume dairy products or fish on a regular basis, you may be at risk of becoming deficient. Interestingly the thyroid gland will store iodine from the food sources listed below, and save it for days when iodine may not be as high in the diet – pretty clever stuff!
Table 3 below, produced by the BDA, shows the iodine content of a variety of foods that are commonly eaten in the UK:
As you can see, dairy foods and white fish provide the highest sources of iodine and plant-based sources of iodine are somewhat limited.
Milk and dairy – major source of iodine
Milk is definitely the largest contributor to iodine intakes, providing around 62% of intakes for 1.5-3 year olds and around 40% of iodine intakes for 11-18 year olds. However generally, milk and dairy products are the main sources of iodine in the UK diet.
Milk and dairy foods also tend to be higher in iodine in winter months as cows are given fortified feed inside during the winter which is fortified with iodine. There has also been an emergence of evidence showing that the iodine content in organic milk is significantly lower than cow’s milk (almost by 35-40% less) but farming practices may be underway to change this. Do not let this put you off organic milk if it is a staple in your home, it can still provide an important contribution to iodine intakes.
Iodine in plant-based milks
For those who do not consume dairy foods, there is a risk that iodine levels will be low (especially if fish are also not eaten). Plant-based milks, unfortunately, often don’t fortify with iodine as standard practice, although in recent years some bands have started to do so and so it’s worth checking labels if you use plant-based alternatives to dairy.
Fish is another good source of iodine and it is recommended in the UK that we have at least two portions of fish per week (one being oily). Some fish can be dangerous to the development of a baby so please read a recent post of mine which covers fish recommendations for babies and toddlers.
Iodine supplements – do I need them?
It is worth beginning this section by stating that many women who follow a healthy and balanced diet that contains a wide range of food sources should be more than able to meet the UK recommended iodine requirements.
However, those who may be a risk of iodine deficiency, such as anyone who avoids fish and/or dairy products, may wish to consider taking an iodine supplement. The British Dietetic Association state that iodine supplements should be in the form of “potassium iodide” or “potassium iodate” and should not exceed the daily adult requirement of 150 mcg.
During pregnancy and breastfeeding, many multivitamin and mineral pregnancy supplements will contain iodine, so it is important that you check the label! On the whole, if your pregnancy supplement provides around 140 to 150 mcg, you should be able to meet the remainder of your recommended iodine intake (it’smore during pregnancy) from foods in your diet.
Seaweed or kelp supplements are not recommended due to potential variation from the value claimed on the label and the actual iodine content of the supplement – potentially leading to excessive intakes of iodine.
Nonetheless, please speak to your GP if you are concerned about your iodine intake and especially before taking an iodine supplement.
Take home points:
- Too little iodine may cause unwanted symptoms and has been shown to be detrimental to the development of the baby’s brain during the early stages of pregnancy, potentially leading to neurological or behavioural disorders, such as ADHD.
- Iodine supplements should be used with caution and only taken on advice from a doctor, Dietitian or Nutritionist.
- Seaweed and kelp supplements should be avoided (especially for pregnant women) as they may cause excessive intakes of iodine.
- Iodine food sources are ideal as a staple in the diet, but especially for those who are of childbearing age or planning a pregnancy. Ensuring that iodine recommendations are met prior to pregnancy may be of benefit.
- Iodine requirements increase during pregnancy and breastfeeding and these requirements should be met to ensure the correct development of baby’s brain.
- If you don’t eat dairy foods or fish, it may be worth taking an appropriate supplement containing iodine (e.g. pregnancy multivitamin) before you become pregnant – speak with your GP before doing so.
Thank you for reading!
Article written by Holly Roper MSc student University of Sheffield with support from SR Nutrition.
Further Reading and References:
- Iodine as Essential Nutrient during the First 1000 Days of Life (Velasco et al., 2018)
- A review of the iodine status of UK pregnant women and its implications for the offspring (Bath and Rayman, 2015)
If you would like to read more about the importance of iodine, Sarah Bath is a leading research in iodine and you can find her published papers here: https://www.ukiodine.org/dr-sarah-bath/