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Sep 26

Is your morning soya latte putting you at risk of iodine deficiency?

Iodine is an essential part of a balanced diet, required to produce the thyroid hormones that regulate growth and metabolism. It is found in a variety of foods, including white fish, shellfish, eggs, milk and dairy products. Iodine is of specific importance for women during pregnancy as it is vital for foetal brain development: even mild iodine deficiency during pregnancy can affect a child’s development later in life. There is growing concern over iodine levels in the UK, with the Iodine Global Network recently identifying pregnant women in the UK as ‘iodine deficient’.

In the UK, milk and dairy products are the primary source of dietary iodine, accounting for 30-40% of iodine consumption, with cows’ milk being a particularly good source of iodine. However, due to dairy allergies and intolerances, environmental concerns or perceived health choices, consumers are increasingly choosing plant-based milk-alternatives in place of cows’ milk.

Researchers at the University of Surrey have recently performed a systematic study (1) to determine the levels of iodine in 47 different milk-alternative drinks currently on the supermarket shelves in the UK. These alternatives cover the more common – soya, almond, coconut – and the more unusual – oat, rice, hazelnut and even hemp.

Based on our expertise in high accuracy iodine quantification (2)(3) and our long-standing collaboration with Professor Margaret Rayman (4), LGC was asked to perform the iodine analysis for this study.

Iodine has historically been difficult to quantify using inorganic mass spectrometry due to the limitations in the sensitivity of the instrumentation (poor ionisation efficiency). However, recent advances in technology such as the Agilent 8800 ICP-QQQ-MS have significantly improved this, enabling much lower levels (low part per billion) to be accurately quantified.

LGC applied an external calibration method using ICP-QQQ-MS (validated in-house against a primary reference method (2), limit of quantification 3.6 µg/kg) to the milk-alternative drinks. The majority of the 47 milk-alternative drinks analysed did not have adequate levels of iodine, with concentration levels found on average to be around 2% of those found in cows’ milk. One brand of iodine-fortified milk-alternatives (Marks & Spencer) was available at the time of the study; these fortified products contained levels around 80% of those found in cows’ milk and could be considered a reasonable substitute in terms of iodine levels.

This study highlights the need for greater awareness among consumers of their risk of iodine deficiency if avoiding milk and dairy products. These consumers must ensure they find additional sources of dietary iodine or via supplementation. This is particularly important for pregnant women and those planning a pregnancy in order to avoid potential foetal developmental issues.

 

 

If you would like to find out how you could use our inorganic measurement expertise to address your measurement challenges, contact LGC’s Measurement Services.

 

References

(1) Bath SC et al. Iodine concentration of milk-alternative drinks available in the UK in comparison with cows’ milk. Br J Nutr (2017) DOI:10.1017/S0007114517002136

(2) Santamaria-Fernandez R et al. A high accuracy primary ratio method for the determination of iodine in complex matrices by double isotope dilution using MC-ICPMS and 129I spike. J Anal At Spectrom (2006) 21:413–421.

(3) Merrick J et al. Final report on CCQM-K125: elements in infant formula. Metrologia (2017) 54 Tech Suppl 08013. Have a look at the excellent LGC results for iodine.

(4) Bath SC et al. Iodine concentration of organic and conventional milk: implications for iodine intake. Br J Nutr (2012) 107:935–940.

 

Skimmed milk reference materials

In our National Measurement Laboratory role, LGC provided values for iodine (and other elements) to the reference material ‘milk powder – essential nutrients and trace elements’ (ERM-BD150, ERM-BD151). Contact LGC Standards for more information on these materials.

 

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