Iodine nutrition in UK – is there enough for pregnancy? Dr Sarah Bath MRC Research Fellow Registered Dietitian 17 th March 2016

Iodine information in the UK NHS iodine page –No mention of role of iodine in pregnancy –Milk not listed as a source of iodine –Suggest supplement of up to 500 μg/day is safe NHS pregnancy pages –Iodine not listed –Milk and fish recommended (for other nutrients)

Knowledge and awareness of iodine Study of UK pregnant women/new mothers (n=1026) 64% had not received information on iodine Only 16% aware of the role of iodine in pregnancy 56% unable to identify iodine-rich food sources Only 9% correctly identified milk as a source Combet et al Br J Nutr doi: /S

Dietary sources of iodine in the UK

Food sources of iodine Rose et al., 2001 J Environ Monit 3, ; Bates et al., 2014 NDNS report

Role of milk and dairy products for iodine intake in the UK

Milk-iodine concentration and milk consumption by country

Daily iodine intake from milk

Goitre endemic 1 Iodine sufficiency assumed Present Summary of UK Iodine Status 1. Phillips, 1997 Epidemiol Community Health 51, Lee et al Lazarus et al Lancet 372, Kibirige et al 2004 Arch Dis Child Fetal Neonatal Ed 89, F ; 5. Bath et al 2013 Lancet 382, Areas of endemic goitre in the past Phillips D 1997

How goitre was eradicated Iodine concentration of milk increased Three-fold increase in iodine intake between 1950s and 1980s* Milk consumption increased *Phillips D 1997;

Re-emergence of concern 3,4,5 Goitre endemic 1 Iodine sufficiency assumed Present Summary of UK Iodine Status 1. Phillips, 1997 Epidemiol Community Health 51, Lee et al Lazarus et al Lancet 372, Kibirige et al 2004 Arch Dis Child Fetal Neonatal Ed 89, F ; 5. Bath et al 2013 Lancet 382,

Milk: a variable source of iodine  Iodine concentration in milk varies according to farming practice  There is a large seasonable variation  Winter milk has a higher iodine concentration than summer milk 400 µg/L in winter 200 µg/L in summer

 Organic milk in the UK is lower in iodine than conventional milk 1  35% (winter) 1  42% (summer) 2  Recent meta-analysis found conventional milk to be 74% higher in iodine (six studies) 3 Organic milk as an iodine source 1. Payling et al. Food Chem 2015;178: Bath et al Br J Nutr 107, ; 3. Średnicka-Tober et al. Br J Nutr doi: /S OrganicConventional Iodine conc. (ng/g) Iodine (µg) per 200g2949

What is the relationship between milk and iodine status in the UK?

Pregnancy 1. Bath et al. (2014) Br J Nutr. 2. Bath et al. (2015) Am J Clin Nutr. Higher iodine status with higher milk consumption Study in Surrey 1 : Study in Oxford 2

Milk-alternative drinks “Dairy-free” diets are popular There has been a rise in popularity of milk- alternative drinks (e.g. soya/rice/coconut drinks) Most drinks are not fortified with iodine No information about iodine on the label Individuals who consume unfortified milk- alternative drinks may be at risk of iodine deficiency 1. Bath et al. (2015) Proc Nutr Soc

Iodine content of dairy products McCance and Widdowson (2014)

Iodine in fish White fishOily fishShellfish McCance and Widdowson 2014 Composition of foods integrated dataset

Can requirements be met through diet? UK pregnancy recommendations relevant to iodine: –2-3 portions of dairy products –Protein foods daily (including fish) –Specific recommendation for fish 1-2 portions per week One of which to be oily No more than two portions of oily fish

60 μg 75 μg 15 μg + + Milk and dairy products portions per day McCance & Widdowson 2014 Total from three portions = 150 μg 100% of adult RNI 60% of RNI for pregnancy

Protein foods 52 μg 9 μg 7 μg 6 μg McCance & Widdowson 2014

Fish 14 μg 12 μg 277 μg 284 μg 49 μg 50 μg McCance & Widdowson 2014

Iodine supplements Single iodine supplement is not available in the UK Need to warn against taking kelp or seaweed supplements Not all prenatal supplements contain iodine McCance & Widdowson 2014 SupplementIodine (μg) Nutrimum museli (100g)200 Pregnacare Tablets200 Seven Seas Pregnancy 150 Centrum during pregnancy150 Sainsbury's150 Tesco multi-plus pregnancy150 Waitrose LOVE Life Pregnancy Tablets150 Efalex Mother and Baby150 ASDA Pregnancy Multivitamins & Minerals140 Boots Pharmaceuticals Pregnancy Support140 Nutrimum bars (40g)100 Sanatogen mum-to-be0

Conclusions Milk and dairy products are important sources of iodine in the UK diet Non-fish consumers and those with a low intake of milk may be at risk of deficiency Pregnant women and those planning a pregnancy need to have specific information on dietary sources of iodine, including appropriate supplements