Transcript + + Milk and dairy products

Iodine nutrition in UK – is there enough for
pregnancy?
Dr Sarah Bath
MRC Research Fellow
Registered Dietitian
17th 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. 2015 Br J Nutr doi:10.1017/S0007114515001464
Dietary sources of iodine in the UK
0.6
10
0.4
5
0.2
0
0
Percentage contribution (%)
Iodine content (mg/kg)
Rose et al., 2001 J Environ Monit 3, 361-365; Bates et al., 2014 NDNS report
Beverages
15
Potatoes & Vegetables
0.8
Sugars & Fats
20
Fruit & Nuts
1
Eggs
25
Milk and Dairy
1.2
Fish
30
Meat & Poultry
1.4
Bread
35
Iodine concentration (mg/kg)
Percentage contribution (%)
Food sources of iodine
Role of milk and
dairy products
for iodine intake
in the UK
Milk-iodine concentration and milk consumption
by country
450
400
350
300
250
200
150
100
50
0
Milk iodine concentration (mcg/L)
Milk intake (litres/capita/annum)
Daily iodine intake from milk
90
Iodine per day from milk (mcg/day)
80
70
60
50
40
30
20
10
0
Summary of UK Iodine Status
1900
1920
Goitre endemic 1
1940
1960
Areas of
endemic
1980
goitre in 2000
the past
Present
Iodine sufficiency assumed 2
Phillips D 1997
1. Phillips, 1997 Epidemiol Community Health 51, 391-393 2. Lee et al. 1994 3. Lazarus et al. 2008 Lancet 372, 888.
4. Kibirige et al 2004 Arch Dis Child Fetal Neonatal Ed 89, F436-439; 5. Bath et al 2013 Lancet 382, 331-337
How goitre was eradicated
Iodine concentration of milk
increased
Milk consumption
increased
Three-fold increase in iodine intake
between 1950s and 1980s*
*Phillips D 1997;
Summary of UK Iodine Status
1900
1920
Goitre endemic 1
1940
1960
1980
2000
Iodine sufficiency assumed 2
Present
Re-emergence of
concern 3,4,5
1. Phillips, 1997 Epidemiol Community Health 51, 391-393 2. Lee et al. 1994 3. Lazarus et al. 2008 Lancet 372, 888.
4. Kibirige et al 2004 Arch Dis Child Fetal Neonatal Ed 89, F436-439; 5. Bath et al 2013 Lancet 382, 331-337
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 as an iodine source
 Organic milk in the UK is lower in
iodine than conventional milk1
 35% (winter)1
 42% (summer)2
 Recent meta-analysis found
conventional milk to be 74%
higher in iodine (six studies)3
Organic
Conventional
Iodine conc. (ng/g)
146.5
246.1
Iodine (µg) per 200g
29
49
1. Payling et al. Food Chem 2015;178:327-330 2. Bath et al. 2012 Br J Nutr 107, 935-940.;
3. Średnicka-Tober et al. Br J Nutr doi:10.1017/S0007114516000349
What is the
relationship
between milk and
iodine status in
the UK?
Pregnancy
Higher iodine status
with higher milk
consumption
Study in Surrey1:
Study in Oxford2
Iodine-to-creaitnine ratio (mcg/g)
200
180
160
140
120
100
80
60
40
20
0
None
<140 ml
140-280 ml
Daily maternal milk intake
1. Bath et al. (2014) Br J Nutr. 2. Bath et al. (2015) Am J Clin Nutr.
>280 ml
Milk-alternative drinks
• “Dairy-free” diets are popular
• There has been a rise in popularity of milkalternative 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 milkalternative drinks may be at risk of iodine
deficiency
1. Bath et al. (2015) Proc Nutr Soc
Percentage of adult RNI (150 mcg/day)
Iodine content of dairy products
100
90
80
70
60
50
40
30
20
10
0
Average portion of dairy product
McCance and Widdowson (2014)
Iodine in fish
500
Iodine per portion (mcg)
450
400
350
300
250
200
150
100
50
0
White fish
Oily fish
Shellfish
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
Milk and dairy products
• 2 - 3 portions per day
+
+
15 μg
60 μg
75 μg
• Total from three portions = 150 μg
• 100% of adult RNI
• 60% of RNI for pregnancy
McCance & Widdowson 2014
Protein foods
6 μg
52 μg
7 μg
9 μg
McCance & Widdowson 2014
Fish
277 μg
14 μg
284 μg
12 μg
McCance & Widdowson 2014
50 μg
49 μg
Iodine supplements
Supplement
• Single iodine supplement is
not available in the UK
• Need to warn against taking
kelp or seaweed supplements
• Not all prenatal supplements
contain iodine
Iodine (μg)
Nutrimum museli (100g)
200
Pregnacare Tablets
200
Seven Seas Pregnancy
150
Centrum during pregnancy
150
Sainsbury's
150
Tesco multi-plus pregnancy
Waitrose LOVE Life
Pregnancy Tablets
150
Efalex Mother and Baby
ASDA Pregnancy
Multivitamins & Minerals
Boots Pharmaceuticals
Pregnancy Support
150
Nutrimum bars (40g)
100
Sanatogen mum-to-be
McCance & Widdowson 2014
150
140
140
0
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