Monitoring sodium and iodine
Iodine deficiency can lead to thyroid disorders. Iodine is an important component of thyroid hormones, which are crucial for growth and metabolism. In the Netherlands, foods do not naturally contain sufficient iodine and therefore iodized table and baker salt is used. In 2010 the intake of iodine was in agreement with the recommendation, but the intake was lower compared to 2006. Because the food industry lowers the sodium levels in their foods, it is important to monitor iodine intake in the coming years.
Why is this important?
High salt intake has an adverse effect on blood pressure and hypertension increases risk on cardiovascular disease risk. Previous research in Doetinchem performed in 2006 and 2010 showed that the salt intake exceeds the recommended maximum intake of 6 gram salt per day. About 80% of the salt intake comes from commonly consumed foods such as bread, cheese, processed meat, soups and snacks. In 2014, the Minister of Health, Welfare and Sports signed the 'Agreement on Product Improvement' with the industry to reduce sodium levels in processed foods.
Potassium is an essential nutrient to regulate blood pressure and fluid balance. For healthy adults it is almost impossible to consume too much potassium. A low potassium intake can cause problems with blood pressure, especially when people also consume too much salt.
Salt and iodine intake could not be accurately determined in food consumption surveys because the quantity of (iodized) salt added during and after cooking is difficult to assess. The most accurate way to measure the intake of sodium and iodine is by measuring excretion in 24 hour urine. RIVMNational Institute for Public Health and the Environment started to monitor the salt, iodine and potassium intake via 24 hour urine samples in 2006. Up and until 2006, there was little information on the intake of sodium and iodine in the Netherlands.
What are the results?
Similar to 2006 and 2010, the salt intake in 2015 exceeded the recommended maximum intake of 6 grams per day. Half of the participating men had a salt intake of more than 9.7 gram per day, which is 3.7 gram per day above the recommended maximum intake. Half of the participating women had a salt intake of more than 7.4 gram per day.
Figure 1: Trend in salt intake (in g/d) in Doetinchem over the period 2006 - 2015
Regarding iodine intake, half of the participating men had an intake of more than 179 microgram per day; half of the participating women had an intake of more than 153 microgram per day. The adequate intake is 150 microgram per day and the risk of an inadequate intake is low.
Figure 2. Trend in iodine intake (in μg/d) in Doetinchem over the period 2006-2015
Half of the participating men had a potassium intake of more than 3818 milligram per day (recommended daily intake is 3500 mg for men); for women this intake was 3255 milligram per day (recommended intake is 3100 mg). There is a small risk of an inadequate intake.
Figure 3. Trend in potassium intake (in mg/d) in Doetinchem over the period 2006 - 2015.