Otago research reveals most Kiwis eating too much salt

Nearly two-thirds (65%) of adult New Zealanders are consuming more sodium than current nutrition guidelines recommend, according to analysis of urine samples taken from 3000 people who took part in the latest New Zealand Adult Nutrition Survey.

High sodium intake is a cause of high blood pressure, cardiovascular disease (heart disease and stroke), and kidney disease. It is also associated with an increased risk of stomach cancer.

Sodium intake estimates drawn from the 2008/09 survey were presented for the first time at a scientific meeting in Queenstown today. The average sodium intake for New Zealand adults was estimated to be around 3500mgs per day (equivalent to around 9 grammes of salt per day). The recommended upper level of sodium intake is 2300mgs.

Dr Rachael McLean of the University of Otago’s Edgar National Centre for Diabetes and Obesity Research presented the findings at the Joint Annual Scientific Meeting of the Nutrition Society of New Zealand and the Nutrition Society of Australia. This is the first time that urine sodium from a nationally representative sample of New Zealanders has been measured and analysed to provide intake estimates.

Dr McLean says that younger New Zealanders and men had higher estimated sodium intakes, with men aged 19-44 years of age having mean intakes almost double the recommended upper level of intake for adults. One surprising result was that there was no significant difference in intake by ethnicity or deprivation as measured by the New Zealand deprivation index.

Previous research shows that the vast majority (around 90%) of sodium is consumed as salt, and it is estimated that around three quarters of salt is consumed from that already in processed foods, she says.

“Although data from the Adult Nutrition Survey showed that adding salt to food after it has been cooked was associated with a higher sodium intake, even those who reported never adding salt afterwards had a mean sodium intake exceeding the recommended upper level.”

Dr McLean says that individual measures such as limiting addition of table salt will clearly not be enough to reduce intake to the recommended level and that processed foods need to be reformulated to contain less salt.

“Lowering population sodium/salt intake to below 2300 mgs per day (or six grammes of salt per day) for adults would have substantial benefits in reducing high blood pressure, heart disease and stroke in the New Zealand population.”