A cross-sectional study of an Irish population estimating dietary salt intake, and its association with hypertension and obesity

• Project start date: 1 December 2007
• Project status: Completed
• Discipline: Food marketing
• Principal researcher/s: Prof Ivan Perry, University College Cork
• Collaborator/s: Single supplier

Research objective

• To provide accurate and well validated estimates of dietary salt intake in the Irish population to support the ongoing evaluation of policy initiatives over the past decade designed to reduce it. 
• To estimate dietary salt intake in the Irish population based on analyses of the existing SLÁN-07 nutritional dataset and linked random ('spot') urine samples from this national health and lifestyle survey (Phase I study), and studies of additional samples of adults with estimates of salt intake based on 24-hour urinary sodium excretion (Phase II study) 
• To describe variation in salt intake by age, sex, and measures of obesity. 
• To assess the dietary sources of salt. 
• To estimate potassium intakes based on 24-hour urine collection and describe the distribution of sodium to potassium ratio in the population.

Outputs

Research report

• Title: Salt: Hard to shake
• Publication date: 5 October 2010
• Summary: Dietary salt intakes in Irish adults remain high, with the majority of the population exceeding the current tolerable upper limit of 6 g per day.
• Findings:
  • Self-reported dietary salt intake levels estimated were 8.1g/day for men and 7.6g/day for women. It was found that FFQ underestimates salt intake in men by approximately 15% whereas estimates for women are accurate with an error of less than 1%.
  • Cereals, breads and potatoes, meat, fish and poultry products, together accounted for over 50% of the salt in our diet.
  • The mean sodium intake density was similar in men and women. In multivariate analyses, sodium intake density increases significantly with age but not with obesity. 
  • The estimated mean for salt intake per day in adults aged over 45 years were 10.3 grams in men and 7.4 grams in women. 
  • The association between estimated salt intake and blood pressure was examined. Positive associations with both systolic and diastolic blood pressure were observed. 
  • Estimates of salt intake derived from 24- hour urine collection by age, gender and obesity measures: Estimated dietary salt intake was 9.3 g/day with higher intakes in men 10.4 g/day than in women, 7.4 g/day. It was found that 86% of Irish men and 67% of Irish women consume more than 6 g/day with only 1.3% and 11.5% consuming less than four grams per day. Significant variation in salt intake with age was not detected. 
  • Estimates of potassium intakes and sodium to potassium ratios derived from PABA validated 24-hour urine collections: The Recommended Daily Allowance (RDA) for potassium is 3,100 mg/day. Estimated intakes for men were 3630 mg/day and for women, 2780 mg/day. Sodium to potassium ratio was similar in men and women but varied inconsistently with age.
• Recommendations:
  1. Statutory agencies should engage more intensively with the food sector to ensure that further reductions in the salt content of processed food are achieved. 
  2. Health promotion initiatives should highlight the health consequences of excess salt intakes and promote lower salt products, and the use of less discretionary salt should be adopted. 
  3. There is a need for a multifaceted approach with an emphasis on focused health promotion initiatives. 
  4. Campaigns that raise awareness and promote choosing lower salt products, and for using less discretionary salt are needed. 
  5. Specific at-risk groups in the Irish population should be targeted by interventions. 
  6. The issue of clear and accurate labelling of the salt content of processed food, using simple formats, should be reviewed. The practice within the food industry of referring to a salt intake of 6 grams/day as a 'guideline daily amount' should be discontinued. 
  7. The statutory regulation of the salt content of processed food should be considered. Mandatory changes in permissible salt concentrations in processed food could be phased in over a reasonable time scale to allow consumers and the food industry to adapt. 
  8. There is a need for ongoing population monitoring for salt intake as part of national nutrition surveillance systems, particularly in children and adolescents. 
  9. The annual health and economic costs of excessive salt intake should be modelled for the ROI.