Urinary Sodium Excretion and Dietary Sources of Sodium Intake in Chinese Postmenopausal Women with Prehypertension Zhao-min Liu 1 *, Suzanne C. Ho 2 , Nelson Tang 1 , Ruth Chan 1 , Yu-ming Chen 3 , Jean Woo 1 * 1 Department of Medicine &Therapeutics, the Chinese University of Hong Kong, Hong Kong Special Administrative Region, PR, China, 2 Division of Epidemiology, The Jockey Club School of Public Health and Primary Care, the Chinese University of Hong Kong, Hong Kong Special Administrative Region, PR, China, 3 Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, Guangzhou, PR, China Abstract Background: Reducing salt intake in communities is one of the most effective and affordable public health strategies to prevent hypertension, stroke and renal disease. The present study aimed to determine the sodium intake in Hong Kong Chinese postmenopausal women and identify the major food sources contributing to sodium intake and urine excretion. Methods: This was a cross-sectional study among 655 Chinese postmenopausal women with prehypertension who were screened for a randomized controlled trial. Data collection included 24 h urine collection for the measurement of sodium, potassium and creatinine, 3-day dietary records, anthropometric measures and questionnaire survey on demographic data and dietary habits. Results: The average salt intake estimated from urinary excretion was 7.863.2 g/d with 82.1% women above WHO recommendation of 5 g/day. Food groups as soup (21.6%), rice and noodles (13.5%), baked cereals (12.3%), salted/ preserved foods (10.8%), Chinese dim sum (10.2%) and sea foods (10.1%) were the major contributors of non-discretionary salt. Discretionary salt use in cooking made a modest contribution to overall intake. Vegetable and fruit intake, age, sodium intake from salted foods, sea foods and soup were the independent determinants of urinary sodium excretion. Conclusions: Our data revealed a significant room for reduction of the sodium intake. Efforts to reduce sodium from diets in Hong Kong Chinese postmenopausal women should focus on both processed foods and discretionary salt during cooking. Sodium reduction in soup and increase in fruit intake would be potentially effective strategy for reducing sodium. Citation: Liu Z-m, Ho SC, Tang N, Chan R, Chen Y-m, et al. (2014) Urinary Sodium Excretion and Dietary Sources of Sodium Intake in Chinese Postmenopausal Women with Prehypertension. PLoS ONE 9(8): e104018. doi:10.1371/journal.pone.0104018 Editor: Pal Bela Szecsi, Gentofte University Hospital, Denmark Received February 11, 2014; Accepted July 7, 2014; Published August 1, 2014 Copyright: ß 2014 Liu et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: The study was funded by the Chinese University of Hong Kong Research Committee Direct Grant No. 2041783. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * Email: liuzhaomin@cuhk.edu.hk (ZML); jeanwoowong@cuhk.edu.hk (JW) Introduction Reducing salt intake in communities is one of the most effective and affordable public health strategies to prevent hypertension, decrease the risk of stroke, heart and renal diseases,the three major causes of mortality globally as well aslocally [1]. Elevated blood pressure (BP) may also aggravate the positive association between urinary sodium excretion and risk of coronary heart disease [2]. Despite campaigns that encourage reduced sodium intake, excessive consumption remains a major public health problem in most populations [3]. In addition to the sodium naturally present in foods and drinking water, other important sources of sodium in our diet come from the salt used during cooking or at the table (discretionary salt), salt added in processed foods, as well as non- salt sodium containing ingredients such as monosodium glutamate (MSG) (flavor enhancer), sodium nitrate (preservative) and sodium carbonate (tenderizers) etc. Dietary survey methods tend to underestimate sodium intakes since only a portion of sodium can be captured by dietary assessment. The timed 24-hour urinary sodium excretion is considered the gold standard method to estimate intake since 85–90% of ingested sodium is excreted through the kidneys and provide an estimate of total sodium intake from all sources. Dietary sodium intake and the major sources vary among different regions and populations, largely determined by cultural preference [3]. Awareness of contemporaneous sodium intake and identification of food sources of sodium in diets will inform more specific tailoring of salt reduction policies in local population. However, studies estimating salt consumption using timed urine samples, characterizing the food groups to assess contributions to the source of sodium as well as the associations with urinary sodium excretion are limited in Asian population. No study had been conducted among postmenopausal women with pre-hyper- tension or early hypertension, a population at high risk of cardiovascular diseases (CVD), declining renal function as well as osteoporosis (the major adverse medical conditions [4] [5] [6] linked with excessive sodium intake). Furthermore, potassium has PLOS ONE | www.plosone.org 1 August 2014 | Volume 9 | Issue 8 | e104018