ILSI at ICN: Thursday, 19 October, 08:00 – 10:00

Challenges and Opportunities in Sodium Reduction in the US

Christine Taylor, PhD (Session Chair)
US Food and Drug Administration (retired)
USA

Reduction in sodium intake has been a public health goal in the US for more than 40 years. Efforts to reduce intake have ranged from consumer education to calls for voluntary reduction on the part of the food industry. These activities have not proven very effective, and the average sodium intake in the US continues to be more than 3,400 mg of sodium per day.

In the past several years government agencies, public health professionals, the food industry, and consumer groups have focused on dialogues, public meetings and research to clarify and focus the key considerations in reducing sodium in the food supply. In June 2016 in response to a 2010 Institute of Medicine report as well as other factors, the US Food and Drug Administration (FDA) issued draft guidance for industry to support a voluntary sodium reduction in foods. The guidance specifies target mean and upper bound concentrations for sodium in commercially processed, packaged and prepared foods. Its goal is a small initial reduction as a first step in a long-term process to gradually lower intake levels consistent with current and future targets as they emerge. The activities are to be carried out concomitant with up-front research, special studies and technological exchanges and workshops. Change is to be introduced slowly and gradually. Approximately 200 comments were submitted concerning the FDA guidance. Topics included technical challenges, definitions for food categories, and strategies for measuring changes in sodium intake as well as sodium levels in the food supply. FDA is currently considering these comments in light of possible future revisions to the guidance.  As a voluntary program, a number of companies have begun implementation of activities consistent with the guidance. Monitoring industry participation and impact will be important.

Some scientists have questioned the goal of reducing sodium intake below 2,300 mg/day, arguing that data for benefit are unclear and expressing concern about possible harm. While these debates will need to be resolved, it is noteworthy that the US government has put in place a systematic evidence review – Effects of Dietary Sodium and Potassium Intake on Chronic Disease Outcomes and Related Risk Factors – to be completed in mid-2017 by the Agency for Healthcare Research and Quality. This report will be available for an anticipated review of Dietary Reference Intakes for sodium and potassium to be conducted by the National Academy of Medicine beginning in late-2017. In any case, sodium research should continue with particular focus on the interaction between sodium and taste preference, technological work-arounds for sodium’s role in food, the impact of reduced sodium on food safety, and strategies for monitoring and quantifying sodium intake and presence in the food supply.

Progress on Sodium Reduction in the Americas

Mary L'Abbe, PhD
The University of Toronto
Canada

Reducing dietary salt is recommended by the 2011 United Nations Summit Declaration on Prevention of Non communicable Diseases and the World Health Organization Global Action plan for Prevention and Control of Noncommunicable Diseases, where one of the 9 global targets is a relative reduction of sodium intake by 30% by 2025. High blood pressure is a contributory factor in at least 40% of all heart disease and strokes which represent approximately 45% of NCDs. In the Americas, hypertension is a major health risk, as between 15-35% of the adult population has elevated blood pressure. This evidence led many governments in the Americas, including Argentina, Brazil, Canada, Chile, and the National Salt Reduction Initiative in the US to set salt reduction targets.  These national level targets formed the basis of the Pan American Health Organization (PAHO) regional targets for the Americas for 12 major food categories and several sub-categories.

In Canada, the targets for salt reduction (for 2010-2016) were used to assess interim progress in monitoring changes in sodium levels in foods between 2010 and 2013.  Overall, 58% of foods met at least 1 of the 3 phases of the sodium reduction benchmark targets and the proportion exceeding maximum benchmark levels decreased from 25.2% to 20.8%. The greatest reductions in sodium were seen in imitation seafood (26%), condiments (20%), breakfast cereals (20%), canned vegetables/legumes (19%), plain chips (19%), hot cereals (15%), canned condensed soup (14%), and sausages and wieners (11%), (all p<0.01), although significant reductions were not yet seen in many food categories. In 2015, PAHO in collaboration with representatives of the LatinFoods network in Argentina, Brazil, Barbados, Chile, Costa Rica, Cuba, Ecuador, Guatemala, Jamaica,  Mexico, Paraguay, Panama, Peru and Trinidad and Tobago, conducted a baseline survey of packaged foods in 14 countries in the region in order to be able to assess progress in meeting the PAHO regional targets during the upcoming years for: 1) breads; 2) soups, wet and dry, noodles in broth; 3) mayonnaise; 4) cookies and biscuits; 5) cakes; 6) meat; 7) breakfast cereals; 8) dairy (cheese and processed cheese products); 9) butter/dairy spreads; 10) snacks; 11) pasta; 12) seasonings and condiments.  These baseline results will be presented per food category and by country. Together these results can help with monitoring progress to reduce sodium levels in packaged foods in the Americas and will also provide information for development of enhanced sodium reduction targets and in a broader range of foods in the upcoming years.  Monitoring progress in sodium reduction is an important component of national and regional efforts to reach the sodium reduction goals set by the WHO.

Sodium and Potassium Intakes and their Ratios in the US Diet

Regan Bailey, PhD, MPH
Purdue University
USA

Background
The dietary ratio of sodium to potassium (Na:K) has been more strongly associated with increased risk of cardiovascular (CVD) disease and CVD-mortality than either sodium or potassium alone.

Objective
To estimate the usual sodium and potassium intakes, the dietary Na:K ratio, energy-adjusted sodium and potassium intakes (per 1,000 kcal), and the percentage of individuals with a dietary Na:K ratio of <1.0 by age, sex, and race/ethnicity among non-pregnant, non-lactating U.S. adults (³20 y; 2393 men and 2337 women) from What We Eat In America, NHANES 2011-2012.

Methods
NHANES is a nationally representative, cross-sectional survey that samples noninstitutionalized, civilian U.S. residents using a complex, stratified, multistage probability cluster sampling design. Two 24-hour dietary recalls are collected, weighted for day of the week of collection to assure equal distribution across each day of the week, using the USDA’s Automated Multiple-Pass Method. The National Cancer Institute method was used to estimate usual dietary intakes. Multiple pairwise t-tests were used for all comparisons between population groups, statistical significance was set at P ≤ 0.01.

Results
U.S. adults consumed approximately 2000 kcal/d, 3600 mg/d sodium, and 2800 mg/d potassium. Most adults (90% ± 0.8%) had sodium intakes of >2300 mg/d, whereas <3% had potassium intakes of > 4700 mg/d. Asians had the highest sodium intakes (per 1,000kcal) when compared to all other race/ethnic groups. Women had a significantly lower dietary Na:K ratio than men (1.32±0.0 versus 1.45±0.02). Non-Hispanic whites had a significantly lower Na:K ratio than non-Hispanic blacks and non-Hispanic Asians (1.34±0.02 compared with 1.54±0.03 and 1.49±0.04, respectively). Only 12.2% ± 1.5% of U.S. adults had an Na:K ratio of <1.0. More women (18%) than men (7%) met the recommended Na:K ratio. A significantly higher proportion of whites had an Na:K ratio of <1.0 than did all other racial/ethnic groups. Among men and women, the dietary Na:K ratio decreased linearly as age increased.  Mixed dishes (e.g., combinations of foods consumed together) contributed the most sodium (34 ±1%) and potassium (19%±1%) to the American diet. However, grains and vegetables were among the highest contributors to sodium intakes of individuals with Na:K ratios of <1.0, compared with protein foods and grains for those with Na:K ratios of ≥1.0. Vegetables as well as milk and dairy products constituted the primary dietary sources of potassium for individuals with dietary Na:K ratios of <1.0, whereas mixed dishes and protein foods contributed the most potassium for individuals with dietary ratios of ≥1.0. Individuals with an Na:K <1.0 were less likely to consume mixed dishes and condiments and were more likely to consume vegetables, milk and dairy products, and fruit compared to those with a Na:K ≥ 1.0.

Conclusion
Only about one-tenth of U.S. adults have a dietary Na:K ratio consistent with the World Health Organization guidelines for reduced risk of mortality. Our data suggest that blacks and Asians have the most unfavorable dietary Na:K ratio in the U.S. Continued efforts to reduce sodium intake in tandem with novel strategies to increase potassium intake are warranted.

Modeling the Relationship of Sodium, Potassium, Calcium and Magnesium Intakes to Blood Pressure

Connie Weaver, PhD
Purdue University
USA

Background
Intakes of sodium, potassium, and their ratios have been associated with modifying systolic and diastolic blood pressure (SBP and DBP).  Dietary patterns associated with blood pressure reduction are high in calcium and magnesium as well as potassium.

Methods
We evaluated sodium, potassium, calcium, and magnesium intakes from food and supplements and their ratios for predicting blood pressure in US adults from 2011-2014 NHANES (2266 men and 2454 women after excluding 5404 who were pregnant or lactating, taking hypertension medications, smoked, had GFR <30 mL/min, or had missing or implausible BP values).

Results
The target mineral ratios for most adults based on recommended intakes of the single nutrients according to the IOM and (% meeting those) were less than 0.49 for Na:K (0.54%), less than 2.3 for Na:Ca (15.63%), less than 5.75 for women (7.23%) and 7.42 for men (13.63%) for Na:Mg, and 2.5 for women (31.02%) and 3.22 for men (53.69%) for Ca:Mg.  Distributions of minerals, their ratios, and blood pressures were skewed and therefore were expressed as logarithms.  Values beyond 3SD of the mean were excluded. Data for males and females were analyzed separately.  For females SBP, age expressed as a quadratic and race (Asian, black, Hispanic, other, white) explained 20% of the variation. When added to this model, statistically significant positive relationships were found with Na, Na:K, Na:Mg, Ca:Mg, Na:Ca and statistically significant negative relationships were found with K and Mg.   For each of these, the increase in the percent of variation explained was 2% or less.  Addition of BMI and the Income/Poverty Index explained an additional 5%.  For females DBP, age expressed as a quadratic and race explained 8% of the variation. When added to this model, statistically significant positive relationships were found with Na:K, Na:Mg, and Ca:Mg and statistically significant negative relationships were found with K and Mg.   For each of these, the increase in the percent of variation explained was 1% or less.  Addition of BMI explained an additional 2%.  For males SBP, age expressed as a quadratic and race explained 10% of the variation.  When added to this model statistically significant negative relationships were found with Ca and Mg.   For each of these, the increase in the percent of variation explained was less than 1%.  No statistically significant effects of minerals or their ratios were found.  Addition of BMI explained an additional 8%.  For males DBP, age expressed as a quadratic and race explained 11% of the variation.  Addition of BMI explained an additional 4%.

Conclusions
Our findings suggest that dietary patterns, which favor lower intakes sodium, higher intakes of K, and Mg, and lower Na:K, Na:Mg, Ca:Mg, Na:Ca should be encouraged for protection against hypertension.

Christine Taylor, PhD
US Food and Drug Administration (retired)
USA

Christine Lewis Taylor began her career in 1985 as a scientist with the Food and Drug Administration (FDA). In 2000 she was named Director of the Office of Nutritional Products, Labeling and Dietary Supplements at FDA's Center for Food Safety and Applied Nutrition. In this capacity, she oversaw a staff of more than 50 scientists who were responsible for research, regulation and enforcement related to nutrition issues and dietary supplements. During this she also served as a lead of the U.S. delegation to the United Nations-sponsored Codex Alimentarius Committee on Nutrition Labeling. From 2004 to 2006 FDA assigned Dr. Taylor to the World Health Organization where she worked on the topic of approaches for determining dietary supplement safety. Following her retirement from the agency, Dr. Taylor was named a Scholar in the Institute of Medicine at The National Academies in Washington DC. She functioned as the Study Director for four projects including an evaluation of the process for setting Dietary Reference Intakes, consensus recommendations for the standards for school lunch, identification of strategies for reducing sodium in the diet, and an evaluation of the recommended intakes for vitamin D and calcium. Dr. Taylor has served as a consultant since 2011 and has worked most closely with the Office of Dietary Supplements at the National Institutes of Health.

Mary L'Abbe, PhD
The University of Toronto
Canada

Dr. Mary L’Abbé is the Earle W. McHenry Professor and Chair of the Department of Nutritional Sciences, Faculty of Medicine, at the University of Toronto, where she leads a research group on Food and Nutrition Policy for Population Health.  Her research examines the nutritional quality of the Canadian food supply, food intake patterns, and consumer research on food choices related to obesity and chronic disease. Dr. L’Abbé is a member of several committees of the WHO including the Nutrition Guidance Expert Advisory Group on Diet and Health and the Global Coordinating Mechanism for NCDs and chairs the Technical Advisory Group on Sodium for the Pan America region of the WHO. She was Chair/Vice Chair of Canada’s Sodium Working Group which developed the Sodium Reduction Strategy for Canada. Dr. L’Abbé is the Director of the WHO Collaborating Centre on Nutrition Policy for NCD Prevention.  Dr. L’Abbé holds a PhD in nutrition from McGill University and has authored over 215 peer-reviewed scientific publications, book chapters and government reports.

Regan Bailey, PhD, MPH
Purdue University
USA

Regan Lucas Bailey is an Associate Professor in the Department of Nutrition Science at Purdue University. Prior to academic life, Dr. Bailey was a Nutritional Epidemiologist and Director of Career Development and Outreach at the Office of Dietary Supplements, Office of Disease Prevention at the National Institutes of Health. The overarching goal of her research program is to prevent or lessen the risk of chronic disease through nutrition. Dr. Bailey’s specific research interests include: nutritional epidemiology; B vitamins; dietary assessment methods and measurement error; dietary patterns; dietary supplements; nutrition screening; and, nutrition and aging, particularly as it relates to reducing the risk of cognitive impairment and osteoporosis. She has considerable expertise working with the National Health and Nutrition Examination Survey.

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