Sodium and chloride DRVs bring decade-long recommended nutrient overhaul to close

12 Sep 2019 --- The publication of the European Food Safety Authority (EFSA)’s dietary reference values (DRVs) for sodium and chloride marks the end of a ten-year overhaul. Nutrition scientists compiled research to set science-based nutrient reference values for the daily intake of macronutrients, vitamins and minerals in healthy populations. The safe and adequate intake of chloride for adults is now set at 3.1g a day, while the sodium value is 2g a day. The DRVs will now be used by policymakers to establish food-based dietary guidelines that help consumers make healthy dietary choices.

“In 2005, the European Commission (EC) asked EFSA to review the advice of the Scientific Committee for Food dated from 1993 on DRVs for the European population to ensure that community action in the area of nutrition was underpinned by the latest scientific evidence,” Agnès de Sesmaisons-Lecarré, Scientist in EFSA’s Nutrition Unit, tells NutritionInsight. 

As well as DRVs being used by policymakers, risk managers also refer to them when setting labeling reference values to inform consumers of the nutrition composition of prepacked foods. Nutrition and health professionals also use them in dietary assessment and diet planning, while food manufacturers use them in product formulation.

Although sodium and chloride are naturally present in most foods, they are primarily consumed via salt in Western diets. “The body needs them to function but, when consumed in excess, they can cause elevated blood pressure, a risk factor for cardiovascular disease. EFSA experts concluded that 2g of sodium per day is both safe and adequate for the adult population. European intakes in adults are typically higher so EU decision-makers can use this value where appropriate to set population targets for reducing sodium intake,” explains de Sesmaisons-Lecarré.

Sodium and chloride are examples of the challenges of setting DRVs when there is a complex physiological interplay between several nutrients.“Sodium and chloride are good examples of the challenges of setting DRVs when there is a complex physiological interplay between several nutrients. Knowing how much of these nutrients are necessary, adequate or tolerable are multifaceted scientific questions,” adds Androniki ‘Ada’ Naska, another EFSA scientist.

The task was entrusted to the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA). The Panel set the foundations for this task in an inaugural opinion published in 2010, which addressed the general principles for deriving and applying DRVs, de Sesmaisons-Lecarré continues. “A total of 34 scientific opinions were then published over nine years, covering water, fats, carbohydrates and dietary fiber, protein, energy, as well as 14 vitamins and 15 minerals. Sodium and chloride were the last two nutrients on the list. The order of priority for the review was defined by the EC.”

DRVs were initially developed to address undernutrition, for example, a lack of calories or micronutrients due to insufficient foods. However, there has been a rise of diet-related chronic diseases such as obesity, Type 2 diabetes, cardiovascular diseases and some cancers, which has moved the focus of nutrition research in the last few decades. This means that DRVs are now set with consideration being given to new types of data – such as large-scale population studies – to see how nutrient intakes and the risk of diseases come into play.

Additionally, Monika Neuhäuser-Berthold, another EFSA scientist, emphasizes that DRVs are not nutrient goals or recommendations for individuals, which vary by life-stage and gender. Insufficient or excessive dietary intakes of nutrients are associated with an increased risk of diseases.

The process
The scientists note that weighing up the scientific literature was by far the greatest challenge. For example, the process of determining sodium values involved reviewing the literature systematically, critically appraising eligible studies and then carrying out a meta-analysis, which is a statistical method for combining data from multiple sources. 

“Modelling helped us to identify dose responses, which we needed to set reference values. We further quantified the uncertainties in our conclusions to enhance transparency. It was an exhaustive process,” says Naska.

Evaluating the scientific evidence in an interdisciplinary setting gave the scientists a profound insight into the currently available knowledge of DRVs. “We identified several data gaps and uncertainties too, which will stimulate further research activities at universities or inform discussions at national authorities or scientific conferences,” notes Neuhäuser-Berthold.

The comprehensive results are now published in the EFSA Journal, with them also being available in the DRV finder, a user-friendly interactive tool launched last year. Users can search by nutrient or by target population, with professionals also able to check definitions and access corresponding scientific opinions of EFSA.

By Katherine Durrell

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