Academic: Government sodium targets are incompatible with rest of dietary guidelines

In ‘A Conflict Between Nutritionally Adequate Diets and Meeting the 2010 Dietary Guidelines for Sodium’​, Dr Matthieu Maillot and Dr Adam Drewnowski reveal that meeting targets for sodium and​ complying with the rest of the 2010 dietary guidelines is impossible without wholesale changes to eating patterns.

A fundamental conflict between very low sodium guidelines and a nutritionally sound diet ​

The article, published online ahead of print in the American Journal of Preventive Medicine​, highlights a “fundamental conflict between the very low sodium guidelines and a nutritionally sound diet”, ​Drewnowski told FoodNavigator-USA.

The authors used federal nutrient composition and dietary intake databases to create modeled food patterns for people of different ages and genders using linear programming techniques. The patterns were designed to meet nutritional standards for 27 nutrients as the mean sodium content was progressively reduced to the target 1500 mg/day.

The goal was to determine at what point the 1500mg/day target would begin to interfere with the model’s ability to create food patterns that met adequacy standards for 27 nutrients, explained Drewnowsk, who is director of the Center for Public Health Nutrition at the University of Washington in Seattle.

Should dietary guidelines be viewed as merely ‘aspirational’?​

The results quickly debunked the myth that simply maintaining your current eating patterns but switching to lower-sodium versions of your favorite foods would be enough to meet the 1500mg target, he said.

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“Many people think that they will simply eat lower sodium version of the foods they eat and continue to get the nutrients they need.”​

But in reality, he said, the only way to achieve this was to switch to a diet that was so far removed from what Americans actually eat as to make the sodium targets merely ‘aspirational’.

“The nutrient-adequate food patterns that were achievable at lower levels of sodium were ‘fructivore’ diets, largely composed of fruit juices, nuts, and seeds. By contrast, meats and grains were totally absent from the modeled food patterns because of their sodium content, as were many vegetables.”​

A major reformulation of the American food supply​

He said: “At very low levels of sodium (1500mg/d), there is no way to get adequate nutrition. For young men, the goal is simply not feasible - there is no theoretical solution possible. For older men, the goal can be achieved - at least in theory - but may be difficult in practice. ​

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“Women, young and old, were better able to meet the sodium guidelines without sacrificing adequate nutrition - but at the cost of altering eating habits.​

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“So there are two options - a wrenching change in dietary patterns where whole groups of foods are removed from the diet and/or a major reformulation of the American food supply.​

He added: “There is a third option. The guidelines can be viewed as merely ‘aspirational’.”​

‘Wrenching deviations from existing eating behaviors’​

The 2010 Dietary Guidelines advised Americans to reduce daily sodium intake to less than 2300 mg/day, with a lower goal of 1500 mg/day for people who were aged 51+, all African-Americans and anyone with hypertension, diabetes, or chronic kidney disease.

The study is the fırst feasibility analysis of sodium goals based on linear programming, claim the authors. “The shape of the linear programming objective function can usefully pinpoint when modeled food patterns begin to depart from existing diets. ​

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“At that point, substitutions within food groups are no longer suffıcient to meet nutrient goals, so that shifts across food groups must be made. ​

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“For example, the 2300-mg/day sodium target could be achieved by most age– gender groups by selecting lower-sodium options within each major food group.​

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“However, linear programming modeling showed that sodium levels in the 1500–2000-mg/day range were associated with wrenching deviations from existing eating behaviors. ​

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“For age– gender groups including people aged 50 years, the proposed sodium goal of 1500 mg/day was incompatible with nutrient-adequate diets.”​

Source​: American Journal of Preventive Medicine​ 2012;42(2):174 –179) published online ahead of print

‘A Conflict Between Nutritionally Adequate Diets and Meeting the 2010 Dietary Guidelines for Sodium.’​

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Authors​: Matthieu Maillot, PhD, Adam Drewnowski, PhD