The complexity of foods that are both high in sodium and key nutrients creates challenges for sodium reduction efforts when reformulating foods, according to new research led by the University of Toronto. The work was supported by the Institute for the Advancement of Food and Nutrition Sciences (IAFNS) and was published in Nutrition Today.

Understanding the nutritional profile of the top contributors to sodium intake from food has implications for public health, dietary guidance, and food reformulation efforts. It is also crucial to understand the levels of different nutrients in foods of public health concern to ensure that ongoing efforts to reduce sodium intake do not inadvertently compromise the overall nutritional quality of the diet.

In this context, the researchers conducted their analysis to “avoid unintended consequences, such as reductions in shortfall nutrients or displacement of nutrient-dense foods.”

Sodium’s Role in Food Safety and Quality

Moreover, as explained by Caitlin Karolenko, Ph.D. for Food Safety Magazine, sodium is not just a flavor enhancer; it also plays a critical role in food safety and quality.” For example, the addition of sodium to foods like processed meats and cheeses helps inhibit the growth of pathogenic bacteria and spoilage microorganisms in foods by reducing the water activity of the product. Sodium reduction in processed meats and cheeses can both shorten shelf life and alter the taste and texture of foods.

Sodium and Nutrients Are Not Mutually Exclusive

Exemplifying the complexity of the trade-off between sodium and nutrition, pizza provides moderate amounts of iron, folate, and calcium. Additionally, the researchers found that sodium-rich foods like cold cuts, meat-mixed dishes, burritos and tacos, burgers, poultry, and chicken nuggets are the highest contributors (40–50 percent) to protein consumption.

Therefore, the researchers concluded that the major sources of sodium in a person’s diet are also important contributors of key nutrients, which should be considered during sodium reduction and reformulation efforts. Reformulating some food products to lower sodium by 10–30 percent is feasible “but should also be implemented in ways to preserve the nutrient contributions of these foods,” the authors said.

Analyzing Real-Life U.S. Dietary Habits

The analysis drew on nationally representative data from the 2017–2018 U.S. National Health and Nutrition Examination Survey (NHANES), a continuous, cross-sectional survey of people living in the U.S. The participants completed an in-person, 24-hour dietary recall and health examination. Researchers captured data from a variety of different groups and demographic categories.

The researchers’ analysis of the NHANES data showed that many top food category contributors to sodium intakes such as vegetables, cheese, cold cuts, and breads are also sources of nutrients that Americans are under-consuming.  These so-called “shortfall” nutrients include potassium, fiber, calcium, and vitamin D. In addition, the top contributors of sodium intake include food groups of public health importance like dairy, vegetables, and grains.

Conversely, some of these foods can also include what scientists call “nutrients-to-limit” such as sodium, saturated fat, and sugars.

Potential Solutions to a Complex Problem

The researchers concluded, “Given the complexity of foods that are simultaneously high in sodium and sources of key nutrients, interpretive front-of-pack labeling systems may help consumers… Evidence from other countries suggests that such systems may encourage shifts toward lower-sodium and healthier products.”

According to Mavra Ahmed, Ph.D., first author on the study and a Research Associate/Fellow in the Department of Nutritional Sciences at the University of Toronto’s Temerty Faculty of Medicine, the findings highlight a “critical tension in sodium reduction policy—many of the foods contributing most to sodium intake also provide essential nutrients. Therefore, policies must take a more nuanced, systems-level approach to avoid unintended nutritional trade-offs.”

Mary L’Abbe’, Ph.D., principal investigator on the study and Professor Emeritus of Nutritional Sciences at Temerty Medicine, remarked, “These results show that it is important that manufacturers continue to focus efforts on reducing sodium levels in foods, particular those that are high in sodium and also contribute other important nutrients that Americans need in their diets.”