Scientific review published in Advances in Nutrition finds limited evidence on the impact of salt taxes due to limited use in practice
Excessive salt intake has been linked to high blood pressure, cardiovascular disease and kidney disease, making it a leading cause of death and disability globally. In fact, excessive salt intake has been associated with more than 3 million deaths per year. Although some individual studies do not agree with these findings, independent scientific reviews have concluded that the weight of the evidence clearly indicates that most salt intakes around the world are too high, leading to serious public health problems.
The question therefore is, how can we reduce salt intake? Taxing products high in salt content may be a solution. A growing body of evidence has demonstrated that taxing products high in sugar can be effective in reducing sugar consumption. Taxing salt therefore might have the same effect on salt consumption; however, there is less evidence to prove it.
Published in Advances in Nutrition, the American Society for Nutrition’s international scientific review journal, “Effectiveness and Feasibility of Taxing Salt and Foods High in Sodium: A Systematic Review of the Evidence” provides new insights to guide public policy of salt taxation. The authors began their review with a comprehensive search of the scientific literature, leading them to 18 relevant studies. Some of the studies were based on real-world experience in implementing salt taxes; however, because few countries have experimented with salt taxes, other studies were based on modelling, experimental design, or attitudes and perceptions.
According to the authors, results from modeling studies “were consistently positive, but of varying magnitude and difficult to compare given the range of measures used.” On the other hand, the four “real-world” studies that the authors examined produced mixed results. A study conducted in Hungary, for example, found that 11 to 16% of those consuming salty snacks and condiments reported changing their behavior due to the country’s tax designed to curb salt intake. However, while the tax changed behaviors, only 5% of those who changed their consumption habits switched to healthier alternatives. The majority switched to cheaper brands. As a result, overall levels of salty food consumption remained high.
Where salt taxes have been introduced, they are more likely to be applied to particular products such as instant noodles rather than to all foods above a certain salt threshold. Modeling studies suggest that taxing all foods based on their salt content is likely to be more effective than taxing specific products high in salt, given that salt is pervasive in the food chain. However, the authors noted that “the limited experience we found suggests that policy-makers favor taxing specific products.”
In general, this Advances in Nutrition review “found some positive, theoretical evidence on the potential for fiscal policies to reduce salt consumption and improve diet, but limited ‘real-world’ evidence on the impact of salt tax in practice due to limited use to date.” Given “the strong evidence for the need to reduce salt intake,” the authors concluded that “further consideration on the use of fiscal measures to reduce salt intake is warranted.”
Reference Rebecca Dodd, Joseph Alvin Santos, Monique Tan, Norm R C Campbell, Cliona Ni Mhurchu, Laura Cobb, Michael F Jacobson, Feng J He, Kathy Trieu, Sutayut Osornprasop, Jacqui Webster, Effectiveness and Feasibility of Taxing Salt and Foods High in Sodium: A Systematic Review of the Evidence, Advances in Nutrition, nmaa067, https://doi.org/10.1093/advances/nmaa067.
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