Gradual reduction of sugar in soft drinks without substitution as a strategy to reduce overweight, obesity, and type 2 diabetes: a modelling study

Summary

Background

Sugar-sweetened beverages are a major source of free sugar intake in both children and adults, and are an important contributor to obesity and obesity-related diseases, including type 2 diabetes. We proposed an incremental and stepwise reduction in free sugars added to sugar-sweetened beverages by 40% over 5 years without the use of artificial sweeteners and assessed the effect of the proposed strategy on energy intake and weight status.

Methods

In this modelling study, we used nationally representative data from the National Diet and Nutrition Survey rolling programme (NDNS RP) from 2008–12 and British Soft Drinks Association annual reports to calculate sugar-sweetened beverage consumption (both with and without fruit juices) and its contribution to free sugar and energy intake in the UK population. We then estimated the predicted reduction in energy intake resulting from the proposed strategy at an individual level. We further predicted the reduction in steady-state bodyweight for each adult using a weight loss model. By scaling up the distribution of the predicted bodyweight in the NDNS RP to the UK adult population, we estimated reductions in the number of overweight and obese adults, and the number of adults with type 2 diabetes.

Findings

A 40% reduction in free sugars added to sugar-sweetened beverages over 5 years would lead to an average reduction in energy intake of 38·4 kcal per day (95% CI 36·3–40·7) by the end of the fifth year. This would lead to an average reduction in steady-state bodyweight of 1·20 kg (1·12–1·28) in adults, resulting in a reduction in the prevalence in adults of overweight by 1·0 percentage point (from 35·5% to 34·5%) and obesity by 2·1 percentage points (from 27·8% to 25·7%). This reduction would lead to a reduction of roughly 0·5 million adults from being overweight and 1 million adults from being obese, which in turn would prevent about 274 000–309 000 incident cases of obesity-related type 2 diabetes over the two decades after the predicted reduction in bodyweight is achieved. If fruit juices were excluded from the category of sugar-sweetened beverages (because of potential challenges for reformulation), the corresponding reductions in energy intake and steady-state bodyweight would be 31·0 kcal per day (95% CI 28·6–33·7) and 0·96 kg (0·88–1·04), respectively. These reductions would result in a 0·7 percentage point (0·3 million) reduction in overweight and a 1·7 percentage point (0·8 million) reduction in obesity, which would in turn prevent about 221 000–250 000 cases of type 2 diabetes over two decades after the predicted reduction in bodyweight is achieved. The predicted effect was greater in adolescents, young adults, and individuals from low-income families (who consume more sugar-sweetened beverages).

Interpretation

An incremental reduction in free sugars added to sugar-sweetened beverages without the use of artificial sweeteners is predicted to reduce the prevalence of overweight, obesity, and type 2 diabetes. The proposed strategy should be implemented immediately, and could be used in combination with other approaches, such as taxation policies, to produce a more powerful effect.

Funding

None.

Introduction

Over the past two decades, obesity has increased substantially worldwide¹ and is estimated to be associated with more than 3 million deaths per year.¹ In the UK, roughly two in three adults and more than one in four children were overweight or obese in 2013.² Meanwhile, consumption of sugar-sweetened beverages has also risen worldwide,3, 4 and it is the largest source of added sugar (roughly 30% of all added sugar) for children and the second largest in adults in the UK.⁵ Sugar-sweetened beverages provide so-called empty calories, with less feeling of fullness or satiety compared with solid food.⁶ Clear evidence now exists that consumption of sugar-sweetened beverages is an important contributor to obesity in both children and adults7, 8 and is also linked to an increased risk of type 2 diabetes.⁹ Roughly 184 000 deaths a year worldwide are estimated to be attributable to the consumption of sugar-sweetened beverages.¹⁰

The UK developed and implemented a successful national salt reduction programme by getting the food industry to gradually reduce the amount of salt added to processed food over the past decade. The programme was pioneered by the Food Standards Agency, with input from Consensus Action on Salt and Health, and is now being implemented by many other countries.¹¹ The key to the success of the programme was setting incremental salt reduction targets for more than 80 food categories with a clear timeframe for the food industry to achieve this. Average and maximum targets to be achieved in 4 years were set, and the targets were reset 2 years after the setting of the initial targets; the intention was to continue to reset these targets until maximum adult salt intake met the target of 6 g per day. As a result of this programme, salt intake fell from 9·5 g per day to 8·1 g per day between 2003 and 2011, accompanied by a substantial fall in population blood pressure and a substantial reduction in mortality from stroke and ischaemic heart disease.¹²

Research in context

Evidence before this study

We searched PubMed, Embase, and Google Scholar for scientific literature published up to Oct 1, 2015, with no language restrictions, using the following terms: (“carbonated beverages” OR “SSB” OR “sugar sweetened beverages” OR “soft drinks” OR “sweet drinks” OR “soda” OR “sugary drinks” OR “fruit drinks” OR “sport drinks” OR “cold drinks” OR “non-alcoholic drinks”) AND (reduc* OR limit* OR decrea*) AND (“energy” OR “weight” OR “calorie” OR obes*) AND (“strategy” OR “intervention” OR “policy” OR “way” OR “approach”). Among these terms, “carbonated beverages” was used as a MeSH term in PubMed. We screened the retrieved results for research articles, reviews, commentaries, and reports of public health strategies related to sugar-sweetened beverages. Based on existing evidence, several countries have worked to develop and implement strategies that focus on reducing the consumption of sugar-sweetened beverages through increasing marketing price, limiting its availability, and raising public awareness. These strategies included tax policies, public education through media and school, restricting the portion size and availability of sugar-sweetened beverages, and clear labelling. A meta-analysis of all quantitative studies showed that a 10% increase in the price of sugar-sweetened beverages would lead to reduction of about 13% in sugar-sweetened beverage demand, based on the experience of several countries including France, several US states, and Mexico. Other studies have modelled the risks and benefits of substituting sugars added to sugar-sweetened beverages with non-caloric sweeteners. However, we did not identify any studies in which a strategy to gradually reduce sugars added to sugar-sweetened beverages was proposed and systematically assessed with respect to its effect on weight status.

Added value of this study

To our knowledge, our study is the first to propose and assess an innovative strategy for the gradual and stepwise reduction of free sugars added to sugar-sweetened beverages. Our findings suggest that this approach could potentially lead to an effective and sustainable reduction in population energy intake and bodyweight, which would in turn reduce the prevalence of obesity and obesity-related diseases nationwide and lead to cost savings. The previous success of a similar strategy to reduce salt intake suggests that this approach should be both feasible and effective.

Implications of all the available evidence

A systematic and gradual reduction in free sugars added to sugar-sweetened beverages by 40% over 5 years is a feasible and potentially important public health strategy, which could be implemented immediately. The proposed strategy could be used in combination with other approaches for the reduction of sugar-sweetened beverage consumption, such as tax policies, to produce a more powerful effect.

The UK Scientific Advisory Committee on Nutrition (SACN) has recently recommended reducing free sugar intake to no more than 5% of daily energy intake.¹³ Meanwhile, Action on Sugar, a non-governmental organisation similar to Consensus Action on Salt and Health, has produced an action plan to reduce free sugars added to food by 40% by 2020.¹⁴ Sugar-sweetened beverages are a major source of free sugars and should be targeted immediately. The removal of free sugars from sugar-sweetened beverages does not affect the volume and should be easier to achieve than the removal of free sugars from solid foods. Application of this approach to solid food would affect its mass and therefore mass substitutes such as insoluble fibre would be needed to maintain the same weight. In this study, we propose a strategy in which free sugars added to sugar-sweetened beverages are reduced gradually by 40% over 5 years without the use of artificial sweeteners, and assess the effect of this strategy on population energy intake and overweight and obesity.