Professor Judith Buttriss, Director General of the British Nutrition Foundation, responds to questions on the role of sugars in diet and health.
What are the facts about sugars intake and obesity?
Average non-milk extrinsic sugars (NMES) intakes are higher than recommendations in all age groups in the UK. High intakes have the potential to distort dietary balance and cause inadequate micronutrient intakes. The Scientific Advisory Committee on Nutrition (SACN) reported evidence that high sugars intakes may also be associated with a high energy intake, especially when sugars-sweetened drinks are the source. There are also a number of other dietary short falls – saturated fat and salt intakes are too high and fibre, fruit & vegetable and oily fish intakes are too low. Alongside this, adult obesity has tripled since the 1980s (now 1 in 4); two thirds of adults, 1 in 5 children aged 4-5 years and 1 in 3 children aged 10-11 are overweight or obese. Physical inactivity and a sedentary lifestyle is widespread.
To what extent are sugars responsible for obesity?
Sugars provide calories (4kcal/g) but these are no more responsible for obesity than other calorie sources consumed in excess of energy expenditure (e.g. fat at 9kcal/g and alcohol at 7 kcal/g).
According to recent reviews undertaken to inform draft reports from WHO and SACN, there is moderately good evidence that stringent reductions in free sugars intake would reduce or almost eliminate dental caries but it is less clear that such targets will reducethe prevalence of overweight and obesity. The latter evidence is of mixed quality and uses a range of methodologies.
Is there a significant body of evidence linking sugars to obesity?
Studies where isoenergetic diets are compared show no effect of sugars intake on bodyweight indicating that the mechanism for weight gain islikely to be excess energy intake rather than any physiological or metabolic effect of sugars per se.
WHO described the overall quality of the available evidence for changes in body weight in relation to both increasing and decreasing free sugars intake in adults as ‘moderate’ in quality. The association in children between a reduction in free sugars and reduced body weight was of ‘moderate’ quality, whereas the quality of the evidence for an associationbetween an increase in free sugars and increased body weight in children was considered low.
Should we adopt the draft WHO recommendation to further reduce sugars intake to below 5% of total energy intake per day?
We should wait for the final report from SACN which is due in late spring. In the meantime, the UKrecommendation is a population average at or below 10% total energy (11% food energy).
WHO made three draft recommendations:
- Strong recommendation - reduced intake of sugars throughout the life course
- Strong recommendation - reduced intake of free sugars to less than 10% of total energy. (The <10%Erecommendation is based on ‘moderate quality evidence from observational studies of dental caries’)
- Conditional recommendation - a further reduction of the intake of free sugars to below 5% of total energy.
Conditional recommendation means that there is less certainty about the balance of benefits and harms. The evidence to support this was not from the obesity literature and was graded as ‘very low’ quality by the WHO. It was based on three ecological dental health surveys conducted in Japan in the late 1950s.So, the WHO recommendations are primarily derived from the dental health literature.
The statistics for obesity in the UK certainly create cause for concern – but evidence to support sugar as a primary cause is incomplete at best; getting the cause and associated mitigation strategies wrong couldpose a serious risk to tackling the obesity epidemic effectively. A broader, systems approach, not a single nutrient focus, is required.
Is a sugar tax a good idea?
The calls for a new tax tend to be linked to reducing childhood obesity but the evidence base to support asugars tax being effective is weak. Most of the discussion has focused on beverages. There have been a few short term Randomised Controlled Trials that have manipulated the price of sugar-sweetened drinks (e.g. in canteens) but most of the reported evidence is from modelling.
Modelling cannot readily predict the decisions/unintended consequences of a tax. There is a lack of information about how beliefs and attitudes about sugar and sweetness affect food choices. Will people swap to a cheaper brand of sugar-sweetened drink? Will they buy another source of non-taxed sugars? Will the extra money spent on taxed products affect the amount of healthier foods purchased (especially among poorer people)? Will the taxes be noticed given the wide range in price that already exists for own label vs brand leaders? A tax of 20% has been modelled but the reduction in obesity was very modest.
A number of countries have introduced sugar taxes over the past couple of decades but this has usually been for revenue generation rather than public health gain. Many of the taxes have since been withdrawn. Most of the examples from the US applied a tax of 3-8% and the reduction in sugar sweetened beverage intake was trivial – 7.5ml per day in one analysis with a 10% tax. In comparison taxation on cigarettes is over 300% (and many people still smoke).
Health related food taxes are regressive – poorer people pay a greater proportion of their incomein tax. VAT is already applied to soft drinks and confectionery. If a new tax is introduced, revenue should be ploughed back into public health.
Is the food industry doing enough to reduce sugars content in foods?
Over the past year there have been some major initiatives by retailers to take sugar out of their own brand soft drinks and consequently reduce the energy content. Manufacturers of beverages have also been expanding the ranges of reduced and sugar-free drinks.
By contrast, removing sugar from dry products is far more challenging. For example, if sugar is removed from a breakfast cereal, the energy per 100g will not fall unless the sugar is replaced by fibre (which has a lower energy content). If it is replaced by starch the energy will remain the same; if it is replaced by the addition of other ingredients, such as a combination of nuts and seeds and dried fruit, the energy is likely to increase due to the higher fat content.
Reduced sugar versions of many foods are widely available but consumers need to make the switch to reduce sugars intake. Much more work is needed to understand thehierarchy of motivations that drive people’s choices in terms of sugars, sugar substitutes and sweetness, including the impact of sugars intake on taste perception.
Is reformulation by stealth the best approach?
Reformulation by stealth has had its successes e.g. stepwise reduction in salt. But only so much can be achieved even by stealth, given the importance consumers attach to taste and palatability. Unless the changes span the market, there will not be a level playing field and high sugar options will remain available.
How can we best educate consumers to reduce sugars in their diet?
A recent government survey showed that almost half of parents believe that their family consumes too much sugar; the majority were concerned about their children’s sugar intake.
Food labels provide information on total sugars (rather than free sugars or NMES) and so consumers will need support if they are to distinguish foods containing sugars from milk and fruit from those in which the sugars are ‘free’. (Reducing intake of milk and fruit is not part of the draft SACN and WHO recommendations.)
There is a need for consistent and clear language (e.g. sugars not sugar) that guides people and debunks the myths. Reduced ‘sugar’ does not necessarily mean reduced calories and a red or amber sugars icon on Front of Pack labelling does not necessarily mean that the sugars are ‘free sugars’, e.g. the product could be a dairy product with fruit but no added sugar, or a fruit salad with banana or mango.
What role should government play in helping to reduce consumption of excess sugars?
The Government should be taking the lead in determining the language used to explain sugars content of foods. It is expected to launch a package of evidence-based initiatives later this year. Core to the success of these initiatives will be tackling the myths and helping consumers identify foods/drinks that provide large amounts of ‘free’ sugars/NMES, as this information is not directly available on labels (the Food Information Regulation requires total sugar). The Government should use diverse routes for delivering consistent messages, e.g. via schools, local authority initiatives, upskilling the nutrition knowledge of healthcare professionals.
What is the BNF doing to inform the public about problems associated with too much sugar in the diet?
We have highlighted key statistics on this topic via a series of web pages and through media work (TV, radio and press conferences). The aim has been to support clear messaging and to put information about sugars into the wider context of diet and lifestyle.
We have an on-line training course on nutrition available via our website including information about sugars and health. We also provide resources on nutrition and healthy eating for schools.
Although there has been some improvement over the past decade, the National Diet and Nutrition Survey shows that average sugar intakes are above the 10% total energy intake in all age groups, the highest levels being in teenagers and young adults (18% E in boys aged 11-18 years). Reducing sugars intake remains a major challenge but must be considered in the context of healthy eating.
Professor Judith Buttriss is Director General of the British Nutrition Foundation, Imperial House 6th Floor, 15-19 Kingsway, London, WC2B 6UN, UK
Tel: +44 (0)207 557 7930 Email: J.Buttriss@nutrition.org.uk Web: www.nutrition.org.uk, www.foodafactoflife.org.uk