Siân Astley, Senior Researcher & Communications Manager, EuroFIR AISBL, Brussels (BE)
Perhaps surprisingly, food-based dietary guidelines date back to only the 1990s and, although public health has a longer timeline, advice about healthy living is still relatively recent and, arguably, unsophisticated (i.e., be an appropriate weight for your height, do not smoke, consume alcohol in moderation, eat a mixture of coloured fruits and vegetables, and take regular exercise). Some advice is now more specific, such as at least five portions of coloured fruits and vegetables (with the emphasis on vegetables rather than fruit) and ca. 75-150 minutes of cardio- and two strength-based exercises per week.
Eat more fish, including at least one portion of oily fish per week, was the first advice to be tailored, subsequently, to different sections of the population; men, boys, and post-menopausal women can eat up to four portions of oily fish per week, whilst women of childbearing age are advised to have a maximum of two portions per week. Advice for salt intake (adults – less than 5 g per day) is much more specific. Most of us eat too much (ca. 9-12 g per day) and there is a direct link between hypertension, which is a risk factor for cardiovascular disease, and high consumption of sodium and insufficient potassium (< 3.5 g per day). When it comes to sugar, however, things start to get a bit more complicated. Generally, it is agreed that we eat too much free sugar, defined as “all monosaccharides and disaccharides added to foods by the manufacturer, cook, or consumer, plus sugars naturally present in honey, syrups, and fruit juices”. Non-free sugars are those contained within the cell structure (e.g., sugar in fruit [not including juices] and vegetables, starchy carbohydrates, grains, and lactose), which have less of an impact on blood glucose. Whether free sugars are refined or otherwise makes no difference to their impact once consumed.
Free sugars should not make up more than 5% of energy intake daily, which for an adult is about 30 g or seven sugar cubes (there are about nine sugar cubes in a 330 ml can of cola). The problem for most consumers, however, is that free and non-free sugars are included together in total sugar values on nutrient information labels and, in ingredients lists, sugar might be called dextrose, fructose, glucose, any number of syrups, corn or invert sugar, isoglucose, levulose, maltose, molasses, or sucrose. High sugar products are those with more than 22.5 g total sugars per 100 g, whilst low sugar products should contain 5 g total sugars or less. This complexity in understanding sugar content is one reason why traffic light and other labelling schemes around the world aim to help consumers understand the contributions of individual products to daily intakes of nutrients including sugar.
The most common sources of dietary free sugars are sucrose (table sugar), preserves (e.g., jam) and confectionary (e.g., chocolate, fruit pastilles), alcoholic and non-alcoholic (soda) drinks, biscuits and cakes, dairy products (e.g., sweetened fruit yogurts and fromage frais), and savoury foods (e.g., ketchup, sweet and sour sauces), and many are now available as reduced- or even sugar-free versions. Just as reducing salt is challenging for the industry and consumers, it is not simple to stop adding sugar or remove free sugars altogether without impacts on taste, texture, or other quality aspects. However, sweeteners and sweetness enhancers do not just present technical issues for the food industry. Consumers express considerable scepticism about synthetic compounds (e.g., aspartame), with little or no scientific justification and considerable help from ill-informed sectors of the media, although plant-sourced compounds are viewed more favourably (e.g., stevia).
Some individuals do not like the taste of products containing many substitutes, irrespective of their source, and there has been limited exploration about why this might be, beyond a reluctance to embrace alternatives to sugar. Furthermore, whilst sweeteners and sweetness enhancers have been thoroughly tested and found repeatedly to be safe at dietary levels, currently, our understanding of their role in health (e.g., blood chemistry, gut-brain responses, satiety an associated food intakes, effects on gut microbiota, food choices, age, sex, and weight status) and potential long-term benefits of their consumption, particularly amongst populations that would be benefit most from their use (e.g., over-weight and obese), is limited largely to the impact of reduced intakes of free sugars.
We know even less about whether the use of sweeteners and sweetness enhancers is sustainable, environmentally, socially, or economically.
Biological differences in responses to dietary components have been evident for decades (e.g., cholesterol and saturated fat intake). Potentially, with more in-depth investigation, responses to sugar and/ or sweeteners and sweetness enhancers might also be shown to be diverse amongst humans. One potential influencing factor might be differences in taste. We know some bitter compounds are perceived, and inherited (recessive trait), following a Mendelian pattern. Half of all individuals are aware of the bitterness, but find it acceptable or grow to appreciate it, whilst the remainder of the population divide equally into those who cannot taste these compounds and ‘super-tasters’, who experience an intense aversion not only to the compounds in isolation but also foods containing them. Given sweetness is a basic taste (like bitterness), it is possible that some of us really do have a ‘sweet tooth’, gaining considerable hedonistic pleasure from sugar, and/ or experiencing sweeteners and sweetness enhancers as unpleasant tasting.
Equally, it might simply be that we need to re-educate our palettes away from free sugars, much as we can with salt, where adjusting gradually to smaller amounts in our diet eventually means previously acceptable larger intakes become increasingly unappealing.
Our body needs some sugar, not least because the brain cannot store fuel and requires a continuous supply of glucose (ca. 120 g daily or ca. 420 kcal). Once, we ate free sugars rarely (e.g., honey) and most dietary sugars were in the form of non-free sugars (e.g., fruits and berries, grains, etc.), and we expended considerably energy acquiring these precious resources. Our pleasure in sweet foods probably reflects this past rarity. However, over consumption of free sugars is contributing to weight gain and obesity at individual and population levels, and with this increased risk of non-communicable diseases (e.g., cardiovascular disease, cancer, type 2 diabetes, etc.). Despite hunger still being an issue in the 21 century, nutrient poverty – including over consumption of energy, most commonly in the form of free sugars – is a growing problem globally, not only in developed economies, and we need to find alternatives alongside free sugars that are not just safe but also acceptable, efficacious, and sustainable as soon as possible.