How can sugar cause caries and weight gain?

Author- Dr Akshay Alawani ANutr, Faculty Head, INFS

'Control or limit sugar' is a piece of general health advice shared by professionals and authorities to promote health. Contrarily, there is a strong argument that it's the weight loss that improves health reports in overweight, and hence the focus should be on energy deficit. Many swear by the 'flexible dieting' method which suggests reducing calories but at the same time allows indulging (in the limit) in favourite snacks. The known evidence will help you make a rational decision for yourself.

'Free-sugars' (mentioned only as sugar later) are monosaccharides and disaccharides (single sugar units and two sugar units joined together) that are added to foods externally by the manufacturer, cook or consumer. These sugars are naturally present in honey, syrups and unsweetened fruit juices.

The causative relation of excess sugar consumption, mainly sucrose, to dental caries is well established in dental science. It was observed that reducing sugar intake to less than 10% of total calories leads to a reduction in dental caries. 'Do not eat too many candies' advice is quite robust. Sucrose promotes plaque (yellowish layer) formation over teeth which eventually wears out tooth surface and causes caries. A few years back, the UK took some decisive steps to reduce sugar intake on a national level (revising guidelines to 5% and increasing tax on high sugar products), which showed slight but notable development in children's oral health. The policies were not largely successful in reducing sugar intake, but the main criticism they received was their failure to reduce obesity. The rate of rising in obesity persisted.

The point of sharing this story is that the responsibility of healthy weight restoration cannot be alone achieved with sugar reduction. Undoubtedly, calories from sugar provide poor satiety, and they are not well-compensated. Put easily, a burger vs burger and coke lunch – they both fill you up equally. The addition of coke in your meal indeed brings calories, but it doesn't qualitatively contribute to anything. However, if you eat another burger instead, it is more likely to keep you full longer, and you may have a lighter dinner. A meta-analysis (study of many studies) presented similar evidence. Then why does controlling sugar intake doesn't translate to at least some weight loss? The reason lies with the nature of the obesity challenge.

Obesity has complex roots that include factors such as individual psychology, societal influences, and physiologic adaptations that work together in different ways to cause a gain in weight. So the expectation that the reduction in the intake of just one low-satiety component (sugar) will reduce weight is overoptimistic. It might get compensated from elsewhere. For example, we imagine that an avoided coke will get compensated with water, but as mentioned before, it mostly gets compensated by another dense energy source like a burger.

Calories from sugar add no qualitative benefit to the diet. Controlling or avoiding sugar intake is undoubtedly essential, which will surely improve oral health. However, to lose weight and maintain that more intelligent efforts are needed.

References:

• Alawani, Akshay. (2020) 'Dietary Sugar Intake'. University of Surrey. Unpublished essay.

• Amies-Cull, B., Briggs, A. D. M. and Scarborough, P. (2019) 'Estimating the potential impact of the UK government's sugar reduction programme on child and adult health: Modelling study', BMJ (Online). BMJ Publishing Group, 365. doi: 10.1136/bmj.l1417.

• Koulourides, T. et al. (1976) 'Cariogenicity of Nine Sugars Tested with an Intraoral Device in Man', Caries Research. Karger Publishers, 10(6), pp. 427–441. doi: 10.1159/000260235.

• MacLean, P. S. et al. (2011) 'Biology's response to dieting: The impetus for weight regain', American Journal of Physiology - Regulatory Integrative and Comparative Physiology. American Physiological Society Bethesda, MD. doi: 10.1152/ajpregu.00755.2010.

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• Public Health England (2018) Public Health Profiles, Public Health Outcomes Framework. Available at: https://fingertips.phe.org.uk/profile/public-health-outcomes-framework/data#page/4/gid/1000042/pat/15/par/E92000001/ati/6/are/E12000004/iid/20602/age/201/sex/4 (Accessed: 13 March 2020).

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• Strasser, B., Spreitzer, A. and Haber, P. (2007) 'Fat loss depends on energy deficit only, independently of the method for weight loss', Annals of Nutrition and Metabolism, 51(5), pp. 428–432. doi: 10.1159/000111162.