Salt and Obesity

Introduction

Levels of obesity have more than doubled since 1980 worldwide. In 2014 more than 600 million adults aged 18 and over were obese, equivalent to 13% of the global population (1).

Obesity is huge health burden and is associated with many health conditions. These include diabetes, hypertension, cardiovascular disease, sleep apnea and shortness of breath. Once thought to be a health condition of high-income countries, obesity is on the rise in developing nations. In Africa the number of children who are overweight or obese doubled from 5 million in 1990 to more than 10 million in 2014 (1). Many low and middle income countries now face a double burden of communicable disease, such as malaria and HIV as well as non-communicable disease such as obesity. It is also becoming more common to find undernutrition and obesity co-existing in these countries.

Who is at risk of obesity?

Everyone is at risk of obesity if they consume an unhealthy diet or have an unhealthy lifestyle. However, those most at risk include ex-smokers, people of black African descent, inactive individuals and children (or adults) who also have a high intake of sugared-soft drinks.(2)

How does salt contribute?

Whilst salt is not a direct cause of obesity it is a major influencing factor through its effect on soft drink consumption.  Salt makes you thirsty and increases the amount of fluid you drink. 31% of the fluid drunk by 4-18 year olds is sugary soft drinks2 which have been shown to be related to childhood obesity.(3,4)

It has been estimated that a reduction in salt intake from 10 g/d to the WHO recommended level of 5 g/d would reduce fluid consumption by ≈350 mL/d. A study which analysed the sales of salt and carbonated beverages in the USA between 1985 and 2005 showed a close link between the two, as well as a parallel link with obesity. (5)

An analysis of the NDNS for young people (4 – 18years) showed salt intake was associated with both fluid intake and sugar-sweetened soft drink consumption.(2) A reduction in salt intake by 1 g/d was found to be associated with a difference of 100g/day in total fluid and 27 g/d in sugar-sweetened soft drinks. This demonstrates that salt intake is an important determinant of total fluid and sugary soft drink consumption in children. Reducing salt intake could therefore be important in reversing the current trend of increasing childhood obesity.

Figure 1Relationship between salt intake and fluid consumption in children and adolescents. Source: He et al, 2008 (2)

Current Salt Intake and Dietary Advice

Many populations consume too much salt. The World Health Organisation recommends that we consume no more than 5 grams a day but many countries have intakes of 9-12 grams per day – double the recommended maximum.

People with or considered at risk of obesity should ensure that they keep their salt intake below the recommended maximum of 5g. This can be achieved by simple changes, such as consuming less processed foods and checking product labels before purchase.

To further reduce your risk of obesity you should make sure you eat at least 5 portions of fruit/vegetables per day, increase the amount of exercise you do (at least 30 minutes, 5 times a week) and reduce the amount of saturated fat, fat, sugar and calories that you eat.

References

  1. WHO Obesity and overweight, 2016 http://www.who.int/mediacentre/factsheets/fs311/en/ (accessed 08/05/2017)
  2. NHS Information Booklet. Statistics on Obesity, Physical Activity and Diet: England, 2006.  http://www.ic.nhs.uk/webfiles/publications/opan06/OPAN%20bulletin%20finalv2.pdf [accessed 04/09/09)
  3. He FJ et al. Salt Intake Is Related to Soft Drink Consumption in Children and Adolescents: A Link to Obesity?  Hypertension. 2008; 51, 629-634
  4. Ludwig DS et al. Relation Between Consumption of Sugar-sweetened Drinks and Childhood Obesity: a prospective, observational analysis. Lancet. 2001; 357, 505-508,
  5. James J et al.  Preventing Childhood Obesity by Reducing Consumption of Carbonated Drinks: Cluster Randomised Controlled Trial. British Medical Journal. 2004; 328,1237
  6. Karppanen H, Mervaala E: Sodium Intake and Hypertension. Prog Cardiovasc Dis. 2006; 49, 59-75
  7. Hoffman IS & Cubeddu LX. Salt and the Metabolic Syndrome. Nutr Metab Cardiovasc Dis. 2009; 19(2), 123-12