Research on rats has found that sugar is more addictive than opioid drugs such as cocaine, and that there can be withdrawal symptoms such as depression and behavioural problems when people try cutting out sugar completely. Should we be treating refined sugar with even more caution?
A review published in the British Journal of Sports Medicine has claimed that refined sugar has a similar effect on the brain as illegal drugs such as cocaine.
In studies on rats, it has been found that there are significant similarities between eating sugar and drug-like effects such as bingeing, craving, tolerance, withdrawal, dependence and reward.
The research scientists claim that sugar alters mood and can induce reward and pleasure, in the same way drugs such as cocaine affect the brain. They cite studies in rats where sugar was preferred to cocaine, and studies in mice where the mice experienced sugar withdrawal symptoms.
The review looked at all the existing research about sugar and its potential addictive qualities.
Lead author of the review, James DiNicolantonio of Saint Luke’s Mid America Heart Institute, has said that, unlike salt, there is no ‘aversion signal’ to sugar – a built-in safety mechanism that protects us from eating too much salt. This isn’t present in sugar and so people can eat a lot of it and still want more. Whereas once people have eaten enough salt, they don’t want any more.
Of the withdrawal symptoms the authors of the review claim are present when giving up sugar completely, DiNicolantonio said: “Withdrawal symptoms from sugar come from dopamine deficiency in the brain. This may lead to symptoms such as attention deficit hyperactivity disorder, and it may even create a similar state in the brain as found in patients with depression.”
Dopamine deficiency can be temporarily relieved by eating more sugar. DiNicolantonio claims that sugar can over-ride our self-control mechanisms – hence the term ‘sugar fix’.
According to Public Health England, sugar intake in England is nearly three times the recommended limit, and that consumption of sugar and sugar-sweetened drinks is particularly high in school-age children.
On average, sugar contributes between 12% and 15% of our energy intake, whereas the Scientific Advisory Committee on Nutrition recommends that sugar should not exceed 5% of our total dietary energy.
Eating too much sugar can lead to weight gain, which then increases the risk of heart disease, type 2 diabetes, stroke and some cancers. But sugar also alters our mood and provides feelings of being rewarded and euphoria; hence the comparison to illegal drugs.
However, there are opponents of the argument around sugar and addiction, with some other experts disputing the claim. An article in the journal Clinical Nutrition in 2010 claimed that there is no support from studies on humans that sugar is physically addictive or that addiction to sugar plays a role in eating disorders.
And another study of research on the effect of sugar on rats argued that the addiction-like behaviours that are seen are only if the animals are restricted to having sugar two hours every day; whereas if they are allowed to have it whenever they want it, these behaviours aren’t seen.
Opponents of the theory argue that there is a reward system in the brain that controls eating behaviour, but, unlike sugar, illegal drugs such as cocaine hijack those systems and turn the normal controls off. They also argue that rats choosing sugar over cocaine in some experiments is not surprising as animals will always choose the substance that will give them energy.
What all scientists agree on is that people should try and reduce the amount of sugar in their diet, for health reasons and to protect their teeth from tooth decay.
While some argue that cutting out sugar completely means we won’t get addicted, others reason that there are much more nutritional foods that we should be eating instead. Sugar doesn’t offer anything from a nutrition perspective, and filling the diet with sugar can lead to over-eating and weight gain.