The thought of a cupcake, skillfully frosted with fluffy vanilla icing, may put a smile on your face, but research suggests that, in the long term, a sweet tooth may turn that smile into a frown – but not for the reasons you think. In a new study, published in Scientific Reports, my colleagues and I found a link between a diet high in sugar and common mental disorders.
The World Health Organisation recommends that people reduce their daily intake of added sugars (that is, all sugar, excluding the sugar that is naturally found in fruit, vegetables and milk) to less than 5% of their total energy intake. However, people in the UK consume double – in the US, triple – that amount of sugar. Three-quarters of these added sugars come from sweet food and beverages, such as cakes and soft drinks. The rest come from other processed foods, such as ketchup.
At the same time, one in six people worldwide suffers from a common mental disorder, such as a mood or anxiety disorder. Could there be a link between high sugar consumption and common mental disorders?
Earlier research, published in 2002, examined the link between depression and sugar consumption in six countries. The researchers, from Baylor College in the US, found that higher rates of refined sugar consumption were associated with higher rates of depression.
Since then, a handful of studies have investigated the link between added sugar consumption and subsequent depression. In 2011, researchers in Spainfound that when they grouped participants based on their commercial baked food consumption, those who ate the most baked food had a 38% increased chance of developing depression compared with those in the group with the lowest intake. The association remained even after accounting for health consciousness and employment status.