High intake of sugary foods and drinks may harm men's mental health, suggest researchers.
Researchers found that men who consumed more than 67 grams of sugar daily from sweetened foods and beverages were much more likely to develop anxiety, depression, and other common mental disorders after 5 years, compared with men with a lower daily sugar intake.
Lead study author Anika Knüppel, of the Institute of Epidemiology and Public Health at University College London in the United Kingdom, and colleagues recently reported their findings in the journal Scientific Reports.
The Dietary Guidelines for Americans recommend that added sugar - that is, sugar that is added to foods and drinks during manufacturing or that we add ourselves - should make up no more than 10 percent of total daily calories for adults and children.
According to the Centers for Disease Control and Prevention (CDC), however, adults aged 20 and older consumed around 13 percent of their total daily calories from sugar between 2005 and 2010, with most added sugars coming from sugar-sweetened beverages, cakes and cookies, candy, and ice cream.
Previous studies have also indicated that there may be a link between high sugar intake and increased risk of depression, though Knüppel and team note that researchers have suggested that this association may be down to "reverse causation."
"Reverse causation refers, in this context, to the possibility that a mood disorder may lead to higher sugar intake, so that the diet-mental health association is wholly or partly the result of poor mental health rather than of high sugar intake," the authors explain.
For this latest research, the team set out to gain a better understanding of whether sugar consumption might influence the development of mental health disorders.
High sugar intake and mental health
Knüppel and colleagues analyzed data from the Whitehall Study II, including 10,308 participants (66.9 percent of whom were men) who were aged between 35 and 55 years during the first phase of the study.
Over 22 years of follow-up, participants completed food frequency questionnaires at four time points. The researchers used information from these questionnaires to calculate the participants' daily sugar intake from 15 sweetened foods and beverages, including soda, cakes, and tea and coffee.
Subjects also completed general health questionnaires and interviews at numerous time points during follow-up, which the team used to identify participants' development of common mental health disorders, such as anxiety and depression.
Compared with men who had lowest daily sugar intake (under 39.5 grams daily), men who had the highest daily sugar intake (more than 67 grams daily) were 23 percent more likely to develop common mental disorders 5 years later.
This finding remained after accounting for a number of possible confounding factors, including sociodemographic factors, other dietary factors, and the presence of other health problems.
No link between incident mental health disorders and sugar intake was observed for women.
Reverse causation does not explain findings
Additionally, the researchers found that men and women with mood disorders who had a high daily sugar intake were more likely to develop depression after 5 years, compared with those who had a lower sugar intake.
However, this association diminished once sociodemographic and other dietary and health factors were considered.
Interestingly, the team also found that sugar intake among men and women with mental health disorders was no higher than that of men and women without mental health disorders. This thwarts the theory that the link between high sugar intake and greater risk of mental health disorders is down to reverse causation.
Based on their findings, Knüppel and team believe that we should move away from eating sugary foods as a means to boost mood, as it may do more harm than good.
"Sweet food has been found to induce positive feelings in the short-term. People experiencing low mood may eat sugary foods in the hope of alleviating negative feelings. Our study suggests a high intake of sugary foods is more likely to have the opposite effect on mental health in the long-term."