You can add one more entry to the good old "How sugar is bad for you list." Except this one is a bit more surprising.
Eating a lot of sugar makes you fat - and we eat way more sugar than we need. But it's not just that. Sugar causes cavities, increases the risk of heart disease, can lead to insulin resistance (which leads to diabetes), and is even associated with some types of cancer. As Anika Knüppel at the University College London and her colleagues found out, it can even make you more depressed or anxious.
They studied data from over 8,000 adults who were asked to fill out health questionnaires regularly since the 1980s. The participants' weight and height were also routinely measured, and they undertook regular mental health surveys. Among other things, they had to answer things like "how often do you eat cake" or "how often do you drink fizzy drinks."
After looking through the data, they found that men who consumed more sugary foods and drinks were 23 per cent more likely to develop depression or anxiety. Ironically, this trend was not present in women, contradicting one of the most common stereotypes.
"I had a feeling we'd see the 'Bridget Jones-like women eat chocolate' idea," says Knüppel. "But it turns out people underestimate that men's sugar intake is super high." However, women only made up one third of the people included in the study, so it is possible sugar may have a similar effect for women that wasn't picked up due to the smaller sample size.
It's also interesting to note that depression and anxiety themselves did not affect sugar consumption, so people who eat a lot of sugar are more likely to develop depression or anxiety, but the reverse is not true.
It's not really clear why this is happening, and the study didn't aim to explain it. It's just a correlation that was established, no causation was discussed. However, there are several mechanisms which could explain it, Knüppel says. Someone who eats a lot of sugar might be hit stronger when blood levels go low, and in the long run, this could have taxing effects. It's also possible that sugar increases inflammation which in turn could affect depression.
It's also important to keep in mind that sugar isn't the main driver of depression or anything like that. But it can be significant, and it can just be that something that pushes you over the edge. It's another reason to keep an eye on your sugar consumption.
"There are numerous factors that influence chances for mood disorders, but having a diet high in sugary foods and drinks might be the straw that breaks the camel's back. There is increasing evidence for the physical damage sugar has on our health. Our work suggests an additional mental health effect."