Sugars make you stupid

Sugar is copping it in the media of late. A few weeks ago we reported on calls for a sugar tax to help reduce sugar consumption and its effects on weight gain, heart disease, and the modern epidemic of diabetes. If these health effects of sugar don’t encourage you to cut down a little, and while we wait for a sugar tax to heighten the motivation, maybe it will make sense to you to cut refined carbs if it is possible that they might be making you dumb.

It is hard to get an exact line on how much sugar Australians consume annually. The ABS (Australian Bureau of Statistics) gave up publishing the sugar consumption statistics in 1999, a statistic they had been collecting for 60 years. The reason they stopped publishing on this topic was the difficulty in producing anything meaningful. You can measure sugar produced and imported or exported without trouble but the problem for the ABS came when they tried to measure how much sugar of varying types was added to pre-packaged foods brought into the country. Consumption of refined sugar probably stands at about 60 kilograms per person per year in Australia, that’s a lot but it does not take into account sweeteners used in processed foods and soft drinks. These products contain not only sugar itself (sucrose) but other “sugars” like high fructose corn syrup which is six times sweeter than sugar and is very popular in soft drinks, particularly those manufactured in the United States.

The use of fructose as a sweetener is a big problem. It is not an issue when the fructose comes from fruit since in that form there is fibre and other nutrients present that buffer the fructose impact. As an isolated sweetener however, fructose is bad news.

Fructose is not absorbed straight into all of your cells the way that glucose is. Instead, fructose must be dealt with by your liver. This puts stress on your liver and the result is elevated uric acid, cholesterol, and blood pressure. Fructose also causes inflammation and decreases sensitivity to insulin. The action of fructose in your liver also reduces the levels of an appetite control hormone called leptin. This combined effect of fructose (and its independence of insulin) may interfere with your ability to control your appetite. This may explain why some soft drinks for instance, fail to make you feel full even though you are consuming lots of extra kilojoules.

The real nail in the coffin though is that new research is suggesting that high levels of fructose consumption can make you stupid.

In the new research two groups of rats were both given a fructose solution as their drinking water for six weeks. In addition, one of the groups also received omega-3 fatty acids which protect the connections between neurons in your brain.

Five days before starting the experiment the rats were fed standard rat “chow” and tested how well they were able to navigate a maze with numerous holes but only one exit. Visual cues were placed throughout the maze to help the rats learn and remember their way.

After six weeks on the fructose solution the two groups were tested on the maze again. The group of rats who had been given omega-3 fatty acids completed the maze much faster than those who had not been given omega-3s. The rats who had only been given fructose also showed reduced activity in the synapses between neurons in their brains. Their behaviour in the maze showed that they had reduced memory and a decline in ability to think clearly.

Examination of the rats showed that six weeks of exposure to fructose had caused an increased resistance to insulin and that insulin had lost much of its power to influence brain cells. The omega-3 fats however, reduced these changes significantly.

On the one hand then omega-3 fats protect against some of the damage that a high sugar diet can do. It also seems that a high sugar diet in the form of fructose can interfere with how brain cells metabolise sugar into energy required for processing thoughts and emotions. In essence, too much fructose, not buffered by omega-3 fats, made these rats dumb.

It’s only a hop, skip, and jump across sweetener creek to imagine how the massive consumption of sugars in the modern diet is impacting the modern human’s capacity for thinking. It’s cold comfort, but now we understand why soft drink and processed food manufacturers are so eager to advertise during reality television programs: they are building their market.