We’ve all heard it: sugar is not just bad, it’s really bad. It can make us fat, give us cavities and can be linked with all sorts of health problems, from diabetes to heart disease.
Most governments advise their citizens to cut back on foods that contain a lot of sugar, such as soft drinks and sweets like cakes and candy.
But there’s less research behind these recommendations than you might think, according to Stina Ramne from Lund University and her colleagues. Not that many studies have been done on how sugar actually affects our general health, and the studies that have been done have found conflicting results.
There is much to suggest that consuming a lot of sugary soft drinks is associated with a greater risk of illness and premature death, but the same has not been clearly demonstrated for sugar in general.
Ramne and her colleagues tried to remedy this problem by analysing data on sugar consumption, disease and death from two Swedish population surveys with almost 50,000 participants in total.
And the results were a little surprising.
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Higher mortality rates with lots and little sugar
What is not that surprising is that the data show a connection between a lot of added sugar and an increased risk of dying prematurely.
The few individuals in the study who ate a diet with more than 20 per cent of their daily calories from added sugar had a 30 per cent higher risk of premature death.
In a normal diet of 2000 calories a day, 20 per cent would be more than 100 grams of pure added sugar each day, or the equivalent of the sugar in a litre of cola.
The research results clearly suggest that eating a lot of sugar is not good for your health.
But they also show another, and perhaps more unexpected relationship. The risk of premature death was also increased for individuals who ate the least amount of sugar, or less than 5 per cent of their daily calorie consumption.
However, it is important to interpret these results carefully, researchers say.
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A generally unhealthy lifestyle might be part of the problem
“The study cannot say anything about causation,” said Christian A. Drevon, a professor emeritus of nutrition science from the University of Oslo, in an email.
He believes the science in the article is good, but that it also has some limitations, mainly that the data come from self-reported diets.
“The major weakness is that people probably have a number of other unreported lifestyle habits that may influence their health,” Drevon wrote.
Observational studies like the Swedish study can never show what causes what. In practice, this means that the researchers cannot actually say that dietary choices increased the risk of premature death. In other words, something else in the sugar-lovers’ lifestyle might have been at the root of the findings.
For example, the study showed that the group that ate a lot of sugar also had a less healthy lifestyle in general, compared to those who ate just a little sugar.
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Not enough coffee breaks?
Nor can the results confirm that it is dangerous to eat too little sugar. There may be many reasons why people who ate the least amount of sugar had a higher risk of premature death, Drevon believes.
“This group is probably special in that there are many under-reporters who describe unreasonably low consumption of many foods — and they may have an over-representation of different diseases,” he wrote.
The Swedish researchers also wondered if some of these individuals might have known they were at high risk for diabetes and heart disease, and thus were extra careful about cutting sugar.
Another hypothesis is that Swedes have a strong tradition of sharing coffee and cakes with colleagues when they take a break from work. That might mean that Swedes who consume very low amounts of sugar have a poor social life, which in turn is linked to a greater risk of illness and death.