Medical myths: All about sugar
Written by Tim Newman on January 18, 2021 — Fact checked by Anna Guildford, Ph.D.
In this episode of Medical Myths, we discuss some of the many misunderstandings surrounding one of the sweetest nutritional topics: sugar.
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Today is the first day of Sugar Awareness Week. With this in mind, the Medical Myths truth wagon will take a cruise to Sugar Town via Misconception Lane.
Over the centuries, this crystalline sweetener has invaded everyone’s snacks, drinks, guts, and minds. It has caused its fair share of controversy, too.
Although everyone is familiar with sugar as a concept, we’ll start with a brief explainer.
What is sugar?
Sugar is a soluble carbohydrate — a biological molecule consisting of carbon, hydrogen, and oxygen atoms. Other carbohydrates include starch and cellulose, which is a structural component of plant cell walls.
Simple sugars, or monosaccharides, include glucose and fructose. Granulated sugar is a compound sugar, or disaccharide, known as sucrose, which consists of glucose and fructose. During digestion, the body breaks down disaccharides into monosaccharides.
Still, the chemistry of sugar does not explain its infamy. The substance gained its dastardly reputation because it tastes delicious and, if consumed too freely, is bad for our health.
1. Sugar is addictive
Some experts believe sugar is an addictive substance. For instance, the authors of a controversial narrative review in 2017 write:
“Animal data has shown significant overlap between the consumption of added sugars and drug-like effects, including bingeing, craving, tolerance, withdrawal, cross-sensitization, cross-tolerance, cross-dependence, and reward and opioid effects.”
However, this review focuses on animal studies. As the authors of another review explain, “there is a methodological challenge in translating this work because humans rarely consume sugar in isolation.”
Dr. Dominic M. Dwyer from Cardiff University’s School of Psychology explains, “Although certainly present in some people, addiction-like behaviors toward sugar and other foods are present only in a minority of obese individuals. However, we should remember that sugar can drive the overconsumption of foods alongside its addiction-like potential.”
Along similar lines, Prof. David Nutt, Chair of the Independent Scientific Committee on Drugs and head of the Department of Neuropsychopharmacology and Molecular Imaging at Imperial College London, writes:
“There is not currently scientific evidence that sugar is addictive, although we know that sugar has psychological effects, including producing pleasure, and these are almost certainly mediated via brain reward systems.”
It is worth noting that even though health experts do not class sugar as an addictive substance, that does not make it healthful.
2. Sugar makes kids hyperactive
This is perhaps the most common myth associated with sugar: eating candy causes children to run wild. In fact, there is no scientific evidence that sugar increases hyperactivity in the vast majority of children.
For instance, a 1995 meta-analysis in JAMA combined data from 23 experiments across 16 scientific papers. They concluded:
“This meta-analysis of the reported studies to date found that sugar (mainly sucrose) does not affect the behavior or cognitive performance of children.”
However, people with children may doubt the truth of this conclusion. For those interested in reading more, we address this myth extensively in an earlier edition of Medical Myths.
3. Sugar causes diabetes
Another relatively common myth is that sugar directly causes diabetes. However, there is no direct link between the two. The confusion perhaps arises because there is an intrinsic association between blood sugar levels and diabetes.
The story is a little more complicated, though. Overweight and obesity are risk factors for type 2 diabetes, and consuming high levels of sugar does increase the likelihood of developing overweight or obesity. However, sugar is not the direct cause of type 2 diabetes.
As for type 1 diabetes, dietary and lifestyle factors do not play a part.
4. Avoid fruit when dieting
Fruits are delicious, partly because they are sweet, thanks to naturally occurring sugars. Because of their sugar content, some people believe that we should avoid eating fruit when maintaining a moderate weight.
This is a myth. Fruits contain a range of healthful compounds, including a variety of vitamins and minerals, and fiber.
Fruit consumption is associated with health benefits, including a reduced mortality rate.
One study concluded that freeze-dried mango “does not negatively impact body weight but provides a positive effect on fasting blood glucose.” Another study found that consuming blueberries enhanced insulin sensitivity.
However, it is worth noting that the two studies mentioned above received grants from the National Mango Board and the United States Highbush Blueberry Council, respectively.
Make of that what you will, but there is no doubt that consuming fruit benefits health. Removing it from our diet to reduce sugar intake would be a mistake.