Hyperactive disorders could be rooted in an human foraging instinct triggered by eating fructose-loaded foods like biscuits and ice cream, a study has suggested.
University of Colorado researchers have argued that low levels of fructose trigger a pathway that promotes foraging and the storage of energy as fat.
However, in excessive amounts, the same pathway becomes hyperactive — leading to cravings, impulsivity and aggression that increases the risk of behavioural issues.
These include ADHD, manic depression and bipolar disorder, the team said.
Fructose — or fruit sugar — is found naturally in many plants and honey, but has become more common in modern diets through refined sugar and corn syrup.
Food and drinks containing high levels of fructose today include ice cream, cookies, cakes, apples, grapes, fruit juices, peas, sugary beverages and fruit yoghurts.
In fact, it is estimated that our fructose intake has increased 40-fold since the 18th century — potentially also explaining modern incidences of diabetes and obesity.
While a small amount of sugar daily is fine, according to the World Health Organisation, most people in the UK still consumer too much.
This motivated the introduction of the so-called ‘sugar tax’ on soft drinks, which came into force in April 2018.
Hyperactive disorders could be rooted in an human foraging instinct triggered by eating fructose-loaded foods like biscuits and ice cream, pictured, a study has suggested
‘Behavioral Disorders are common and are associated with obesity and western diet,’ wrote paper author Richard Johnson of the University of Colorado and colleagues.
‘Excessive intake of fructose in the form of high fructose corn syrup and refined sugars may largely contribute to these conditions.’
‘Identification of fructose as a risk factor does not negate the importance of genetic, familial, physical, emotional and environmental factors that shape mental health.’
However, he added, ‘we propose that excessive intake of fructose present in refined sugars and high fructose corn syrup may have a contributory role in the pathogenesis of these conditions.’
‘We do not blame aggressive behaviour on sugar, but rather note it may be one contributor.’
In their paper, the team reviewed previous studies into fructose and its impact on the human body to develop their case.
‘Fructose, by lowering energy in cells, triggers a foraging response similar to what occurs in starvation,’ the researchers explained.
‘This foraging response stimulates risk taking, impulsivity, novelty seeking, rapid decision making, and aggressiveness to aid the securing of food as a survival response,’ they added.
‘While the fructose pathway was meant to aid survival, fructose intake has skyrocketed during the last century and may be in overdrive due to the high amounts of sugar that are in the current Western diet.’
‘Unfortunately, overactivation of this process from excess sugar intake may cause impulsive behaviour that could range from attention deficit hyperactivity disorder, to bipolar disorder or even aggression.’
‘One study, for example, reported subjects who scored higher on ADHD traits tended to also show more exploratory behaviour, consistent with the idea ADHD may reflect a type of foraging response,’ Professor Johnson said.
University of Colorado researchers from the have argued that low levels of fructose trigger a pathway that promotes foraging (illustrated, left) and the storage of energy as fat. However, in excessive amounts, the same pathway becomes hyperactive — leading to cravings, impulsivity and aggression that increases the risk of behavioural issues
Some experts, however, have met the study’s findings with scepticism.
‘This is an elegant and biologically plausible model grounded in sophisticated bioecological thinking,’ developmental psychologist Edmund Sonuga-Barke of King’s College London told the Times.
‘Unfortunately, the notion that there is a consistent link between sugar consumption levels and ADHD in humans was largely debunked decades ago,’ he added.
The full findings of the study were published in the journal Evolution and Human Behavior.
ATTENTION DEFICIT HYPERACTIVITY DISORDER
Attention Deficit Hyperactivity Disorder (ADHD) is a behavioural condition defined by inattentiveness, hyperactivity and impulsiveness.
It affects around five per cent of children in the US. Some 3.6 per cent of boys and 0.85 per cent of girls suffer in the UK.
Symptoms typically appear at an early age and become more noticeable as a child grows. These can also include:
- Constant fidgeting
- Poor concentration
- Excessive movement or talking
- Acting without thinking
- Little or no sense of danger
- Careless mistakes
- Difficulty organising tasks
- Inability to listen or carry out instructions
Most cases are diagnosed between six and 12 years old. Adults can also suffer, but there is less research into this.
ADHD’s exact cause is unclear but is thought to involve genetic mutations that affect a person’s brain function and structure.
Premature babies and those with epilepsy or brain damage are more at risk.
ADHD is also linked to anxiety, depression, insomnia, Tourette’s and epilepsy.
There is no cure.
A combination of medication and therapy is usually recommended to relieve symptoms and make day-to-day life easier.
Source: NHS Choices