All children like sweet foods. Maybe now we know why.

All humans appreciate sweetness in foods. However, this preference for sweetness is not constant throughout life; it’s age-dependent, being strong in children but relatively weak in adults. The transition occurs in late adolescence, in both sexes. This is not a western phenomenon – it is experienced in all races and cultures.

But why is it so? What purpose does the preference for sweetness in childhood serve? Is it a problem? And should nutritionists intervene to manage children’s preference for sweetness?

Children’s dietary preferences

As any parent knows, when it comes to food children are not little adults. They have a stronger preference for sweetness and a greater dislike of bitterness than their parents, even though both genes and environment are shared. The dislike of bitterness presumably evolved to discourage the consumption of potentially toxic plant foods as dietary habits developed. Children’s wariness of Brussels sprouts may have more to do with their genes than we give them credit for.

The preference for sweetness helps to shape the diets of children in another way, ensuring the appeal of breast milk to newborns and encouraging the consumption of nutritious foods, such as fruits, later in life. So, it comes as no surprise that the sweetness of foods is a key factor determining which foods children consider acceptable and unacceptable to eat.

Why does it change?

Why does the heightened preference for sweetness in children decline during the journey to adulthood? Currently, there is no accepted explanation but there are several hypotheses focussing on physiological, hormonal and psychological mechanisms.

The physiological case states that a strong preference for sweetness throughout childhood encourages intake of sufficient calories to support growth and maturation. The hormonal argument notes that puberty is associated with changes in relation to insulin and leptin, both of which are known to be linked with lower preference for sweetness. Perhaps this is the body’s way of blowing the whistle on high calorie intake as the growth phase reaches its conclusion. Alternatively, perhaps the apparent decline in preference for sweetness during adolescence is driven by psychological factors, such as heightened awareness of body image and body weight.

Challenging findings

These potential mechanisms were explored in a study conducted in the United States and the results were challenging. Stage of puberty was not associated with preference for sweetness, indicating that hormonal changes played little role in its decline during adolescence. And there were no associations with any of the psychological factors. However, the researchers found an association between linear growth and sugar preference in childhood which they described as an ‘elegant link between taste preferences and biological need’. The implication is that children’s preference for sweet foods is not only innate and universal; it’s a reflection of basic biology.

Then, a very thought provoking statement: … if we accept sugar liking as a natural concomitant to growth in childhood, then it brings into question the assumption that this propensity is invariably unhealthy and undesirable among this age group.

Now there is food for thought.

Image: source

The dilemma for nutritionists

Given that this generation of nutritionists is charged with the responsibility of dealing with an obesity epidemic, how should we interpret this information and how should we act? Should we see children’s innate preference for sweetness as a vulnerability to a modern diet with more sweet foods than nature ever intended? Is our job to intervene and encourage control of both children’s biological urge to eat sweet foods and the composition of the foods available?

Alternatively, if children’s preference for sweetness is inevitable, should we just accept it and work within these boundaries, encouraging healthier options among sweeter foods? For example, if a child wants a sweet drink, there is always the option of a low-calorie soft drink. Or a sweetened milk drink – at the least the calories will be accompanied by nutrients and the associated satiety.

This is one of those idealism versus pragmatism dilemmas that nutrition throws up all the time. No doubt the profession will divide right down the middle on the issue.