Prohibiting the consumption of certain food products, re-educating the Portuguese population in terms of eating habits and creating healthier alternatives are the ways by which the Government intends to generate behavioural changes. After the order issued at the end of last year, we sought to obtain insights from experts.

Manuel Carvalho is a Psychiatrist at the Santa Maria Hospital (HSM) and a member of the Eating Behaviour Disorders Team of the Psychiatry Department since 2008.

Isabel do Carmo is an Endocrinologist and the Coordinator of the modules on obesity and diabetes of the Metabolic Diseases and Eating Behaviour Course (post-graduate programmes) of the Faculty of Medicine of the University of Lisbon. She was the Founder of the Portuguese Society for the Study of Obesity and of the Eating Behaviour Disorders Centre (Scientific Society) and is a Member of the Portuguese Society of Endocrinology and the Portuguese Society of Diabetology.

We talked with both to find out what the real problem with sugar is and if we consume it out of need or pleasure. We also wanted to understand if our craving increases when we are denied access to something that gives us pleasure.

How does sugar damage our health? Is it the main cause of obesity and diabetes in Portugal?

IC:Sugar is indeed damaging to our health; I am talking about the sugar we find in the sugar bowl, in our kitchen – sucrose –, which is a constituent of the so-called ‘sweets’ and fructose, which is used in the form of a syrup, and is added, not only to what we call ‘sweets’, but also to other food products. We should explain, and healthcare professionals are also responsible for explaining to the general public, that sugars are all carbohydrates, which are divided into complex and simple carbohydrates, known as monosaccharides. Complex carbohydrates are the main nutrient of bread, pasta, rice, couscous, beans, and chickpeas; we eat these every day and they have formed the basis of our diet since the Neolithic period. So, we should not mistake it with the word ‘sugar’ that we commonly use to refer to carbohydrates, which started being rejected as part of one of the many dietary trends that are currently circulating in our society. Sucrose, the sugar we find in sugar bowls, is a disaccharide consisting of two simple sugars, glucose and fructose, which are hexoses. In a glucose tolerance test, glucose is diluted in a liquid and administered to the person who is taking the test to generate a glucose peak. When we eat a piece of sweet fruit we are taking in fructose, which will turn into glucose and generate a peak sooner or later, depending on the fruit. Sooner in the case of oranges, later in the case of apples.

Ever since there was (fortunately) an increase in the availability of food products in more developed countries, particularly since the 1950’s, there was a change in our eating patterns. Unfortunately belatedly in Portugal, together with a reduction of food insecurity, with all its benefits, there was also, as in other countries, a greater availability of both good and bad food products. For example, the consumption of soft drinks has been continuously increasing since the National Statistics Institute (INE) began studying food balances. Sweets and treats became cheaper and available even to those who live below the poverty line. It is logical and natural for a person who has no money to pay for a housing loan, electricity, school books, meat, fish and fruit to have money to buy a cake or a candy bar, which, moreover “stave off hunger”. This easy consumption affects not only the poorest, but all the other social classes as well. The widespread advertising of these products, particularly in TV shows for children and young adults and in internet games, program the impulse to buy into our automatisms, as all commercial advertising does.

We have, thus, been invaded by sugar, which, in the case of sweets, is cooked together with fat and these are the high calorie-dense food products we eat beyond our needs and will therefore lead us to accumulate calories in the form of fat. Eventually, the accumulation of fat leads to obesity. Of course, in addition to this environmental factor we need to consider the genetic factor. We have now identified genes that are a possible breeding ground for obesity. However, several research works allowed concluding, both in the Framingham cohort and in the island of Samoa, that the obesity gene (which, before being identified, was already known as the “economic” gene) only produced obese individuals once there was an abundance of food – a historical/biological moment marked, in both cases, by the end of World War II.

This sugar invasion will require insulin for the cells. The pancreas “burns out” and type II diabetes Sets in.

There is much literature that demonstrates the introduction of fructose into the most common food products. Particularly in processed foods, the introduction of fructose creates a mild sugary taste that agrees with our innate and ancestral taste. There was a time when it was even recommended that sucrose was replaced by fructose. The food industry is very powerful. In fact, fructose has a lower peak and a lower Glycemic Index than glucose and sucrose, insulin levels do not rise as high after its ingestion and its caloric value is slightly lower. But those are not the only references for measuring bad consequences. A critical review of research on the effects of fructose on metabolic and cardiovascular diseases was published in 2017. In this review, the authors reached the conclusion that the ingestion of fructose increases the levels of uric acid, which is a risk factor, not only for gout, but also for cardiovascular diseases. However, a direct relationship between fructose intake and an increase in the occurrence of cardiovascular diseases is yet to be found.

Nevertheless, there are research works in the field of nephrology that prove the toxicity of monosaccharide and sucrose catabolites for the kidneys.

There is also a research work that establishes a link between an overall decrease in carbohydrate intake and improvements in psoriasis. There is also a relationship between sugar intake and a worse intestinal microbiome, i.e. the intestinal bacteria composition (“good” and “bad” bacteria).

In any case, the intake of sweets and, particularly, of sugary drinks, especially those containing fructose syrup, leads to the need to eat more, and drink more; this involves several mechanisms, including the hormonal messengers of the digestive tract, which reach the central nervous system.

What do you think of this ban?

IC: I totally agree with this ban. Telling patients not to drink soft drinks or eat sweets and having them for sale in a display a few meters away was highly contradictory. Our automatism works faster and at lower levels than cognition, reasoning, and willpower. Our ability to make choices is weakened when we are faced with stimuli. And the ban is justified because the “recommendation” issued for school bars, which intended to avoiding a drastic ban, did not work. Only bans were effective in the cases of road safety and smoking as well. Human nature owes a lot to our animal evolution.

Does our body have appetite for sugar, or was it the food consumption culture that made us learn to want it?

IC: Our body has a strong appetite for sugar…That was how the human race survived. When we were hunters-gatherers we ate game, but we were also collecting seeds and fruits containing sugar, and we developed a particular ability to distinguish that flavour. This happened over thousands of years. I believe that men were essentially hunters while women were essentially gatherers. It is not hard to imagine who ate more game and who ate more seeds and fruits. These gender studies are seldom explored, but at the clinic, I see that there are far more women liking sweets than men. Human beings developed an appetite for sugar and, throughout history, they also developed a tendency to resist insulin and, therefore, to save sugar and store it as fat (triglycerides, fatty acids) in times of hunger or extra needs, associated, for example, with pregnancy. The issue is that this appetite was selected, stored. And now we have fat reserves, a strong resistance to insulin and pancreases tired of producing so much of it.

I read an opinion piece that said “now, when a child throws a tantrum when visiting its grandfather at the hospital, it can no longer eat a cake and stay quiet, because the consolation prize is a lettuce leaf”

IC: Children are not limited to a lettuce leaf. They have sandwiches, milk, yoghurt, low-fat cheese. And sweets should be eaten only once a week.

There is a statistical study that states that sugar is eight times more addictive than cocaine. Is eating sugar really the same as taking cocaine?

MC: Despite the fact that we are starting to hear about “food dependence” or “sugar dependence”, a notion proposed by some authors, for what is described as a tendency towards an excessive consumption of food products with a high caloric value (lipids and/or carbohydrates), there is not enough data to prove that this entity is an independent nosological entity, there is no scientific consensus about the matter, and no clear neurobiological correlation has been found as of yet. So, it is not listed in the DSM-V (Diagnostic and Statistical Manual of Mental Disorders).

Could you tell me about something called dopamine, which makes us feel good? And what is the relationship between dopamine and sugar?

MC: Dopamine is a neurotransmitter (a chemical substance produced by neurons that allows the transmission of information between nerve cells), which plays many important roles in the brain and the rest of the body. The brain has several dopaminergic pathways, one of which plays an important role in the reward-motivated behaviour system. Most rewards increase the level of dopamine in the brain (a positive experience, a pleasurable activity, a prize, a good meal, etc.), something that also happens when using additive substances. So, there is an attempt to correlate the increase of dopamine resulting from the excessive consumption of sugar with the one that results from the consumption of substances with proven addictive potential. Dopamine is also involved in movement control, learning, mood, emotions, cognition and memory

Isn’t the prohibition the ultimate temptation to want more of what used to be available to everyone?

MC: I believe that limiting the sale of food products rich in simple, high-calorie carbohydrates in healthcare-related facilities, as well as in schools, could foster the availability of food products that are usually seen as “healthier” or “less harmful” to health. Perhaps we can look at the proposed measure as a way of increasing the availability of a variety of food products that are currently harder to find in bars and restaurants, also because they are more difficult to preserve, such as fruit, yogurt, salads and others, and not as a restriction on what is sold. So, there may be an incentive to diversify the type of food products that are offered, namely healthier food products. How often do we go to a cafe or a bar and end up choosing a cake or a salty snack because it’s readily available and because there is no alternative? Offering healthier alternatives, particularly in places that should be related to the promotion of health and good eating habits, may be one way of contributing to improve the population’s eating habits. Dietary habits are introduced from an early age and are related to the habits of our parents and family, and the promotion of a Mediterranean diet in schools, hospitals and healthcare centres may prevent several diseases, including obesity.

Joana Sousa

Editorial Team