The fireworks in our heads - what does chocolate do in our brains?

The Germans eat about 11 kilo of chocolate a year on average; a big part of that probably around Christmas. Modern measurement methods are able to show what chocolate and sugar do with our brains.

It is said that chocolate makes you happy, but not everybody does believe in that saying. Still, it is true and Dr Swen Hesse can even see it. Not looking at the happy smile on his patients faces, but in images of their brain that he is able to take with the so-called PET, the positron emission tomography. "During christmas, when people eat a lot of sugar and chocolate, there is a downright light orgy in the brain," says the specialist for nuclear medicine, "that is because sugar is reflected by little colourful explosions in the brain." Fireworks in the head.

"We want to be able to have a better explanation for eating disorders and adiposity," says Dr Swen Hesse. Processes in the brain of a morbidly overweight person are executed differently than the same processes in the brain of a normal weight person. The chemical changes behind that are, however not very well studied so far. Swen Hesse will study those in his research project at the IFB AdiposityDiseases. His main focus will be the studying of changes of particular semiochemicals, so-called neurotransmitters. For example they are connected with a certain emotional reaction during eating. A well-known semiochemical is serotonin, widely known as "happy hormone". "The more serotonin there is, the better our mood is. The preliminary stage of this substance, the tryptophan, is contained in a lot of food, e.g. chocolate, bananas, fish, dairy products, poultry and eggs," explains Dr Swen Hesse. This connection backs up the assumption that chocolate makes people happy.

The body needs a balance of its semiochemicals

Additionally to that more semiochemicals are of interest to him: cannabinoids that inhibit an appetizing effect, noradrenalin and dopamine and also appetite-inhibiting substances such as cocaine. Dopamine especially is responsible for desire - not only for food. "Without dopamine, noradrenalin and serotonin our brain would not be able to process information. Their individually different co-operation creates satisfaction and mental balance," says Hesse. "The interplay of all those semiochemicals that we investigated with the PET also controls appetite, satiation and they dictate our choice of nutrition." He therefore assumes that the balance among the semiochemicals has to be represented in a balanced nutrition - following the slogan "the body will get exactly what it needs." It is therefore also possible that special diets will lead to changed concentrations of those substances.

The hypothalamus shows what eating causes in our brains

Eating and adiposity are connected to the activiation of certain brain areas, modern neurosciences have already proven as much. What eating causes in the human brain can be seen best in the hypothalamus: "That is apparently the most important brain area for weight regulation. In evolutionary terms it is a very old region, conducting many basic needs such as hunger and thirst." Additionally the hypothalamus initiates the production of the stress hormone cortisol wich helps us react in dangerous situations chosing fight or flight. Nowadays it is a known fact that constant stress leads to weight gain because the sugar intake of the body is defective and fats are increasingly taken in. "With slim persons stress leads to moderate increase of cortisol levels, but to a heavy increase with overweight persons, so you can assume differences in cortisol production - especially under chronic strain. We want to put those differences in perspective to the availability of seratonin in the brain."

Connection between BMI and serotonin concentration

But not only stress but also daylight has a heavy influence on our appetite. "During the dark season the consume of sweets increases climaxing around christmas in a true light and sugar orgy," says Hesse. A reason for that is that both, light and sugar, release the mood-improving serotonin. The low serotonin level is easily increased by sugar during the dark season.
"Our first analyses suggest that there is a difference in availability of serotonin binding site that is subject to the body-mass-index (BMI): persons with a high BMI exhibit a bigger number of binding sites in the hypothalamus that persons with a normal BMI. This could be an expression of a serotonin shortness that would explain the increased sugar intake of adipose persons," says Hesse, "we will deepen our research on this now."

PD Dr. Sven Hesse is researching the role of neurotransmitters in the development of eating disorders and adiposity at the IFB AdiposityDiseases. The specialist for nuclear medicine uses PET for that, which makes those reactions in the brain visible.