Brain research finds new appetite- suppressing nutrient
21 January 2010
A vitamin-like nutrient called citicoline could be the next weapon in the battle against the obesity epidemic in developed countries.
Scientists at McLean Hospital and professors at Harvard Medical School in the US have explored the effects of Cognizin citicoline supplementation on the neurobiological systems involved in appetite and eating behaviour regulation.
They found it has potential to reduce food cravings and increase feelings of satiety. Their work was published in the January issue of the International Journal of Eating Disorders.
Dr Deborah Yurgelun-Todd, then Associate Professor of Psychiatry at Harvard Medical School and McLean Hospital, monitored the effect of nutrients such as citicoline on the dopamine neurons in the brain, which have been shown to have a direct effect on the motivation to eat and the rewarding value of food.
She explains, "We know that appetitive responses are highly regulated by homeostatic mechanisms in the hypothalamus portion of the brain, including hormones and dopamine. Previous research has measured the effect that hormones and dopamine — and nutrients like citicoline that may increase these compounds — may have in a variety of substance abuse and addictive behaviour disorders such as cocaine addiction and pathological gambling. In this latest study, we applied a similar set of theories to study citicoline and both regulation of food intake and motivation to eat."
This study compared the effects of open label treatment with citicoline at two different dosages (500 mg/day versus 2,000 mg/day) for six weeks on changes in appetite ratings (using questionnaires), weight, and brain response to images of high-calorie foods (using magnetic resonance imaging).
In the stimulation phases of the study, at baseline and following the 6-week treatment, participants were monitored via MRI while viewing a series of colourful visuals that included both high-calorie foods and non-food objects in a quick 150-second series of photos. Each image was viewed for a brief, three seconds. Study participants included 16 healthy adults (8 men, 8 women) ranging from 40 to 57 years of age, and across a range of Body Mass Index values from 20 to 38.
Appetite ratings did decline significantly for the group as a whole, as assessed by questionnaire responses. The decline for the high-dose group did reach significance, however the low-dose group did not. There was no significant weight change in weight for either group overall, although individuals did show weight loss.
"The most interesting findings are that with the use of brain imaging studies we are able to visualize the differences between baseline and after 6-weeks of citicoline supplementation. Scans from the high-dose group illustrate the shift in how their brains interpreted the food images," explains Yurgelun-Todd, now the Director of the Cognitive Neuroimaging Laboratory and The Brain Institute at the University of Utah.
There are three regions of the brain that are particularly relevant to appetite control and behavioural inhibition: the lateral orbitofrontal cortex, the insular cortex and the amygdala. In a direct correlation, those high-dose participants who had the greatest activation of these three portions of the brain saw the greatest decline in appetite for high-calorie foods.
"The citicoline may have affected their appetite by stimulating regions of the brain used to normalize or regulate their response to the food images. These three regions may help the participant see food as less rewarding, and therefore have a lesser desire to eat it," added Yurgelun-Todd.
Citicoline has a number of different mechanisms of action, and it has yet to be determined which may be responsible for the changes in brain responses.
The vitamin-like nutrient has been known to function as a precursor of phospholipid and acetylcholine synthesis; citicoline also enhances of the release of neurotransmitters such as norepinephrine and increased synthesis of phospholipids including cardiolipin and sphingomyelin.
Citicoline has also been recognized for neuroprotective effects with stroke or other brain injuries, protection from cognitive decline. Though this research is still preliminary, researchers will continue to investigate whether these effects are related to citicoline properties, or from the effect citicoline has on the dopamine or other systems.