With the advent of the development of complete human genetic profiles scientists are able to develop personalized nutrition plans based on an individual’s genetic make up and how specific genes react to nutrition. Epigenetics, (the influence of the environment, which includes nutrition, on genes), has become one of the fields with specific research focus on what can be done to prevent certain health conditions or diseases.
In one genome wide association study originating from Italy, Dr Nicola Pirastu and Dr Antonietta Robino, from the University of Trieste and the IRCCS Burlo Garofolo Institute for Maternal and Child Health, Trieste, Italy, investigated the novel genes and pathways involved in taste perception and food preferences, and to investigate their implications in protecting against or predisposing to diet-related disorders such as overweight, obesity, and diabetes. “To date most studies have focused on specific taste receptors, especially bitter ones, and this has been partly successful in an attempt to understand the genetics behind the perception of specific compounds such as caffeine and quinine,” said Dr Robino. “Our work has expanded these studies to the whole genome, with the goal of clarifying which specific genes drive individual differences in taste perception and food preferences.”
The study participants consisted of 2311 Italian subjects, and 1755 research participants from other European countries and Central Asia. They uncovered 17 independent genes related to liking for certain foods, including artichokes, bacon, coffee, chicory, dark chocolate, blue cheese, ice cream, liver, oil or butter on bread, orange juice, plain yoghurt, white wine and mushrooms. None of the genes thus identified belonged to the category of taste or smell receptors and the researchers commented on the amount of work that still needs to be done in the field.
“There is still much that needs to be done to understand what are the characteristics of certain foods affected by the genetic make-up of an individual,” said Dr Pirastu. “For example, we found a strong correlation between the HLA-DOA gene and white wine liking, but we have no idea which of the characteristics of white wine this gene influences. Our studies will be important for understanding the interaction between the environment, lifestyles, and the genome in determining health outcomes. Although there has been a lot of work on food-related diseases such as obesity, this has rarely taken food preferences into account. This is a major limitation which our work attempts to remedy, and as yet we have only really scratched the surface of this issue.”
In a second study, the researchers gathered the response of around 900 healthy adults from North Eastern Italy to salt, and correlated this to a DNA sequence variation found on the KCNA5 gene. Salt perception and the related genetic variation in taste receptors are important determinants of individual differences in salt intake, which in turn represents an important risk factor for the development of hypertension and cardiovascular diseases. “Genetic variations for taste perception are well known for bitter, sweet, and umami taste, but until now we knew little about their role in salt perception and liking,” said Dr Robino. “Identifying the receptor associated with individual differences in the perception of salt could help us better understand how chemosensory differences can interact to influence and predict food choices and hence human nutritional behaviour. This could also play an important role in the development of salt substitutes, in which there is a growing commercial interest.”
To test the study hypothesis that a personally tailored genetic nutritional plan has a greater impact than a traditional diet the researchers devised a standard weight-loss diet subtracting 600 calories from individual nutritional needs, and analysed DNA from the test group for 19 genes known to affect different metabolic areas and taste. The diets were modified based on the individual genetic profiles; people whose genetic profile showed that they had less efficient lipid metabolism were given fewer lipids in their diet with the overall amount of calories the same for everyone.
“Although there were no significant differences in age, sex and BMI between the two groups at the beginning of the trial, we found that people in the group who had followed the gene-based diet lost 33% more weight than the controls over two years, and the percentage of lean body mass also increased more in this group,” said Dr Pirastu.