Studying genetic diseases: Finding out about the person
One of the first steps in carrying out a study about any disease is to find out as much as possible about the patients.
Phenotype diversity
Each human has individual physical and physiological characteristics. Different people will respond differently to different foods.
The combination of a person’s physical and physiological characteristics is called their phenotype.
Details about personal history and lifestyle
The details about personal history and lifestyle, including such things as exercise habits and stress levels, might also be important. In the nutrigenomics study, the researchers used detailed questionnaires to get this information.
The responses to the questionnaires were digitised, and a range of bioinformatic data analysis was done. The researchers were looking for patterns – things that are either more or less common in people who have a particular disease, for example, inflammatory bowel disease (IBD), compared with those who don’t. This meant that the questionnaires also had to be filled out by people who did not have the disease. They were called the ‘control’ group.
The Nutrigenomics New Zealand team worked with just under 600 people with IBD and a similar number of control subjects from Auckland. The team also actively collaborated with other sites internationally, providing joint access to data from 18,405 individuals with Crohn’s disease, 14,308 individuals with ulcerative colitis and 34,241 control subjects.
Investigating genetic diseases: Find out about the patients first
Dr Andrew Shelling from the University of Auckland talks about the importance of thoroughly examining the physical characteristics of their patients before they start to study the genetic sequences, or the genotype, of the patients. Later, computers are used to look for patterns between physical characteristics (the phenotype) and genetic characteristics (genotype). It may be, for example, that certain physical characteristics are common amongst patients who have a particular disease.
Investigating genetic diseases: Find out about the patients first
Dr Andrew Shelling from the University of Auckland talks about the importance of thoroughly examining the physical characteristics of their patients before they start to study the genetic sequences, or the genotype, of the patients. Later, computers are used to look for patterns between physical characteristics (the phenotype) and genetic characteristics (genotype). It may be, for example, that certain physical characteristics are common amongst patients who have a particular disease.
Details about family history
Often, diseases run in families. This suggests that there might be a genetic link to the disease. The researchers asked people in the study about their family history and whether or not family members also have the disease. They were able to identify genetic links to the disease. They also confirmed that specific foods may trigger an inflammatory response in certain individuals that will in turn trigger disease development and/or progression.
Details about diet
With IBD, the food a patient eats seems to have a big effect on the symptoms of the disease. Researchers were therefore very interested in finding out more about the diets of people with IBD. Again, a questionnaire was used to find out this information.
The Nutrigenomics New Zealand team identified foods and nutrients that are likely to be especially beneficial in certain individuals.
Human clinical trials
The definitive way to test the efficacy of a food or diet regime is through a human clinical trial. The final stages of the Nutrigenomics New Zealand programme involved a number of human clinical trials.
Mediterranean diet
A Mediterranean-inspired diet was trialled on IBS patients and a control group. It is high in vegetables, legumes, fruit, nuts and healthy fats like olive oil. Fish and chicken are favoured over red meats.
One trial sought to test a health supplement – Lester’s Oil – on the inflammation that occurs in IBS patients. Another looked at the impact of a Mediterranean-inspired diet on the inflammation. The Mediterranean diet is often prescribed to reduce heart disease. It is characterised by lots of vegetables and healthy fats like olive oil. The results showed that the Mediterranean-inspired diet appeared to benefit the health of people with Crohn’s disease, with participants showing a trend for reduced inflammation and a normalising of the microbiota.
Finding out about genes
Alongside the data on disease characteristics/phenotypes collected from people, the Nutrigenomics New Zealand study also looked at the genotypes of the individuals and analysed data on genetic variations.
Find out more in the article, Studying genetic disease: Finding out about the genes.
Useful link
Nutrigenomics New Zealand published many articles on their research and results. To find out how scientists report their findings, read this article, which was published in Human Genomics (This journal is peer-reviewed, which means that each article is reviewed by others in the field before it can be published.)
