Using genetics to find links between diet and disease

Understanding how diet affects our long-term health is a major challenge in nutrition research.

Randomised controlled trials are considered the best way to test cause-and-effect relationships. In this type of study, participants are randomly assigned to groups. In nutrition research, the groups follow different diets. Researchers then look at what effects the different diets have on the health of the different groups.

However, it can be difficult to work out whether changes in participants’ health are due to their diet or to something else. Also, researchers usually only study participants’ health for a short time, so it is not clear how their diet affects their risk of disease years later.

A possible solution is to use a method called Mendelian randomisation. This method uses people’s genetic differences to help understand links between a cause and an effect – in this case diet and risk of disease. However, it is hard to apply in nutrition research because it is hard to find gene variations that have a similar effect to changes in diet.

Project aims

This project will combine the methods of randomised controlled trials and Mendelian randomisation to create a new way of studying diet and health.

We will use data from a short-term randomised controlled trial in which 60 people changed how much sugar and carbohydrate they ate over 12 weeks.

Using Mendelian randomisation, we will:

1. Look at which proteins in the blood changed due to diet
2. Find gene variations that produce these proteins
3. Look at what diseases are caused by these gene variations

This will allow us to estimate how the participants’ diets could affect their risk of disease.

What we hope to achieve

We will demonstrate a practical way to combine randomised controlled trials and Mendelian randomisation, that other nutrition researchers can use. This approach will give us a clearer understanding of how diet affects long-term disease risk, without needing long, expensive studies.

In the long term, this work could lead to better advice on healthy eating and help shape public health guidelines.