Nutrigenomics – can your DNA tell you what to eat?
“Let food be thy medicine and medicine be thy food” Hippocrates
When you follow a diet, the focus is on reducing your calories in order to lose weight. However the same foods can affect people in very different ways; the same food can help one person lose weight and another put on weight. This makes it very hard to have the perfect diet. But personalised nutrition may hold the key to a successful diet that will work. Researchers have been interested for years in how different people respond to different foods, for example, why do the Inuit people who rely on a diet high in fat and low in fruit and vegetables have a low rate of heart attacks. It turns out that Inuits have genetic variations that enable them to process a diet rich in proteins and Omega 3 fats found in fish.
Nutrigenomics is the study of the effects of food and food constituents on gene expression as well as how individual genetic composition correlates with dietary intake. Scientists can analyse DNA to determine what foods are healthiest. Diseases such as obesity, diabetes and high cholesterol levels are associated with the genetic profile of an individual as well as the environment. So the application of a personalised diet could be beneficial. For example, the gene CYP1A2 is involved in the metabolism of caffeine; a defect in this gene will mean that caffeine is metabolised more slowly in some people. Furthermore some other conditions such as phenylketonuria, coeliac disease and lactose intolerance arise from nutrient and gene interactions and so may guide personal food choices. If lactose-containing foods are limited or lactase supplements are taken this will help prevent gastrointestinal discomfort caused by lactose intolerance.
Californian startup HABIT creates an individualised food plan by looking at the person’s DNA. The customer receives a simple blood sample kit, which involves a finger prick to obtain samples that are then sent to the lab. HABIT’s scientists look at a series of more than 60 biomarkers to identify genetic variations in the DNA that indicate how food is broken down and metabolised. That information is processed and uploaded into an app where users can log in for a 30 minute session with a dietician. They can then learn which foods they best respond to. For example someone that has trouble breaking down fats and carbohydrates is encouraged to eat a diet high in protein. For an extra charge HABIT will deliver eating plans and ingredients to the client’s home.
There are several other companies that are trying to capitalise on the personalised nutrition movement such as Canadian Nutrigenomix which offers to help you ”eat according to your genes” and UK’s DNAFit who claims that “our groundbreaking DNA test will change the way you think about fitness and nutrition forever”
However there is still a huge gap between what is known about nutrition genomics and what companies like HABIT claim to offer. There is not enough scientific evidence available to accurately predict the most healthy diet for an individual. And certainly no reliable data to support the claims made by these companies. There is a lot of secrecy about the algorithms that they use and their methods have never been tested in a clinical trial.
A large European study, Food4Me, looking at the impact of personalised nutrition on people’s health choices involved more than 1,500 participants. The results showed that the group that had received personalised dietary and lifestyle advice ate healthier diets compared with the control group but that this was regardless of whether this personalisation was based on diet alone, phenotype or genotype.
A study in 2015 found that there was no reliable data to support the claims of the “nutrigenomics” companies. No statically significant association was found for any of the 38 genes included in nutrigenomics tests provided by various private genetic testing laboratories.
So although the current personalised nutrition plans currently available are not going to revolutionise our health, nutrigenomics is a very promising strand of precision medicine and the need for thorough research is essential.