Enter the age of personalised nutrition!
We are all different, from the colour of our eyes to the curl of our hair, and this is all mostly due to genetics. Since the full genome sequence was published in 2003, we’ve come a long way in the understanding of the impact of our genes on how we look and how our bodies work. Before diving into nutrigenetics, you first need to understand the basics of genetics.
A gene is a section of DNA that contains instructions for you to produce proteins, each of which has a specific function in the body.
Genotype - what do your genes say?
The specific version of every gene that you carry is called your genotype. Each gene has a specific job to do, and how effectively and efficiently that gene functions in your body depends on your genotype for that gene.
These variations in genotypes are known as Single Nucleotide Polymorphisms (SNPs). The instructions in genes come in the form of a ‘code’ made up of a sequence of nucleotides represented by the letters A, T, C and G. A change in the ‘code’ is usually a deletion, substitution or addition of one of these letters. This means that the protein made from the code will be slightly imperfect, and may not perform its function in the body as effectively.
You can compare a SNP to a spelling mistake. If you accidentally add, remove or choose the wrong letter, you would still be able to read the word, but it would be not be perfect and may reduce the impact of your message.
Phenotype - who you are!
Your phenotype is who you are, how you look and how your body works. Your genes determine some of these physical characteristics, but most of your characteristics result due to a combination of your genes and environment. Environmental factors would include factors such as diet, smoking, exercise, and general lifestyle.
The simplest definition of nutrigenetics (or nutrigenomics) is as the word suggests: the link between nutrition and genetics. This involves how genetic variations alter an individual's response to their diet. This can involve how effectively nutrients are digested, absorbed or utilized and can ultimately affect our long term health. Nutrigenetic risks are classified as either monogenic or complex.
Monogenic nutrition disorders
A monogenic disorder is caused by a change in a single gene. For these disorders, a genetic test of a single gene can be used to diagnose the condition. It is estimated that 10 000 human diseases are monogenic. [cite]
An example of a monogenic disorder is lactose intolerance. The LCT gene contains instructions for the production of lactase, an enzyme required to digest lactose. About 70% of the world’s population possess variations of the LCT gene that prevent the enzyme lactase from being produced. Without lactase, the lactose found in dairy products is not broken down, resulting in gut-related symptoms such as bloating and abdominal cramps. [cite]
Complex risk factors
Genetic based risks related to chronic diseases and nutrition are usually more complicated than changes in single genes. Most lifestyle diseases are associated with a combination of several genes related to diet as well as environmental factors. [cite]
As an example, versions of genes such as FTO and PPARG have been associated with obesity with a high fat diet. It’s not to say you will definitely gain weight if you have these gene versions. However if you have these genes, and you follow a typical Western diet that is high in fat, you are more likely to be obese than with someone who does not have the genetic variations. [cite]
Why nutrigenetics matters
We already know that diet plays a vital role in health and wellbeing and for the prevention of chronic diseases such as type 2 diabetes and heart disease. Public health nutrition recommendations are taken as an average of what the general population requires. While these recommendations take the basics into account, they do not account for individual differences. This is where personalised nutrition in the form of nutrigenetics comes into play. [cite]
A small study compared the long term weight effects of a standard weight loss diet versus nutrigenetic tailored plan at a weight loss clinic. After the 300 day study period, the researchers concluded that using nutrigenetic tailored diets resulted in better compliance, long-term maintenance of weight loss, as well as improved blood glucose levels.
And improvements in weight loss is just the tip of the iceberg! Nutrigenetics can also allow us to test, for example, an individual’s ability to process caffeine and alcohol, allowing us to choose our drinks with care. Your requirements of nutrients such as vitamins B, C, D and E and Omega 3 can also be tailored to your genes to best reduce your risk of chronic diseases such as heart disease or osteoporosis. Knowing this can help us focus on where we need to boost our nutrient intake to protect our bodies.
So, it’s all down to genes?
Not entirely! Using nutrigenetics is definitely beneficial for personalised nutrition, but should never be used in isolation. The International Society of Nutrigenetics and Nutrigenomics (ISNN) suggests the three tiers of personalised nutrition should include public health recommendations, phenotype measures (your nutrition and health status) as well as genotype.
Nutrigenetics alone won’t determine future wellbeing. Genes really only provide a tendency not a destiny. The most important thing is to make the right nutritional choices for your genetic make-up, goals and lifestyle. This way you can truly optimize your health and wellbeing.