Your Body’s Unique Instruction Manual
Think of your DNA as a vast, incredibly detailed instruction manual for building and running your body. This manual is written in a simple four-letter alphabet (A, C, G, and T) and contains billions of letters of code. It’s what makes you human, and it’s almost identical to the manual inside every other person on the planet.
Almost. The tiny differences in that code are what make each of us unique. They influence everything from the colour of your eyes to how your body processes the food you eat. One of the most common and well-studied types of these variations is called a SNP, and understanding it is the first step into the fascinating world of personal genetics.
So, What Exactly Is a SNP?
SNP stands for Single Nucleotide Polymorphism. That sounds complicated, so let’s break it down.
- Single: It means just one
- Nucleotide: This is the scientific name for the individual letters of your DNA code (A, C, G, and T)
- Polymorphism: This is a term from Greek that means ‘many shapes’. In genetics, it simply refers to a variation that is common, appearing in a significant portion of the population
So, a SNP is a place in your DNA sequence where a single letter is different from the most common one. Imagine your DNA instruction manual is millions of pages long. A SNP is like a one-letter typo on a single page. For example, where most people’s manual might read ‘cat’, yours might read ‘act’. It’s a tiny change, but it can sometimes alter the meaning of the instruction.
These ‘typos’ are not rare mistakes. They are incredibly common, with millions of them scattered throughout our DNA. They are the most frequent type of genetic variation among people and a major reason why we are all so different.
How Do SNPs Influence Your Body?
Many SNPs occur in parts of our DNA that don’t contain instructions for making proteins, and these often have no observable effect on us. They are simply silent variations that make your genetic code unique to you.
However, when a SNP occurs within a gene (a specific section of DNA that provides instructions for building a protein), it can sometimes change that instruction. Proteins, such as enzymes, are the workhorses of the body. They carry out countless jobs, from digesting food to building hormones.
A SNP might alter the instructions so that the resulting enzyme works a little faster, a little slower, or slightly differently than the more common version. Think of it like a recipe. A SNP could be the difference between a recipe that says ‘bake for 30 minutes’ and one that says ‘bake for 35 minutes’. Both recipes will produce a cake, but the results might be subtly different.
This is why some SNPs are associated with specific traits. They might influence how efficiently your body processes vitamin D, how you metabolise caffeine, or how well you handle certain types of fats. They contribute to the subtle biochemical differences that make your body work in its own particular way.
Are SNPs ‘Good’ or ‘Bad’?
It’s natural to think of genetic variations in terms of being ‘good’ or ‘bad’, but that’s not really how SNPs work. They are simply differences. A variation that might be disadvantageous in one environment could be neutral or even beneficial in another. They are a product of human history and evolution, representing the diversity that has allowed us to thrive in different conditions all over the world.
For example, a SNP that makes an enzyme work more slowly is not inherently ‘bad’. It’s just different. Understanding that you have this variation can simply provide you with information about your body’s tendencies.
SNPs vs. Mutations
You might have also heard the term ‘mutation’. While people sometimes use it interchangeably with SNP, in genetics they usually mean different things. A SNP is a common variation, found in at least 1% of the population. A mutation is typically a much rarer genetic change and is more often associated with a specific, often inherited, disease. The genetic variations we look at in the context of nutrition and wellness are almost always SNPs.
How Does This Impact Histamine Intolerance
Your DNA is a detailed instruction manual for running your body, meaning that everything your body has to do or make, is being handled by your DNA. There are two specific enzymes that your body creates to break down histamine, DAO and HMNT, and the creation of these is handled by two specific genes. SNPs occurring in these genes can create a predisposition towards histamine intolerance.
- The AOC1 gene contains the instruction manual for DAO production, which is the enzyme created in your gut to handle histamine ingested from food and drink
- The HMNT gene contains the instruction for breaking down histamine that is within your bloodstream, which might be from food (if your histamine bucket has overflowed) or naturally created histamine within the body
We explore this in more detail in our article on how your genes influence histamine breakdown.
Genes Are Not Your Destiny
This is perhaps the most important point of all. Discovering you have a particular SNP does not seal your fate. Your genes are just one part of a much bigger and more complex picture.
Your actual health and traits, known as your ‘phenotype’, are the result of an intricate dance between your genes (your ‘genotype’), your diet, your environment, your stress levels, your sleep, and all the other lifestyle choices you make every day. Your DNA provides a blueprint, but you are the architect who decides how to build with it.
Learning about your SNPs can be an empowering tool. It can offer clues about your body’s predispositions, helping you to make more personalised and informed choices. It’s not about finding problems or receiving a diagnosis; it’s about gaining a deeper layer of self-awareness to help you work with your body, not against it.