One Size Fits None: The Science of Biochemical Individuality

Imagine if your body came with a manual — not just any manual, but one tailored precisely to your genes, enzymes, metabolism, and environment.
That’s the essence of biochemical individuality: the understanding that when it comes to health, nutrition, and medicine, “average” simply doesn’t exist.

One Size Fits None: The Science of Biochemical Individuality

You’re not a statistic.
You’re not a lab average.
And when it comes to health, nutrition, and supplementation, "one-size-fits-all" fits almost no one.

Welcome to the real-world science of biochemical individuality — the principle that no two people metabolise nutrients, respond to foods, or process medicines in exactly the same way.

Your genetic blueprint, gut microbiome, enzyme activity, hormonal balance, and lifestyle habits all combine to create a unique biological environment.
An environment that determines:

• Which supplements work for you (and which don’t).
  
• How you respond to foods.
  
• How quickly or slowly you recover.
  
• And how you can unlock better health — or miss it entirely.
  

In this blog, we’ll unpack:

• Why two people can take the same supplement and experience completely different outcomes.
  
• How your genes interact with your lifestyle choices (and how you can influence them).
  
• And why understanding your personal biology is the key to lasting optimisation — not just chasing the latest TikTok trend.
  

It’s not about hacking your body.
It’s about mastering your unique biology.

What Is Biochemical Individuality — and Why Should You Care?

First coined by Dr. Roger J. Williams in his seminal book Biochemical Individuality (1956), the concept describes how each human being has a unique biochemical profile shaped by genetics and environment.

No two people have identical enzyme activities, gut microbiomes, metabolic rates, or hormonal balances — a fact first demonstrated in Williams' original work with micronutrient requirements across populations.

This means the way you absorb nutrients, respond to foods, and metabolise drugs could differ dramatically from the person next to you — even if you’re eating the same meals or taking the same supplements.

For instance, consider vitamin D. Research by Wang et al., 2010  — demonstrated that common genetic variants in the vitamin D receptor (VDR) gene substantially affect vitamin D levels and requirements, leading to huge variation in optimal dosing.

Supplements: Miracle for Some, Mayhem for Others

Personalisation isn’t just a buzzword — it’s a biological necessity.

Take B vitamins:
Variants in the MTHFR gene (Frost et al., 1995) impair the body's ability to methylate folate, meaning some individuals require methylated forms (like L-5-MTHF and methylcobalamin) to function properly. Others without the variant can thrive on standard forms.

Similarly, Stein MB et al., 2005 found that differences in the COMT gene (Catechol-O-Methyltransferase) influence the breakdown of dopamine and norepinephrine, which can alter individual responses to stimulants like caffeine or energy-boosting supplements.

Without personalisation, supplementing can be like throwing darts while blindfolded.

Food Responses: Not All Carrots Are Created Equal

Even whole foods interact differently with different bodies.

In the foundational study by Perry et al., 2007, researchers showed that AMY1 gene copy number (which influences salivary amylase production) varies widely between individuals and correlates with starch digestion efficiency.
High AMY1 = excellent starch metabolism; low AMY1 = sluggish, uncomfortable digestion after carbohydrate-rich meals.

Similarly, work by Corpe et al, 1999 detailed how variants in the SLC23A1 gene impact vitamin C absorption efficiency — meaning some people need significantly more dietary vitamin C to maintain antioxidant protection.

This explains why one person thrives on a plant-heavy diet, while another feels depleted and sluggish.

Pharmaceuticals: The Wildest Card of All

Drugs perhaps showcase biochemical individuality at its most dramatic.

According to Zhou, 2009, variations in the CYP2D6 gene profoundly impact the metabolism of more than 25% of common medications, including antidepressants, beta-blockers, and painkillers like codeine.

Depending on your CYP2D6 genotype, you might metabolise these drugs too quickly (rendering them ineffective) or too slowly (leading to dangerous accumulation and side effects).

Pharmacogenomic research is fast becoming a cornerstone of personalised medicine, precisely because of this variability.

Epigenetics: You’re Not Doomed by Your Genes

The most empowering revelation? You are not trapped by your genetics.

Research from Feil & Fraga, 2012 explains how environmental inputs — diet, stress, exercise — can modify gene expression via epigenetic mechanisms.

For example, the FTO gene is associated with higher obesity risk, but as shown by Kilpeläinen et al., 2011, physically active individuals can significantly reduce or blunt the gene’s negative impact on weight.

Similarly, emerging research in 2024 suggests that lifestyle interventions — particularly diet and exercise — can dramatically lower Alzheimer's risk, even in individuals carrying the APOE4 genetic variant.

Your genes load the gun, but your choices pull the trigger.

Detox Genes: Cleaning Up the Genetic House

Even if you inherit weaker detoxification capacity — such as a GSTM1 gene deletion — you’re far from powerless.

While a missing GSTM1 gene can reduce your ability to neutralize certain toxins, research suggests that strategies like increasing cruciferous vegetable intake, supporting glutathione production with N-acetylcysteine (NAC), and minimising environmental toxin exposure can strengthen overall detox pathways and help offset potential vulnerabilities.

Once again: the internal environment you cultivate matters far more than the genetic hand you were dealt.

The Takeaway: Master Your Unique Biology

Biochemical individuality isn’t just an interesting theory — it’s the bedrock of real health optimisation.

Personalised nutrition, supplementation, and medicine honour the symphony of genes, enzymes, and lifestyle factors that make you you.

The future of health isn’t mass-produced pills or diet templates.
It’s precision — guided by biomarkers, genetic insight, and deep self-awareness.

One size fits none — and the path to peak health starts with understanding yourself.

A Note on Expertise

While we’ve done our best to present a clear and accurate overview of biochemical individuality, epigenetics, and pharmacogenomics, we don’t claim to be experts in these fields — and we deeply respect those who are.

This blog represents our understanding of the current science, aimed at helping you think more critically about personalisation in health.

For deeper reading, we highly recommend:

• Biochemical Individuality by Roger J. Williams (1956)
  
• Dirty Genes by Dr. Ben Lynch
  

The deeper you dive, the more you’ll appreciate just how powerful — and personal — true health really is.

Check out the final blog in this trilogy: 

Blueprints for Better Health: How to Personalise Your Supplements and Nutrition