One Size Fits None: The Science of Biochemical Individuality

Imagine if your body came with a manual.

Not a generic leaflet with vague advice about eating more greens and getting more sleep, although, to be fair, still useful.

A real manual.

One tailored precisely to your genes, enzymes, metabolism, gut microbiome, nutrient needs, hormone patterns, lifestyle and environment.

That is the essence of biochemical individuality: the understanding that when it comes to health, nutrition, supplementation and medicine, “average” simply does not tell the full story.

You are not a statistic.

You are 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 helps determine:

• Which supplements work for you, and which do not

• How you respond to foods

• How quickly or slowly you recover

• How you tolerate caffeine, stimulants or certain nutrients

• How your body processes medicines

• How you can unlock better health, or miss it entirely

This is why how to stack supplements properly starts with the person, not the trend.

In this article, we will unpack:

• Why two people can take the same supplement and experience completely different outcomes

• How your genes interact with your lifestyle choices

• Why genetic variants matter, but do not define your destiny

• Why personalised nutrition and supplementation are the future of serious health optimisation

• Why chasing the latest TikTok trend is a poor substitute for understanding your own biology

It is not about hacking your body.

It is about mastering your unique biology.

Quick Answer: What Is Biochemical Individuality?

Biochemical individuality is the idea that every person has a unique biological makeup that affects how they respond to food, supplements, medicines, exercise, stress and lifestyle choices.

This uniqueness comes from differences in genes, enzymes, gut bacteria, nutrient status, hormone balance, metabolism and environment.

It helps explain why one person may feel brilliant on a supplement while another notices nothing, why some people tolerate caffeine easily while others feel wired and anxious, and why the same diet can produce completely different results in different people.

In simple terms:

You are not average.

Your biology is personal.

Your health strategy should be too.

What Is Biochemical Individuality, and Why Should You Care?

The term biochemical individuality was popularised by Dr Roger J. Williams in his 1956 book Biochemical Individuality.

The concept describes how each human being has a unique biochemical profile shaped by genetics, environment, diet, lifestyle and internal biology.

No two people have identical enzyme activity, gut microbiomes, metabolic rates, hormonal rhythms or nutrient requirements.

That matters because the way you absorb nutrients, respond to foods and metabolise medicines could differ dramatically from the person next to you, even if you are eating the same meals or taking the same supplements.

This is not wellness fluff.

It is one of the reasons nutrition science can feel so frustrating.

A study may show that a nutrient, food pattern or supplement works well on average.

But “average” does not tell you how you will respond.

That is the uncomfortable little detail marketing prefers to ignore.

Supplements: Miracle for Some, Mayhem for Others

Personalisation is not just a buzzword.

It is a biological reality.

Take B vitamins.

Variants in the MTHFR gene can influence the body’s ability to convert folate into its active methylated form. This is one reason some individuals may benefit from methylated forms such as L-5-MTHF or methylcobalamin, particularly where nutrient status, homocysteine levels or specific genetic context make them relevant.

Others may do perfectly well with standard forms.

This is why methylation and nutrient cofactors matter. The question is not simply whether a nutrient looks more advanced on a label. The question is whether it suits the person, the formula and the purpose.

Similarly, differences in the COMT gene can influence the breakdown of catecholamines such as dopamine, adrenaline and noradrenaline.

That may affect how some people respond to caffeine, stimulants, stress and energy-support formulas.

One person takes a pre-workout and feels focused.

Another takes the same dose and feels like they can hear the Wi-Fi.

Same product.

Different biology.

Without personalisation, supplementation can become a game of educated guessing.

Better than blind guessing, admittedly.

Still guessing.

Why the Same Supplement Can Feel Different for Different People

Two people can take the same supplement and have completely different experiences because their starting points are not the same.

Your response may depend on:

• Baseline nutrient status

• Digestive function

• Gut microbiome diversity

• Genetic variants

• Enzyme activity

• Hormone balance

• Stress load

• Sleep quality

• Training volume

• Diet quality

• Medication use

• Age

• Body composition

• Inflammation status

This explains why one person swears ashwagandha changed their life, while another finds it does very little.

It explains why magnesium improves sleep for some people but mainly loosens stools for others.

It explains why caffeine is productivity fuel for one person and an anxiety grenade for another.

It also explains why some supplements take time to show noticeable effects.

For that deeper timing piece, see supplements take time to work.

Food Responses: Not All Carrots Are Created Equal

Even whole foods interact differently with different bodies.

This does not mean vegetables are now controversial.

Please do not make carrots the next casualty of online nutrition discourse.

It simply means that people process foods differently.

Research on AMY1 gene copy number has shown that salivary amylase production can vary between individuals. Since amylase helps break down starch, this may influence how efficiently someone digests carbohydrate-rich foods.

In simple terms:

Some people handle starch better than others.

High AMY1 activity may support more efficient starch digestion.

Lower AMY1 activity may contribute to a less comfortable response after carbohydrate-heavy meals.

This helps explain why one person thrives on a higher-carbohydrate diet while another feels sluggish, bloated or unstable with the same approach.

The same idea applies to nutrient absorption.

Variants in genes involved in vitamin transport, metabolism or receptor activity can influence how efficiently someone uses nutrients such as vitamin C, vitamin D, folate or B12.

The food may be the same.

The biological response may not be.

Vitamin D: A Useful Example of Personal Variation

Vitamin D is a strong example of biochemical individuality in action.

People vary widely in vitamin D status and requirements because of differences in:

• Sun exposure

• Skin pigmentation

• Geography

• Time spent outdoors

• Body composition

• Diet

• Age

• Supplement use

• Absorption

• Genetics

• Vitamin D receptor activity

Common genetic variations in vitamin D-related pathways, including the vitamin D receptor, may influence vitamin D levels and individual requirements.

This is one reason testing can be useful.

One person may maintain reasonable vitamin D status with modest supplementation and sunlight exposure.

Another may need more structured support.

Another may be taking a dose that looks sensible on paper but barely moves their levels.

The label gives a dose.

Your bloodwork gives context.

Biology enjoys being difficult like that.

Pharmaceuticals: The Wildest Card of All

Medicines perhaps show biochemical individuality at its most dramatic.

Pharmacogenomics is the study of how genes influence drug response.

Variations in genes such as CYP2D6 can affect how quickly or slowly people metabolise certain medicines, including some antidepressants, beta-blockers and pain medicines.

Depending on your CYP2D6 genotype, you may metabolise a drug too quickly, reducing its effectiveness, or too slowly, increasing the risk of side effects.

This is one reason personalised medicine is growing rapidly.

It is also a reminder that individuality is not just about whether you prefer oats or eggs for breakfast.

It can affect real clinical decisions.

Supplements are not medicines, but the principle still applies.

People process compounds differently.

That matters.

Epigenetics: You Are Not Doomed by Your Genes

Here is the empowering part.

Your genes matter.

But they are not the whole story.

Epigenetics refers to changes in gene expression influenced by factors such as diet, stress, exercise, sleep, environment and lifestyle.

Think of your genes as the hardware.

Epigenetics is part of the software controlling how that hardware is used.

Research has shown that lifestyle factors can influence gene expression and help modify risk patterns associated with certain genetic variants.

For example, the FTO gene has been associated with higher obesity risk, but physical activity may reduce or blunt some of that risk.

That does not mean lifestyle solves everything.

It does mean your biology is dynamic.

You are not simply a helpless passenger in your genetic vehicle.

You can still influence the route.

Your Genes Load the Gun, But Lifestyle Pulls the Trigger

The phrase is blunt, but the principle is useful.

Genes may influence risk, tolerance, metabolism and response.

But lifestyle often influences whether that risk becomes meaningful.

Your daily choices can affect:

• Blood glucose regulation

• Inflammation

• Gut microbiome composition

• Sleep quality

• Hormone balance

• Stress resilience

• Detoxification pathways

• Muscle mass

• Mitochondrial function

• Nutrient status

• Recovery capacity

This is why genetic testing can be useful, but it should never become fatalistic.

A gene variant is not a life sentence.

It is information.

Useful information, ideally.

Not an excuse to buy seventeen supplements and announce that your COMT made you do it.

Detox Genes: Cleaning Up the Genetic House

Detoxification is another area where biochemical individuality matters.

Some people carry genetic variants or deletions that may affect detoxification pathways, such as GSTM1 deletion.

The GST family of enzymes helps support glutathione-related detoxification processes.

If someone has reduced capacity in certain detox pathways, it does not mean they are broken.

It means their internal system may benefit from stronger lifestyle and nutritional support.

That might include:

• Adequate protein intake

• Cruciferous vegetables

• Sulphur-containing foods

• Glutathione-supporting nutrients

• N-acetylcysteine, where appropriate

• Reducing unnecessary toxin exposure

• Supporting liver and gut health

• Sleep

• Hydration

• Regular exercise

Again, the internal environment you cultivate matters enormously.

Your genes may influence the starting point.

They do not write the whole ending.

The Gut Microbiome: Your Internal Ecosystem

Your gut microbiome is another major driver of biochemical individuality.

The bacteria, fungi and other microbes living in your gut help influence digestion, nutrient metabolism, immune signalling, inflammation, neurotransmitter production and even how you respond to certain foods.

Two people can eat the same meal and produce different metabolic responses partly because their microbiomes differ.

The gut can affect:

• Fibre tolerance

• Polyphenol metabolism

• Short-chain fatty acid production

• B vitamin production

• Immune activity

• Gut barrier health

• Mood-related pathways

• Inflammatory signalling

This is one reason personalised nutrition is so complex.

You are not feeding only yourself.

You are feeding an ecosystem.

A very small, very opinionated ecosystem.

For more on this area, see gut health and mood regulation.

Lifestyle: The Great Modifier

Lifestyle is where biochemical individuality becomes practical.

You may not be able to change your genetic code.

But you can influence your biological environment.

That includes:

• Sleep quality

• Training style

• Recovery

• Protein intake

• Micronutrient intake

• Hydration

• Stress management

• Alcohol intake

• Sunlight exposure

• Meal timing

• Fibre intake

• Caffeine intake

• Supplement routine

This is why fundamental diet principles still matter.

Personalisation does not mean ignoring the basics.

It means applying the basics intelligently to the person in front of you.

A poor diet is still a poor diet, even if you have a very interesting genetic report.

The Takeaway: Master Your Unique Biology

Biochemical individuality is not just an interesting theory.

It is the bedrock of real health optimisation.

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

The future of health is not mass-produced diet templates or supplement routines copied from someone with good lighting and a discount code.

It is precision.

Guided by biomarkers, genetic insight, self-awareness, sensible testing and practical lifestyle change.

One size fits none.

And the path to better health starts with understanding yourself.

A Note on Expertise

While we have done our best to present a clear and accurate overview of biochemical individuality, epigenetics and pharmacogenomics, we do not claim to be experts in these fields, and we deeply respect those who are.

This article represents our understanding of the current science, with the aim of helping you think more critically about personalisation in health.

For deeper reading, we highly recommend:

• Biochemical Individuality by Roger J. Williams

• Dirty Genes by Dr Ben Lynch

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

Next Steps: Want to Go Deeper?

To turn this idea into a practical routine, read personalise your supplements and nutrition next.

That is where the theory becomes the blueprint.

References

Williams RJ. Biochemical Individuality. 1956.

Frosst P, Blom HJ, Milos R, et al. A candidate genetic risk factor for vascular disease: a common mutation in methylenetetrahydrofolate reductase. Nature Genetics. 1995;10(1):111-113.

Wang TJ, Zhang F, Richards JB, et al. Common genetic determinants of vitamin D insufficiency: a genome-wide association study. The Lancet. 2010;376(9736):180-188.

Stein MB, Fallin MD, Schork NJ, Gelernter J. COMT polymorphisms and anxiety-related personality traits. Neuropsychopharmacology. 2005;30(11):2092-2102.

Perry GH, Dominy NJ, Claw KG, et al. Diet and the evolution of human amylase gene copy number variation. Nature Genetics. 2007;39(10):1256-1260.

Corpe CP, Eck P, Wang J, Al-Hasani H, Levine M. Intestinal dehydroascorbic acid transport mediated by GLUT8 and GLUT2. The Journal of Biological Chemistry. 2013.

Zhou SF. Polymorphism of human cytochrome P450 2D6 and its clinical significance. Clinical Pharmacokinetics. 2009;48(11):689-723.

Feil R, Fraga MF. Epigenetics and the environment: emerging patterns and implications. Nature Reviews Genetics. 2012;13(2):97-109.

Kilpeläinen TO, Qi L, Brage S, et al. Physical activity attenuates the influence of FTO variants on obesity risk: a meta-analysis of 218,166 adults and 19,268 children. PLoS Medicine. 2011;8(11):e1001116.

Written By

Written by Chris Simon, Founder of One Life Foods.

Chris has worked in the supplement industry since 2009 and is known for seeking out exceptional ingredients, products, and formulations. Read more about Chris and the story behind One Life Foods.