Custom Supplements Personalised to Your Body: to Your Answers, or to You?

Written by Dr Jatin Joshi, co-founder and Chief Medical and Scientific Officer of Personally, and a researcher at the University of Oxford's Centre for Evidence-Based Medicine. I have a financial stake in this company, and you should weigh what follows with that in mind.

You typed something honest into a search bar. Custom supplements tailored to my body. Not to a goal, not to a category, to you.

It is the right thing to want. The word attached to it on almost every label is personalised, and that word is carrying a great deal of weight for something nobody defines. So before you pay for anything, it is worth knowing what a given product is personalised to.

The short version. Most personalised supplements are personalised to your answers on a form, which is a smaller thing than being personalised to your body. Being personalised to you means the formula is built from your real inputs, your quiz, your blood markers and your wearables, and that it keeps moving as you do. Three questions will tell you which one you are looking at.

A quiz personalises to what you say. You tick boxes about your goals, your diet, your energy, and an algorithm matches those answers to a formula.

That is fine as far as it goes. The honest part is how far that is. A quiz does not know what medications you take unless it asked and you happened to say. It does not know what your blood markers show. It cannot see the distance between how you described your diet on a Tuesday evening and how you actually eat across a month, which is a gap most of us have and none of us report accurately.

So it is personalised, genuinely. Personalised to the version of you that fits on a form.

It means the formula is built from what is true of you, not only what you reported.

At Personally that comes from three inputs, because between them they see what a form on its own cannot.

Your quiz tells us your goals, your symptoms and what you take, and your declared medications are screened before anything is built. Your blood markers, if you choose to share them, give real numbers rather than a self-report. Your wearables show how you have actually been sleeping, moving and recovering, day after day, rather than how you remember it when someone asks.

A formula built on those three is personalised to you. A formula built on a questionnaire alone is personalised to your answers.

There is a third thing, and it is the one that gets left out.

You are not the same person across a year. A formula built for you once, in month one, was built for someone who has moved on by month six. Adaptation is the formula being rebuilt as your inputs change, month to month, rather than freezing at the moment you signed up. I have written about why that matters at more length in what adaptive nutrition actually means.

Here is the useful part, and it applies to us as much as to anyone else. Three plain questions.

Does it ask what medications you take, and screen against them before anything is made?

Can it use your real data, your blood markers and what your wearable records, rather than only your description of yourself?

And does it adapt when you change, or was the quiz the last time it ever moved?

Three yeses and you are looking at something personalised to you. If it is matching a form you filled in once, it is personalised to your answers, which is a different and smaller thing. Personally is built to answer yes to all three. That is the reason it exists, and it is a fair test that another company could pass.

None of this is magic, and more inputs do not mean more is better. Quite often the honest answer is that you need less than you think. Food comes first, and your doctor comes before any of it.

Personalisation is about getting what you do take right for you. It is not about taking more.