Personalised supplementation: the promise and the arithmetic
Algorithmic packs built on blood panels and genotypes, and the point where the personalisation outruns the data.
Key takeaways
- Personalised packs are still subject to the same claims rules as ordinary supplements.
- A result outside a reference interval is not automatically a deficiency.
- Genotype guided nutrient dosing, such as MTHFR based folate choices, lacks trial evidence for clinical benefit.
- The personalisation itself prevents any comparison that could prove it works.
The supplement market has moved from a shelf of bottles to a sachet with your name printed on it. The model is consistent across providers: a questionnaire, sometimes a blood panel, sometimes a genetic profile, then an algorithm that assembles a daily pack. The framing is appealing because it borrows the logic of medicine, where treatment is chosen for a particular person with a particular problem.
It is worth being precise about what a deficiency is. It is a state in which the amount of a nutrient available to the body is too low to sustain normal function, usually with a biochemical marker and, if it persists, a clinical consequence. A result slightly outside a laboratory reference interval is not automatically that. Reference intervals are constructed to exclude the outer few per cent of a reference population, so a proportion of healthy people will always sit outside them. A handful of deficiencies are common enough in the general population to be worth looking for when there is reason: iron, particularly in menstruating women, vitamin B12 in older adults and in those on plant based diets or long term metformin, vitamin D at high latitudes and in people with little sun exposure, and folate in pregnancy. Most of the panel around them exists because it can be measured cheaply, not because knowing the number changes anything.
Pharmacogenomic tailoring of nutrients is where the gap is widest. Variants such as MTHFR C677T are routinely used to justify particular forms of folate, and the evidence does not support that as a basis for individual supplementation decisions in people with normal folate status. There are no adequately powered trials showing that genotype guided supplement packs improve any clinical outcome compared with the same nutrients given without the genotype.
Personalisation is a formidable marketing frame for a reason that has nothing to do with biology. The buyer receives something that cannot be falsified. There is no comparison group of one, no way to know what the standard pack would have done, and no outcome specific enough to be disappointed by.
Notes and sources
Each regulatory statement in this article is set against the document it comes from, so you can read the original rather than our summary of it.
1. Personalised products remain subject to the same claims rules as any other supplement
2. Health related consumer genetic tests are regulated as in vitro diagnostic devices in the EU
Regulation (EU) 2017/746 on in vitro diagnostic medical devices
3. Nutrient reference values used on labels are population figures, not individual targets
