Dr Ula: What your supplements are actually doing and how you would know

Most people take a supplement because someone told them they should. Fewer can tell you what it's doing. The honest answer requires a baseline, a therapeutic dose, and lifestyle work alongside it. Here is how we think about it.

You've been taking a multivitamin for two years. You feel roughly the same as you did two years ago. Is anything in your biology different?

It is one of the most common questions we hear, and most people cannot answer it. Not because they have not been diligent — most of the patients we see have been remarkably diligent — but because nobody gave them a baseline.

They started a supplement because a friend recommended it, or a podcast suggested it, or a label promised it. They have stayed on it because stopping feels like undoing something. But they have no measurement that tells them whether the bottle is doing biological work or sitting in a cupboard at a price point.

This is not a small distinction. A supplement that does not move a marker is not doing nothing, it is doing nothing measurable. And in clinical terms, that is the only kind of “nothing” that matters.

A supplement is a push in the right direction

The clearest way to think about supplementation is this: it is a push in the right direction for a specific biological pathway? It is not a substitute for the lifestyle inputs that govern the pathway underneath. It is not a standalone intervention. And it is never recommended on its own.

When we prescribe a supplement, we prescribe it alongside the lifestyle work calibrated to the same picture — sleep architecture, nutrition density, movement, stress regulation. The two pieces work together. The supplement is targeted; the lifestyle work is foundational. Neither is sufficient on its own, and the order is not sequential. They are concurrent, from the start.

This matters because the alternative framings are both common and both wrong. “Take a supplement and you don't need to worry about lifestyle” is not how the biology works. Neither is “fix your lifestyle and you'll never need a supplement.” The honest position is in between: lifestyle work plus targeted supplementation, calibrated to a tested baseline.

The first question is not which supplement. It is which pathway

The body does not run on supplements. It runs on biological pathways. Vitamin D regulates immune function, bone metabolism, and a great deal else. Magnesium sits inside more than 300 enzyme reactions, including the ones that govern sleep architecture and nervous system regulation. B12 and folate carry methylation — the chemical process the body uses to turn genes on and off, and to clear homocysteine, a cardiovascular risk marker that does not appear on a standard blood panel. Zinc, omega 3 fish oils, vitamin D — each is a specific pathway, not a general “boost.”

A supplement supports a specific pathway that is not running optimally on its own. Which means the right question is not “which supplement should I take.” It is “which pathway is suboptimal?” And that question is answered by a blood test, not a podcast.

A label is information. It is not personalisation

This is where the supermarket-shelf approach falls down structurally.

A general multivitamin contains a little of everything, in case anyone is short of anything. The formulation is built for a population average — a useful assumption when you have no data on the individual, and a poor one when you do. Most of the patients we test are not short of most of what is in a multivitamin. They are running suboptimal in one or two specific pathways and unremarkable in the rest.

Reading the label tells you what is in the bottle. It does not tell you whether any of it is what your biology needs. Some ingredients you may need at a higher dose than a multivitamin provides — vitamin D and magnesium are the most common. Some almost certainly do not need at the dose included. And some — iron is the clearest case — can sit unhelpfully high in the body if you take it without a measured deficit. A label that lists iron tells you nothing about whether your ferritin is low.

A targeted protocol, built around the markers that came back suboptimal, does more biological work than a broad one. At a fraction of the dose, and at a fraction of the cost over the longterm.

Therapeutic dose, not label dose

Once a deficit is identified, the question of dose becomes the next thing that matters. Most supermarket supplements are formulated to a maintenance dose — enough to sit inside a daily reference intake, not enough to correct a clinical deficit. A 1000 IU vitamin D capsule maintains a healthy person. It does not correct a tested deficiency. The two doses do different jobs.

A therapeutic dose is the dose required to move a specific marker in a specific person, calibrated to a tested baseline and reviewed by a clinician. The practitioner-only ranges we work with in clinic are formulated to therapeutic doses, sourced from manufacturers operating under tighter regulatory frameworks, and reviewed before they reach a patient. Different category. Different purpose.

When supplementation is long-term

There are two situations where a supplement is not a short corrective and is, instead, an ongoing part of the picture.

The first is the food supply itself. The nutrient density of what is on the plate is materially lower than it was fifty years ago. Industrial farming practices have depleted soil mineral content. Harvest timing favours yield and shelf life over nutrient development. Even excellent eating — varied, fresh, well-sourced — runs into a structural ceiling for several specific nutrients. For some pathways, the lifestyle inputs cannot fully close the gap, regardless of how diligent the patient is. Long-term supplementation is the honest answer.

The second is elevated risk. Family history of a specific disease, findings on DNA testing, or a measured risk configuration that places someone above population-average risk for a particular condition. Where the risk is structural and ongoing, the supplementation that addresses the relevant pathway is structural and ongoing too. This is a clinical judgement, made on the patient's specific picture, not a default.

Both of these situations require a tested baseline, a clinical reason, and a periodic retest to confirm the supplement is still doing what it was prescribed to do. “Long-term” is not a synonym for “set and forget.”

What investigation before supplementation actually looks like

We test the markers that govern the relevant pathways. Vitamin D, B12, folate, ferritin, magnesium, zinc, fasting insulin, HsCRP — a marker of chronic systemic inflammation not routinely tested on a standard NZ GP panel.

Where a marker sits suboptimal, we prescribe a therapeutic dose from a practitioner-only range, alongside the lifestyle changes calibrated to the same picture, and we re-test. The retest is the only thing that tells us the protocol is doing what we asked it to do.

A sensible next step

If you have been on supplements for a while and never had the markers measured, the question to sit with is not whether to keep taking them or stop. It is whether you would like to know what they are doing.

Investigation precedes supplementation. The lifestyle work travels alongside it.

Dr. Ula

Co-Founder and Lead Physician, Autonomy

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