Shop like a doctor: How I read a supplement label

By Dr Amina | Founder, PolyBiotics | Women's Health Doctor

As the founder of a women's health supplement company, I spend a surprising amount of time looking at products I don't sell.

Sometimes it's because a customer emails me asking whether a competitor's supplement is worth trying. Sometimes it's because I'm researching an ingredient. More often than not, it's because I'm curious.

One thing I've noticed over the last few years is that women are becoming much harder to market to.

They're comparing labels. Looking up ingredients. Reading reviews. Asking questions about dosage, absorption and evidence. Some are even reading the studies brands cite on their websites.

As a supplement founder, you're making my job really difficult.

And honestly? I think that's fantastic.

Because once you know how to read a supplement label properly, a lot of what looks impressive stops looking impressive very quickly. At the same time, some of the products that seem almost boring start to stand out for all the right reasons.

When I assess a supplement, I don't start with the front of the box.

I start with the back.

The front is marketing.

The back is where the truth usually lives.

Step 1: Find the Full Ingredient List, Not Just the Supplement Facts Panel

Most people look at the Supplement Facts panel and stop there. That's the table showing the active ingredients and their amounts per serving.

But there are actually two ingredient lists on every supplement.

The first is the Supplement Facts panel itself. This tells you which vitamins, minerals and compounds the product is built around.

The second is the full ingredient list, usually sitting underneath in much smaller print. This includes fillers, binders, capsule materials, anti-caking agents, preservatives and anything else required to manufacture the product.

Both matter.

The Supplement Facts panel tells you what the product is trying to do. The full ingredient list tells you how it has been built.

A formulation can look excellent on the first list and much less impressive on the second.

Likewise, don't be fooled by brands boasting "nothing but active ingredients". Sometimes small amounts of excipients are unavoidable because they exist within the raw material itself. Vitamin D3 ingredients, for example, often contain tiny amounts of carriers or stabilisers. If a label looks impossibly clean, that isn't always a sign of transparency. Sometimes it's the opposite.

If the full ingredient list isn't available, that's a red flag.

You cannot make an informed decision about a product if you don't know everything that's inside it.

Transparency shouldn't be optional.

Step 2: Look at the Form, Not Just the Name

Listing an ingredient isn't the same thing as delivering it effectively.

Magnesium is probably the best example.

Most consumers know magnesium matters. Fewer realise that magnesium never exists on its own in a supplement. It must always be attached to another molecule, and that molecule can dramatically influence both absorption and tolerability.

This is why "contains magnesium" tells you very little.

Magnesium oxide and magnesium glycinate are both magnesium, but they behave very differently. Magnesium oxide contains a high percentage of elemental magnesium by weight, around 60%, which makes the number on the label look impressive. Magnesium glycinate contains considerably less elemental magnesium by weight, around 14%, but is generally much better absorbed and better tolerated.

That's why two products containing the same headline amount of magnesium can perform very differently. One is a larger number. The other is more of it actually reaching your cells.

Whenever I look at a supplement, I want to know the form first.

The name of the nutrient is only half the story.

Step 3: Understand the Difference Between Total and Elemental

This is where many supplement labels become genuinely misleading.

You'll often see a product advertising something like "1,000mg Magnesium Complex".

It sounds substantial. But what does it actually mean?

Magnesium compounds contain both the magnesium itself and the molecule it's attached to. When we talk about elemental magnesium, we mean the actual magnesium content your body has the opportunity to absorb. The rest is molecular weight that never becomes available to you.

A transparent label should tell you both figures.

For example:

Magnesium Bisglycinate 1,000mg
Providing 140mg Elemental Magnesium

Without that second figure, you cannot accurately compare products. You are comparing marketing rather than nutrition.

This matters even more with blends. Some products buffer a well-absorbed form like glycinate with a cheaper, higher-elemental-weight form like oxide. Adding even a small amount of oxide inflates the elemental magnesium figure on the label significantly, because oxide is around 60% elemental by weight. The number gets bigger. What your body actually absorbs does not necessarily follow.

I've also seen independent laboratory testing find products where the elemental magnesium percentage was higher than the stated compound could mathematically account for, meaning additional unlisted forms were present. That isn't a labelling quirk. It's an integrity problem.

This is also where upper limits become relevant. EFSA, the body that sets nutrient safety thresholds for the UK and EU, sets the tolerable upper intake level for supplemental magnesium at 250mg elemental per day. The lowest level at which adverse effects, typically gastrointestinal, have been observed in adults is around 360 to 365mg elemental per day from supplements.

If a product lists only a gram figure for a magnesium blend without declaring elemental content, you cannot assess whether you're within safe limits from that product alone, let alone when combined with your diet.

That is not sophistication. That is opacity.

Step 4: Count the Ingredients, Then Ask Why They're There

One of the biggest misconceptions in the supplement industry is that more ingredients automatically means a better product.

I've never found this to be true.

In fact, some of the best formulations I've seen are remarkably simple. Every ingredient has a purpose. Every dose has a rationale. Nothing has been included because it sounds good in marketing copy.

By contrast, some products look as though they were built by adding every trending ingredient available and hoping consumers would be impressed.

This is where sprinkle dosing comes in.

An ingredient appears on the label. The research behind that ingredient exists. But the amount included is so small that it bears little resemblance to the evidence being cited. The ingredient is technically present. The science is technically real. The connection between the two is often much weaker than consumers realise.

I call the multi-form version of this complexity theatre. Products boasting five, six or seven forms of the same nutrient in a single formulation. It sounds sophisticated. It sounds expensive. But whenever I see a formulation like this, I find myself asking a simple question.

Why?

Not why seven sounds impressive. Why seven are actually necessary. What role is each form playing? How much of each is included? Would the formulation perform differently if half of them disappeared tomorrow?

Those questions rarely make it onto the front of the pack.

A longer ingredient list doesn't indicate a better formulation. Sometimes it just indicates a longer ingredient list.

Step 5: Check the Dose Against the Evidence

This is the step most people skip. It's also the step that tells you the most.

Supplement companies love citing studies. The problem is that many consumers never read them. If they did, they'd often find that the dose used in the study is significantly different from the dose in the product.

Take myo-inositol. most protocols use 2000mg to 4000mg a day. Yet some products reference this same body of research while supplying a few hundred milligrams per serving.

The study is real. The results are real. The product dose and the study dose are not the same thing.

This isn't a niche problem. It appears across categories: inositol, B vitamins, zinc, vitamin D. The citation is used as a credibility signal. The actual dose comparison is left for you to find, if you go looking.

Whenever a brand cites research, I ask a few questions. What dose was used in the trial? Does the product match it, or is it meaningfully lower? Who was studied, and does that match my situation? How many participants were included, and has the finding been replicated?

A citation should be the beginning of your investigation, not the end of it.

Step 6: Know the Upper Limits, Not Just the Recommended Amounts

Most people are familiar with recommended daily amounts. Far fewer know about upper limits, and they matter just as much.

Upper limits are the point at which total intake from all sources combined, food, fortified products and supplements, may begin to cause problems. They exist because nutrients in excess can cause harm, and because supplements don't sit in isolation from the rest of your diet.

Products that obscure elemental content behind gram figures or multi-form blends make this calculation impossible.

Transparency makes checking upper limits straightforward. Complexity makes it unnecessarily hard. That gap is not accidental.

Step 7: Ask One Final Question

After reviewing the ingredient list, the forms, the elemental declarations, the doses and the evidence, I ask myself one final question.

Can I explain why every ingredient is here?

Not why it's fashionable. Not why it looks good on a website. Not why consumers recognise the name. Why it belongs in the formulation, at that dose, in that form.

If I can't answer that question, the brand probably can't either.

The supplement industry has spent years teaching consumers to equate complexity with quality. More ingredients. More forms. More citations. More grams on the front of the pack.

Increasingly, women are asking a different question.

Does this formulation actually make sense?

As a doctor, it's the question I ask every day.

As a founder, it's the question that guides every product we make.

And as a consumer, it's the question I hope you'll start asking too.

Because the best formulations aren't usually the most complicated.

They're the most intentional.

Dr Amina Hersi is the founder of PolyBiotics and a practising women's health doctor. PolyBiotics formulates nutritional supplements for women's hormonal health.