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If you've shopped for supplements lately, you've probably seen the marketing: "no fillers", "no nasties", "clean", "free from magnesium stearate". The implication is that ingredients like magnesium stearate, silicon dioxide, microcrystalline cellulose and dicalcium phosphate are something to worry about — additives sneaked in that you'd be better off without.
As a company that actually presses its own tablets, we want to give you a straight answer, because the reality is very different from the marketing. These ingredients are called excipients, they're used in tiny, carefully controlled amounts, they're well established as safe, and — importantly — a tablet genuinely cannot be made without them. Here's the full picture.
It helps to understand where the worry comes from. "Free-from" is a powerful marketing tactic. If you can make a customer afraid of an ingredient, you can then sell them the solution — a product that proudly leaves it out. The fear does the selling. It's the same playbook used across the food industry, and supplements are no exception.
The problem is that the fear is usually built on a misreading of the science (we'll get to the specifics below), and it often comes from sellers who don't manufacture their own products and may not fully understand why these ingredients are there in the first place. We do manufacture our own, so we're in a good position to explain what these ingredients actually do.
An excipient is any ingredient in a tablet that isn't the active nutrient itself. They don't provide the vitamin or mineral you're buying — instead they make it physically possible to produce a consistent, accurate, stable tablet. Every tablet ever made, whether it's a supplement or a prescription medicine, contains them. They fall into a few simple jobs: bulking, binding, lubricating and flow.
This is the part the "no fillers" marketing never mentions. Many active ingredients are needed in tiny quantities. A dose might be just a few micrograms — far too little to form a tablet on its own, and far too little to measure accurately at high speed on production equipment.
Bulking agents like microcrystalline cellulose and dicalcium phosphate bring the tablet up to a consistent, workable weight. That's not padding — it's precisely what allows each tablet to contain the correct, even dose of the active ingredient. Without a bulking agent, the active would be unevenly distributed through the blend, and the amount in each tablet would vary from one to the next. So the "filler" is doing something genuinely important: it's what makes your dose reliable and the same in every tablet. A tablet with no excipients at all isn't a purer product — it's a less accurate one.
We use the same four in every tablet, in minimal necessary amounts, and we disclose all of them on every label.
This is purified plant fibre — a wood-pulp-derived cellulose that's completely food grade. It bulks the tablet to the right weight and helps hold it together so it doesn't crumble. When consumed, it's simply an indigestible fibre. It's one of the most widely used and best understood excipients in the world.
A calcium and phosphate compound used as a bulking agent to help achieve the correct tablet weight. It's also a source of calcium and phosphorus, both of which are normal dietary minerals. It's stable, neutral and very widely used in both supplements and foods.
This is the one that attracts the most fear, so we'll cover it in detail below. Its job is to lubricate the blend so the tablet releases cleanly from the press without sticking. We use it at roughly 0.5% of the tablet — a tiny amount. Ours is vegetable-sourced.
Silicon dioxide — essentially a purified form of silica, which occurs naturally in many foods — is an anti-caking and flow agent. It stops the powdered blend from clumping so it flows evenly through the machinery, which again helps keep each tablet consistent. Used, like the others, in a very small amount.
Magnesium stearate is the ingredient the "clean" marketing targets hardest, with claims that it's toxic, suppresses your immune system, or forms a coating that blocks nutrient absorption. None of these stand up to scrutiny.
The immune-suppression claim traces back to a single 1990 laboratory study in which immune cells from mice were exposed to large amounts of stearic acid in a dish. There are two problems with using that to indict supplements. First, cells bathed directly in a substance in a petri dish behave nothing like cells in your gut — at sufficient concentration, almost anything is toxic to isolated cells in vitro. Second, the study used mice, which lack an enzyme (delta-9 desaturase) that humans have for processing stearic acid into oleic acid, a common and well-tolerated fatty acid. The finding simply doesn't translate to humans eating a normal amount, let alone the tiny amount of magnesium stearate in a tablet. No human study has shown immune suppression from it at any realistic intake.
The "blocks absorption" claim is similar. It comes from in-vitro experiments where tablets containing magnesium stearate dissolved slightly more slowly in artificial gastric fluid. But controlled bioavailability studies — the ones that actually measure what ends up in the bloodstream — consistently show no meaningful reduction in absorption when magnesium stearate is used at normal levels. Your stomach acid and digestive enzymes break down fats like stearic acid routinely; the idea of a "waxy coating" surviving digestion misunderstands how the gut works.
You may have noticed some brands announcing they've removed magnesium stearate. It's worth understanding what that really means, because there's an important distinction between capsules and tablets.
A capsule is filled — the powder is simply dropped into a shell. A tablet is compressed: the blend is pressed under high force, at high speed, between steel punches and dies, then ejected. For that to work cleanly, the blend has to release from the tooling without sticking — and that's exactly what a lubricant like magnesium stearate does. Without an effective lubricant, tablets stick, cap and crack, and the tooling gums up.
So a brand removing magnesium stearate from a capsule is making a relatively easy change in response to consumer preference. Doing it in a compressed tablet is a different matter entirely — in a tablet, a lubricant isn't an optional extra you can drop to follow a trend; it's part of how the tablet physically gets made. It's much easier to claim "no magnesium stearate" when you aren't pressing tablets yourself.
We don't play the "free-from" fear game, because we don't believe in scaring people about ingredients that are safe and necessary. What we do instead is straightforward:
The goal is an honest product that delivers the dose on the label, reliably, in every tablet. That's what these ingredients make possible — and we'd rather explain them clearly than pretend they're something to fear.
This article is general information and not medical advice. If you have a specific allergy or sensitivity, always check the full ingredient list on the label, and speak to your GP or pharmacist if you're unsure.
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