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Sustained-release supplements: when delayed release makes sense

Reviewed by Dr. Daniel Wallerstorfer, molecular biologist and founder of Novogenia · Updated: 11 October 2026 · Reading time: 9 min

Fast vs sustained release: the difference

Most capsules, tablets and powders release their nutrients as soon as they dissolve – quickly and all at once. With sustained release, release is deliberately slowed down and spread over a longer period. The terms sustained release, slow release, extended release and timed release essentially mean the same thing; in German-speaking markets, the pharmaceutical term “Retard” is common.

This is different from an enteric coating (often called delayed release in the pharmaceutical sense): it is not about how long release takes, but where it starts – only after the stomach. The two can be combined.

Why timing can matter

The stomach works like a sorting station. Thin liquids leave it quickly, small solid particles take longer, and large indigestible pieces stay behind until a cleaning wave between meals moves them on. Studies with human volunteers show that solid particles of up to roughly 3 mm can leave the stomach even after a meal. So when a nutrient arrives in the small intestine depends on the dosage form – and on how quickly it releases the nutrient.

From a formulation perspective, there are several plausible reasons to control release:

• Spreading the load: when less arrives at once, according to a Novogenia laboratory study it is less likely that several nutrients compete for the same transport routes in the intestinal wall.
• Avoiding reactions: according to the same study, interactions in which nutrients oxidize each other become less likely.
• Using more of the gut: absorption can also take place in later sections of the small intestine.
• Separating interfering nutrients: nutrients that hinder each other can be released at staggered times – within the same daily serving.
• Closer to a meal: continuous release over several hours more closely resembles the way nutrients become available from ordinary food.

It is just as important what these reasons do not say: the fact that a nutrient is released slowly does not prove that it works better or is better absorbed. Whether a sustained-release profile brings an advantage for a particular nutrient depends on the nutrient, the dose and the formula as a whole. For some purposes, fast release is the better choice – for example, when a nutrient is meant to arrive together with a meal.

How sustained release works technically

Manufacturers use different principles, often in combination. If you are looking for a slow release vitamins manufacturer, this overview helps you put offers into context:

Many small units have a practical advantage: within one serving, beads with different profiles can be mixed – fast for one nutrient, slow for another. Which technique fits depends on the nutrient, the desired release duration and the dosage form. For an overview of formats, see Supplement dosage forms compared.

Stomach-acid-resistant coating

A stomach-acid-resistant (enteric) coating stays closed in the acidic environment of the stomach and only opens in the intestine. It protects acid-sensitive ingredients and ensures that release only begins after the stomach. Combined with a sustained-release layer, it creates a unit that passes through the stomach closed and then releases its contents over hours.

This is exactly how the slow format in Novogenia’s laboratory study was built: an acid-resistant outer layer that keeps it closed in the stomach, plus an inner layer that controls how quickly the content can diffuse out and how fast the layer itself erodes.

Ask: How was the acid resistance tested – and does the result apply to your nutrient and your dosage form?

Separating interfering nutrients, releasing complementary ones together

An underrated benefit of controlled release lies in the formula itself. Nutrients that interfere with each other’s absorption often used to be split across two products or two intake times. If release is controlled per nutrient, this works within a single daily serving: one nutrient is released quickly, the other spread over hours. Nutrients that complement each other, on the other hand, are deliberately released together.

For your customers, this keeps intake simple: one serving a day instead of an intake schedule. Which combinations are typically critical is shown in Developing a formula: dosage, upper limits, interactions.

How Novogenia measured release

Whether a sustained-release technique works can be measured. Novogenia’s laboratory studied two types of pellets, each 2 mm in diameter, both with vitamin C as the test nutrient. The fast format consists of a water-permeable matrix without an acid-resistant barrier; the slow format has the double layer described above. Measurements were taken in an intestinal buffer at 37 °C with gentle stirring, over 0 to 8 hours, read out in 10-minute steps. Because vitamin C is an acid, release could be tracked via the pH of the liquid.

For the timeline from swallowing, the study combined the measured release with values from human studies on gastric emptying: plain liquids leave the stomach quickly – half of the water is gone after about 13 minutes – while small solids leave with a short delay over roughly 2 to 4 hours.

What the study does not show – it names its own limitations:

• The test liquid is a simple buffer. Media containing bile salts and phospholipids would come closer to the real small intestine.
• The stomach values are averages from the literature. Meal size, meal composition and individual differences shift them.
• The timelines are calculated, not measured in people. To show clinical relevance, the study itself calls for follow-up work, for example with blood-level measurements.
• The pH method works because vitamin C is an acid. Other nutrients need other measurement methods.
• The pellets were developed, produced and tested in the manufacturer’s own laboratory, and the work was funded by the manufacturer of the Microtransporters.

All details and the study as a download are available at How a Microtransporter releases its nutrients.

What to ask a manufacturer

“Sustained release” is easy to print on a pack. Whether there is a measured release profile behind it, you will only find out if you ask:

• Which release profile is planned for which nutrient – and why?
• Are there release data? Using which method, in which medium and over what period?
• Was your nutrient measured, or a test nutrient? Can the result be transferred?
• How was the acid resistance tested?
• Does the profile stay stable over the entire shelf life?
• Can fast and sustained release be combined in one serving?
• How does the sustained-release technique affect volume, development time and cost?
• Which statements about release can I make in marketing based on the available data?

Caution in marketing

Sustained release is a good selling point – and a frequent source of non-compliant advertising. The basic rule: you may describe a technical property of the dosage form factually, as long as it is substantiated. Claims about a better effect or health benefits are a different matter: health claims are only allowed in the EU if they have been expressly authorized.

Laboratory release data are not proof of efficacy in humans – Novogenia’s study says so about itself, too. Whoever sells the product under their own name is responsible for the statements on the pack, the website and in advertising. So have your marketing claims checked by an expert before launch.

Frequently asked questions

Related: Study: how Microtransporters release nutrients · Slow-release contract manufacturing at Novogenia · Developing a formula

Note: This guide is general information and does not constitute legal advice. Regulations can change; errors and changes excepted. Always have legal questions about your specific product checked by a qualified expert.