Most conversations about supplement quality focus on the active ingredient: the dose, the form, the purity. The capsule shell is part of every serving, but it's rarely part of the conversation.
At Augment Life, we use HPMC capsules across our entire product range. HPMC, or hydroxypropyl methylcellulose, is a plant-derived alternative to gelatine that has been used in pharmaceutical manufacturing for decades. In May 2026, we sent a batch of our capsule shells to an independent, ISO-accredited laboratory for microbiological, chemical, and contaminant testing. This page shares the full results and explains what each measurement means.
The Capsule Is Part of the Product
A capsule does more than hold ingredients together. It protects the contents from moisture, oxygen, and light during months of storage and transit, and determines how reliably the product dissolves after ingestion. Whatever material it is made from also becomes part of what you consume with every capsule.
A typical HPMC capsule shell weighs between 60 and 100 mg. One supplement capsule a day adds up to roughly 36 grams of capsule material per year. Across multiple products, the figure rises. The shell is not a neutral container; it is an ingredient, and it is worth understanding what it is made of.
Why We Use HPMC
HPMC is made from cellulose, the structural fibre found in plant cell walls. Through a controlled manufacturing process, it is converted into a stable polymer widely used in pharmaceutical and nutritional products (1).
The most visible difference from gelatine is dietary: HPMC is entirely plant-based, making it suitable for vegetarian and vegan consumers. But the more important differences are often functional. HPMC and gelatine behave differently in storage, manufacturing, and interaction with sensitive ingredients, which can influence product quality and shelf life.
Lower moisture content. Gelatine has a high moisture content of 13–16%, which is associated with instability under elevated temperature and humidity conditions (2). HPMC capsules contain approximately 4–6% moisture and remain structurally stable at moisture levels as low as 2% (2,3). This means HPMC tolerates a much wider range of storage conditions without compromising the shell. Moisture is one of the primary drivers of degradation in vitamins, antioxidants, and plant extracts over time, and the lower moisture content of HPMC reduces how much water is available to migrate from the shell into the contents during storage (4).
No cross-linking. Certain compounds can bond with the protein chains in gelatine, a reaction known as cross-linking. Botanical aldehydes (found in ingredients like turmeric and cinnamon) are one example; some reactive minerals are another (3). As these bonds form, the capsule shell becomes progressively harder and slower to dissolve, reducing the release of the active ingredient. HPMC contains no protein structures, so it does not cross-link, and its dissolution behaviour stays consistent throughout shelf life (5).
Dissolution performance. A study that tracked capsule disintegration in real time after ingestion found no meaningful difference between HPMC and gelatine capsules in fasted subjects (2). The stability and compatibility advantages of HPMC come without a trade-off in how the capsule behaves in the gut.
No secondary gelling agents. Some HPMC capsules use an added gelling agent such as carrageenan, together with processing aids like polyethylene glycol (PEG), to help the shell set during manufacture. Augment Life use PEG- and carrageenan-free capsules.
Our Independent Lab Results
In May 2026, we sent a batch of our HPMC capsule shells (Batch HPMC00) to J.S. Hamilton Poland, an ISO/IEC 17025 accredited laboratory, for independent testing. The full laboratory report can be found below.
The testing covered three areas of primary relevance for a plant-derived capsule material:
- Microbiological safety
- Ethylene oxide residues
- Heavy metals
Results
- No Salmonella or E. coli detected
- Yeasts and moulds below detection limits
- No detectable ethylene oxide
- Heavy metal levels within established safety guidelines
These results confirm that the capsule material met strict quality and safety standards across all tested parameters.
A Note on Testing
At Augment Life, quality is assessed at every stage of development, including components that are often overlooked, such as capsule shells. Independent testing is part of that process, and publishing the results is how we make it visible.
The results provide additional reassurance that our HPMC capsules meet the standards we expect for safety, quality, and consistency.
Literature Sources
- Vlad RA, Pintea A, Pintea C, Rédai EM, Antonoaea P, Bîrsan M, Ciurba A. Hydroxypropyl Methylcellulose-A Key Excipient in Pharmaceutical Drug Delivery Systems. Pharmaceutics. 2025 Jun 16;17(6):784. doi: 10.3390/pharmaceutics17060784
- Tuleu C, Khela MK, Evans DF, Jones BE, Nagata S, Basit AW. A scintigraphic investigation of the disintegration behaviour of capsules in fasting subjects: a comparison of hypromellose capsules containing carrageenan as a gelling agent and standard gelatin capsules. Eur J Pharm Sci. 2007;30(3–4):251–255. doi: 10.1016/j.ejps.2006.11.008
- Yang N, Chen H, Jin Z, Hou J, Zhang Y, Han H, Shen Y, Guo S. Moisture sorption and desorption properties of gelatin, HPMC and pullulan hard capsules. Int J Biol Macromol. 2020;159:659–666. doi: 10.1016/j.ijbiomac.2020.05.110
- Waterman KC, Adami RC. Accelerated Aging: Prediction of Chemical Stability of Pharmaceuticals. International Journal of Pharmaceutics. 2005;293:101–125.
- Faulhammer E, et al. Multi-methodological investigation of the variability of the microstructure of HPMC hard capsules. International Journal of Pharmaceutics. 2016;511(2):840–854. doi: 10.1016/j.ijpharm.2016.08.005
