What Are Supplement Capsules Made Of? A Complete Guide 2025

When checking nutrition labels, most of us focus strictly on the active ingredients—the vitamins, minerals, or herbs listed on the back. However, the outer shell of your capsule supplements plays a critical role in digestion, stability, and dietary compliance that is often overlooked.

This guide explores exactly what goes into the manufacturing of these delivery systems, breaking down the composition of the three most common capsule types: traditional Gelatin (animal-based), HPMC (standard vegetable), and Pullulan (organic starch). Whether you are navigating dietary restrictions like Veganism and Halal, or simply concerned about avoiding synthetic additives, this article will provide a complete breakdown of the ingredients holding your daily vitamins together.

The Traditional Standard: Gelatin Capsules

For decades, gelatin has been the undisputed king of the capsule world. If you picked up a bottle of vitamins ten years ago, it is almost certain the shells were made of gelatin. Even today, it remains the most widely used material in the global supplement industry due to its long history of safety and reliability.

What Exactly is Gelatin?

In short, gelatin is an animal byproduct. It is a protein substance derived from collagen—a structural protein found in animal connective tissues. To create gelatin suitable for capsules, manufacturers extract collagen from the skin, bones, and tendons of animals through a process of boiling and hydrolysis.

Once processed, this material forms a tasteless, odorless substance that can be molded into a hard, durable shell that dissolves rapidly once it reaches the warmth and moisture of the stomach.

Primary Sources

Not all gelatin comes from the same place. The vast majority of gelatin capsules on the market today are sourced from two primary animals:

• Bovine (Cow): Derived primarily from cow hides and bones.
• Porcine (Pig): Derived primarily from pigskin.

There is also a third, less common option: Piscine (Fish) gelatin. Often marketed as “Marine Gelatin,” this is sometimes used to cater to pescatarian diets or specific religious requirements where bovine or porcine sources are restricted, though it is generally more expensive to produce.

The Pros and Cons of Gelatin

Why has gelatin been the standard for so long, and why are many brands now moving away from it?

✅The Advantages:

• Cost-Effective: Gelatin is significantly cheaper to manufacture than plant-based alternatives, keeping the final cost of supplements down for consumers.
• Bioavailability: These capsules dissolve very quickly in the stomach, allowing for rapid release and absorption of the nutrients inside.
• Durability: Gelatin shells are mechanically strong. They are less likely to crack or break during bottling and shipping compared to some vegetarian options.

❌The Disadvantages:

• Dietary Restrictions: This is the biggest drawback. Gelatin is unsuitable for vegans, vegetarians, and those observing strict kosher or halal diets (unless specifically certified).
• Environmental Sensitivity: Gelatin is highly sensitive to heat and moisture. If left in a hot car or a humid bathroom, these capsules can become sticky, melt together, or become brittle.

The Modern Standard: Vegetarian (HPMC) Capsules

The surge in preference for non-animal goods has crowned HPMC as the premier “clean label” substitute for traditional animal-derived ingredients in items marketed as vegan or plant-based, decisively shifting the landscape of Gelatin vs. Vegetarian (HPMC) Capsules.

What is HPMC?

The name sounds intimidatingly synthetic, but its origins are natural. HPMC stands for Hydroxypropyl Methylcellulose.

Often referred to simply as “vegetable cellulose” on ingredient labels, HPMC is derived from wood pulp—specifically, the cellulose fibers found in pine or poplar trees. Through a manufacturing process, these plant fibers are modified to create a stable polymer that mimics the useful properties of gelatin without using any animal products.

Because they are derived from wood rather than food crops like corn, they are naturally GMO-free.

The “Clean Label” Appeal

HPMC capsules have become the preferred choice for premium supplement brands because they solve the major hurdle of gelatin: dietary restrictions. They are universally accepted across virtually all diets, making them inherently suitable for vegans and vegetarians, and easily certified as Halal and Kosher.

Why Choose HPMC? Pros and Cons

While they were created to solve the “animal origin” issue, HPMC capsules actually offer some functional advantages over gelatin, particularly regarding product stability.

✅The Advantages:

• Universally Accepted: They meet nearly all dietary, religious, and ethical requirements.
• Low Moisture Content: Gelatin typically holds 13-16% moisture. HPMC holds much less (around 4.5–6.5%). This makes HPMC the superior choice for ingredients that are sensitive to moisture, such as probiotics or certain herbal extracts that might degrade if exposed to the higher water content of a gelatin shell.
• Temperature Resistant: They are more stable in varied climates and less likely to become brittle in low humidity or sticky in high heat compared to gelatin.

❌The Disadvantages:

• Higher Cost: Manufacturing HPMC capsules is more complex and expensive than producing gelatin capsules.
• The “Synthetic” Label: Although derived from natural tree fibers, HPMC is considered a semi-synthetic polymer due to the chemical processing required to create it. Because of this processing, HPMC capsules cannot currently be certified USDA Organic.

The Premium Choice: Pullulan Capsules

If Gelatin is the traditional standard and HPMC is the modern staple, then Pullulan is the luxury option. Pullulan capsules are a newer entrant to the market, designed to meet the demands of the most discerning consumers who want a plant-based product that is not just vegetarian, but also naturally fermented and organic.

What is Pullulan?

Unlike HPMC, which is derived from wood fibers, Pullulan is a water-soluble polysaccharide produced through a natural fermentation process.

It is made by fermenting starch (most commonly from tapioca or corn) using a specific fungus called Aureobasidium pullulans. Think of it similarly to how yogurt or kombucha is fermented. This process results in a pristine, tasteless, and odorless material that is incredibly strong and has an attractive, glossy finish similar to gelatin.

Hard Shell vs. Softgels: What’s the Difference?

So far, we have discussed the materials used to create standard, two-piece capsules. But if you open your medicine cabinet, you will likely notice another type of capsule entirely: the squishy, often translucent “softgel.”

While they serve the same purpose—delivering a dose of nutrients—their structure and composition are fundamentally different.

The Hard Shell Capsule

This is the standard capsule we have been discussing up to this point. Whether made of Gelatin, HPMC, or Pullulan, it consists of two distinct parts: a longer “body” that is filled with the ingredient, and a shorter “cap” that is snapped over the top to seal it.

• Best For: Dry ingredients such as powders, ground herbs, granules, or tiny timed-release beads.
• Consumer Ability: You can usually twist these open if you prefer to mix the powder into a smoothie or yogurt (though check with a doctor before altering dosages).

The Softgel

A softgel is a hermetically sealed, single-unit capsule. It is formed, filled with liquid, and sealed all in one continuous operation on a specialized machine. They are typically thicker and sturdier than hard shells but remain flexible to the touch.

• Best For: Liquids, oils, and fat-soluble nutrients that would leak out of a two-piece hard shell. Think Fish Oil, Vitamin D, Vitamin E, and CoQ10.

What Makes a Softgel “Soft”?

Almost all softgels start with a base of gelatin. However, to transform hard, brittle gelatin into a flexible, squishy casing, manufacturers must add plasticizers.

Think of plasticizers as moisturizers for the capsule shell. Without them, the gelatin would dry out and crack. The most common plasticizers you will see on labels are:

• Glycerin (Glycerol)
• Sorbitol

Are There Vegan Softgels?

Because standard softgels require gelatin to form that unique sealed shape, 95% of the softgels on the market are animal-based.

However, vegan technology is catching up. Vegetarian softgels do exist. Instead of gelatin, they typically use a combination of modified tapioca starch and agents derived from seaweed, such as carrageenan, to create a similar flexible shell. Because these are more difficult and expensive to manufacture, they are usually reserved for premium vegan brands.

Other Hidden Ingredients in Capsule Shells

Up until now, we have focused on the primary material that forms the structure of the capsule. However, if you look closely at an ingredients label, you will rarely see just “Gelatin” or “Hypromellose (HPMC).”

To make capsules aesthetically pleasing, stable, and functional, manufacturers often add “inactive” ingredients to the shell formulation. While these are generally considered safe in small amounts, educated consumers in 2025 are increasingly paying attention to these additives.

Here is a breakdown of the hidden ingredients you might find in the shell.

The Opacifier Controversy: Titanium Dioxide

If you have a capsule that is solid white or opaque colored (meaning you cannot see the powder inside), it likely contains an opacifier.

For decades, the standard opacifier has been Titanium Dioxide (TiO2). It is a naturally occurring mineral used as a white pigment to brighten foods, cosmetics, and paints. In supplements, it is used to protect light-sensitive ingredients or simply to hide unpleasant-looking herbal powders.

Because of this, there is a massive trend in the industry toward “Titanium Dioxide-Free” capsules. Many clean-label brands are switching to natural alternatives like calcium carbonate to achieve opacity, or simply using clear capsules.

Colorants: Natural vs. Artificial

Capsules come in every color of the rainbow for branding purposes or to help consumers differentiate between morning and evening doses.

Preservatives

Because gelatin is an animal protein containing moisture, it can be susceptible to bacterial and fungal growth if not stored properly. Therefore, some gelatin capsules may contain small amounts of preservatives like methylparaben or propylparaben.

HPMC and Pullulan capsules are plant-based polymers with lower moisture content, making them naturally resistant to microbial growth, so they rarely require added preservatives.

How to Read the Label (Comparison Table)

Here is a more detailed comparison table to help you quickly decode the “Other Ingredients” section of your supplement bottle.

Quick Label Decoder

If the label says…	It means the capsule is…	Primary Source	Common Certifications
“Gelatin”	Animal-Based	Cow, Pig, or Fish Collagen	None (unless specified)
“Vegetable Capsule”	Plant-Based (HPMC)	Pine or Poplar Wood Fiber	Vegan, Vegetarian, Kosher, Halal
“Vegetable Cellulose”	Plant-Based (HPMC)	Pine or Poplar Wood Fiber	Vegan, Vegetarian, Kosher, Halal
“Hypromellose”	Plant-Based (HPMC)	Pine or Poplar Wood Fiber	Vegan, Vegetarian, Kosher, Halal
“Pullulan”	Plant-Based (Fermented)	Tapioca or Corn Starch	Vegan, Kosher, Halal, USDA Organic
“Plant Polymer”	Plant-Based (Pullulan)	Tapioca or Corn Starch	Vegan, Kosher, Halal, USDA Organic

As we have explored, the question “what are supplement capsules made of?” does not have a single, simple answer. The industry has evolved from relying solely on animal-based gelatin to offering a diverse range of high-quality, plant-based alternatives like HPMC and Pullulan to meet every dietary and ethical need.

Ultimately, there is no single “best” capsule type. Gelatin remains a cost-effective and reliable powerhouse, HPMC has become the versatile vegetarian standard, and Pullulan offers a premium solution for certified organic and oxygen-sensitive formulations.

The key is transparency. When a brand decides to bring a new product to market, choosing the right Capsule Supplements Manufacturer is a critical step. A quality manufacturer helps ensure that the capsule material—whether it’s a bovine gelatin shell or an organic Pullulan casing—aligns perfectly with the ingredients inside and the values of the consumer buying it.

By understanding these differences and knowing how to read the label, you can now make the most informed decisions about the supplements you take as part of your health regimen in 2025 and beyond.

• Fish Gelatin: Current Nutritional, Medicinal, Tissue Repair Applications, and as a Carrier of Drug Delivery(source link: https://pubmed.ncbi.nlm.nih.gov/35088658/)
• HPMC stands for Hydroxypropyl Methylcellulose.(source link: Hydroxypropyl Methylcellulose—A Key Excipient in Pharmaceutical Drug Delivery Systems – PMC)
• HPMC Temperature Resistant: They are more stable in varied climates and less likely to become brittle in low humidity or sticky in high heat.(source link: Comparative Evaluation of Gelatin and HPMC Inhalation Capsule Shells Exposed to Simulated Humidity Conditions – PMC)
• Gelatin typically holds 13-16% moisture. HPMC holds much less (around 4.5–6.5%). (source link:https://pmc.ncbi.nlm.nih.gov/articles/PMC12299881/#:~:text=Buttini%20et%20al,with%20specific%20formulations.)
• What is Pullulan？ (source link：https://en.wikipedia.org/wiki/Pullulan）
• Pullulan is currently the only capsule material that can be officially certified as USDA Organic.(source link：https://www.nutritionaloutlook.com/view/pullulan-can-be-used-in-made-with-organic-tablets-and-capsules-usda-final-rule-states#:~:text=This%20regulatory%20development,not%20readily%20available.%E2%80%9D）
• A softgel is a hermetically sealed, single-unit capsul.(source link：https://pmc.ncbi.nlm.nih.gov/articles/PMC11468233/#:~:text=As%20the%20die%20rolls%20rotate%2C%20both%20gelatin%20ribbons%20are%20hermetically%20sealed%20(standard%20temperature%20range%2037%E2%80%9340%20%C2%B0C%5B%2012%20%5D)%20and%20cuts%20out%20the%20filled%20capsules.