Capsules in Nutraceuticals:
Versatile Dosage Forms for Modern Supplement Delivery
Capsules are among the most popular dosage forms in the nutraceutical industry, prized for their ease of swallowing, precise dosing, efficient manufacturing, and consumer-friendly aesthetics. Whether in the form of hard capsules (two-piece) or softgels (single-piece, liquid-filled), they offer unique advantages in delivering a wide variety of active ingredients – ranging from dry powders and granules to oils and emulsions. In today’s dynamic market, capsules also support important product claims such as vegan, clean-label, natural, and sugar-free, making them a preferred format for formulators and consumers alike.
Capsule Types in Nutraceuticals
Hard capsules (Hard Shell Capsules), also known as hard shell capsules, are a widely used oral dosage form characterized by their two-piece cylindrical structure, consisting of a cap and a body. These capsules are typically filled with solid formulations such as powders, granules, pellets, beads, microtablets, or even mini-tabs. Thanks to their versatility and ease of use, hard capsules are a preferred choice for delivering a range of nutraceutical ingredients. Common applications include multivitamin complexes, herbal blends, amino acids, digestive enzymes, probiotics, and essential minerals. Their protective shell helps mask unpleasant tastes and odors, while offering precise dosing and an attractive presentation.
Softgels (Soft Gelatin Capsules), or soft gelatin capsules, are a popular oral delivery form known for their smooth, one-piece, hermetically sealed structure. Designed primarily to hold liquids or semi-solids, these capsules are ideal for formulations involving oils, emulsions, suspensions, pastes, or even actives dissolved in a suitable vehicle. Their unique structure not only ensures high bioavailability but also enhances product stability and consumer convenience. Softgels are commonly used for lipid-based ingredients such as omega-3 and fish oils, coenzyme Q10, curcumin, vitamin D, and evening primrose oil, making them especially well-suited for fat-soluble nutrients and functional health applications.
Advantages of Capsules in Nutraceuticals
Capsules offer a range of benefits that make them a highly attractive option for nutraceutical delivery. Their smooth surface and ergonomic shape make them easy to swallow, significantly improving consumer compliance. Capsules are also excellent at masking unpleasant tastes, odors, or visually unappealing actives – ideal for ingredients that are bitter, smelly, or brightly colored. From a formulation perspective, they provide remarkable versatility, accommodating a wide variety of fill types including powders, oils, beads, and even complex combination fills.
In addition to their functional advantages, capsules are favored by consumers for their modern and premium appearance – especially softgels, which convey a high-end image. They also allow for design flexibility, with both clear and opaque options available. This enables either a clean, transparent look or protection from light and oxidation-sensitive ingredients. Furthermore, the ability to customize capsule color, add imprints, and incorporate branding elements makes them a powerful tool for brand differentiation in a competitive market.
Capsule Shell Materials Used in Nutraceuticals
The capsule shell is a crucial component, as it determines dietary suitability, stability, and sensory appeal. Here’s a breakdown of commonly used shell materials:
Hard Capsule Shells
- Gelatin (Bovine or Porcine)
- Source: Animal collagen
- Notes: Traditional material, widely accepted; excellent performance in high-speed filling; not suitable for vegans or vegetarians
- HPMC (Hydroxypropyl Methylcellulose)
- Source: Cellulose-based, plant-derived
- Brands: Vcaps®, Quali-V®, Vegicaps®, EMBO CAPS® VG
- Notes: Vegan, non-GMO, non-animal, clean-label-friendly; slower disintegration than gelatin in some cases
- Pullulan
- Source: Polysaccharide from fermentation of tapioca or starch
- Notes: Transparent, natural, and neutral taste; excellent for oxygen-sensitive actives
- Starch-based (e.g. HPMC + Gellan Gum blends)
- Notes: Plant-sourced options with good oxygen barrier properties; some are free of plasticizers
- Marine gelatin (Fish-derived)
- Source: Fish collagen
- Notes: Used for religious dietary restrictions (e.g., kosher, halal) or fish oil capsules
Softgel Shells
- Gelatin (Bovine, Porcine, Fish)
- Most common shell material for softgels
- Plasticizers used: Glycerin, sorbitol
- Notes: Excellent for oil-soluble actives; not suitable for plant-based markets
- Plant-based Softgel Shells
- Materials: HPMC, carrageenan, starch, pectin, alginate
- Commercial examples: G-CAPS®, Vegesoft®, Tapiocaps™, Seacure™
- Notes: Suitable for vegan/vegetarian consumers; growing in popularity, especially in North America and Europe
Note: This is just a short summary. We have dedicated articles for the softshell topic. Have a look here
Formulation Considerations for Capsules
When developing capsule products, it is important to consider the specific characteristics of hard capsules and softgels. Hard capsules are typically filled with powders, beads, or granules, making them ideal for dry formulations. In contrast, softgels are designed to contain oils, suspensions, or emulsions, offering a solution for liquid or semi-solid fills. Moisture sensitivity differs significantly between the two. Hard capsules generally have less moisture in the fill and often require desiccant packaging to maintain stability. Softgels, especially those with gelatin-based shells, inherently contain moisture within the shell itself, which must be managed carefully. Regarding stability, hard capsules tend to perform better with hygroscopic (moisture-absorbing) active ingredients.
On the other hand, softgels are more suitable for protecting oxidation-sensitive lipids, such as omega-3 oils or fat-soluble vitamins. Both capsule types offer excellent taste-masking properties, helping to improve consumer acceptance of less palatable actives. However, the manufacturing requirements are distinct: hard capsules require capsule-filling machines (such as dosator or tamping pin systems), while softgels necessitate specialized rotary die encapsulation equipment. Finally, shelf life can also vary. Hard capsules generally offer a long shelf life if moisture is effectively controlled, whereas the longevity of softgels depends largely on the choice of shell material and plasticizer system used during production.
When to Use Hard Capsules vs. Softgels in Nutraceuticals
Hard capsules are an ideal choice for nutraceutical formulations that involve dry powders, blends, or multiple active ingredients. They offer significant flexibility in development, allowing for faster turnaround and adaptable tooling. This makes them especially well-suited for product lines that demand quick scaling or customization. Additionally, hard capsules are often preferred when clean-label declarations or vegan-friendly options are important to consumers. Their ability to hold high-dose, compact formulations further enhances their utility in efficient dosing and product design.
Softgel capsules are the preferred format when dealing with lipid-soluble actives or formulations that require emulsions. They provide a premium consumer experience with uniform dosing, enhanced bioavailability, and visually appealing aesthetics. Softgels are particularly advantageous when the actives are sensitive to oxidation – such as coenzyme Q10 (CoQ10) or DHA – as the hermetically sealed capsule offers superior protection. Moreover, softgels are excellent at masking unpleasant tastes or odors, making them ideal for sensory-sensitive products that aim for a high-end market positioning.
Conclusion
Capsules – both hard and soft – are a cornerstone of modern nutraceutical dosage form design. They offer unparalleled flexibility in formulation, visual appeal, and dosing precision. Whether you’re creating a botanical blend in a vegan HPMC shell or delivering fish oil in a glossy softgel, capsule formats provide both function and marketability. With a growing array of materials and shell technologies now available, formulators can meet regulatory, dietary, and branding requirements without compromising performance or sensory quality.