What matters in this format
A softgel is a one-piece, hermetically sealed shell around a liquid or semi-solid fill. It suits oils, oil solutions and oil suspensions, the forms most fat-soluble vitamins and lipids already come in. Most of the constraints come from the shell and from what the fill does to it.
- Fill nature. The fill must be lipophilic or a suspension in a lipid carrier. Water, low-molecular-weight alcohols and strongly hydrophilic components migrate into the shell and soften or deform it.
- Fill volume. The die size limits the fill mass per capsule. Bulky actives quickly push a label claim to several softgels per portion.
- Suspension behaviour. Crystalline powders suspended in oil must stay uniformly dispersed during encapsulation and storage. Viscosity and particle size, stated on the specification sheet, decide whether a suspending agent is needed.
- Oxidation. Unsaturated oils and fat-soluble vitamins degrade with oxygen, light and trace metals. Oxidised oils can form aldehydes that cross-link gelatin and slow shell rupture.
- pH and reactivity. Strongly acidic or alkaline fills, and reactive groups such as aldehydes, alter gelatin over time.
- Moisture and temperature. Shells equilibrate with ambient humidity. Heat and high humidity make capsules tacky or cause them to stick together.
Ingredients that suit it
| Ingredient | Why it fits a softgel | What to watch |
|---|---|---|
| Omega-3 (EPA and DHA) oils | Liquid oil fills the capsule directly | Oxidation and odour; antioxidant choice; novel-food status of some oil sources |
| Cholecalciferol (vitamin D3) | Fat-soluble; dissolves in a carrier oil | Microgram amounts need accurate dilution and content uniformity; light and oxygen |
| Retinyl acetate (vitamin A) | Fat-soluble ester, oil-compatible | Sensitive to oxygen and light |
| Vitamin E and vitamin K forms | Oil forms blend into the fill | Choose the form for oil solubility; vitamin K needs light protection |
| Coenzyme Q10 | Lipophilic; dissolved or suspended in oil | Crystallisation in the fill; the reduced form oxidises readily, see ubiquinol vs ubiquinone |
| Beta carotene and astaxanthin | Carotenoids handled as oil suspensions | Intense colour; oxidation; settling |
| Conjugated linoleic acid | Free-flowing oil | Oxidation of the unsaturated chain |
| Curcumin, resveratrol, quercetin | Poorly water-soluble powders that suspend in oil | Settling and viscosity; often needs a suspending agent |
| Mineral salts | Possible as suspensions | High mass per label claim; abrasion and settling; tablets or hard capsules usually fit better |
For vitamin claims given in international units, the vitamin unit converter does the conversion to micrograms. Fat-soluble vitamins usually need an overage to hold the label claim through shelf life; the overage calculator handles the arithmetic.
Excipients and processing aids
Only a few items from the excipients range belong in a softgel.
- Gelatin is the standard shell former. Bovine, porcine and fish gelatin differ in gel strength, viscosity and label positioning. The specification sheet states source and gel-strength grade.
- Sorbitol acts as a plasticiser, alone or with glycerol. The plasticiser ratio sets shell flexibility and how the shell responds to humidity.
- Silicon dioxide in colloidal form thickens oil fills and slows settling of suspended powders.
- Citric acid and trisodium citrate adjust the pH of gelatin solutions or hydrophilic fill components. Citric acid also chelates trace metals that catalyse oil oxidation.
- HPMC (hypromellose) and pullulan form hard-capsule shells, not one-piece softgels. They become relevant when a non-animal shell is required and the liquid fill is moved to a sealed hard capsule.
Microcrystalline cellulose, magnesium stearate, sodium stearyl fumarate, mannitol, erythritol, polydextrose and pectin serve tablets, capsules and gummies rather than softgels. SoleChem sends the specification sheet and certificate of analysis for each excipient and active with its quote.
Regulatory and labelling points
Vitamins and minerals in the fill must be in a form listed in Annex II of Directive 2002/46/EC; see permitted vitamin and mineral forms. Oils such as fish, algal or krill oils are “other substances”, and some sources may be novel foods under Regulation (EU) 2015/2283. Check each source against the Union list and the novel food guide.
Gelatin is used as a food ingredient. Plasticisers such as sorbitol and glycerol, shell colours, and antioxidants in the fill are food additives. Their use in food supplements must be authorised in Annex II of Regulation (EC) No 1333/2008, and they must meet the specifications in Regulation (EU) No 231/2012. Titanium dioxide is no longer authorised as a food additive in any food category, food supplements included, which affects opaque shell formulas.
Under Regulation (EU) No 1169/2011, polyols above the threshold in Annex III trigger a mandatory laxative-effect statement. Fish is a listed allergen in Annex II. Its exemption for fish gelatin is worded for carrier use in vitamin or carotenoid preparations, so a fish-gelatin shell normally needs an allergen declaration.
Nutrient amounts are declared per recommended daily portion, so the number of softgels per portion fixes the content per capsule. The labelling guide covers the full set of mandatory particulars.