Inositol (myo-Inositol)

Grades and forms of myo-inositol

Myo-inositol is the stereoisomer of inositol used in food supplements, supplied as a white powder. EU law does not treat it as a vitamin or mineral. Its use in supplements therefore depends largely on the national rules of each member state. This page covers the grades manufacturers buy, that regulatory position and how the powder behaves in formulations.

Inositol has nine stereoisomers. Supplement products almost always specify the myo form, and the specification states the assay for that isomer. The grade sets the standard the certificate of analysis is tested against: a food-grade specification, or a pharmacopoeia monograph if your customer or dossier requires one.

Particle size is the main physical choice. Fine powder disperses and dissolves quickly in sachets and drink powders. Coarser or granulated material flows better in capsule fillers and suits direct compression. State the grade and particle size you need in the quote form.

EU regulatory status

Directive 2002/46/EC sets compositional lists for vitamins and minerals only. Its Annex I lists the vitamins and minerals that may be used, and inositol is not among them. Myo-inositol therefore counts as one of the “other substances” that the directive leaves to national law, although this site files it with the vitamins. The directive’s general rules, such as its definition and labelling requirements, still apply to the finished supplement. The permitted forms guide explains what Annexes I and II cover.

National rules on other substances differ. Some member states keep lists of permitted substances or set maximum amounts, and some require notification before a product goes on sale. Check each target market with its competent authority rather than assuming one country’s rules apply elsewhere.

Regulation (EC) No 1925/2006 sets out a procedure, in Article 8, for restricting or prohibiting other substances in foods. Confirm that inositol is not listed in Annex III of that regulation before launch. Also confirm its status under Regulation (EU) 2015/2283 for your intended use and source; the novel food guide explains that check.

The name on the label must comply with Regulation (EU) No 1169/2011 and the national rules of the market; see the labelling guide. Any health claim must comply with Regulation (EC) No 1924/2006. Check the EU Register of nutrition and health claims and the health-claims guide before writing any wording.

Formulation notes

Myo-inositol is highly soluble in water and gives a clear solution. That suits sachets, drink powders and liquid formats. Its taste is mildly sweet, so it rarely needs masking, and in flavoured powders it adds some sweetness to the flavour system.

It is a cyclitol with no free carbonyl group, so it is not a reducing sugar. It does not take part in Maillard browning with amino acids or proteins. This simplifies blends with glycine and other amino acids.

Myo-inositol is not a salt, so there is no elemental-content correction: the label declares the substance itself. The only adjustment is for assay:

• Material per serving = label claim ÷ (assay % ÷ 100).
• Add any overage after that step; the overage calculator handles it.

For a 1,000 mg label claim, divide 1,000 mg by the assay fraction stated on the certificate of analysis. Declared amounts are often large, so serving mass usually decides the format.

• Capsules: large claims need several capsules per serving. Fine powder may need a flow aid such as silicon dioxide. See ingredients for capsules.
• Tablets: a high active load leaves little room for binders. Granulated material or wet granulation helps compaction. See ingredients for tablets.
• Powders and sachets: the common format for large servings, with fast dissolution. See ingredients for powders.

Blends with folic acid combine a vitamin declared in micrograms with a substance declared in grams. Use a pre-diluted folic acid premix or geometric dilution, and test content uniformity on each batch.

SoleChem sends the specification sheet and certificate of analysis with its quote. They state the assay, particle size and other test parameters for the grade supplied, and the storage conditions to apply.