Plant Sterols (Phytosterols)

Plant sterols, or phytosterols, are a group of steroid alcohols found only in plants. They share cholesterol's steroid skeleton with a hydroxyl group at C-3 and differ from it in the side chain at C-17. The material sold as "phytosterols" is a defined mixture rather than a single substance: principally β-sitosterol (CAS 83-46-5) with campesterol (CAS 474-62-4), stigmasterol (CAS 83-48-7) and, depending on the source, brassicasterol (CAS 474-67-9) and the saturated stanols sitostanol (CAS 83-45-4) and campestanol (CAS 474-60-2). Two commercial routes dominate and they give measurably different profiles. Vegetable-oil sterols are recovered from deodoriser distillate, the volatile fraction stripped during refining of soybean, rapeseed, sunflower or corn oil, which carries roughly 8-20% phytosterols and 5-15% tocopherols before separation by transesterification, distillation and solvent crystallisation. Tall-oil sterols come from tall oil pitch, the residue of kraft pulping of Pinus species, where phytosterol content runs 5-15% and recovery is by saponification, neutralisation, distillation and solvent recrystallisation. Tall-oil grade is sitosterol- and sitostanol-rich with stigmasterol below 1%; vegetable-oil grade carries 14-24% stigmasterol. If a formula depends on the stigmasterol figure, the source has to be named in the specification, not left open. Physically these are high-melting crystalline waxy powders or prills, melting between 138 and 158 °C, with under 0.01 g dissolving in 100 g of water and only about 2.5% solubility in fat at ambient temperature. That insolubility is the whole formulation problem. Esterification with fatty acids from vegetable oils converts the powder into a liquid or semi-liquid ester that behaves like an edible fat and disperses into spreads, dairy and beverages; in the ester the sterol backbone is about 60% and the fatty acid tail about 40% by weight, which is the conversion factor a label needs when it declares free sterol equivalents. Where the free sterol is wanted, micronised and carrier-dispersed grades are used instead. Assay is by capillary gas chromatography with flame ionisation detection on the trimethylsilyl derivatives, which reports both total content and the individual sterol distribution; esterified material is saponified first, typically on the ISO 12228 principle, before silylation. Thovek offers 90% and 95% minimum total sterol grades, free or esterified, with the full GC profile on the certificate rather than a single number. Two regulatory points are commercially load-bearing. First, allergen status: Annex II of Regulation (EU) No 1169/2011 lists soybeans as a declarable allergen but exempts plant sterols and plant sterol esters derived from vegetable oils, and plant stanol esters produced from vegetable oil sterols, from that declaration. Soy-derived phytosterols therefore do not trigger a soy allergen declaration in the EU - but the exemption is EU-specific and must be confirmed independently for the United States, Canada and other destinations rather than assumed. Second, labelling: Commission Regulation (EC) No 608/2004 requires that foods with added phytosterols use the terms "plant sterol" or "plant stanol", carry "with added plant sterols/plant stanols" in the same field of vision as the product name, state the added amount in the ingredient list, define a portion, and carry statements that the product is intended exclusively for people who want to lower their blood cholesterol level, that patients on cholesterol-lowering medication should consume it only under medical supervision, that it may not be nutritionally appropriate for pregnant and breastfeeding women and children under five, that it should be used as part of a balanced diet including fruit and vegetables to help maintain carotenoid levels, and that consumption of more than 3 g per day of added plant sterols or stanols should be avoided. Products are accordingly presented in portions of at most 3 g, or at most 1 g where three portions a day are intended. Thovek states these obligations as regulatory facts and makes no health claim of its own; claim wording is the brand owner's responsibility in each market. The material is vegan and vegetarian, gluten-free, and non-GMO status is declared where the origin is soy or corn.