Polyphenols & Flavonoids

What manufacturers buy here

This category covers plant-derived phenolic compounds supplied as isolates or standardised materials for food supplements. Most are flavonoids, stilbenes or curcuminoids. A few related compounds sit here because formulators use them alongside polyphenols.

• Flavonols, flavones and flavonoid glycosides: quercetin, rutin, hesperidin, myricetin and apigenin. Rutin is a glycoside of quercetin. Hesperidin is a flavanone glycoside from citrus.
• Stilbenes: resveratrol.
• Curcuminoids: curcumin, from turmeric rhizome.
• Isoflavones: genistein and mixed isoflavone materials.
• Anthocyanins: water-soluble pigments from berries and other coloured plant material.
• Related compounds: berberine hydrochloride, an isoquinoline alkaloid salt, and salidroside, a phenylethanoid glycoside.

Whole-plant and multi-component extracts are listed under Botanical Extracts.

Choosing within the category

• Purity and assay basis. One name can describe a high-purity isolate or an extract standardised to a marker compound. The specification sheet and certificate of analysis state the assay, its basis and the method. Base label-claim arithmetic on that assay, not on the weight of material.
• Solubility and format. Curcumin, quercetin and resveratrol have low water solubility. They suit capsules and tablets more readily than clear drinks. Glycosides such as rutin and hesperidin, and anthocyanins, behave differently in water, so test dispersion in the final matrix.
• Colour, taste and stability. Curcumin, quercetin and berberine are strongly yellow, and berberine is markedly bitter. Anthocyanin colour shifts with pH. trans-Resveratrol isomerises under light, so protect it during processing and in packaging.

For fill-weight and blend considerations, see ingredients for capsules. The assay you need can be stated in the quote form.

Regulatory notes

These compounds are not vitamins or minerals, so Annexes I and II of Directive 2002/46/EC do not cover them. Where no EU measure applies, their use in food supplements is governed by national rules on “other substances”, which can differ between member states. Regulation (EC) No 1925/2006 also applies: its Article 8 allows the Commission to restrict or prohibit specific substances. Some materials, sources or purities may be novel foods under Regulation (EU) 2015/2283; check each against the Union list and the novel food guide before formulating.