Astragalus extract: a sourcing guide for immune-support formulas
Where this guide comes from. We quote astragalus for U.S. immune-support brands most weeks, and the specification question comes up in almost every first enquiry — usually after two quotations have already been compared on price. The points below are what we ask the extraction facility to confirm before any figure goes to a buyer.
Ask three suppliers for astragalus extract and you will get three prices and, quite often, three different sets of numbers. This guide is about making those numbers comparable before price enters the conversation.
What astragalus extract is
Astragalus extract is a water-extracted preparation of the root of Astragalus membranaceus (Fisch.) Bunge — the same botanical used in traditional Chinese medicine as Huangqi. In the Western supplement market it is one of the most widely formulated immune-support botanicals, and the supply chain behind it is concentrated in northern China, including Shaanxi province where we work.
The extract is standardised on two compounds, and this dual assay is the single most important thing to understand about the ingredient:
- Polysaccharides, measured by UV-VIS, typically supplied at 20%, 40% or 50%. This is the water-soluble carbohydrate fraction — the traditional extract profile.
- Astragaloside IV, measured by HPLC, typically supplied at 0.3% or 0.5%. This is a specific triterpene saponin, and the figure a quality-focused brand usually insists on.
Both figures come from the same root, but they are different compounds measured by different methods. A specification that names only one of them is incomplete.
Why the second number matters more than buyers expect
Most first-time buyers focus on the polysaccharide percentage, because it is the bigger number and it appears first on most quotations. The astragaloside IV figure is the one that separates grades in practice.
A lot that reads 50.4% polysaccharides by UV with 0.52% astragaloside IV by HPLC is a well-controlled extract. A lot that reads 50% polysaccharides but carries almost no astragaloside IV is a cheaper material that will not support the same formulation claim. Both can be sold honestly — as long as the specification says which one you are buying.
The polysaccharide figure tells you about the extract's traditional profile. The astragaloside IV figure tells you about the grade.
What to ask before you compare prices
Get every supplier to answer these in writing, then compare:
- Botanical name and plant part (root, not stem or leaf)
- Extraction solvent (water, food grade, for the standard grade)
- Polysaccharide assay: percentage and method (UV-VIS)
- Astragaloside IV assay: percentage and method (HPLC)
- Appearance, particle size (80 mesh is the standard; 100 mesh on request), loss on drying and total ash limits
- Whether the material is pure extract or carried on maltodextrin
The documentation you should expect
A batch-specific Certificate of Analysis covering the polysaccharide and astragaloside IV assays for your lot, plus moisture, ash, heavy metals (lead, arsenic, cadmium, mercury) and microbiological results. With it: a specification sheet, MSDS/SDS, allergen and non-GMO statements, and a pre-shipment sample drawn from the actual production lot — not a retained demonstration batch.
If a supplier cannot produce the astragaloside IV figure for the current lot, they are quoting a grade they do not control. That is useful information before you commit, not after.
Frequently asked questions
What is the difference between astragalus polysaccharides and astragaloside IV?
Polysaccharides are the water-soluble carbohydrate fraction, measured by UV-VIS and typically supplied at 20%, 40% or 50%. Astragaloside IV is a specific triterpene saponin, measured by HPLC and typically supplied at 0.3% or 0.5%. Both come from the same root, but they are different compounds measured by different methods, and a complete specification names both.
What assay grades do you supply?
Standard production grades are polysaccharides 20% / 40% / 50% by UV-VIS and astragaloside IV 0.3% / 0.5% by HPLC, water-extracted and food grade. Alternative assays, mesh sizes and carrier systems can be produced to your specification.
What documents come with an astragalus order?
A batch-specific COA (polysaccharides, astragaloside IV, loss on drying, total ash, heavy metals and microbiological results), specification sheet, MSDS/SDS, allergen and non-GMO statements, and a pre-shipment sample drawn from the actual production lot.
Related: Astragalus Polysaccharides (APS) — full specification, grades and documentation.