Osha

Six-dimension breakdown

Why this scored 42/100

Osha is a Prairie Star Botanicals single-ingredient liquid extract containing Osha (Ligusticum porteri), positioned for lung and immune function. Osha is a Rocky Mountain Indigenous respiratory herb with strong regional traditional use. No modern RCT evidence supports the positioning. Osha is also at-risk from overharvest — United Plant Savers lists it as a species of concern. Not for pregnancy (potential uterine stimulant). Well-tolerated at label doses. Prairie Star Botanicals is a small US herbalist line built around locally-harvested (where possible) single-herb liquid extracts. The single-ingredient tincture format is honest — you can see exactly what you're taking. What Prairie Star Botanicals does NOT publish at the product level: third-party certificates of analysis, per-lot heavy-metal or microbial testing, herb-to-menstruum extraction ratios, or standardized marker-compound percentages. That opacity is what caps most of the line at Standard-tier or below in Vyvata's rubric even when the herb itself has real evidence.

Evidence & sources

The Vyvata score's Evidence dimension measures the quality of published RCT support for a product's active ingredients at the label dose. Our source hierarchy: double-blind RCTs in MEDLINE-indexed journals > single-blind RCTs > open-label trials > observational studies > mechanism papers > N=1 case studies (anecdotes). Predatory journals and manufacturer-authored studies without independent replication are weighted down.

Product-specific evidence citations for this item are embedded in the analysis text on the "Analysis" tab. For the full framework and evidence hierarchy, see the methodology page.

How to read the Evidence dimension

• 80–100: Multiple double-blind RCTs in indexed journals directly testing this product OR the exact ingredients at the exact dose.
• 60–79: Single double-blind RCT + supporting ingredient literature at the studied dose.
• 40–59: Open-label trials + ingredient literature; no product-specific double-blind evidence.
• 20–39: Ingredient literature only; no product-specific trials or trials in predatory venues.
• 0–19: No credible evidence base or unverifiable claims.

FAQ data has not been generated for this product yet. See the site FAQ for general questions.

Customer reviews

All the data we have on this product

Every VSF-related metafield surfaced verbatim. Nothing hidden. If you spot data that looks wrong, let us know.

VSF score

42 / 100

Tier

Rejected

Category

Supplements

Subcategory

immune antioxidants

Last scored

August 29, 2026

Third-party certifications

None on record at time of scoring

Vendor

Prairie Star Botanicals

Product type

Singles

Tags

Prairie Star Botanicals, Shopify Collective

Every score is set from the published rubric, audit-logged, and rescored whenever new evidence emerges (published trials, updated labels, third-party testing releases). Every vendor is scored on the same criteria — no pay-to-play. See our editorial-independence disclosure for the full policy, including brands with an editorial relationship to this site.