Folate (Vitamin B9)
Of 11,779 on-market folate (vitamin b9) products in the January 2026 DSLD dump, the median declared dose is 400 mcg DFE, and 92.1% list Folic Acid as the primary form.
Form share
Of 11,416 products with an identifiable primary form, here is the share held by each form of Folate (Vitamin B9) on the market today.
| Form | Quality tier | n | Share |
|---|---|---|---|
| Folic Acid | Tier 2 | 10,513 | 92.1% |
| Calcium L-5-Methyltetrahydrofolate (Metafolin, brand) | Tier 1 | 466 | 4.1% |
| L-5-Methyltetrahydrofolate (L-Methylfolate, free acid) | Tier 1 | 245 | 2.1% |
| Quatrefolic (glucosamine salt of L-5-MTHF, brand) | Tier 1 | 192 | 1.7% |
Form share over time
Entry-year breakdown of the top forms, 2012–2025.
Dose distribution
Deciles of declared dose per serving (mcg DFE), among 11,238 products with a disclosed amount, against the RDA of 400 and UL of 1000.
- 6.8% of products fall below the fairy-dust threshold (80 mcg, 20% of the studied low dose).
- 0.4% of products don't disclose an amount because Folate (Vitamin B9) is declared inside a proprietary blend.
By dosage form
By target group
Top brands
| Brand | Products |
|---|---|
| Douglas Laboratories | 285 |
| Centrum | 180 |
| DC | 169 |
| Cellucor | 146 |
| Nature's Way | 133 |
| Wonder Laboratories | 130 |
| Nature Made | 121 |
| Source Naturals | 118 |
| MegaFood | 118 |
| Metagenics | 111 |
| Emergen-C | 109 |
| Pure Encapsulations | 100 |
| Higher Nature | 99 |
| NOW | 97 |
| Life Extension | 95 |
| New Chapter | 95 |
| Bluebonnet | 94 |
| The Vitamin Shoppe | 92 |
| XYMOGEN | 91 |
| Country Life | 87 |
| Puritan's Pride | 85 |
| Bayer One A Day | 85 |
| Vitamin World | 83 |
| GNC Mega Men | 83 |
| Solgar | 80 |
Forms explained
Extremely well-evidenced for neural-tube-defect prevention and highly stable/cheap, but requires multi-step enzymatic reduction (DHFR then MTHFR) to become active 5-MTHF -- a pathway that can be rate-limited in people with reduced-function MTHFR variants (C677T/A1298C).
Source: MRC Vitamin Study Research Group 1991, PMID 1677062; Hekmatdoost A et al. 2015, PLoS One 10(12):e0143569, PMID 26630680
The natural, circulating, already-"active" form that bypasses the MTHFR conversion step entirely; raised serum folate more effectively than folic acid in an RCT, though that trial found no additional miscarriage-prevention benefit over folic acid regardless of MTHFR genotype -- avoid overselling the MTHFR-relevance angle.
Source: Hekmatdoost A et al. 2015, PLoS One 10(12):e0143569, PMID 26630680
Elemental fraction: 92.3% (free-acid L-5-MTHF MW 459.46 / calcium salt MW 497.53 (confirmed PubChem formula))
Same active-form rationale as L-5-MTHF -- the calcium salt is simply the stabilized, tabletable version of the same active molecule (not separately tested head-to-head).
Source: Hekmatdoost A et al. 2015, PMID 26630680 (parent vitamer's tier rationale)
Elemental fraction: 56.2% (free-acid L-5-MTHF MW 459.46 / Quatrefolic MW 817.81, a diglucosamine salt (confirmed PubChem formula))
Same active folate species as Metafolin/L-5-MTHF, using glucosamine instead of calcium as the salt-forming counterion for solubility. No head-to-head trial of Quatrefolic vs Metafolin vs generic L-5-MTHF was found -- treat any distinction between these three brands as uncertain.
Source: uncertain -- needs review for a brand-specific comparison
Reference values
- RDA (adult): 400 mcg DFE
- Tolerable Upper Intake Level (adult): 1000 mcg DFE — Applies specifically to synthetic folic acid from fortified foods and/or supplements; no UL for folate naturally occurring in food
- Studied clinical dose range: 400–4000 mcg
- MRC Vitamin Study Research Group 1991, Lancet 338(8760):131-137, PMID 1677062 -- landmark RCT, 4mg/day (4000mcg) folic acid reduced neural-tube-defect recurrence risk ~72% in women with a previously affected pregnancy -- a high-risk-population dose, distinct from the general-population 400mcg RDA (studied_dose_low).
- Note: DFE conversion (1 mcg DFE = 1 mcg food folate = 0.6 mcg folic acid from fortified food/supplements with meals = 0.5 mcg folic acid from supplements on an empty stomach) is applied ONLY when the label itself declares DFE units -- older/non- conforming labels declaring plain mcg folic acid are flagged (unit_flagged), not silently converted, per reference/amount_conventions.md.