A natural fiber-like substance from fermented soybeans (natto) with a long, reassuring safety record. Its clearest signal is helping the gut absorb more calcium, especially in those who absorb it poorly. Other effects on body fat, blood sugar, and immunity remain animal-only. Low-risk and inexpensive, with a plausible but unproven calcium role. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Serum 25-hydroxyvitamin D | 40–60 ng/mL | Vitamin D is required for the calcium absorption γ-PGA aims to enhance |
| Serum calcium (albumin-corrected) | 9.4–9.8 mg/dL | Detects any over-absorption when combined with high-dose calcium/vitamin D |
| 24-hour urinary calcium | 100–250 mg/24 h | Flags excess calcium load and kidney-stone risk |
| Parathyroid hormone (PTH) | 15–40 pg/mL | Reflects whether calcium status is adequate; falls when calcium absorption improves |
| Serum magnesium / ferritin (zinc if indicated) | Mg 2.0–2.5 mg/dL; ferritin 50–150 ng/mL | Screens for any reduced absorption of other minerals from cation binding |
Cadence: Baseline, then every 6–12 months for long-term bone use; at 3 months if combined with aggressive calcium/vitamin D