Ferrous bisglycinate is an oral iron used to refill empty stores, not a longevity tonic. In deficient people it rebuilds the oxygen-carrying protein as well as, sometimes better than, ordinary iron, often at lower dose with fewer gut symptoms. Extra iron is the risk when stores are full, in men after middle age, or with genes that store extra iron. (Full Review)

Protocol

Standard repletion (integrative and sports clinics)

18–27 mg elemental iron once daily, or every other day

For 8–16 weeks in documented deficiency, then re-test

Time of day

Morning, fasted

When hepcidin is lowest; evening doses collide with higher hepcidin and with magnesium or calcium often taken at night

Baseline ferritin

Repletion reserved for ferritin <30 ng/mL without inflammation

Or <50 ng/mL in a symptomatic, inflamed, or pregnant person

Time to effect

Hemoglobin repletion

2–4 weeks

Reticulocytes (young red blood cells) move in days

Lower self-reported fatigue

After hemoglobin rise

Energy shifts, when they occur, usually lag the first hemoglobin bump

Restoration of iron stores

8–12 weeks

Ferritin and stores take 8–12 weeks, often 3–6 months if losses continue

Benefits

High: Hemoglobin repletion in iron deficiency; Fewer gut side effects than iron salts; Lower self-reported fatigue when stores are low

Medium: Restoration of iron stores

Low: Restless legs symptoms; Exercise capacity in iron-deficient athletes; Cognitive performance when stores are low

Speculative: Longevity via avoiding deficiency-related energy failure

Contraindications

Hereditary hemochromatosis (especially HFE C282Y homozygotes or C282Y/H63D compound heterozygotes) and other primary iron-overload syndromes

Iron-replete men and postmenopausal women without documented low ferritin or a named ongoing loss

Active hemolytic or transfusion-dependent iron loading (thalassemia major, similar)

Uninvestigated anemia in men or postmenopausal women, until bleeding and malabsorption work-up is underway

Infants and small children as an unsupervised household product

Key Interactions

Levothyroxine (and liothyronine) (separate at least 4 hours)

Levodopa (carbidopa–levodopa) (separate at least 2 hours)

Tetracyclines (doxycycline, minocycline) and fluoroquinolones (ciprofloxacin, levofloxacin) (at least 2 hours before or 4–6 hours after iron)

Bisphosphonates (alendronate, risedronate) (separate by several hours)

Proton pump inhibitors (omeprazole, esomeprazole) and histamine-2 blockers (famotidine)

Calcium, zinc, and magnesium supplements (separate by 2 hours)

Tea, coffee, and high-phytate meals

Other iron products and intravenous iron (hold around infusion days)

Vitamin C (useful in deficiency, unhelpful once ferritin is full)

Risk & Side Effects

High: Gastrointestinal irritation; Binding to other oral drugs and minerals

Medium: Accidental pediatric overdose

Low: Iron overload from unsupervised long-term use; Gut microbiome and pathogen pressure

Speculative: Faster tissue aging from mild iron surplus

Monitoring

Marker	Target	Why
Ferritin	50–150 ng/mL	Confirms stores; the treatment on/off switch
Transferrin saturation	25–45%	Shows circulating iron available to marrow
Hemoglobin	No established target exists; track rise toward the person's own baseline	Confirms oxygen-carrying recovery
Mean corpuscular volume	No established target exists; track rise from low toward the lab mid-normal	Tracks iron-limited red-cell production
C-reactive protein	Low; ideally <1.0 mg/L	Interprets ferritin; high CRP can hide deficiency
Soluble transferrin receptor	No single functional target; track fall toward the lab mean	Separates true deficiency from inflammation

Cadence: Baseline full iron panel plus C-reactive protein before the first capsule; 4 weeks if anemia is present (hemoglobin); 8–12 weeks for ferritin in non-anemic deficiency; then every 3–6 months if menstrual or training losses continue, or at the next annual panel if the course has stopped and stores are stable

Qualitative Assessment

Energy and afternoon stamina relative to the person's own baseline
Exercise heart rate and perceived effort at familiar paces
Restless legs or nocturnal movement
Hair shedding, brittle nails, and pallor
Gut comfort on the chosen dose (constipation, nausea, dark stool)

Ferrous Bisglycinate for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment