The dose-goal reference table
| Health goal | Evidence-based dose | Trial duration | Primary mechanism |
|---|---|---|---|
| Iron maintenance (adequate baseline) | 3–5 g/day + vitamin C | Ongoing | Non-heme food-matrix iron, ~1–3 mg absorbed/day |
| Iron repletion (mild deficiency, ferritin 20–40 ng/mL) | 8–10 g/day + vitamin C | 12–16 weeks | 3–8 mg absorbed iron/day; verify with ferritin retest |
| LDL cholesterol reduction | 4–8 g/day | 12 weeks minimum | GLA reduces VLDL synthesis; phycocyanin inhibits LDL oxidation |
| Triglyceride reduction | 1–4 g/day (effect visible at 1 g) | 8–12 weeks | GLA increases fatty acid oxidation; reduces hepatic VLDL output |
| Blood pressure (mild hypertension) | 4.5 g/day | 6 weeks | ACE-inhibitory peptides; endothelial NO support (Ku et al., 2013) |
| Allergic rhinitis (hay fever) | 2–4.5 g/day | 6–12 weeks, pre-season start | Th1/Th2 balance; IL-4 reduction; phycocyanin mast cell stabilisation |
| Athletic endurance performance | 5–7.5 g/day | 4–6 weeks minimum | NO pathway; antioxidant capacity; iron for O₂ transport |
| Exercise recovery / DOMS | 6 g/day | 4 weeks (Kalafati trial) | Phycocyanobilin reduces COX-2; maintains glutathione post-exercise |
| Anti-inflammatory support (general) | 3–5 g/day quality spirulina | Ongoing | 300–500 mg/day phycocyanin targeting NF-κB and COX-2 |
| Blood glucose (type 2 diabetes adjunct) | 2–5 g/day | 8–12 weeks | Phycocyanobilin inhibits NADPH oxidase; reduces insulin resistance |
| Liver health (NAFLD adjunct) | 4.5 g/day | 12 weeks | GLA reduces hepatic VLDL; phycocyanin inhibits hepatic NF-κB |
| Sarcopenia prevention (older adults) | 6–8 g/day | 12 weeks | Complete protein (PDCAAS 0.97); phycocyanin reduces inflammaging |
| Gut microbiome support | 3–5 g/day | 8+ weeks | Polysaccharide prebiotics; calcium spirulan antimicrobial |
| Pregnancy (iron + nutrition, verified product) | 3–5 g/day | Ongoing | Iron, folate, B vitamins in food-matrix form |
Why dose varies by goal
Different health goals activate different spirulina mechanisms, which have different dose-response relationships:
Iron: content-limited
Iron is a fixed nutrient at approximately 0.8–1.6 mg per gram. More spirulina = more iron, linearly. Optimised with vitamin C pairing; impaired by coffee, tea, or calcium timing.
Cholesterol: dose-responsive with plateau
GLA-driven VLDL reduction shows a dose-response up to approximately 8 g/day, beyond which additional benefit is marginal. The LDL oxidation protection from phycocyanin is effective across a wider dose range.
Hay fever: Th2 modulation
The allergic rhinitis trials used 2–4.5 g/day. The immune modulation mechanism (Th1/Th2 balance, IL-4 reduction) appears effective at lower doses than the cardiovascular or sarcopenia applications.
Athletic performance: phycocyanin + iron combined
The Kalafati 2010 trial (the primary performance trial) used 6 g/day for 4 weeks. Performance effects require adequate preloading time — acute single doses do not improve performance. The iron and NO pathway effects are cumulative.
Starting and titrating doses
Regardless of your target dose, begin with the escalation protocol:
- Week 1: 0.5–1 g/day
- Week 2: 1–2 g/day
- Week 3: 2–3 g/day
- Week 4+: move toward your target dose
This prevents the GI adjustment symptoms (loose stools, mild nausea) that cause people to abandon spirulina in the first two weeks. The dose escalation also allows taste adaptation through gradual receptor desensitisation.
Quality matters more than dose
At the same nominal dose, higher-quality spirulina (15–25% phycocyanin) provides 2–3× the active compound versus commodity spirulina (5–8% phycocyanin). For goals driven by phycocyanin mechanisms (anti-inflammatory, antioxidant, cholesterol), quality is more important than quantity beyond the 3–5 g range.
A practical approach: choose verified phycocyanin content first, then adjust dose to achieve 300–500 mg/day phycocyanin as a minimum target for anti-inflammatory effects.
What to measure at baseline and follow-up
| Goal | Baseline test | Follow-up timing |
|---|---|---|
| Iron | Ferritin, full blood count | 12–16 weeks |
| Cholesterol/cardiovascular | Lipid panel, blood pressure, CRP | 12 weeks |
| Blood glucose | Fasting glucose, HbA1c | 12 weeks |
| Liver | ALT, AST, GGT, ultrasound if available | 12 weeks |
| Thyroid users (levothyroxine) | TSH | 6–8 weeks after starting |