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Spirulina (Arthrospira platensis)

Blue-green algae with meta-analysis signal for modest lipid reduction and a separate signal for allergic rhinitis.

Why

Spirulina (Arthrospira platensis and A. maxima) is a blue-green algae long used as a food in central American and African cultures. Meta-analyses of RCTs report modest reductions in total cholesterol, LDL and triglycerides at 1–10 g/day. A smaller body of work supports use in allergic rhinitis, RCTs report reductions in nasal symptoms and serum IgE at 2 g/day. Heavy metal and microcystin contamination of poorly-sourced spirulina is the practical safety limit.

How it works

Phycocyanin and γ-linolenic acid (GLA) reduce lipid peroxidation and modulate inflammatory cytokine signalling. Mechanism in allergic rhinitis involves Th1/Th2 balance shift and reduced IL-4 production. Protein content (~60% by weight) provides essential amino acids.

Expected onset · Lipid effects over 8–12 weeks; allergic rhinitis effects over 2–8 weeks

How to take

Dosage

Lipid effect: 1–10 g/day divided. Allergic rhinitis: 2 g/day divided. Tablets or powder dissolved in liquid.

Timing

Divided 2–3 times daily with food

On the label

Organic certified spirulina with stated heavy-metal testing. Avoid bulk wild-collected material, microcystin contamination is real.

Ideal for

Adults with mild dyslipidaemia or seasonal allergic rhinitis seeking a dietary approach; people exploring plant-protein sources with concentrated micronutrients.

Safety

Heavy metal and microcystin contamination has been documented in poorly-sourced products. Buy from suppliers with third-party heavy-metal testing. Phenylalanine content, contraindicated in PKU. May worsen autoimmune disease (theoretical Th1 polarisation). Caution with anticoagulants. Pregnancy: limited data; choose tested products only.

Evidence

At a glance

Serban 2016 Clin Nutr meta-analysis (7 RCTs, n=522): spirulina reduced total cholesterol by 0.61 mmol/L, LDL by 0.42 mmol/L and triglycerides by 0.55 mmol/L vs control. Cingi 2008 RCT (n=129 allergic rhinitis): spirulina 2 g/day significantly reduced nasal discharge, congestion and itching vs placebo over 6 months. Effect modest but consistent.

Where to get it

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