Spirulina

Introduction

Spirulina (Arthrospira platensis) is not a plant but a cyanobacterium, a microscopic "blue-green alga". It grows naturally in warm, highly alkaline lakes (pH 8.5 to 11). Dried, it is very rich in protein: about 60 to 70% of its dry weight, according to Memorial Sloan Kettering and the FAO.

History

Sixteenth-century Spanish accounts describe the Aztecs harvesting a green paste called techuitlatl near Tenochtitlan and drying it into cakes. On the other side of the world, Kanembu women on the shores of Lake Chad still filter spirulina to make cakes called dihé. French botanist Pierre Dangeard described it in 1940, and the Léonard expedition of 1964–65 brought it to scientists' attention (FAO, 2008).

Traditional uses

In Chad, dihé is crumbled into a tomato and chilli sauce served with millet. Today spirulina is mostly taken as tablets or as a powder stirred into juice, smoothies or yoghurt.

Scientific studies

A 2018 meta-analysis of 12 clinical trials (807 people) found lower total cholesterol, LDL and triglycerides in people taking spirulina, with no effect on HDL, body weight or HbA1c. Spirulina is a food supplement, not a medicine.

Precautions

• Choose a tested product: spirulina grown in polluted water can contain toxins (microcystins) or heavy metals.
• Not advised for people with phenylketonuria (it contains phenylalanine) or an autoimmune condition.
• It may affect blood clotting: take care with blood thinners.
• Talk to your doctor before taking it, especially during pregnancy or breastfeeding.

Further reading: Harvard Health · Memorial Sloan Kettering