Botanical atlas

Spirulina

Spirulina platensis

Long before it appeared in supplement aisles, spirulina was gathered as food. The Aztecs skimmed it from the alkaline waters of Lake Texcoco and dried it into cakes called tecuitlatl, prized as a staple protein. Around the same time and continuing today, communities near Lake Chad in Africa harvest a wild relative from the lake's edges, sun-dry it into cakes known as dihe, and use it to thicken and enrich soups and sauces. In both traditions, spirulina was valued less as a remedy than as a dependable, nourishing food, one that sustained people through lean seasons.

Safety.

Spirulina should come from a tested, reputable source, since poorly grown batches can carry liver-toxic microcystins or heavy metals. Avoid it if you have PKU, since it contains phenylalanine, and use it cautiously if you have a thyroid condition, take blood thinners or immunosuppressant medication, or have an autoimmune disorder.