Walk into any health food shop and spirulina and chlorella tablets are usually sitting on the same shelf, often lumped together under the same 'superfood algae' label. It's an understandable pairing — both are sold…

Probiotics have moved from a specialist corner of the health-food shop into an everyday category. You now see them in capsules, chewables, powders, yoghurts and products aimed at different life stages. That wider choice can…