30+ - Sweet Potato

Originating in South America and brought to Europe by Spanish explorers in the 15th century, decades before the unrelated potato. The potato is from the nightshade family whilst the sweet potato is a morning glory tuber. There are 400 varieties of many colours - orange, white, purple and yellow.

High in Vitamin C, potassium, beta-carotene (yellow/orange), anthocyanins (purple), anti-oxidants, phytonutrients and the enzyme, catalase. Catalase is needed to break down the ROS (reactive oxygen species), hydrogen peroxide. Levels can be elevated with smoking, pollution and poor diet. Build up of hydrogen peroxide inhibits production of pigment in hair causing greying. Studies show smokers go grey more quickly than non-smokers.

During cooking, starch is converted to the sugar, maltose, making the potato sweeter. The slower the cooking process, the sweeter the potato. Despite its sweetness, the sweet potato has a low glycaemic index.

Sweet potato leaves are also edible and are high in vitamins A, C, B1, B2, B3 and folate. They can be eaten in salads or added to stir-fries, stews, soups and curries.