海藻糖（Trehalose）是自然界的动植物和微生物中广泛存在的一种双糖，它是由2个葡萄糖通过 α,α-1,1-糖苷键所形成的非还原性糖，按其化学结构可写成 α-D-吡喃葡萄糖基-(1→1)-α-D-吡喃葡萄糖苷，此外还有α,β-型的新海藻糖和β,β-型的异海藻糖两种异构体，但在自然界中很少见。

从稀乙醇中析出的海藻糖二水物为无色或白色斜方晶系双榍状结晶，有甜味。用作食品添加剂和甜味剂，甜度相当于蔗糖的45％。由于不属于还原性糖，因此与氨基酸和蛋白质共热时不会发生美拉德反应褐变。

Trehalose, also known as mycose or tremalose, is a natural alpha-linked disaccharide formed by an α,α-1,1-glucoside bond between two α-glucose units. In 1832, H.A.L. Wiggers discovered trehalose in an ergot of rye, and in 1859 Marcellin Berthelot isolated it from trehala manna, a substance made by weevils, and named it trehalose. It can be synthesised by bacteria, fungi, plants, and invertebrate animals. It is implicated in anhydrobiosis — the ability of plants and animals to withstand prolonged periods of desiccation. It has high water retention capabilities, and is used in food and cosmetics. The sugar is thought to form a gel phase as cells dehydrate, which prevents disruption of internal cell organelles, by effectively splinting them in position. Rehydration then allows normal cellular activity to be resumed without the major, lethal damage that would normally follow a dehydration/rehydration cycle. Trehalose is not an antioxidant, because it is a non-reducing sugar and does not contain nucleophilic groups in its molecule. However, it was reported to have antioxidant effects.