A nutritional supplement may be able to slow the development of some cancers and enhance the effects of treatment, a study in mice suggests.
Mice with pancreatic, lung or skin cancer were given mannose, a sugar also found in cranberries and other fruits.
It significantly slowed the growth of their tumours, with no obvious side-effects, researchers found.
However, patients are being told not to start supplementing with mannose because of the risk of side-effects.
Scientists hope to test the supplement in people soon.
Mannose, which can be bought in health food shops and is sometimes used to treat urinary tract infections, is thought to interfere with the ability of tumours to use glucose to grow.
Scientists also looked at how mannose might affect cancer treatment by giving it to mice that had been treated with two of the most widely used chemotherapy drugs, cisplatin and doxorubicin.
They found it enhanced the effects of chemotherapy, slowing the growth of tumours and reducing their size. It also increased the lifespan of some mice.
In further tests, cells from other types of cancer, including leukaemia, osteosarcoma (bone cancer), ovarian and bowel cancer were exposed to mannose in the laboratory.