Nature Vast areas of rain forest habitat continue to be cleared for oil palm plantations like this in Sarawak. Photo credit: Ben Sutherland Exposure to high concentrations of a dietary fatty acid contained in palm oil promotes the metastasis of mouth and skin cancer cells in mice, according to a paper published in Nature. Changes in the uptake and metabolism of fatty acids have been linked to cancer metastasis — the process by which cancer cells spread to other parts of the body. However, it is unclear which dietary fatty acids in particular might be responsible for these changes, and the biological mechanisms involved. Salvador Benitah and colleagues exposed human mouth and skin cancer cells to one of three types of dietary fatty acid — palmitic acid (the main saturated fatty acid in palm oil), oleic acid or linoleic acid — for four days, before introducing them into corresponding tissues in mice fed a standard diet. Although tumour initiation was not found to be influenced by any of