LONDON (Reuters) - Birth control pills can protect women against ovarian cancer for 30 years or longer after they stop taking them and have so far prevented 100,000 ovarian cancer deaths worldwide, British researchers said on Thursday.

The longer women stay on the pill, the lower their risk of developing the disease, which is more common after age 50, the researchers wrote in the journal Lancet. For example, women who take the pill for 15 years cut their risk in half, they said.

Cancer prevention is important, but it is particularly crucial for those types of cancer not easily detected early. Ovarian cancer, for example, often has no symptoms in early stages and is frequently diagnosed at a more advanced stage, resulting in poorer survival rates than other cancers.

But could natural compounds in plant-based foods help to prevent ovarian cancer?