Professor Graznya Jasienska and colleagues at Jagiellonian University’s Institute of Public Health (Cracow, Poland) established a link between increased calorie intake, increased levels of oestrogen and progesterone in saliva, and increased risk of breast cancer. The team studied women from Bolivia, the Congo, Nepal, Poland and the US.

Noting the established influence of nutrition on fertility, Professor Jasienska suggested that both eating less and exercising more would protect women from breast cancer. He prioritised exercise as it had already been shown to reduce hormone levels whilst dieting can encourage osteoporosis.