Food provides a link between the population health and climate stabilisation agendas. This paper argues that a broader view of food security for the 21st century in Australia and internationally is needed--one that judges the food system for its nutritional quality, social value and impact on the environment. If done well, climate change mitigation and adaptation policies provide ways to achieve this. This paper focuses on mitigation strategies, and describes how the reduction of greenhouse gas emissions from the agricultural sector through a reduction in consumption of animal source foods can improve food security and reduce the levels of chronic diseases such as cardiovascular diseases and some cancers.