In this chapter, we present a brief overview of major developments in the field of nutrition science over the past 150 years as a means of contextualising the 13 core chapters that make up Food Marketing and Selling Healthy Lifestyles with Science. Demonstrating how understandings around what we eat and how it affects our bodies have evolved from the late nineteenth century to modern day provides a framework for much of the discussion that follows in terms of how scientific claims are used in food marketing. Across the volume, we see how food advertisements are reflective not only of the social and cultural zeitgeist but are also strongly linked to nutritional and dietetic understanding. We begin this chapter by briefly exploring the concept of nutrition in the Ancient World and throughout the centuries that followed until the Chemical Revolution of the late 1700s when the foundations were laid for modern nutrition science. Our focus then shifts to key nutritional research conducted throughout the nineteenth and early twentieth centuries, which ultimately led to the identification of individual micronutrients. Finally, we outline how the now well-established field of nutrition science has continued to develop over the past century and the state of the research area today. © 2025 selection and editorial matter, Lauren Alex O’Hagan and Göran Eriksson; individual chapters, the contributors. All rights reserved.