The period between adolescence and adulthood is a time of great change, mentally, physically and socially. Such changes can have a profound impact on nutrient intake. Yet whilst some short-term studies have attempted to assess dietary change during adolescence, few have considered how diet changes over the longer term, spanning the transition between adolescence and adulthood. This article describes the findings of the first British study to assess the change in macronutrient and micronutrient intake from early adolescence into adulthood. The study sample comprised 202 participants of a dietary survey carried out on Northumberland 12 years olds in 1979-80 who were followed up at 33 years old. At both time-points dietary intake was measured using two 3-day food diaries with follow-up interviews to record estimated portion size. The most notable findings were that between 12 and 33 years old, for both males and females, % food energy intakes of fat, total sugars and carbohydrate had fallen and protein intakes had risen, whilst absolute intakes of unavailable carbohydrate and all micronutrients considered (vitamin C, iron, calcium, vitamin D), with the exception of retinol equivalents, had increased. These changes in intake were generally consistent in direction between males and females. In conclusion, nutrient intake undergoes considerable change between adolescence and adulthood and, in most respects, this is in a direction in line with dietary recommendations. This does not imply that efforts should not be made to improve childhood and adolescent diet given the importance of diet on health in adolescence and later in life and evidence that dietary intake is, to some extent, established at an early age.