Background: Sugar intake has increased substantially in most parts of the world over the past 50 years. Soft drinks seem to be the largest contributor to this increase. A high intake of sugar is correlated with tooth decay, and has been linked to the risk of becoming overweight, developing diabetes type 2 and other lifestyle diseases. One part of the prevention strategy for these diseases may therefore be to promote a reduced intake of foods and beverages high in sugar. To be able to design and implement an efficient prevention strategy, we need to know how intake of sugary foods and beverages develops from childhood into adulthood. Very few studies have looked at the stability of soft drink and sweet intake over this time period. The aim of this thesis is to assess the change in and tracking of soft drink and sweet intake from age 15 years (1981/1979) to age 40 years (2006), and total sugar intake from age 33 years (1999) to 40 years. The association of long-term intake of soft drinks, sweets, and sugar with BMI is assessed. In addition, cross-sectional analyses on the association of demographic and health-related behaviours with soft drink, sweet, and sugar intake at age 40 years is assessed.
Design: Longitudinal cohort study over 27 years, from 1981/1979 to 2006.
Subjects: A total of 1086 subjects from six primary- and secondary schools in Oslo, Norway, were invited to participate at baseline, mean age 15 years (1981/1979). These subjects have been followed up at age 25 years (1991), age 33 years (1999), and at age 40 years (2006), with varying participation rates at the different time points.
Method: Self-administered questionnaires were used in all surveys. Self-reported height and weight were obtained in 1999 and 2006.
Results: The level of tracking of soft drink intake at a group level was moderate to high from age 15 to age 40 years, and high during adult years. Sweet intake did not show a significant level of tracking from age 15 to 40 years. However, from age 25 to 40, as well as from age 33 to 40 years, the level of tracking of sweet intake was high. At the individual level, the level of tracking of soft drink, sweet, and sugar intake was moderate from age 33 to 40 years. Sugar and soft drink intake decreased substantially between age 33 and 40 years. Long-term intake of soft drinks, sweets, and sugar were not associated with BMI. Intake of soft drinks and sugar at age 40 years were, however, associated with other unhealthy lifestyle variables like smoking and a low level of leisure time physical activity.
Conclusion: At group level, relative intake frequency of soft drinks seems to be stable from adolescence into adulthood, while for sweet intake it seems to be relatively unstable. From age 25 years, both the relative intake frequency of soft drinks and sweets seem to be stable at group level. Long-term intake of these foods and beverages, and intake of sugar in general, were not found to be associated with
BMI in this study. Soft drinks and sugar seem to be markers of an unhealthy lifestyle in general.