Change in potato consumption among Norwegian women 1998-2005—The Norwegian Women and Cancer study (NOWAC)

Studies have shown that potato consumption in Norway have been on the decline in recent years. Increase in income and the association of potato consumption with weight gain and chronic diseases like type 2 diabetes have been identified as some of the factors responsible for the change. The aim of this study was to describe the change in potato consumption within persons and how non-dietary variables influenced that change among participants in the Norwegian Women and Cancer study (NOWAC). A prospective analysis was performed in the NOWAC cohort using linear regression. Data on dietary, lifestyle, socioeconomic and health-related factors were collected by mailed questionnaires. The change in potato consumption among 38,820 women aged 41-70 years was investigated using two measurements taken at intervals of 4-6 years. At baseline, mean intake was 112g per day; this had decreased to 94.5g per day at the second measurement. Results showed that the percentage of women who reported that they ate less than 1 potato a day increased from 24.6% at baseline to 35.5% at the second measurement. Those who reported that they ate more than 3 potatoes a day had decreased from 20.2% of the participants at baseline to 12.1% at the second measurement. Multivariable adjusted results show that geography was an important predictor of potato consumption at second measurement. Living in the north compared to Oslo (the capital) was associated with higher intake of potato at second measurement (B: 0.60, 95% CI: 0.55-0.65). Compared to women living with a partner, living alone was associated with lower potato intake at second measurement (B: -0.13, 95% CI: -0.17 --0.09) while living with children tended to be associated with higher potato intake at second measurement (B: 0.01, 95% CI: -0.02-0.04). Younger age, more years of education, higher income or BMI was associated with a lower potato intake at second measurement. Smoking was associated with a higher intake of potato at second measurement (B: 0.03, 95% CI: 0.00-0.06 for smokers compared to non-smokers). Having diabetes at baseline was associated with lower intake of potato at second measurement (B: -0.04, 95% CI: -0.14 --0.06 for non-diabetics compared to diabetics). Potato consumption among women in the NOWAC study showed a decline over the period studied. Change in the consumption was found to be influenced by age, education, income, household structure, region of residence as well as health-related factors like smoking and diabetes. The use of repeated measures is necessary to continue the monitoring and also to understand the stability and direction of the possible change in diet of a population.