Dietary patterns and lifestyle: Their determinants and associations with chronic disease burden

In this thesis we investigated in a Dutch cohort dietary patterns and other lifestyle habits in relation with disease burden. Our aim was to define the healthiest dietary pattern in the Netherlands and provide insight in the lifestyle factors that are associated with this pattern. Quality Adjusted Life Years (QALYs) were used to measure the burden of chronic diseases. QALYs can be interpreted as the healthy life expectancy. In our study, never smoking, a normal weight (defined as BMI<25 kg/m2), a physically active life and adherence to a Mediterranean-style of diet were all positively associated with healthy life expectancy. A Mediterranean-style diet is characterized by a high intake of vegetables, fruit and fish, moderate intake of alcohol and dairy and low intake of meat. A dietary pattern resembling the Mediterranean diet was associated with a longer life in good health: participants who scored high on this pattern had 0.17 [95% CI 0.05;0.30] more QALYs than participants with a low score, equivalent to a two months longer life in good health. For a dietary pattern that was in agreement with guidelines of the World Health Organization, measured with the Healthy Diet Indicator, we found similar relations with QALYs (0.15 95% CI [0.03;0.27]). A combination of a healthy diet with never smoking, a normal weight and being physically active was associated with almost 2 years of life longer in good health, 1.75 QALYs [95% CI 1.37;2.14]. We investigated relations between alcohol consumption and healthy survival in greater detail. Moderate drinkers (5-14.9 g for women, 5-29.9 g for men) had a lower chronic disease burden (mean DALYs: -0,27 [95% CI -0,43;-0,11]), while former drinkers had a higher disease burden (mean DALYs: 0,81 [0,03;1,59]) than light drinkers (0-4.9 g). This association was mainly observed among older participants and was, as expected, driven by a lower disease burden due to cardiovascular diseases. An inactive lifestyle, a large waist circumference, no dietary supplement use and skipping breakfast were all associated with an unhealthy dietary pattern, both in low and high educated participants. Only: in low educated persons smoking was related to an unhealthy dietary pattern, while in high educated persons current and former smoking was related to a healthier diet. We also found that women who had been moderately or severely exposed to the Dutch famine (1944) in their early adolescence later became more frequent smokers, at higher doses. Severely famine exposed women also became more often physically inactive than unexposed women. Our results imply that, next to having direct biological effects that increase chronic disease risk, famine exposure might indirectly relate to chronic disease risk through unhealthy lifestyle factors. We conclude that in a Dutch population adherence to a Mediterranean-style diet is associated with the lowest disease burden. An unhealthy pattern is associated with several other unhealthy lifestyle characteristics. And, a combination of healthy lifestyle behaviors is related with a significantly longer healthy life. This indicates that public programs aiming at improving health could benefit from targeting at a cluster of modifiable lifestyle factors.