BACKGROUND: Exposure to adverse lifestyle can lead to cardiovascular diseases in adulthood. Risk may be reduced with healthy diet, physical activity, and avoidance of tobacco smoke by inducing beneficial effects on metabolism, including serum lipoproteins and fatty acids. Still, little is known about these links at young age.

PARTICIPANTS: This thesis is part of the prospective, randomized Special Turku Coronary Risk Factor Intervention Project (STRIP) aiming to influence risk factors of cardiovascular diseases mainly via dietary counselling. The repeated dietary intervention, with a key target to decrease intake of saturated fat, continued from age 7 months until age 20 years. Data on diet, physical activity and smoking habits were gathered by food records and questionnaires. Serum cotinine (indicator of tobacco smoke exposure) was measured using gas chromatography and metabolic measures were quantified by nuclear magnetic resonance metabolomics in 338–554 participants between the ages of 9 and 19.

AIM: The aim of this thesis was to study the associations of dietary intervention, achieving the dietary targets of the intervention, physical activity, and exposure to tobacco smoke on a comprehensive metabolic profile from childhood to adulthood. RESULTS: The intervention reduced intake of saturated fat and increased intake of polyunsaturated fat. The intervention and physical activity were directly associated with a less saturated serum fatty acid profile with inverse associations seen for monounsaturated fatty acids ratio while the associations for tobacco smoke exposure were opposite. The intervention and dietary targets were inversely linked with lowdensity lipoprotein lipid concentrations. Physical activity was inversely associated with very-low-density lipoprotein (VLDL) concentration and size, and directly with high-density lipoprotein (HDL) particle concentration, size, and cholesterol. Passive tobacco smoke exposure was directly associated with VLDL particle size, and inversely associated with HDL particle size. Non-lipid results were mostly weak.

CONCLUSIONS: Repeated dietary counselling, achieving its targets, or being physically active are beneficially associated with metabolic profile while exposure to tobacco smoke is detrimentally associated with circulating metabolic measures.