The novel observations in the present study were that the majority (72%) of asymptomatic middle-aged participants had elevated LDL cholesterol concentration, over half were overweight or obese, and 72% displayed borderline or increased arterial stiffness. As assessed with the SCORE [20, 21], only half of the participants could be categorized into the low risk group, and furthermore when the LDL cholesterol concentration was taken into consideration, then only seven individuals could be considered as real low-risk persons who would not benefit from lifestyle intervention. The SCORE was associated with arterial stiffness. Regarding the risk patterns of this study population, it can be stated that their dietary habits were far from ideal. Over two thirds were consuming too much saturated fat, 90% consumed too little carbohydrates, and about 70% too little fiber. Of the other lifestyle habits, although only 8% of the participants were current smokers, for the vast majority physical activity did not reach the recommended levels .
These results suggest that a large number of the asymptomatic participants had increased CHD risk factors and increased arterial stiffness. This finding may reflect the same phenomenon observed in a recent survey conducted by the Finnish National Institute for Health and Welfare, which demonstrated that in 2012, the serum cholesterol concentrations have increased from those values observed in 2007. This represents the end of what has been a beneficial trend which started decades ago [8, 25]. The recent European guidelines on cardiovascular disease prevention in clinical practice emphasize that a healthy diet is the cornerstone of cardiovascular disease prevention e.g. SFA intake should not be more than 10% of total energy intake [20, 26]. Furthermore, according to European guidelines, functional foods containing phytosterols (plant sterols and stanols) can effectively lower LDL cholesterol levels by on average 10% when consumed in amounts of 2 g/day . This cholesterol lowering effect is additional to that obtained with a low saturated fat diet or the use of statins. With respect to the cardiovascular risk level (SCORE) in the present study, it would have been high enough to recommend the initiation of the intervention strategies with dietary changes in almost all of the participants [20, 26]. Recent research has revealed that even individuals with a low risk of vascular events benefit considerably from intensive LDL cholesterol lowering .
Arterial health can be assessed with surrogate markers evaluating arterial stiffness and endothelial function. Arterial stiffness expressed as PWV and endothelial function measured as pulse wave amplitude during reactive hyperemia are novel, non-invasive methods with which to assess subclinical atherosclerosis, even to predict future cardiovascular events [28, 29]. The measurement of endothelial function by PAT has recently been used in nutrition-based interventions [30, 31]. Arterial stiffness and endothelial function evaluate different aspects of the arterial wall and need not correlate with each other. In the present study, RHI was not impaired in this population and this parameter did not correlate with LDL cholesterol concentration, SCORE or with any of the dietary variables. These results indicate that if one wishes to undertake a comprehensive evaluation of vascular health the surrogate markers both of endothelial function and arterial stiffness are needed.
CAVI is an index of arterial stiffness in large arteries reflecting the elastic properties of the arterial wall between the aortic arch and the lower extremities [2–4]. CAVI increases with age and in arteriosclerotic diseases, and is related to the serum LDL cholesterol concentration and to elevated blood pressure . CAVI was elevated in every fifth male Finnish firefighter (mean age 48 yrs) . Aerobic fitness in addition to age was correlated with CAVI . In the present study, which evaluated a slightly older population of mainly white-collar employees, the frequency of impaired CAVI was much greater. In addition to age and the LDL cholesterol concentration, the value of CAVI correlated with the SCORE. This finding suggests that interventions should focus especially on those risk factors which can be modified. In this study population with rather well-controlled smoking and blood pressure, a reduction in the LDL cholesterol concentration would be of special importance. The observation that dietary cholesterol intake was associated with CAVI is important because it connects the dietary habits to arterial well-being.
There are some limitations in this study. There were four participants who had used plant sterol/stanol products before the study, but they were included in the study after a 3 weeks’ wash out period, which is enough for the serum cholesterol concentration to be restored to its initial value [11, 12]. Excluding these four individuals from all statistical analyses did not change the results. In the cross-sectional study, data was collected only at one time point, and thus it is difficult to prove causalities for the associations found. In addition, the study population was of limited size, they volunteered to take part in the intervention, and therefore one cannot extrapolate these results to the general population. However, the study population represented a homogenous population of urban, well-educated, middle-aged participants interested in their health and well-being. Food recording for three to four consecutive days has been found to be sufficient to estimate the intake of energy nutrients at a group level [32, 33]. However, for the monitoring of cholesterol intake, more recording days may be needed . In general, energy intake as measured by dietary records has been found to be 10-30% lower as compared with total energy expenditure measured by doubly-labeled water . Because of the under-reporting, all the intakes have been energy-adjusted, either as percentages of energy or per MJ except for the cholesterol intake was also expressed as mg/d and fiber intake as g/d.