Cardiovascular diseases (CVD) represent one of the main causes of morbimortality in Brazil and in the world [1] . It is treated as a multifactorial disease caused by the interaction of genetic factors, excess weight and body fat, high arterial blood pressure, dyslipidemias, inadequate eating habit, sedentarism and tobaccoism [2] [3] .

The probability of CVD incidence is proportional to the number of risk factors [4] . Dyslipidemias stand out as determining factors of these diseases, being a great public health concern [5] -[7] . They are characterized by abnormal concentrations of lipid or lipoproteins serum levels [8] , sometimes identified in young individuals as children and adolescents [1] .

In growth and developmental stages, the influences of sexual hormones must also be considered, as they are responsible for physiologically increasing lipid serum levels, especially in early puberty [2] .

The importance of tracking the risk factors in childhood and adolescence for planning early interventions stands out, aiming at the maintenance of the identified risk situation in adult life [7] . Besides, as these are resulting of multifactorial etiology, there might be differences according to the characteristics of the studied population, such as the area of residence, urban or rural [9] .

The present study aimed to evaluate the prevalence of dyslipidemias and related factors, in Brazilian adolescents residing in rural and urban areas.

The sampling was constituted by 182 adolescents from rural and urban areas, 62.6% (n = 114) boys, aged 10.02 to 13.95 years, with median and mean ± SD of 11.13 and 11.42 ± 1.0 years, respectively.

Regarding the lipid profile, the most altered parameters between adolescents were mean values for total cholesterol and LDL (Figure 1), with overall mean of 161.1 ± 28.9 and 95.3 ± 25.8 mg/dL, respectively. Median values (minimum - maximum) for HDL and triglycerides were 50.0 (23.0 - 117.0) and 64.0 (14.0 - 248.0) mg/dL, respectively. It was verified that 84.6% (n = 154) adolescents presented some lipid profile alteration.

When total cholesterol, HDL, LDL and triglycerides levels were compared between adolescents, no difference was found according to the residence place. However, when gender was considered, girls presented higher

total cholesterol and HDL levels (Table 1).

Of the evaluated individuals, 21.4% (n = 39) were classified as excess weight and 33.5% (n = 61) as excess body fat. These adolescents presented lower HDL and higher triglycerides values comparing with eutrophic adolescents with appropriate body fat percentage. Besides, those with excess body fat presented higher total cholesterol and LDL serum levels (Table 1).

It is emphasized that both for rural and urban area adolescents, means and medians of the total cholesterol values were higher than 150 mg/dL, both for nutritional status and body fat in adequate or excessive conditions (Table 1).

Table 2 presents results of bivariate analyses for total cholesterol, HDL, LDL and triglycerides levels concerning sociodemographic, sexual maturation, physical activity, nutritional status, body fat, blood pressure and dietetic intake characteristics.

Altered total cholesterol was associated with gender and signs of sexual maturation. Male adolescents presented lower probability of alteration in this parameter (OR, odds ratio, 0.47; IC, interval confidence 95%: −1.4 - 0.15; p = 0.02). Presence of sexual maturation signs represented protection regarding the altered total cholesterol (OR: 0.33; IC 95%: 0.13 - 0.79; p = 0.01) (Table 2).

Regarding the HDL fraction, it was associated with age and signs of sexual maturation variables. Adolescents with age above median (11.1 years) were more protected as for this alteration (OR: 0.45; IC 95%: 0.24 - 0.83; p = 0.01). The presence of sexual maturation signs showed 76% less chance of low HDL values [(1 - 0.24)*100]. In addition, gender (p = 0.14) and lipid intake (p = 0.08) variables were included in the multiple analysis (Table 2).

As for the LDL fraction, association was observed with gender and fiber intake. Male adolescents presented twice as high probability of altered LDL (IC 95%: 1.05 - 3.88; p = 0.03) and those with fiber intake below the recommended level also had more chance of alteration in this parameter (OR: 1.96; IC 95%: 1.06 - 3.63; p = 0.03). Additionally, physical activity (p = 0.15), nutritional status (p = 0.12) and energetic intake (p = 0.09) variables were included in the multiple analysis.

Altered triglyceride was associated with gender, nutritional status, body fat percentage, protein and full fat intake. Male adolescents presented 56% less chance of alteration in this parameter [(1 - 0.44)*100]. Excess weight and body fat increased the chances for this biochemical alteration (OR: 3.15; IC 95%: 1.37 - 7.20; p = 0.006 and OR: 2.97; IC 95%: 1.24 - 7.10; p = 0.01, respectively). Both protein and saturated fat intake above the recommended levels were associated with protection (OR: 0.17; IC 95%: 0.07 - 0.44; p < 0.001), (OR: 0.35: IC 95%: 0.14 - 0.87; p = 0.02), respectively. In addition, physical activity (p = 0.13) and energetic intake (p = 0.19) were included in the multiple analysis.

It was verified that gender (p = 0.03) and sexual maturation signs (p = 0.02) showed association with total cholesterol in the multiple analyses.

Regarding HDL, fiber intake was the variable that maintained associated with it; adolescents with fiber intake below the recommended level presented 1.97 times higher chance to have alteration in this biochemical parameter (Table 3).

SD, Standard Deviation; Med, Median; Min, Minimum; Max, Maximum; HDL, High Density Lipoprotein; LDL, Low Density Lipoprotein. ^a*Paired t-test; ^a**Wilcoxon’s test; ^b*Student t-test; ^b**Mann Whitney’s test p < 0.05.

HDL, High Density Lipoprotein; LDL, Low Density Lipoprotein; OR, Odds Ratio; IC, Interval Confidence. Values in bold represent p < 0.05.

OR, Odds Ratio; IC, Interval Confidence. Values in bold represent p < 0.05.

As for LDL, adolescents presenting sexual maturation signs, showed 76% lower alteration chances comparing with those who did not present these signs [(1 - 0.24)*100] (Table 3).

Factors independently associated with triglycerides alterations were gender (p = 0.04), nutritional status (p = 0.01) and protein intake above the recommended level (p < 0.001) (Table 3).

It is worth emphasizing that gender and sexual maturation were associated in two of the elaborated models (Table 3).

The prevalence of dyslipidemia found in this study was elevated, similar to a study with children and adolescents with excess weight, residing in Campina Grande city (PB, Brazil), in which 85.3% exhibited dyslipidemia [1] .

Although students from Pernambuco (PE, Brazil) aged 10 to 14 years demonstrated inferior prevalence, more than half (63.8%) [20] presented at least one lipid profile alteration. In this sense, investigations on this risk factor between adolescents are relevant, as they represent a disturbing reality.

The absence of lipid profile difference in adolescents, according to area of residence observed in the present study, suggests that other factors inherent to this life stage could be involved with this lipid alteration However, in a study comparing the prevalence of dyslipidemias between 3121 Mexican students aged 12 to 16 years residing in rural and urban areas, higher prevalence was more frequent in adolescents of the rural area (p < 0.001) [9] .

The differences between studies can be due to the area of Viçosa (MG, Brazil) having atypical rural population comparing with other places, with rural population representing only 6.8% the total population [21] . Moreover, the studies were carried out in different countries, with age groups of different stages of adolescence.

The fact that girls presented higher lipid serum levels than boys might be related to sexual hormone alterations due to growth and development, especially in the initial stage of adolescence [2] .

In this sense, in a study carried out with children and adolescents from Pernambuco, only total cholesterol and triglycerides levels were more elevated in girls (p = 0.03 and p = 0.04, respectively) [5] . In Mexico, adolescent girls presented higher serum levels of total cholesterol, LDL, triglycerides and HDL than those of boys [9] . Similar result was found between American adolescents aged 12 to 19 years, for the two last mentioned parameters [22] . However, some studies did not identify differences in the lipid profile between genders [6] [20] [23] .

Excess weight is an important risk factor for the development of cardiovascular alterations, predisposing individuals to the increase in total cholesterol, LDL, and triglycerides serum levels and to HDL reduction [24] .

In the present study, excess weight represented higher chance of triglycerides alteration. Likewise, Pereira et al. [25] evaluated children and adolescents aged 2 to 19 years in rural and urban areas of Itapetininga (SP, Brazil) and verified that individuals with excess weight presented greater risk of total cholesterol and triglycerides increase. Conversely, in the study of Grillo et al. [6] , obesity resulted in 3.27 higher risk for HDL alteration, not significant for the other evaluated lipid parameters. This demonstrates the close relation between excess weight and dyslipidemias.

In addition, Romaldini et al. [26] studied the risk factors for atherosclerosis in 109 children and adolescents with family history of premature coronary artery disease and identified lipid alterations in 57.1% (16/28) of those with excess weight (obese and overweight) and in 32% (26/55) of those with normal or low weight. Adolescents with excess weight presented twice higher chances (IC 95% = 1.16 - 6.81) of dislipidemia, however there was no association between dyslipidemia and family income, parental schooling and practice of physical activity variables.

Likewise, when evaluating clinical-metabolic alterations in obese and non obese adolescents grouped according to gender, color, age, sexual maturation stage and schooling, lower HDL levels and superior triglycerides levels among obese adolescents were observed [24] .

In Tunisia, the prevalence of hypercholesterolemia among school children with excess weight was superior comparing with eutrophic children (14.6% and 7.1%, respectively, p < 0.001). Moreover, girls presented more total cholesterol and LDL alterations (p < 0.001) [7] .

The sexual maturation process described by biological alterations may influence individual [16] lipid and lipoprotein blood levels [2] . Considering this variable in the lipid profile evaluation of 1846 urban Mexican adolescents aged 12 to 16 years, it was identified that during advancing of the pubertal stage, evaluated by self- evaluation according to Tanner, boys were negatively associated with total cholesterol, LDL and triglycerides [27] .

It should be emphasized that besides the biological influence in question, adolescents presenting puberty signs experience higher environment interference in the definition of habits, including eating and physical activity and this will influence the lipid profile [20] . However a limitation of this study was not considered sexual maturation of the annealing of the sample.

The present study reinforces the importance of dietetic factors as determinant of plasmatic lipids, having in mind that inadequate fiber intake was associated with HDL, and proteins above the recommended level, with triglycerides.

In a study with adolescents aged 12 to 19 years who participated in the National Health and Nutrition Examination Survey (NHANES) 1999-2002, it was verified that to each increase in the amount of fiber intake, there was a 20% reduction in the incidence of metabolic syndrome, which corresponds to the set of cardiovascular risk factors, including dyslipidemias (adjusted OR = 0.83, IC 95% 0.68 - 1.00 and p = 0.043) [22] .

Protein ingestion above the recommended level reduced the risk of triglycerides alteration. The opposite was expected, given that the main sources of proteins in the diet are foods of animal origin which also have higher amounts of fat in their composition. However, the source of ingested protein was not investigated in this study.

The modern lifestyle characterized by inadequate offer of caloric foods, with high contents of full fat, trans fat, cholesterol, simple carbohydrates and salt, may lead to an increased consumption and consequently to the development of risk factors like excess weight, high arterial blood pressure, diabetes and dyslipidemias [3] .

The elevated prevalence of dyslipidemias found between adolescents of urban and rural areas reinforces the importance of monitoring this alteration in early ages. It is necessary to consider the influence of sexual maturation and gender, besides planning actions for adjustment of the nutritional status and the adopted lifestyle habits.

Actions taken during childhood and adolescence allow the reduction in the incidence of cardiovascular disease and its consequences in adulthood, favoring the promotion of health of these individuals at all stages of life.

The authors declare that there is no conflict of interest.