Major dietary patterns and cardiovascular risk factors among young Brazilian adults

We assessed the relationships between cardiovascular risk factors and major dietary patterns among young adults, aged 23 years, enrolled in the 1982 Pelotas Birth Cohort Study, a Southern city in Brazil. The common Brazilian dietary pattern was associated with lower levels of total and LDL cholesterol, but also lower levels of HDL cholesterol. This pattern was also associated with lower systolic and diastolic blood pressure, especially among women. On the other hand, the processed food pattern was associated with higher BMI, WC, and total and LDL cholesterol values, but also higher HDL cholesterol levels among men. This pattern was not related to CVD risk factors among women. Although the common Brazilian dietary pattern was generally associated with variables predicting lower risk of cardiovascular disease, the ultimate effects on risk of risk of disease are unclear because of the inverse relation with HDL-c levels.

Although dietary patterns are not completely comparable across countries and cultures, our processed food pattern is similar to the Western type of diet among the American population [5, 12, 26, 27]. The processed food pattern was composed of a varied list of foods, such as hot dog, hamburger, beer, red meat, processed meat, snacks, soda, mayonnaise, pizza, barbecue, French fries, canned vegetables (pickles), and liver, but the highest factor loadings were attributed to meat and meat products [20]. In addition, Western-type diets usually also include foods like potatoes, eggs, soda, and sweets. The processed food pattern contained higher quintiles of processed food scores, higher amounts of total energy, and higher percentages of energy from total fat (Table 1). Therefore, we hypothesized that this food pattern would have adverse effects on CVD biomarkers. However, adverse relationships were observed only in men, and among men, a positive association was seen with HDL-c, again casting uncertainty about the ultimate effect on the risk of cardiovascular disease.

Our study showed that there was a positive relationship between the processed food dietary pattern and BMI and WC among the men. This was maintained after adjustment for potential confounders such as physical activity, energy intake, and socioeconomic characteristics. Extreme quintile comparison yielded increased WC (β = 2.65; 95% CI: 1.15; 4.15) for the processed food pattern among the men. There is no clear consistency among other studies. Nettleton and colleagues observed that diets that included processed meat and higher fat scores were associated with higher BMI and WC in both genders in late adulthood [16]. High intake of potatoes, meat, and meat products was associated with significantly increased WC among Greek adults [28]. Among American adult women, the Western-type diet may contribute toward long-term weight gain [26]. Among the women in our study, the processed food dietary pattern was not found to be associated with either BMI or WC. The traditional dietary pattern identified in young Finns, which was described as posing a greater threat to cardiovascular health than Western food, did not show any association with BMI, either in men or in women [19]. Furthermore, no associations between a diet high in fat and sugar and either BMI or WC were found in Australian adolescents [29].

The processed food dietary pattern showed a positive linear trend with total and LDL cholesterol among the men, but not among the women. Diets characterized by meat and processed meat have showed a worse lipid profile, i.e., increased LDL cholesterol or total cholesterol [15, 16]. The traditional diet of young Finns, which consists of foods that differ from the Western diet but which are also characterized by elevated intake of high fat and high sodium food, was shown to produce elevated total and LDL cholesterol in both genders [19]. Meat intake has been reported as a cardiovascular risk factor, not only as a major source of saturated fat but also through heme iron provided by meat [30]. Higher consumption of heme iron was associated with an increased risk of myocardial infarction among men [31]. Although higher quintiles of the processed food pattern were correlated with higher percentages of saturated fat intake, it is noteworthy that less than 10% of the calories in the higher quintiles came from saturated fat, i.e., within the traditional target. Also higher quintiles were correlated with increased mono- and polyunsaturated fat and lower percentages of calories from carbohydrates (data not presented). Therefore, this could partially explain the higher levels of HDL cholesterol in the upper quintiles of the processed food pattern [32]. Sadakane et al. [15] found a similar relationship with higher levels of HDL cholesterol in a pattern of high meat consumption. The Western diet showed a significant and positive correlation with HDL among adult men in the Health Professionals Follow-up Study [12]. Because the associations for LDL-c and HDL-c would predict opposite risks for coronary heart disease, and the relation of the processed food pattern to other intermediate variables such as thrombotic tendency and arrhythmia were not studied, we cannot predict the effect of this dietary pattern to risk of cardiovascular disease.

Regarding the common Brazilian dietary pattern, we did not have any prior hypothesis regarding the direction of the association with CVD risk factors. Higher quintiles of the common Brazilian dietary pattern showed significant linear trend of decreasing BMI and total and LDL cholesterol values in both genders, yet the trend for WC was observed only among the men. Among the women, significant inverse trends were also observed regarding systolic and diastolic blood pressures. Nevertheless, the common Brazilian dietary pattern was composed of foods that contained refined carbohydrates (i.e., white bread and rice) and also “empty calories” (i.e., sugar). Such nutritional contents have been associated with adverse effects on health, as summarized elsewhere [33]. On the other hand, some specific foods or combination of foods could partially explain the beneficial associations with CVD risk factors. For example, coffee, which is part of the common Brazilian pattern, might have benefits for health. Recent studies have suggested that heavy consumption (six or more cups per day) was associated with a lower risk of fatal CHD in both genders [34]. Among women, the results suggest that coffee consumption may modestly reduce the risk of stroke [35]. In a previous analysis, we observed that 71% of the cohort members consumed at least one serving of coffee every day (data not published), and the usual Brazilian intake is filtered coffee. Furthermore, consumption of black beans, which present high fiber content, could be partially responsible for the beneficial effects. Beans have traditionally been the main source of fiber in the Brazilian diet [36], and the combination of rice and beans has been shown to be protective against obesity among Brazilian adults [37]. In our study, the highest quintile of the common Brazilian diet showed a high value of fiber intake (64.6 ± 7.6 g/day). In general, soluble fiber consumption decreases serum cholesterol and LDL cholesterol and is accompanied by reduction in serum HDL [38]. At least three inter-related factors could account for the lower HDL in the higher common Brazilian diet consumer. First, a fall in serum HDL cholesterol is observed when carbohydrate is consumed along with high-fiber diets [39]. Related to this, HDL cholesterol reductions also could be attributed to an unfavorable effect of lower-fat and high-carbohydrate diets [32]. The upper quintiles of the common Brazilian pattern showed very high-carbohydrate intake (>60% of total energy intake), and low fat intake (<23% of total intake). Moreover, long-term exposure, i.e., chronic intake of a high-carbohydrate diet, is also associated with lower concentration of HDL [40]. The common Brazilian diet is composed of popular foods, such as simple rice, beans, and bread, and is consumed since childhood through adulthood. A better understanding could be obtained from measuring the small lipoprotein particles of HDL; however, it was not in scope of our study, and some caution is necessary to interpret those findings.

Although high-fiber diets have potential benefits regarding weight loss [41], our findings of lower BMI among both men and women in the higher quintiles of common Brazilian should be interpreted with caution. Previous analyses have shown that the common Brazilian pattern was more likely to be followed by subjects with low socioeconomic status (SES) [20]. However, SES was identified as an effect modifier on the relationship between obesity and gender [42] among the members of this cohort, i.e., lower SES was shown to be a protective factor against obesity in men and a strong risk factor among women, in comparison with higher SES. Although our multivariate models were adjusted for SES characteristics, physical activity, and energy intake for both genders, there may have been other potential confounders associated with CVD risk factors and with dietary patterns that might be different in men and women, for which we were unable to adjust.

Some points need to be addressed. We focused our analysis on the dietary pattern approach, because we believe that this is more closely related to real life, in which people eat meals consisting of a variety of foods instead of single nutrients. In this approach, both known and unknown interactions between nutrients are taken into account [2]. Another point relates to the nature of the two dietary patterns investigated: the common Brazilian pattern might be regarded as home-prepared food, in contrast to the manufactured foods that characterize the processed food pattern. In general, these patterns showed opposite associations: the former showed mainly healthier trends and the latter mainly showed harmful trends with regard to CVD risk factors.

Finally, our study had some methodological limitations. First, we performed a cross-sectional analysis, although the subjects belong to a birth cohort study and have been followed for almost 25 years. Complete data on diet and biomarker information were collected only during the eighth follow-up in 2004–2005. Reverse causality might be present in our results, but we supposed that lipid profiles or blood pressure levels were unknown among young adults by themselves, and consequent changes to their diet would not be expected. The exception was with regard to dietary habits and anthropometric, which might have accounted for our findings among women. Secondly, we assessed the nutrient components based on the Brazilian Food Composition Table (TACO) [22], and in the cases of foods not found in the Brazilian table, we used the USDA National Nutrient Database for Standard Reference as an alternative [23]. However, few specific foods were missing from these tables. In addition, imprecise dietary measurements could potentially have influenced our findings, but in fact, random errors in diet measurements might lead to a lack of association, but not the reverse.

In conclusion, our findings suggest that diet has an important role in health from early adulthood onwards. The common Brazilian pattern showed generally healthier trends regarding CVD risk factors, but improvements to the nutritional quality of this dietary pattern appear to be desirable and deserve further investigation.