Behavioral risk factors are responsible for the majority of deaths due to noncommunicable diseases (NCDs)1^,2 and part of the diseases resulting from these conditions.3^-5 Such factors included smoking, abusive alcohol intake, inadequate diet, physical inactivity, obesity, dyslipidemia, excessive animal fat intake and insufficient intake of fruits and vegetables.6^,7 According to a study conducted in 52 countries, these factors, combined with arterial hypertension, diabetes mellitus and psychosocial stress account for 90% and 94% of the attributable risk of cardiovascular disease among men and women, respectively.8

The World Health Organization attributes smoking to an estimated six million deaths per year. Insufficient intake of fruits and vegetables corresponds annually to 2.7 million deaths, 31% of ischemic heart diseases, 11% of cerebrovascular diseases and 19% of gastrointestinal cancers in the world.9 Despite the reduction in the percentage of smokers in Brazil in recent years,10^,11 population-based health surveys have indicated that the prevalence of smoking is greater among adults (40 to 59 years old) and those with a lower education level.10^-12 Moreover, the prevalence of an unhealthy diet is high,10^,13^,14 especially among men, adolescents and individuals with a lower education level.13^,14

NCDs have multiple causes that occur simultaneously, resulting in distinct effects.5 Studies indicate that the accumulation of two or more modifiable risk factors increases the occurrence of NCDs8^,15^,16 and cardiovascular diseases8 and is related to the overall death rate as well as death due to specific causes.1^,2 Risk behaviors are harmful actions that either increase the probability of disease or impede the recovery of health.17 Therefore, behavioral (modifiable) risk factors are component causes that contribute to increased morbidity and mortality rates due to cardiovascular diseases, diabetes mellitus and cancer in adults and seniors.1^,5^,15 The greatest impact of exposure to these factors is seen at more advanced ages. However, early signs of changes in health status occur more frequently from 40 years of age.18^,19

Brazil has an adult population (18 to 59 years of age) of approximately 114 million. The co-occurrence of smoking and an unhealthy diet has been under-investigated in the literature. Exposure to behavioral risk factors begins early in life16^,18 and is consolidated in adulthood,13 with effects on health in different phases of life. Therefore, the objective of this study was to estimate the co-occurrence of smoking and unhealthy eating practices in the Brazilian adult population as well as determine associations with socio-demographic characteristics and health indicators.

A cross-sectional population-based study was conducted with a sample of adults (18 to 59 years old) residing in the capitals of the 26 states of Brazil and the Federal District. The data were extracted from the records of 28,950 individuals interviewed in Sistema de Vigilância por Inquérito Telefônico (Vigitel [Brazilian Health Surveillance Telephone Survey]), in 2014.

A minimum sample of 1,500 individuals in each city was established to estimate the frequency of any risk factor in the adult population20 considering a 95% confidence interval and a maximum error of three percentage points.7 Data collection was performed in three steps. The first step consisted of systematic random selection of at least five thousand telephone lines. This systematic selection stratified by postal code was performed using records of residential landlines registered with telephone companies. The lines selected in each city were submitted to a second random selection divided into replicates of 200 lines, with each replicate reproducing the same proportion of lines per postal code of the original registry. The third step was the random selection of one of the adults residing in the selected homes (after identification) among the lines considered eligible for the system. The following were excluded in this step: business lines, out-of-service or nonexistent lines and lines for which there was no answer after six calls on different days and at different times, including weekends and evening hours7 (Figure 1).

Figure 1

Weighting factors were used to compensate for the bias of the non-universal coverage of landlines. Using a post-stratification weight calculated based on 36 analysis categories by sex (female and male), age group (18-24, 25-34, 35-44, 45-54, 55-64 and ≥65 years old) and level of education (none or incomplete primary school, complete primary school or incomplete high school, complete high school or incomplete university degree and complete university degree), the estimates were adjusted to the population. The “rake” method was used for the calculation of the post-stratification weight of each individual in the sample. Information on the sample design of the Vigitel survey, the data collection instruments and procedures used in the interviews is published elsewhere.7

In the present study, the co-occurrence of smoking and an inadequate diet was considered the variable of interest. A smoker was considered any individual who answered affirmatively to the following question: “Do you currently smoke?,” irrespective of the number of cigarettes, frequency and duration. The indicator of an unhealthy diet was created from a set of foods that serve as markers of the intake profile associated with protection from chronic diseases (beans, fruits, milk, raw vegetables and cooked vegetables) and risk for chronic diseases (red meat, sweets and sweetened beverages). Scores ranging from zero to four were attributed depending on the food and intake frequency. Markers of the protection category ingested daily and those of the risk category never or rarely ingested were not scored (zero). Maximum of four points was attributed to protective foods never or rarely consumed and risk foods ingested daily (Table 1). The total score was determined by the sum of food items and ranged from 0 to 32 points, with higher scores indicating poorer dietary quality. This variable was then categorized considering distribution terciles. Individuals in the 2^nd and 3^rd terciles (14 or more points) were grouped together, creating a dichotomous variable for unhealthy eating (yes or no). Co-occurrence was determined by the simultaneous occurrence of both of these conditions (smoking and unhealthy diet).

The following socio-demographic variables were considered: macro-region of the country (North, Northeast, Central West, South and Southeast), sex (male and female), age group (18 to 39 and ≥ 40 years old), skin color/ethnicity (white, black, yellow, brown and indigenous), marital status (with and without a spouse), education (0 to 8, 9 to 11 and 12 or more years of study) and having a private health insurance plan (yes or no). The following variables related to behavior and health status were considered: body mass index (BMI) (< 25 kg/m², ≥ 25 to < 30 kg/m² and ≥ 30 kg/m²), binge drinking [five or more drinks for men and four or more drinks for women on a single occasion in the previous 30 days (yes or no)], practice of physical activity (active or inactive) and self-rated health (very good/good, fair or poor/very poor). Weight and height were self-reported by the respondents. BMI was calculated for all records based on the imputation of the measures of weight and height using the “hot deck” method.7 The following diseases were also considered: arterial hypertension, diabetes mellitus and dyslipidemia (all categorized as “yes or no”).

Mean age of the sample was 36.4 years (95% CI: 36.1-36.6); the majority was women (53.0%) and young adults (59.4%). The prevalence of the co-occurrence of the risk factors was 8.6% (95% CI: 7.9-9.3).

Table 2 shows the prevalence of smoking and an inadequate diet as well as associations with the other variables. No associations were found between smoking and BMI, physical inactivity, hypertension, diabetes or dyslipidemia (p > 0.05). All variables were associated with unhealthy eating, except for having a private health insurance plan (p = 0.102) and BMI (p = 0.196).

In the simple analysis, differences were found with regard to the region of the country, sex, skin color/ethnicity, education and health insurance (p < 0.05). Associations were found between the co-occurrence of risk factors and both binge drinking (p < 0.001) and self-rated health (p < 0.001). Higher frequencies of the co-occurrence of risk factors were found among individuals residing in the southern and southeastern regions of the country compared to those residing in the central western region. Higher frequencies were also found among individuals who did not have private health insurance, binge drinkers and individuals who reported their health to be fair, poor or very poor at the time of the interview. After controlling for sex and age, the prevalence of the co-occurrence of risk factors was lower among individuals who resided in the northern and northeastern regions of the country, women, individuals with brown skin color, those with a spouse and those with excess weight. The prevalence of the two risk factors also reduced significantly with higher education levels (p < 0.001) (Table 3).

Table 4 shows the hierarchical Poisson regression model of factors associated with the co-occurrence of smoking and unhealthy eating. The prevalence of both factors was lower in the northeastern region of the country (PR = 0.67; 95% CI: 0.54-0.83) and higher in the southern region (PR = 1.40; 95% CI: 1.11-1.77) compared to the central western region. The prevalence was approximately 40% lower among women and was also lower among individuals with brown skin and those who lived with a spouse. The prevalence reduced significantly with higher education levels and was approximately 16% higher among individuals without private health insurance (PR = 1.16; 95% CI: 1.05-1.27) after controlling for region of residence and other socio-demographic factors. Regarding behaviors and health conditions, excess weight was inversely associated with the co-occurrence of both risk factors. The prevalence was higher among those who considered their health to be fair or poor/very poor. Moreover, a strong, independent, statistically significant association was found between binge drinking and the co-occurrence of the risk factors considered (PR = 3.22; 95% CI: 2.70-3.85).

The prevalence of the co-occurrence of smoking and an unhealthy diet was 8.6%. In a study conducted in England with a population aged 16 to 64 years, the prevalence of the co-occurrence of smoking and inadequate diet (measured by the consumption of beans, vegetables and fruits) was 25.5% among men and 23.6% among women.21 In this study, which considered four lifestyle risk factors, the prevalence of smoking was 28.0% and insufficient intake of beans, fruits and vegetables was represented by the failure to have five portions of these foods, as recommended. The divergence in frequencies may be explained by cultural diversity and the diversity of eating habits in different populations. In a study conducted in the city of Botucatu (state of São Paulo, Brazil), Berto et al.22 investigated the association between smoking and other behavioral risk factors in adults and found the co-occurrence of smoking and low intake of fresh fruits and vegetables (12.9% and 12.3% among men and 5.8% and 5.1% among women, respectively). In a study conducted with adults in the city of Florianópolis (state of Santa Catarina), the prevalence of the co-occurrence of smoking and an inadequate diet was 3.5%; inadequate diet was considered the reported intake of fruits and vegetables ≤5 days per week.13

In an American study with an adult population (≥20 years), smokers had a diet of poor quality, with less intake of fruits, vegetables, dairy products and whole grains as well as a greater percentage of energy from solid fats, alcohol and added sugar.23 A study conducted with adult smokers found that fruits and vegetables, noncaffeinated beverages, sweets and dairy products worsened the sensory attributes of cigarettes, whereas meats, alcoholic beverages and caffeinated drinks improved the sensory attributes.24 Haibach et al.25 found that smokers who ingested more fruits and vegetables had lower levels of nicotine dependence and greater occurrence of smoking cessation.

To make the dietary indicator employed in the present study, we considered whole milk a marker of healthy diet. The results of epidemiological studies evaluating dietary sources of saturated fat have revealed the lack of an association or beneficial effects of dairy products on cardiovascular diseases.26^,27 Considering the gaps in the scientific literature on the association between milk consumption and health, Lamarche et al.27 report the need to investigate whether whole milk and skim milk have different effects on health. Data from the 2008-2009 Brazilian Family Budget Survey revealed that the adult population has low consumption of dairy products (100 g/ml per day),28 but high consumption of red and processed meats (90 g per day), with more than 80% of the participants exceeding the limit recommended by the World Cancer Research Fund (300 g per week).29

It should be stressed that the Vigitel survey did not address the consumption of processed meats or quantify the consumption of red meat. Therefore, only the frequency of weekly consumption was considered in the present study, regardless of the presence of visible fat. A previous study evaluating the attributable fraction of cancer in the adult population due to different exposures found that red meat is a risk factor for colon and rectal cancer when ingested at a rate of more than 70 g/day.30

In the present investigation, the co-occurrence of risk factors was higher in the southern region of Brazil and lower in the northeastern region than in the central western region. Reduced prevalence of smoking was found in all regions of the country between 2006 and 2013, but with the highest rates found in the South and the lowest in the Northeast,31 which may partially explain the present findings regarding the co-occurrence of smoking and an inadequate diet. Moreover, according to the 2008-2009 Family Budget Survey, northeastern and southern Brazil have different profiles in terms food purchase, with greater availability of red meat, processed meats, bacon, soft drinks and alcoholic beverages in the southern region.32 Regional disparities in the distribution of modifiable risk factors are found in Brazil.7^,13^,22^,31 In the United States, a study addressing the co-occurrence of five healthy behaviors (not smoking, regular practice of physical activity, not consuming alcohol, maintaining one’s weight and sleeping the recommended number of hours) in the adult population (≥21 years old) found geographic variations in the percentage distribution adjusted for age for the number of grouped factors.33

Regarding other socio-demographic characteristics, studies indicate that the prevalence of multiple risk factors is higher among young adults, men, individuals with a lower socioeconomic status (lower income and education) and those who live alone.13^,21^,34 In the present study, the reduced co-occurrence of risk factors was found with higher education levels. Studies report an association between higher education level and healthy behaviors/health conditions.10^-14^,19^,21^,34 The prevalence of co-occurrence was also lower among those with self-declared brown skin. In the city of Florianópolis (state of Santa Catarina), Silva et al.13 found a greater occurrence of the accumulation of four risk factors in black adults. In the USA, racial/ethnic differences were found for five behaviors considered.33 A study analyzing differences in the prevalence of risk factors for chronic diseases according to ethnicity/skin color found that, compared to whites, brown individuals smoked less and consumed fewer fruits, soft drinks and sweets as well as more beans, whole milk and meat with visible fat.35 No studies were found in the national or international literature on the co-occurrence of smoking and an inadequate diet according to skin color/ethnicity.

The prevalence of the co-occurrence of risk factors was higher among individuals without a private health insurance plan. A study involving Brazilian adults found that individuals with private health insurance smoked less, ate better and practiced more physical activity during leisure hours.36 The Health Ministry has taken several actions for reducing inequalities in the access and offer of healthcare services. The National Health Promotion Policy defends integral care, considering health promotion to be a strategy for organizing the actions and services of the public healthcare system, with a focus on factors that determine the health-disease process, intersectoral actions, social participation and the construction of healthy environments on individual and collective levels.37 The National Food and Nutrition Policy and the Dietary Guide for the Brazilian Population38 are important support instruments for the promotion of healthy eating within the Brazilian public health system (SUS, in its Portuguese acronym).

The prevalence of the co-occurrence of smoking and inadequate diet was lower among adults with excess weight. The inverse association found after adjustment for socio-demographic characteristics, behavioral factors and health conditions may be partially explained by the fact that smoking exerts an influence on metabolic processes; smokers weigh, on average, 4 kg less than non-smokers due to the increase in the metabolic rate, concomitantly with suppression of appetite.39

The prevalence of the co-occurrence of risk factors was higher among adults who reported binge drinking, which is a subgroup with greater vulnerability to NCDs. The planning of disease prevention actions should integrate population-based strategies and strategies directed at high-risk subgroups, as both are necessary and work in a synergistic way.17 In the epidemiology of chronic diseases, the effect of a risk factor depends on the status of the individual for another factor (present/absent). Thus, the presence of two or more modifiable risk factors potentiates the occurrence of NCDs8^,15^,16 and shorter time to the emergence of a disease leads to reduced healthy life expectancy. Data from four cohort studies on smoking, physical inactivity and obesity among individuals aged 50 to 75 in European countries revealed the impact of the co-occurrence of behavioral risk factors on the reduction in the expectancy of a healthy life free of chronic diseases.40

In the present study, the co-occurrence of risk factors was higher among those who did not rate their health positively. The literature describes the association between smoking and a poor perception of health in the adult population.34^,41 A study involving the Brazilian population ≥18 years of age also found poor assessments of health among individuals who did not consume fruits and vegetables regularly.41 A study conducted in Madrid, Spain with 16,043 adults (18 to 64 years old) found that the accumulation of risk factors increased the frequency of perceived poor health in a progressive manner.34

No associations were found between the co-occurrence of risk factors and arterial hypertension, diabetes or dyslipidemia. In the analysis of individual risk factors, these conditions were only associated with an inadequate diet. National studies have not found an association between current smoking and arterial hypertension or diabetes, as found for former smokers.42^,43 A significant reduction in smoking occurred between 2006 and 201531^,44 and a substantial increase in excess weight has occurred as a result of negative changes in the eating patterns of the population.32^,45 It should be stressed that the greatest incidence of these diseases and other health-related problems is found at more advanced ages. In the present study, the co-occurrence of the two risk factors did not necessarily express an additional risk for these outcomes in the adult population analyzed.

Estimates of the clustering of behavioral risk factors for NCDs performed in international studies1^,21^,34^,40 have led to the recognition that many of these factors are interrelated.17 Effective prevention resides in reducing the concomitant occurrence of various risk factors related to these diseases, on both the individual and collective levels. The incidence of a given disease is important to primary prevention, as the risk is low for the majority of individuals, regardless of the disease.15 Strategies on the population level seek to control determinants of the disease with interventions directed at environmental factors that make the disease prevalent.46 Stratification of the population according to risk enables the identification of its distribution in the population and the adoption of specific prevention practices focused on priority subgroups.

Interventions that address multiple risk factors can have a greater impact than those focused on isolated behaviors.2^,15 The co-occurrence of health-related behaviors suggests complementary and substitutive relations. In Brazil, the goal of the Strategic Action Plan to Combat Non-Communicable Diseases is the reduction in the prevalence of smoking in the adult population from 15.1% (2011) to 9.1% (2022). Regarding dietary practices, the goal is to reduce mean salt intake from 12 g (2010) to 5 g (2022). The increase in the consumption of fruits and vegetables is on the list of monitoring indicators of the World Health Organization, but is not on the list of goals.47 Global strategies adopted in specific contexts need to be implemented, broadened and, especially, maintained.

The present study has limitations that should be considered. The sample was restricted to the population with a landline at home, which diminished the participation of the northern and northeastern regions of the country, where coverage rates are lower. However, the use of weighting factors minimized the difference between populations with and without a telephone line.7 Further limitations include the use of self-reported information and the impossibility of establishing causal relations due to the cross-sectional design of the study. It is not possible to affirm whether individuals with excess weight quit smoking and made changes in eating practices or whether smoking and a poor diet led to weight loss.

In the present study, the segments that are more vulnerable to the co-occurrence of smoking and an inadequate diet were residents of the southern region of the country, men, individuals with a lower socioeconomic status and those who reported binge drinking. Interventions addressing multiple behavioral risk factors, adapted to specific contexts, could have a greater impact on the Brazilian population. Regarding the management of healthcare services, information obtained from indicators can help guide the implementation, monitoring and assessment of healthcare models and actions directed at health promotion, as well as disease prevention and control.

Considering the increasing social inequality in Brazil and the consolidation of a dietary system centered on monocultures for the production of ultraprocessed foods that are disseminated throughout all social strata of the population through strong marketing strategies, the promotion of health and prevention of worsening of adverse health conditions are powerful and absolutely necessary strategies for reducing the impact of social profile on health and the access of the population to healthy aging.