obesity and cultural environment in the yucatan region

May 1999: (ll)S78483

Obesity and Cultural Environment in the Yucatan Region Pedro Arroyo, M.D., M.P.H., M.Sc.,* Jeannette Pardio, R.N.,’ Victoria Fernandez, R.N.,’ Lizard0 Vargas-Ancona, M.D.? Grasciliano Canul, M.D.? and Alvar Loria, Ch.D.5

Introduction

The Mesoamerican population is mainly a cross-breed of aboriginal groups mixed with Europeans and to a lesser extent with Africans1 This cross-breeding has been inten- sified in the present century, particularly in the last gen- erations, as a result of internal migrations from rural to urban areas, a phenomenon that has had repercussions culturally and epidemiologically in Mexico and Central America. In Mexico, two sources of information have stimu- lated interest in factors determining the new epidemiology of its population. One was the National Survey of Chronic Diseases 1992-93, which studied the prevalence of obesity and hypertension and other degenerative diseases in the adult urban population currently in the pro- cess of being analyzed by our group. The other source focused on the prevalence of obesity and hypertension in Mexican Americans residing in the U.S.2.3 Both sets of studies have revealed a high prevalence of obesity and hypertension in Mexicans and Mexican Americans. These national results have been confirmed in regional studies in Mexicans4 and Mexican Amer ican~.~ ,~ However, in Mexico, we need more information on obesity and hypertension in some groups, such as rural communities and the aged and the children. In addition, there are geographic and culinary differences and a differential exposure to Western culture that may give rise to regional peculiari- ties in the frequency of obesity. The population of the Yucatan offers an opportunity to gain knowledge in some of the environmental factors, including ethnographic, epi- demiological, and culinary, that may affect the state of nutrition in that population, which we shall briefly dis- cuss below.

Unlike other Mexican regions, the Yucatan was geo- graphically isolated until a railroad and a highway linking it to the rest of the country were built in 1950 and 1970, re~pectively.~-~ The Yucatan is a Mexican region where

“Mexican Health Foundation, Mexico City, TMexican Health Foundation in Yucatan & Hospital O’Horan, Merida, Yucatan., Sinstituto Nacional de Nutricion Salvador Zubiran, Mexico City.

many Mayan sacred cities were built in pre-Columbian times; it currently has a well-developed cuisine with a prestige of its own, which is recognized as distinct from Mexican cuisine. Here we report data on the relationship between energy density and fat content of the urban diet of the population of cities in the Yucatan and their relationship to the incidence of overweight and obesity. In addition, we present some data on routine physical activity, which has changed as a consequence of the population’s incorporation of a more sedentary urban lifestyle.

Ethnography-and Cross-Breeding

Descendants of the Mayans are recognized as such by glottochronology studies. Coe estimates that the 30 Mayan languages spoken today originated from a com- mon ancestor around the year 2000 BC (Proto-Mayan).” The Maya spoken in the Yucatan peninsula originated around the year 1000 BC and is currently a variant developed some 600 years ago. Based on this, it could be in- ferred that the Yucatan population has remained relatively stable in the last six centuries, despite the arrival of the Spanish conquistadors some 450 years ago. There are regional historic data suggesting that the genetic and cultural exchange of aborigines and conquerors was limited to the main cities of Yucatan and to certain g r o ~ p s . ~ - ~ The population of the Yucatan was predominantly monolingual well into the 20th century; Le., 50% of approximately 300,000 people were monolingual in 1930, but by 1970, only 65,000 of 450,000 people were mono1ingual.l

Demography and Epidemiology

The demography of the region changed about 25 years ago when tourism and its collateral activities became a strong factor in the Yucatan economy. Prior to this devel- opment, the Yucatan consisted mostly of a rural population and a rural economy based on the exportation of hemp.”-13 The sales ofhemp fell dramatically with the de- velopment of synthetic fibers. As of 1995, only 34% of Yucatan men are employed in agriculture whereas 25% are employed in industry and 40% in commerce and services.

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These changes have probably contributed to the modifi- cation of the causes of mortality; heart disease, cere- brovascular disease, and diabetes have been the first, third, and fourth causes of death since 1988, displacing infec- tions and parasite- and nutrition-related disease~.'~ Stud- ies in selected urban groups from the Yucatan have confirmed a high prevalence of obesity, diabetes, and dyslipidemias in those populations.

Culinary Culture

Similar to that of other Mesoamerican groups, the Yucatan cuisine is based on maize and beans, but it also has some features that may be termed nutrition-related risk factors. The Yucatan diet generously incorporates foods of high energy density such as pork, and lard is widely used for frying. Fish is not generally consumed. Since drinking water is rich in salts and the climate is hot, this population consumes large quantities of bottled sweetened drinks.I7

Methodology

The overall goal of the study is to estimate the prevalence of obesity, arterial hypertension, diabetes mellitus, and dyslipidemias in the Yucatan region. We shall restrict this report to our findings on the prevalence of obesity in the adult population of Merida, the capital city of the Yucatan, and its association with some features of diet and physical activity.

Sampling A representative sample of 1,212 subjects, aged 2 to 75 years, was obtained using a probabilistic multistage sampling of the population of the city. Distribution according to age and sex was calculated using the 1990 population census, and the sample size was calculated to be representative of subjects of both sexes of low and medium socioeconomic status. The socioeconomic stratification was performed following the criteria of the AMAi (Asociacion Mexicana de Agencias de Investigacibn), which carries out 80% of all marketing research in Mexico. This organization stratifies the population by home ap- pearance, availability of services, and means of communi- cation and transportation, among other indicators. Blocks and dwellings within areas previously classified as being of low or medium socioeconomic status by AMAI were selected. One resident from each dwelling was invited to participate; he or she was selected on the basis of age, gender, and socioeconomic status so as to fulfill our sampling criteria. Ofthe 1,212 subjects, 457 (226 women and 23 1 men) were between the ages of 20 to 75 years and were enrolled as the adult study population. During the first stage of the study, data on social and demographic char- acteristics, feeding habits, and physical activity patterns

were obtained in the 457 adults. During a second visit, 66% of the individuals (1 8 1 women and 125 men) were clinically evaluated, and a blood sample for biochemical and genetic studies was taken. This subsample maintained a distribution of gender and age similar to that of the origi- nal sample. Written consent was obtained from the participants.

Origin The rural-urban structure of the sample was established using the place of birth of the participant as well as that of his or her parents and grandparents. A three-way classifi- cation of each generation was done: a) Merida born (con- sidered urban); b) state born but not in Merida (consid- ered rural); c) out of state.

Anthropometry Height was estimated using a measuring tape on a spe- cially built portable wooden support, and weight was determined with a digital Tanita BWB-600 platfonn scale (1 00 g sensitivity). The measurements were taken indepen- dently by two observers, and the average was used. The observers were trained and certified by the Institute of Anthropological Research of the National University of Mexico and were periodically evaluated during fieldwork. Body massjndex (BMI) was used for two classifications: establishing status of being overweight according to an NIH criterion (BMI above the 85th percentile of the BMI distribution in the US. population), determining the se- verity of obesity (BMI of 35 or more).I*

Dietary and Physical Activity A two-section questionnaire was distributed to study participants, one section pertained to dietary habits and the other focused on physical activity. The questionnaire also incorporated a 24-hour recall (divided in seven periods: before breakfast, breakfast, before lunch, lunch, before dinner, dinner, and after dinner).1g.20 An equal number of participants were surveyed per day. Information about ingredients and preparation methods of homemade dishes was collected only from the person preparing the dish. We also registered foods consumed at the table such as bread, tortillas, sugar, marmalades, dressings, and salt, among others. Here we report only on foods consumed at home.

In the second section of the questionnaire, the participants reported their physical activities.21s22 This section listed 41 activities that might be performed at home, work, or during leisure activities, and each was classified as light, moderate, intense, or very intense in energy ex- penditure. These categories were based on the number of multiples of resting metabolic rate (METs) expended during each activity: light, up to 2 METs; moderate, 3-5; and intense and very intense, 6+ METs.

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Table 1. Prevalence and 95% Confidence Interval of Incidence of Being Overweight and of Severe Obesity in the Present Study Versus National Surveys in Mexico and the U.S.

BMI 35+ (severe obesitv) Males BMI 27.8+

Study % CI Urban Yucatan 45 38-52 Urban Mexicans** 29* 28-30 Mexican Americans*** 36 33-39 m*** 33* 31-35 NHW*** 34* 32-35

Females BMI 27.3+ Males YO CI Yo CI 73 66-80 2 4 6 43* 42-44 2 1.7-2.4 50* 48-52 5 NDA 52* 49-55 7 NDA 34* 31-36 5 NDA

Females % CI

12 8-17 8 7-9

13 NDA 18 NDA 10 NDA

~

* Significantly lower than Yucatan population by gender. NDA - No Data Available. ** P. Arroyo et al., Age trends of overweight and obesity in urban adult Mexicans in comparison with other national surveys (submitted for publication in Obesity Research). *** NHANES I11 survey in the NHB = non-Hispanic blacks. NHW = non-Hispanic whites. - Results

Origin Over half of the participants (55%) were born in Merida; 32% were born in rural communities of the Yuaatan; and 13% were born in other states. There were no large differences by gender in these figures. The parents of the participants were more frequently rural born (45%) than Merida born (37%), and these percentages were similar for the grandparents. These results are consistent with our hypothesis that Merida has undergone a sizable rural immigration in the last generation.

Anthropometry Table 1 gives the frequency by gender of being overweight and severely obese in comparison with national studies in Mexico and the U.S. NHANES I11 ~urvey.2~ The number of women of the Yucatan deemed overweight was signifi-

cantly higher than all other groups listed in Table 1, including men of the Yucatan, who exhibited a higher frequency of being overweight than males in other groups. However, it should be noted that the prevalence of being overweight in the Yucatan did not correspond to a simi- larly high incidence of severe obesity. Rather, men from the Yucatan had the lowest incidence of severe obesity among all the groups, and women from the Yucatan showed a lower incidence of severe obesity than did Mexi- can Americans and African-American women.

feeding Times and Place and Composition of Diet Approximately 90% of the subjects consumed their three daily meals at home. Because of this high consumption of home-prepared food, the information about ingredients, culinary techniques, and accompanying food items pro- vided us with a highly detailed description of the diet at

-

Table 2. Distribution of Subjects Who Recalled Consuming Foods High and Low in Energy Density at Least Once in the Previous 24-hour Period

Males Females Total (n= 226) (n= 231) (n= 457)

Energy** n Y O n Y O n Y O

High energy density Fat (frying) Pork meat Sausage Beef

Bread Tortilla Chicken Fish

Low energy density

Vegetables F G t s Whole milk Soft drinks

884 398 302 297

265 216 215 168 158 103 62 61 48

179 79 63 28 60 27 46 20

1 65 n* 179 79 61 n 7 3 89 44 86 38

151 67 20 1 89 149 66*

1512 76 59 60

139 173 58 9

90 123 169 194 125

83 33 26 26

60 75 25 4

39 53 * 73 84 54

371 139 119 106

304 352 119 16

179 209 320 395 274

81 30 26 23

67 77 26 4

39 46 70 86 60

*When gender difference was > 10%. **Approximate energy value per 100 g food.

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Table 3. Distribution of Subjects Performing Intense, Moderate, or Light Activities at Least Once a Day Males Females Total (n= 226) (n= 231) (n= 497)

Activity n % n Y O n Y O

Intense Lifting heavy objects 39 17

Fast bicycling 31 14 * Running 28 12

Contact sports 4 2

Moderate Lifting light objects 131 58 Walking 116 51 House cleaning 41 18 Slow bicycling 41 18 * Clothes washing 2 1

Light TV watching 1 63 R

25 11 20 7

3 1 0 0

187 81 * 97 42

163 71 * 9 4

28 12 *

187 81

64 14 48 11 34 7 4 1

308 67 213 47 204 45

50 11 30 7

350 77 - Standing 141 62 141 61 282 62

Deskwork 50 22* 19 8 69 15 Ironing 4 2 34 15 38 8

Car driving 86 38 * 31 13 117 26

* Gender difference > 10%. 4

the individual level. Table 2 shows the proportion of per- sons consuming foods both high and low in energy density at least once in the preceding 24-hour period; the energy densities of particular foods are ranked from high- est to lowest in the table. During the 24-hour recall period, most subjects (81%) consumed fat as an ingredient for frying foods, and nearly 30% consumed pork, sausages, or beef. Whole milk was consumed by nearly 90% of subjects; a majority (60% to 77%) ate tortillas and/or bread, fruits, and drank soft drinks. On average, 39% of the subjects ate at least one egg, 26% chicken, and a very small proportion ate fish. There were few gender differences in food consumption, although women consumed more vegetables than men (53% versus 38%), but men consumed more bread and soft drinks than women. These data lead us to the following observations: a) both men and women consumed many foods high in energy density; b) very few subjects consumed fish.

Physical Activity Table 3 details the subjects’ physical activities as reported on the questionnaire. Very few subjects performed intense activities, while a majority (77%) reported watching TV habitually. The gender differences in reported activities were not unexpected in a society in which the traditional roles of men at work and women at home are maintained; i.e., more women were involved in cleaning, washing, and ironing, whereas more men were involved in bicycling, driving, and performing clerical work. When analyzed by age, the incidence of intense and moderate activity de- clined in older subjects, particularly in women. In general, we conclude that this population engages in a low level of physical activity.

Discussion

Based on these data, we can conclude that the men and women of the Yucatan have a very high prevalence of being overw:ight, surpassing both Mexican-Americans and Mexicans. We believe a contributing factor to this finding is the culinary culture of the Yucatan, which en- courages the consumption of foods high in energy density. Another contributing factor may be the shift from a rural lifestyle to an urban one with a corresponding in- crease in sedentariness.

On the other hand, the incidence of being overweight was not accompanied by a corresponding incidence of severe obesity. To gain further insight into the interac- tions of various cultural factors and their association with overweight and obesity in the population of the Yucatan, we analyzed our data using a logistic regression Two BMI cutoff points were tested (overweight, 27.3+ in women and 27.8 in men; obesity, 30+ for both sexes). Food consumption, physical activity, origin, and socioeconomic status were the independent variables. Three-level scales were used to determine the frequency of food consumption (i.e., not consumed, consumed once, or consumed twice or more). A physical activity scale was established, which multiplied the frequency of the activity by its value in METs, resulting in four levels (i.e., light, moderate, intense, and very intense). An origin scale was based on the birthplace of grandparents, parents, and participants. The socioeconomic strata included in the model were medium and low. Age was controlled entering the variable in a first regression block followed by the independent variables in a step-forward fashion. The regression showed significant associations only between BMI and food scales in

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Table 4. Odds Ratios of a Step-forward, Age- adjusted Logistic Regression of Food Variables with Sianificant Association with BMI in 181 Women. Variable Odds ratio 90% CI BMI = 27.3+

Age 1.057 1.032-1.082

Pork 1.887 1.122-3.174 Bread 1.978 1.232-3.1 75

Milk 0.523 0.350-0.782

BMI = 30.0+ Age 1.040 1.024-1.074 Milk 0.502 0.326-0.774 Fat 1.929 1.248-2.984

women. The model showed that there were significant associations between being overweight (BMI of 27.3+) and milk intake and the consumption of pork and bread (see Table 4). Milk appeared to have a protective effect, in contrast to the consumption of pork and bread. Interest- ingly, with the BMI cutoff point of 30+, the association of milk consumption persisted, but the ingestion ofjfat appeared instead of pork and bread. Overall, these results are consistent with our hypothesis that the incidence of Yucatan women being overweight or obese was associ- ated with the consumption of foods high in energy density. Intake of milk was remarkably high in this sample, and its apparent protective effect may be an indicator of consumption of foods lower in energy density. currently, we are not able to offer an explanation for the lack of association between dietary profile and the incidence of being overweight or obese in men from the Yucatan, although there may have been some underreporting of energy intake from alcoh01.2~

Acknowledgment$. This work has been partially sup- ported by the Nest16 Nutrition Fund ofthe Mexican Health Foundation and by the Camegie-Funsalud Maternal and Child Health Research Program.

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Discussion of Lecture by Dr. Pedro Arroyo

R. Valdks: You showed a correspondence between a high consumption of fiber and the frequency of being overweight or diabetic. Could the real reason for this correspondence be the fact that this population consumes many lard-fried foods? P. Arroyo: Our logistic regression analysis did show that cooking in lard was a risk factor for women with a BMI of 30+. We need a larger sample to be more conclusive. H. Bourges: Fat and fiber are not independent, at least not in Yucatan, where fiber comes from tortillas and beans mostly prepared with lard. This interaction is not present in places where fiber comes from fruits and vegetables. On the other hand, I have always thought that it is almost impossible to know what is eaten by anybody, especially with regard to fat in Mexico, where foods are less industri- alized. Furthermore, we cannot tell how much fat there is in home-cooked dishes. The food frequency question- naires continue to be our best option, but we gan only take them as approximations of the truth. P. Arroyo: We are more interested in establishing the rela-

tive position of the individuals in the general distribution of foods eaten than in knowing how much food they ate. Question: Did you use genetic markers to determine whether your population was Mayan-Yucatec? P. Arroyo: No, we did not study them. About half of the cases came from very small communities, but we cannot say how genetically homogeneous they are. We intend to use markers unrelated to diabetes to try to classify them as either Indians or as mestizos with a larger Spanish com- ponent. Question: Are you planning to do similar studies in rural Yucatan, which I believe has a different diet than urban areas and an 80% prevalence of malnutrition in children2 Some years ago, we found anthropometric differences according to income in relatively homogeneous groups of Maya-Yucatecs. P. Arroyo: We are discussing the possibility of doing rural studies. According to previous studies, the problems you cite appear to be caused by protein-energy malnutrition.

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obesity and cultural environment in the yucatan region

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