Julian Esparza

Effects of a Traditional Lifestyle on Obesity in Pima Indians

OBJECTIVE The Pima Indians of Arizona have the highest reported prevalences of obesity and non-insulin-dependent diabetes mellitus (NIDDM). In parallel with abrupt changes in lifestyle, these prevalences in Arizona Pimas have increased to epidemic proportions during the past decades. To assess the possible impact of the environment on the prevalences of obesity and NIDDM, data were collected on members of a population of Pima ancestry (separation 700–1,000 years ago) living in a remote mountainous location in northwestern Mexico, with a lifestyle contrasting markedly with that in Arizona. RESEARCH DESIGN AND METHODS Pima heritage was established by history and by use of Pima language. Measurements of weight, height, body fat (bio-impedance), blood pressure, plasma levels of glucose, cholesterol, and HbA1c were obtained in 19 women (36 ±13 years of age) and 16 men (48 ±14 years of age) and compared with sex-, age- and diabetes status-matched Pimas living in Arizona (10 Arizona Pimas for each Mexican Pima). RESULTS Mexican Pimas were lighter (64.2 ± 13.9 vs. 90.2 ± 21.1 kg, P < 0.0001; means ± SD) and shorter (160 ± 8 vs. 164 ± 8 cm, P < 0.01) with lower body mass indexes (24.9 ± 4.0 vs. 33.4 ± 7.5 kg/m2, P < 0.0001) and lower plasma total cholesterol levels (146 ± 30 vs. 174 ± 31 mg/dl, P < 0.0001) than Arizona Pimas. Only two women (11%) and one man (6%) had NIDDM, contrasting with the expected prevalences of 37 and 54% in female and male Arizona Pimas, respectively. CONCLUSIONS This preliminary investigation shows that obesity, and perhaps NIDDM, is less prevalent among people of Pima heritage living a “traditional” lifestyle than among Pimas living in an “affluent” environment. These findings suggest that, despite a similar potential genetic predisposition to these conditions, a traditional lifestyle, characterized by a diet including less animal fat and more complex carbohydrates and by greater energy expenditure in physical labor, may protect against the development of cardiovascular disease risk factors, obesity, and NIDDM.

Effects of Traditional and Western Environments on Prevalence of Type 2 Diabetes in Pima Indians in Mexico and the U.S.

OBJECTIVE—Type 2 diabetes and obesity have genetic and environmental determinants. We studied the effects of different environments on these diseases in Pima Indians in Mexico and the U.S. RESEARCH DESIGN AND METHODS—Adult Pima-Indian and non-Pima populations in the Sierra Madre mountains of Mexico were examined using oral glucose tolerance tests and assessments for obesity, physical activity, and other risk factors. Results were compared with those from Pima Indians in Arizona. Both Pima populations were typed for DNA polymorphisms to establish their genetic similarity. RESULTS—The age- and sex-adjusted prevalence of type 2 diabetes in the Mexican Pima Indians (6.9%) was less than one-fifth that in the U.S. Pima Indians (38%) and similar to that of non-Pima Mexicans (2.6%). The prevalence of obesity was similar in the Mexican Pima Indians (7% in men and 20% in women) and non-Pima Mexicans (9% in men and 27% in women) but was much lower than in the U.S. Pima Indians. Levels of physical activity were much higher in both Mexican groups than in the U.S. Pima Indians. The two Pima groups share considerable genetic similarity relative to other Native Americans. CONCLUSIONS—The much lower prevalence of type 2 diabetes and obesity in the Pima Indians in Mexico than in the U.S. indicates that even in populations genetically prone to these conditions, their development is determined mostly by environmental circumstances, thereby suggesting that type 2 diabetes is largely preventable. This study provides compelling evidence that changes in lifestyle associated with Westernization play a major role in the global epidemic of type 2 diabetes.

Daily energy expenditure in Mexican and USA Pima Indians: low physical activity as a possible cause of obesity

BACKGROUND: Obesity is caused by an imbalance between energy intake and energy expenditure. However, it is unknown whether increased physical activity protects susceptible populations against the development of obesity and type 2 diabetes.OBJECTIVE: To investigate the potential protective role of environment and physical activity against obesity by measuring total energy expenditure in Mexican and USA Pima Indians.METHODS: We compared the physical activity level of 40 (17 female and 23 male; 37±11 y, 66±13 kg) Mexican Pima Indians from a remote, mountainous area of Northwest Mexico, with 40 age-and-sex matched (17 female and 23 male; 37±12 y, 93±22 kg) Pima Indians from the Gila River Indian Community in Arizona, USA. We measured total energy expenditure (TEE) by doubly labeled water and calculated physical activity by different methods: physical activity level (PAL) as the ratio of TEE on resting metabolic rate (RMR), TEE adjusted for RMR by linear regression, activity energy expenditure adjusted for body weight (AEE), and activity questionnaire.RESULTS: Physical activity was higher in Mexican Pima Indians when compared with USA Pima Indians as assessed by PAL (1.97±0.34 vs 1.57±0.16, P<0.0001), TEE adjusted for RMR (3289±454 vs 2671±454 kcal/day, P<0.0001) and AEE adjusted for body weight (1243±415 vs 711±415 kcal/day, P<0.0001). Questionnaires revealed more time spent on occupational activities among Mexican Pima compared with USA Pima (23.9±13.3 vs 12.6±13.9 h/week, P<0.001).CONCLUSION: These data support a significant role for physical activity in the prevention of obesity in genetically susceptible populations.

Could giardiasis be a risk factor for low zinc status in schoolchildren from northwestern Mexico? A cross-sectional study with longitudinal follow-up.

BackgroundBoth giardiasis and zinc deficiency are serious health problems worldwide. In Mexico, the prevalence of G. intestinalis was estimated at 32% in 1994. It remains a health problem in northwestern Mexico. Recent surveys (1987, 1995, and 1999) reported zinc deficiency in the Mexican population. The association of giardiasis and malabsorption of micronutrients has been well documented, although the association with zinc remains controversial. This study investigated the association between giardiasis and zinc deficiency in schoolchildren from northwestern Mexico.MethodsWe combined a cross-sectional design with a longitudinal follow-up six months after parasite treatment. The baseline sample consisted of 114 schoolchildren (mean age 8.8 yr) from seven suburban public schools, grouped as Giardia-free (n = 65, 57%) and Giardia-infected (n = 49, 43%). Three stool analyses per child were done using Fausts method. Children with giardiasis received secnidazole. Serum zinc was determined by atomic absorption spectrophotometry. Height and weight were measured. Socioeconomic information was obtained in an oral questionnaire, and daily zinc intake was assessed using 24 hour-recalls. Pearsons correlation and ANCOVA and paired t-test analyses were used to determine the association between giardiasis and zinc status.ResultsLongitudinal analysis demonstrated a significant increase of the mean serum zinc levels in the Giardia-infected group six months after treatment (13.78 vs. 19.24 μmol/L μmol/L; p = 0.001), although no difference was found between the Giardia-free and the Giardia-infected groups (p = 0.86) in the baseline analysis. Z scores for W/A and H/A were lower in the Giardia-infected than in the Giardia-free group (p < 0.05). No difference was observed in the socioeconomic characteristics and mean daily intakes of zinc between the groups (p > 0.05).ConclusionsGiardiasis may be a risk factor for zinc deficiency in schoolchildren from northwestern Mexico.