James M. Mendlein

The association between fruit and vegetable intake and chronic disease risk factors.

Understanding the associations between fruit and vegetable intake and other health behaviors is important for properly interpreting the rapidly growing number of studies that link low intakes of fruits and vegetables to the risk of cancer and cardiovascular disease. To examine the association between fruit and vegetable intake and behavioral risk factors for chronic diseases, we analyzed data from a population-based behavioral risk factor survey. Data were collected in 1990 from 21,892 adults in 16 states by a random-digit-dial telephone survey. Respondents answered questions about behaviors related to chronic disease risk, including their frequency of intake of fruits and vegetables, using a six-item questionnaire. Consumption of fruits and vegetables was lowest among those who also reported that they were sedentary, heavy smokers, heavy drinkers, or had never had their blood cholesterol checked. Because fruit and vegetable intake covaries with several other chronic disease risk factors, it is important to account for possible confounding between fruit and vegetable intake and other behaviors in etiologic studies of the risk of cancer and cardiovascular disease.

Intake of Nutrients and Food Sources of Nutrients among the Navajo: Findings from the Navajo Health and Nutrition Survey

Diet has been implicated in the etiology of chronic diseases in many populations, including the Navajo and other American Indian tribes. This report describes the current nutrient intake of the Navajo and identifies the primary food sources of key nutrients. In the Navajo Health and Nutrition Survey, interviewers obtained single 24-h diet recalls from 946 nonpregnant participants age 12-91 between October 1991 and December 1992. Among various sex and age groups, total fat contributed 33-35% of energy and saturated fat contributed 10-11% of energy in the diets. Median fiber intake was 11-14 g/d. Median intakes of vitamin A, vitamin E, vitamin B-6, folate, calcium and magnesium were below sex- and age-specific recommended dietary allowances (RDA) for men and women of all age groups. Intake of vitamin C was below the RDA for men and women age 20 and older. Median iron intake was below the RDA for women under age 60. Fruits and vegetables were each consumed less than once per day per person, as were dairy products. Fry bread and Navajo tortillas, home-fried potatoes, mutton, bacon and sausage, soft drinks, coffee and tea provided 41% of the energy and 15-46% of the macronutrients consumed. Recommendations to increase the intake of essential micronutrients in the Navajo diet are presented.

Diabetes Mellitus among Navajo Indians: Findings from the Navajo Health and Nutrition Survey

Noninsulin-dependent diabetes mellitus is a major health problem among most American Indian tribes. This is the first population-based reservation-wide study of the Navajo that has used oral glucose tolerance testing to determine diabetes status. Employing WHO criteria, we found an age-standardized prevalence of diabetes mellitus (DM) of 22.9% among persons aged 20 y and older. This prevalence is 40% higher than any previous age-standardized estimate for the Navajo and four times higher than the age-standardized U.S. estimate. More than 40% of Navajo aged 45 y and older had DM. About one third of those with DM were unaware of it, with men more likely to be unaware than women. Among persons with a medical history of DM, almost 40% had fasting plasma glucose values > or = 200 mg/dL. Persons with DM were heavier, more sedentary and more likely to have a family history of DM than were persons without DM. Persons with DM had more hypertension, lower HDL levels and higher triglyceride levels than their counterparts without DM. Insulin usage was infrequent among persons with a history of DM, and about one third of women with such a history used no medical therapy to control their diabetes. Although important measures to combat diabetes have already been undertaken by the Navajo, additional efforts are required to slow the progression of this disease and prevent its sequelae.

Risk Factors for Coronary Heart Disease among Navajo Indians: Findings from the Navajo Health and Nutrition Survey

Coronary heart disease was uncommon among the Navajo in the past, but appears to have increased substantially over the last few decades. The 1991-1992 Navajo Health and Nutrition Survey, which included interviews and examinations of 303 men and 485 women between the ages of 20 and 91 y, is the first population-based examination of coronary heart disease risk factors in this tribe. Coronary heart disease risk characteristics were common, particularly overweight (men, 35%; women, 62%), hypertension (men, 23%; women, 14%) and diabetes mellitus (men, 17%; women, 25%). Among 20- to 39-y-olds, a large proportion of men reported that they currently smoked cigarettes (23%); use of chewing tobacco or snuff was also prevalent among these 20- to 39-y-old men (37%) and women (31%). Although serum concentrations of total cholesterol were fairly comparable to those seen in the general U.S. population, fasting serum triglyceride concentrations were high (median: men, 132 mg/dL; women, 137 mg/dL), and concentrations of HDL cholesterol were low, particularly among women (median: men, 42 mg/dL; women, 44 mg/dL). Body mass index was associated with levels of most risk factors, and, independently of the level of overweight, a truncal pattern of body fat was related to adverse lipid levels among men. A large proportion of men (20%) and women (30%) reported not having participated in physical activity during the preceding month. Lessons learned from past intervention activities among the Navajo, particularly those for diabetes, may be useful in managing these risk factors to reduce the future burden of coronary heart disease.

Weight, Body Image, and Weight Control Practices of Navajo Indians: Findings from the Navajo Health and Nutrition Survey

Historically, the Navajo exhibited a low prevalence of overweight, but a number of small studies over the past few decades indicate that the prevalence is increasing. In the population-based Navajo Health and Nutrition Survey conducted in 1991-92, overweight was defined as a body mass index (BMI, kg/m2) at or above the 85th percentile (BMI > 27.8 for men, > 27.3 for women) of the Second National Health and Nutrition Examination Survey. One third of men age 20 and 39 and one half of men age 40 and 59, but fewer than 10% of men age 60 and older were overweight. Two thirds or more of women in all age groups were overweight. Nineteen percent of the participants underestimated their weight status (underweight, appropriate, overweight) relative to their BMI category and 17% overestimated their weight status. Women overestimated their weight status more often than men (P < 0.05), and participants age 20-39 overestimated their weight status more often than older participants (P < 0.001). Men and women age 60 and older preferred heavier body shape models as ideals of health more often than younger participants (P < 0.001). Nearly half of the participants, regardless of their weight status, reported that they were trying to lose weight; most reported using diet and exercise. Because overweight is an important risk factor for many chronic diseases, including diabetes mellitus, cardiovascular disease and cancer, primary prevention of overweight and weight management for adults are recommended to prevent an increase in the burden of chronic disease among the Navajo.

Rationale, Design and Methodology for the Navajo Health and Nutrition Survey

As recently as 1990, there was no reservation-wide, population-based health status information about Navajo Indians. To remedy this shortcoming, the Navajo Health and Nutrition Survey was conducted from 1991 to 1992 to assess the health and nutritional status of Navajo Reservation residents using a population-based sample. Using a three-stage design, a representative sample of reservation households was selected for inclusion. All members of selected households 12 y of age and older were invited to participate. A total of 985 people in 459 households participated in the study. Survey protocols were modeled on those of previous national surveys and included a standard blood chemistry profile, complete blood count, oral glucose tolerance test, blood pressure, anthropometric measurements, a single 24-h dietary recall and a questionnaire on health behaviors. The findings from this survey, reported in the accompanying papers, inform efforts to prevent and control chronic disease among the Navajo. Lessons learned from this survey may be of interest to those conducting similar surveys in other American Indian and Alaska Native populations.