Journal of the American College of Nutrition, Vol. 21, No. 5, 394-401 (2002)
Published by the American College of Nutrition
Diet and Exercise Habits of Patients with Diabetes, Dyslipidemia, Cardiovascular Disease or Hypertension
Marian L. Neuhouser, PhD, RD,
Debra L. Miller, PhD,
Alan R. Kristal, DrPH,
Matt J. Barnett, MS and
Lawrence J. Cheskin, MD
Division of Public Health Sciences, Fred Hutchinson Cancer Research Center (M.L.N., A.R.K., M.J.B.), Seattle, Washington
Department of Epidemiology and Program in Nutritional Sciences, University of Washington (A.R.K.), Seattle, Washington
Division of Gastroenterology, Johns Hopkins University School of Medicine (D.L.M., L.J.C.) Baltimore, Maryland
Address correspondence to: Marian L. Neuhouser PhD, RD, Cancer Prevention Research Program, Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave North, MP-702, P.O. Box 19024, Seattle, WA 98109-1024. Email: mneuhous{at}fhcrc.org
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ABSTRACT
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Objective: The objective of this study was to determine whether free-living individuals diagnosed with diabetes, dyslipidemia, cardiovascular disease or hypertension follow standard dietary recommendations for treatment of these diet-modifiable disorders.
Methods: Data are from 1,782 adult men and women who completed an annual clinic visit as part of a large study of diet and health. Usual dietary intake over the previous month was assessed with a self-administered food frequency questionnaire. Trained staff obtained a detailed medical history and information on health and exercise habits, measured height and weight, and collected a fasting blood specimen to measure total serum cholesterol, triglycerides and carotenoids. Multivariate linear regression was used to test associations of diet-modifiable chronic diseases with diet and exercise habits.
Results: 42% of the study sample reported at least one diet-modifiable disease or risk factor for disease. These individuals had higher total serum cholesterol (p < 0.001) and triglycerides (p < 0.001) compared to those without these conditions. Diabetics consumed a greater percent of energy from fat (p < 0.01), and men with hypertension consumed a greater percent energy from saturated fat (p < 0.05) compared to those without these conditions. There were few other differences in dietary intake between diseased and healthy individuals, and on average, all participants had diets that were not consistent with recommended guidelines for prevention or treatment of these diet-modifiable disorders. Forty-six percent of all participants were overweight or obese, and BMI was significantly higher among participants with at least one diet-modifiable disorder (p < 0.001). Healthy and diseased participants exercised about 17 minutes per day, and compared to non-diabetics, persons with diabetes exercised with 25% less intensity (p < 0.05).
Conclusion: Participants in this sample with diet-modifiable disorders reported that they are motivated to eat less fat, but most are still overweight or obese, consume a diet high in fat and low in fruits and vegetables and engage in very little physical exercise. New strategies are needed to help patients adopt and maintain healthful dietary practices that will reduce their risk.
Key words: diet therapy, plasma lipids, diabetes, hypertension, cardiovascular disease, dyslipidemia, dietary fat
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INTRODUCTION
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Medical nutrition therapy is an important component of the treatment for diabetes mellitus, cardiovascular disease, dyslipidemia and hypertension. The focus of nutrition therapy for these conditions includes individual and group instruction to help patients reduce total fat, saturated fat and cholesterol intakes and to increase fruit, vegetable, and fiber consumption [1]. These interventions are intended to normalize lipid levels, stabilize blood glucose, lower blood pressure and maintain or reduce weight. Substantial evidence suggests that these dietary approaches to disease prevention and treatment are successful, resulting in fewer physician office visits, delay of pharmacotherapy, less frequent hospitalizations and reduced incidence of disease-related complications [2,3]. For example, the Dietary Approaches to Stop Hypertension (DASH) trial showed that a diet high in fruit, vegetables and fiber and low in fat and red meat effectively normalizes blood pressure [4–6]. Jones et al. found that a combined weight loss and dietary intervention were important adjuncts to pharmacotherapy for hypertension [7], while Stevens et al. demonstrated that weight loss alone results in statistically and clinically significant improvements in blood pressure [8]. Three recently published studies from a large randomized trial found that dietary interventions with prepared meal plans led to weight loss, improvements in blood lipid and glucose profiles and reductions in plasma homocysteine and other indicators of risk for cardiovascular disease, diabetes and other chronic conditions [9–11]. Finally, hundreds of dietary intervention studies [12] support the positions of both the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults and the National Cholesterol Education Program, which recommend nutrition therapy and other lifestyle changes as the initial treatment for dyslipidemias [2].
Despite the evidence supporting the effectiveness of medical nutrition therapy for persons with diet-modifiable chronic disease, dietary change and maintenance are difficult, and many patients do not comply with prescribed recommendations [13]. For example, at least four published studies have shown that instead of consuming the suggested 30% or less energy from fat, patients with type II diabetes mellitus obtain, on average, 34% to 40% of energy from fat [14]. Similarly, a study conducted in Japan among 39 patients with mildly elevated blood pressure found that even modest dietary changes were difficult to achieve and maintain [15]. Still other investigations have shown that long-term compliance with dietary regimens to reduce cardiovascular risk factors is difficult [16–18]. Most of these data showing either the effectiveness of medical nutrition therapy or the difficulties with long term compliance are from randomized trials or feeding studies with intensive protocols. Thus, an important question for nutrition professionals is the extent to which free-living patients who have been diagnosed with diet-responsive disorders follow well-known dietary recommendations. To investigate this question, we examined the diet and health practices of free-living individuals who have been diagnosed with diabetes mellitus, dyslipidemia, cardiovascular disease or hypertension, conditions that respond favorably to medical nutrition therapy.
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METHODS
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Study Design and Participants
Data are from adult participants in the cohort phase of the Olestra Post-Marketing Surveillance Study (OPMSS). Details about the design and preliminary results of OPMSS are published [19,20]. Briefly, adults aged 18 years and older were recruited by a random digit dial (RDD) telephone survey in four U.S. cities (Indianapolis, Baltimore, Minneapolis and San Diego) from 1996–2000; these four cities were selected based on their geographic location and minority representation. The telephone survey collected information about usual fruit, vegetable and savory snack consumption, beliefs about diet and health, and demographics. A random sample of respondents who completed the telephone survey were invited to attend a clinic visit where they completed a variety of procedures described below. Clinic staff conducted quarterly follow-up telephone calls with participants to monitor changes in diet and health over a one-year period. At the final telephone call, a subset of these participants were invited to become part of a cohort that was followed for an additional two years, with annual clinic visits and quarterly telephone calls. Of the 2,064 participants who were invited to join the cohort, 1,812 (88%) completed the second clinic visit and 1,702 (83%) completed the third clinic visit. The analyses in this report are from 1,782 cohort participants for whom we have complete data from annual clinic visits conducted between October, 1998 and October, 1999, representing the third clinic visit in Indianapolis and the second visit at the other sites. The Institutional Review Boards of the participating institutions approved all procedures, and participants provided written consent for clinic activities.
Medical History
Trained interviewers collected detailed information about each participant’s medical history by asking: "Has a doctor or health professional ever told you that you had: diabetes; respiratory disease; cardiovascular disease (i.e., heart attack or heart problems); eye disease; hypertension; high cholesterol or triglycerides; kidney disease; cancer; gallbladder disease; ulcers; reflux disease; diverticulitis; irritable bowel; lactose intolerance; or liver disease?" More than one response was permitted, and for each positive response, interviewers inquired about current status of the condition and medication use. Because we were interested in the dietary practices of participants with diet-modifiable chronic diseases, we restricted analyses in this report to those conditions known to respond favorably to medical nutrition therapy (cardiovascular disease, dyslipidemia, hypertension and diabetes).
Dietary Assessment
Nutrient intake was assessed with a 122-item food frequency questionnaire (FFQ) [21], with additional questions on savory snack foods (potato and tortilla chips, extruded snacks and snack crackers) [22]. The reference period for the FFQ was "in the past month." Participants completed the FFQs at home and brought them to the clinic where staff reviewed them for completeness. We derived the nutrient database from the University of Minnesota Nutrition Coordinating Center nutrient database [23], and the algorithms for analysis are published elsewhere [24].
Other Measures
To assess participants’ motivations for changing dietary behavior, we used motivation scales previously tested in a randomized trial of a self-help intervention that promoted lower fat and higher fruit and vegetable consumption [25]. A subset of the questions asked whether participants would eat less fat for the following reasons: 1) to control a medical problem such as high cholesterol or diabetes; 2) to prevent cancer or other diseases; or 3) if a doctor recommended that they do so. Participants who responded affirmatively to each question were asked to indicate if this was a "very important," "somewhat important" or "mildly important reason to eat less fat." Frequency and intensity of leisure and work-related physical activity was measured with standard questions [26]. To estimate intensity of physical activity in metabolic equivalents (mets), we multiplied the reported number of minutes per week spent in physical activity/exercise by an estimate of metabolic equivalents per exercise session [27]. Height, weight, waist and hip circumferences were measured using a standardized protocol, and body mass index (BMI) was calculated as weight (kg)/height (meters)2 [28]. Demographic characteristics (age, gender, race, education) were collected during the initial study recruitment telephone call as noted above.
Blood Collection and Analysis
Phlebotomists used venipuncture to collect semi-fasting (
6 hours) blood samples into serum separating tubes, which were protected from heat and light throughout processing. Specimens were stored at -70°C until batch analysis. Total serum cholesterol and triglycerides were analyzed using enzymatic methods [29]. Precision was evaluated using packaged reagents, pooled human serum and control sera; both interassay precision and bias were < 3%. Total serum carotenoids were assayed by reverse phase HPLC where the interassay CV ranged from 5.7% to 9.2%. All laboratory assays were completed by Quintiles Laboratories (Atlanta, GA).
Statistical Analysis
Multivariate linear regression was used to test associations of diagnosed risk factors or diseases with biochemical indicators of disease risk and dietary intake. We used each medical condition (e.g., diabetes) as the independent variable in separate models to test whether presence of the condition predicted total serum cholesterol, triglycerides and carotenoids, as well as dietary intake of energy, percent of energy from fat and saturated fat, cholesterol and daily servings of fruits and vegetables. These models were adjusted for variables known to be confounders of these associations including age, gender, race, education, body mass index and co-morbid conditions. Because preliminary analyses indicated a statistically significant interaction of gender with diet among participants diagnosed with hypertension and an interaction of gender with serum measures among those diagnosed with cardiovascular disease, we present these results stratified by gender. All dietary and serum measures, except percent of energy from fat and saturated fat were log transformed prior to analysis to improve the normality of their distributions, and we present the back-transformed values in their original units for ease of interpretation. We excluded 83 (5%) FFQs because the energy intakes were outside the range considered reliable and acceptable (<800 kcals/day or >5000 kcals/day for males and <600 kcals/day or >4000 kcals/day for females) [30]. In addition, there were three participants who did not complete an FFQ, leaving n = 1696 for analysis. Additional models tested associations of these disorders with BMI and exercise.
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RESULTS
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Table 1 gives the demographic, lifestyle and health characteristics of the study population. Sixty-three percent of the study sample were female, 78.7% were Caucasian, 39.4% had a college degree and 46.6% were overweight or obese. Twenty-one percent of the sample were current smokers, which is slightly less than the national average of 25% of all adults [31]. Chronic disease, or presence of risk factors for chronic disease (e.g., dyslipidemia), was common in this cohort, as 42% reported at least one condition and 16% reported two or more conditions. The most commonly reported conditions were hypertension (20%) and dyslipidemia (22%). Of the 564 participants with high cholesterol or cardiovascular disease, 32% reported use of cholesterol-lowering medications. There were 354 (19.9%) participants with physician-diagnosed hypertension, of whom 260 (73%) were using anti-hypertensive medication (data not shown).
Table 2 gives data on serum cholesterol and triglyceride concentrations, two biochemical measures of disease risk, as well as total serum carotenoids, which are biomarkers for fruit and vegetable intake and a general indicator of a healthy diet. Compared to participants with no physician-diagnosed medical conditions, those who reported any condition, diabetes or dyslipidemia had statistically significantly higher serum cholesterol; those with any condition or dyslipidemia had significantly higher serum triglycerides. After adjusting for all potentially confounding variables, there were no differences in serum carotenoid concentrations between the groups examined. Although 32% of participants with physician-diagnosed dyslipidemia reported use of medication to control the condition, these participants still had total cholesterol and triglyceride concentrations that were 0.48 mmol/L and 0.26 mmol/L higher, respectively, than participants without these conditions. Males with a history of previous heart attack or heart disease had significantly lower total serum cholesterol compared to males without a history of cardiovascular disease.
Table 3 gives nutrient intakes of participants stratified by diagnosed medical condition. There were few differences in dietary intake between persons with and without diet-modifiable diseases or risk factors, even after statistical adjustment for age, gender, education, body mass index and co-morbid conditions, which can strongly confound these associations. Diabetics, though, consumed 37% of energy from fat, compared to 35% among nondiabetics, and this difference was statistically significant (p < 0.01). There was modest evidence that persons with dyslipidemia were attempting to decrease dietary fat; compared to those without elevated serum lipids; these participants ate less energy from fat and saturated fat and less dietary cholesterol, but the differences were statistically significant only for saturated fat and still exceed standard recommendations. Males with hypertension consumed significantly more percent energy from saturated fat (p < 0.05), with modest differences in total cholesterol and fruits and vegetables (both p = 0.06) compared to men without hypertension. We note that in spite of an apparent lack of adherence to dietary practices (e.g., low fat, high fruit and vegetable) that can improve disease status and long-term prognosis, participants in this study reported high motivation to alter their diets. Eighty percent of participants with cardiovascular disease, diabetes, dyslipidemia or hypertension reported that it would be very important to them to eat less fat in order to prevent serious diseases; 70% to 75% of participants reported that they would eat less fat if a physician told them to, and nearly 90% reported that they would eat less fat if it would help control a medical problem (data not shown).
Associations of BMI and physical activity varied across chronic medical conditions (Table 4). BMI was statistically significantly larger among participants who reported diabetes, dyslipidemia or hypertension compared to participants who did not report those conditions. These estimates were adjusted for age, gender, race, education and co-morbid conditions. We note that 64% of diabetics, 58% of hypertensives, 56% of those with cardiovascular disease and 62% of participants with dyslipidemia reported that they were actively trying to lose weight (data not shown). Both healthy and diseased participants engaged in very little occupational and leisure physical activity, with each group obtaining only 120 and 118 minutes per week (or about 17 minutes per day), respectively. There were large differences in exercise patterns of diabetics compared to non-diabetics. Participants with diabetes exercised at 25% decreased intensity (as measured in metabolic equivalents) compared to non-diabetics.
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DISCUSSION
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The principal finding from this investigation is that the 42% of all adults in this nationally conducted study who reported a history of diabetes, cardiovascular disease, dyslipidemia or hypertension have poor diet and exercise habits. While medical nutrition therapy is widely recognized as an essential component of treatment for these diet-modifiable diseases and conditions, our data showed that, compared to participants who are disease-free, many of the biochemical and physical indicators of disease risk were worse among these participants, who should be especially careful about adhering to health and exercise guidelines. There were few differences in dietary intake between those with and without chronic disease; except for dietary cholesterol intake, mean estimates for all study participants did not meet the guidelines for either disease prevention or treatment, namely less than 30% of total energy from fat, no more than 10% of energy from saturated fat, 300 or fewer mg of cholesterol and at least five servings of fruits and vegetables per day [3].
These findings have several important public health implications. First, there is substantial evidence showing that adherence to dietary recommendations (e.g., low fat, high fruit and vegetable diet) for diet-modifiable diseases will decrease the risk of long term disease complications and occurrence of co-morbid conditions [1–3]. Failure to follow these recommendations places patients at increased risk for progressive disease and poor prognoses, which are strongly associated with reduced quality of life, shortened life span and considerable economic costs. For example, Oster and Thompson estimated that lost earnings and medical costs of cardiovascular disease alone amount to tens of billions of dollars per year [32]. Other published reports have documented the estimated health care dollars that will be saved by Medicare coverage for medical nutrition therapy [33], which began January 1, 2002 [34]. Because nutrition professionals are actively working to expand health insurance coverage of medical nutrition therapy for people with cardiovascular disease and dyslipidemia, and for Americans who have diabetes and hypertension but are not yet covered by Medicare, these findings are especially intriguing and emphasize the need for these important nutrition services.
An important question for nutrition professionals is the extent to which we can bridge the large gap between patient knowledge of the effectiveness of nutrition therapy and the ability to sustain long-term adherence to a prescribed dietary pattern. For example, 80% of our participants with diet-modifiable chronic diseases reported that it would be very important for them to eat less fat in order to prevent serious diseases and 90% stated that they would eat less fat if it would help control a medical problem. Yet, among these same participants, the mean percent energy from fat was nearly 35%, and the fruit and vegetable intake was less than three servings per day. Dietary change and maintenance are difficult, particularly when it must be sustained over the course of many years to control a chronic disease. While there are very few published studies demonstrating effective long-term behavioral strategies for dietary change and maintenance, several investigations are currently underway to explore these important issues [35]. Moreover, we have recently shown that women, persons older than 55 years and well-educated individuals are more likely to be successful with self-initiated dietary change than those who are male, younger and without a college education [36]. These findings suggest that clinicians who work with certain demographic groups may need to devise new ways to help these individuals change and maintain their diets to prevent or treat diet-related chronic diseases.
There are several strengths to our study. First, the random digit dial recruitment strategy allowed us to recruit successfully a diverse study sample from three large U.S. cities. Second, our measures of diet and health have been previously validated in other populations [25,37], and the food frequency questionnaire has been shown to provide good estimates of usual dietary intake [21]. Third, all clinic staff were centrally trained and certified in data collection procedures, and strict quality assurance protocols were instituted and followed at each clinic site. Finally, the combination of objective measures of blood chemistries and body measurements together with reliable self-reported measures of diet and health provide a fairly comprehensive profile of the study participants. There are also limitations. First, we recognize that these data are observational in nature, and we are unable to determine whether any changes in weight or diet have occurred over time or since diagnosis. However, we note that few participants reported a recent diagnosis (11.4% of patients with cardiovascular disease, 16.6% with hypertension, 20.5% with diabetes and 26.0% with dyslipidemia were first diagnosed within the previous year), suggesting that sufficient time had likely elapsed since diagnosis to permit at least some behavior modification. Second, because we did not obtain specific information on whether participants with diet modifiable diseases received nutrition services from a nutrition professional or physician, we are unable to determine associations between actual therapy offered and compliance. Third, our results may not be generalizable to all patients with diabetes, cardiovascular disease, dyslipidemia or hypertension because we studied the behavior of participants in an observational research study who may differ from the general population. Longitudinal studies conducted with similar free-living populations will help to clarify the extent to which patients with diet-modifiable diseases can successfully modify diet and exercise habits.
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CONCLUSION
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We conclude that this examination of the diet and health practices of free-living individuals with physician-diagnosed diabetes, cardiovascular disease, hypertension or dyslipidemia indicates that, while many patients report active engagement in weight loss regimens and are motivated to eat less fat, most are still overweight, consume a high-fat, low fruit and vegetable diet and participate in very little physical activity. New strategies are needed to identify successful methods to help patients adopt and maintain healthful dietary practices. Finally, clinicians should be especially attentive to refer patients with these diet-responsive medical disorders to qualified nutrition professionals for treatment and monitoring and to help patients who qualify to obtain reimbursement for these services under the Medical Nutrition Therapy Act, effective January 1, 2002 [34].
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ACKNOWLEDGMENTS
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This study was supported by the Proctor & Gamble Company (Cincinnati, OH).
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FOOTNOTES
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Dr. Debra L. Miller is currently at Central Soya, Ft. Wayne, Indiana.
This study was supported by the Procter & Gamble Company (Cincinnati, OH).
Received July 26, 2001.
Accepted February 25, 2002.
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ABSTRACT
INTRODUCTION
