Factors associated with calcium absorption efficiency in pre- and perimenopausal women.

BACKGROUND: The amount of calcium ingested by an individual may affect several chronic conditions, including osteoporosis, hypertension, and colon cancer. However, individuals vary in their ability to absorb the calcium they consume. OBJECTIVE: The purpose of this study was to examine sources of interindividual variation in the efficiency of calcium absorption in women. DESIGN: Fractional calcium absorption was estimated in 142 healthy pre- and perimenopausal women. Dietary habits, lifestyle factors, calciotropic hormones, and vitamin D receptor gene polymorphisms were also assessed. RESULTS: Calcium absorption values averaged 35% and ranged from 17% to 58%. Fractional calcium absorption was positively associated with body mass index (r = 0.22, P = 0.007), dietary fat intake (r = 0.29, P = 0.001), serum 1,25 dihydroxyvitamin D [1,25(OH)(2)D] concentrations (r = 0.23, P = 0. 006), and parathyroid hormone concentrations (r = 0.21, P = 0.015). Fractional calcium absorption was inversely associated with total calcium intake (r = -0.18, P = 0.030), dietary fiber intake (r = -0. 19, P = 0.028), alcohol consumption (r = -0.14, P = 0.094), physical activity (r = -0.22, P = 0.007), and symptoms of constipation (r = -0.16, P = 0.059). In stepwise regression analysis, dietary fat, dietary fiber, serum 1,25(OH)(2)D, and alcohol consumption emerged as independent predictors of calcium absorption, explaining 21.02% of the observed variation. Women in the lowest tertile of the ratio of dietary fat to fiber had 19% lower fractional calcium absorption values than did women in the highest tertile of ratio of dietary fat to fiber (test of trend, P < 0.001). CONCLUSIONS: There is a wide range of calcium absorption values in healthy women. The amount of dietary fat consumed relative to dietary fiber appears to have an important role in determining differences in calcium absorption performance among individuals.

Dietary protein restriction and the progression of chronic renal disease: what have all of the results of the MDRD study shown? Modification of Diet in Renal Disease Study group.

The Modification of Diet in Renal Disease (MDRD) Study was the largest randomized clinical trial to test the hypothesis that protein restriction slows the progression of chronic renal disease. However, the primary results published in 1994 were not conclusive with regard to the efficacy of this intervention. Many physicians interpreted the failure of the MDRD Study to demonstrate a beneficial effect of protein restriction over a 2- to 3-yr period as proving that this therapy does not slow disease progression. The authors believe that this viewpoint is incorrect, and is the result of misinterpretation of inconclusive evidence as evidence in favor of the null hypothesis. Since then, numerous secondary analyses of the MDRD Study have been undertaken to clarify the effect of protein restriction on the rate of decline in GFR, urine protein excretion, and onset of end-stage renal disease. This review describes some of the principles of secondary analyses of randomized clinical trials, presents the results of these analyses from the MDRD Study, and compares them with results from other randomized clinical trials. Although these secondary results cannot be regarded as definitive, the authors conclude that the balance of evidence is more consistent with the hypothesis of a beneficial effect of protein restriction than with the contrary hypothesis of no beneficial effect. Until additional data become available, physicians must continue to make recommendations in the absence of conclusive results. The authors suggest that physicians incorporate the results of these secondary analyses into their interpretation of the findings of the MDRD Study.

Differences between women and men with chronic renal disease.

BACKGROUND: The purpose of the present study was to compare the participation of women and men in the protocols of the Modification of Diet in Renal Disease (MDRD) study, a multicenter prospective randomized clinical trial, and to assess gender differences in their renal outcomes. METHODS: Of the 840 participants in the MDRD study, 332 (39.5%) were women who were assigned randomly to the dietary protein and blood pressure groups and followed for a median of 2.2 years. A subgroup analysis of the MDRD study database was carried out to compare women and men participants in recruitment, baseline characteristics, adherence to protocol requirements, safety and outcomes, and progression of renal disease and its response to dietary and blood pressure interventions. RESULTS: Adherence by women to the requirements of the protocol including diet, record keeping, office visits, glomerular filtration rate (GFR) measurements and urine collections was equivalent to that of men. Women had different renal diagnoses, less proteinuria and lower serum creatinine levels for given GFRs than men. When participants were grouped above and below age 52, the younger women had lower mean arterial pressure than did the men. Older women compared with younger had higher mean arterial pressure, body weight and body mass index, and total low density lipoprotein cholesterol. These differences were not seen between males of the same two age groups. During follow-up, the rate of GFR fall was slower in women, especially in the younger group. However, the association between gender and the rate of fall in GFR was attenuated and became non-significant after adjusting for differences in blood pressure, proteinuria and high density lipoprotein cholesterol. In analyses of the full cohort, there were no significant differences between women and men in the effects of the low protein or low blood pressure intervention in patients with either moderate (study A) or advanced (study B) renal disease. However, in subgroup analyses of patients in study A, there was some evidence of a lesser effect in women than in men. CONCLUSIONS: This exploratory analysis of the MDRD study indicates a slower mean GFR decline in women as compared with men. The slower mean GFR decline and suggestive evidence of a lesser beneficial effect of the low protein diet and low blood pressure interventions in women suggest that gender differences should be considered in trials of the effects of these interventions on the progression of renal disease. Also, the participation of women in the MDRD study was excellent and equivalent to that of men.

Effects of dietary fat and fatty acids on coronary artery disease risk and total and lipoprotein cholesterol concentrations: epidemiologic studies.

Because of their large sample sizes, epidemiologic studies can provide important data on the relation between diet, specifically dietary fat and fatty acids, and lipid and lipoprotein concentrations as well as the incidence of coronary artery disease. Although correlation coefficients vary widely (from 0.84 to 0.01) and are frequently low between dietary variables and coronary artery disease or lipids and lipoprotein fractions in the studies reviewed here, intakes of saturated fatty acids and dietary cholesterol are generally positively correlated with blood cholesterol in men and women. Associations between other fatty acids are less consistent and may be related to the considerable differences in these studies in dietary methodologies used, databases used for analyses, and homogeneity of intakes within populations. Relatively few data are available for women, cultural minorities within the United States, or young or elderly populations. However, the trends observed in the United States, ie, lower rates of coronary artery disease as well as lower reported intakes of both total and saturated fats, support the relations observed in the epidemiologic studies.

Quality of lipid and lipoprotein measurements in community laboratories.

OBJECTIVE: To determine the reliability of cholesterol and lipoprotein measurements conducted in local community laboratories. METHODS: Standardized duplicate serum aliquots at three concentrations (low, intermediate, and high) of total cholesterol, triglycerides, and high-density lipoprotein cholesterol were sent to 21 laboratories used by the physicians participating in the Cholesterol-Lowering Intervention Program. Results obtained from the laboratories were compared with values obtained from the Centers for Disease Control and Prevention-standardized Heinz Lipid Laboratory and with the means of the entire sample. RESULTS: The mean coefficient of variation (CV) was 1.3% or less for all three levels of total cholesterol, which demonstrates a high degree of precision. Accuracy was also high; over 80% of all laboratories were within 5% of the Heinz Laboratory low reference value, and all were within the 5% range for the medium and high samples. The CVs for triglycerides (< 2.3%) and high-density lipoprotein cholesterol (< 2.2%) were similar to that for total cholesterol, but up to 56% and 61% of the values fell outside the Heinz reference range for high-density lipoprotein cholesterol (intermediate concentration) and triglycerides (low concentration), respectively. As the Heinz Laboratory has a negative 2.7% bias versus the Centers for Disease Control and Prevention for total cholesterol and high-density lipoprotein cholesterol measurements, a higher percentage of laboratories fell outside the Centers for Disease Control and Prevention range. For medium and high total cholesterol samples, 16% of the laboratories were outside the 5% Centers for Disease Control and Prevention range, and the value was 58% for the low total cholesterol sample. For high-density lipoprotein cholesterol the percentages were 61%, 56%, and 39% for the low, medium, and high samples, respectively. CONCLUSIONS: These data suggest that according to the standards set by the National Cholesterol Education Program Laboratory Standardization Panel, reliability of total cholesterol measurements in local laboratories is high. Lower levels of accuracy were noted for triglycerides and high-density lipoprotein cholesterol measurements.

Methods of dietary and nutritional assessment and intervention and other methods in the Multiple Risk Factor Intervention Trial.

Various dietary assessment instruments were used in the Multiple Risk Factor Intervention Trial (MRFIT), either to assist with the special intervention program or to assess trial outcomes. For the latter purpose, the 24-h recall was the main method and was selected with the understanding that the single recall collected at baseline and at most annual visits--considered by itself--would be useful mainly for assessing groups rather than individuals. Major components of the data collection and analysis system developed for the 24-h recall included central training and certification of nutritionists, a central nutrient coding system, and a food grouping system to assist interventionists in using recall data for counseling. Several additional nutritional assessment methods were used for men in the special intervention group only to assist them in attaining the dietary goals. These goals consisted chiefly of reduced intake of saturated fat and cholesterol and a modest increase in intake of polyunsaturated fat; total fat intake was also decreased, primarily for control of energy intake. Short-term success at attainment of these nutritional goals was evaluated by means of 3-d food records collected before the intervention and after the initial 10-wk intensive intervention period. The MRFIT nutrient goals, which became more vigorous at certain points in the trial, were translated into food patterns. Adherence to these food patterns was also assessed by scoring of 3-d records and by subjective evaluation by nutritionists throughout the trial. Methods of collecting other trial data are also described in this chapter.

Relation of changes in dietary lipids and weight, trial years 1-6, to changes in blood lipids in the special intervention and usual care groups in the Multiple Risk Factor Intervention Trial.

For men in the special intervention (SI) group of the Multiple Risk Factor Intervention Trial, the average decrease in serum total cholesterol was 16.9 mg/dL (6.7%); for men in the usual care (UC) group, the average decrease was 9.7 mg/dL (3.8%). The difference between the two groups for plasma total cholesterol was 6.2 mg/dL. Plasma low-density-lipoprotein (LDL) cholesterol decreased 10.6 mg/dL (6.6%) in SI men and 5.4 mg/dL (3.4%) in UC men. Mean weight losses were 3.0 lb (1.36 kg) and 0.1 lb (0.05 kg) for SI and UC men, respectively. Change in blood total cholesterol was directly related to baseline concentration; for men with serum total cholesterol > or = 220 mg/dL, those in the SI group decreased their total cholesterol by 7.8% (design goal: 10%) and those in the UC group by 4.8% (expected: 0%). Change in dietary lipid intake (summarized by the Keys score) for SI men was significantly related to changes in blood total cholesterol, LDL cholesterol, and triglyceride, but not to change in high-density-lipoprotein (HDL) cholesterol. Controlled for weight change, coefficients for Keys score change were smaller but remained significantly related to each blood lipid except HDL cholesterol. Weight loss was associated with favorable effects on all blood lipids. Influences of change in diet and weight on blood lipids were quantitatively less for hypertensive men for serum total cholesterol, HDL cholesterol, and triglyceride than for nonhypertensive men. Nonsmokers had greater decreases than smokers in blood total cholesterol, LDL cholesterol, and triglyceride.

Nutritional adequacy of diets reported at baseline and during trial years 1-6 by the special intervention and usual care groups in the Multiple Risk Factor Intervention Trial.

This chapter addresses whether a fat-modified diet as implemented by special intervention participants in the Multiple Risk Factor Intervention Trial affected intake of vitamins and minerals, and whether nutritional adequacy was altered by this dietary intervention. Despite likely underreporting of intake, for men in the special intervention group, most mean intakes of 15 micronutrients estimated from 24-h recalls were above established recommended dietary allowances. A few means were slightly below; lowest was zinc at 77% (from 98% at baseline) followed by calcium at 79% (from 102% at baseline). Calculated as nutrient densities (per 1000 kcal), nutrients that were below indexes of nutritional quality (the corresponding standard based on nutrient density) during follow-up, although not reduced below baseline by this measure, were vitamin D, calcium, iron (marginally), and zinc. Analyses by food groups indicated that intake of these nutrients might have been improved by greater replacement of high- and medium-fat dairy products with low-fat dairy products (for vitamin D and calcium) and of high-fat meats with low-fat meats, fish, or poultry (for iron and zinc), or (because iron was adequate) by increasing consumption of vegetables and whole-grain products. The safety of the eating pattern was further confirmed by more favorable micronutrient profiles in men who adhered best to the intervention program, as measured by degree of serum cholesterol reduction and weight loss.

Relation of body mass and alcohol, nutrient, fiber, and caffeine intakes to blood pressure in the special intervention and usual care groups in the Multiple Risk Factor Intervention Trial.

This chapter presents analyses of relations of dietary variables to blood pressure, systolic (SBP) and diastolic (DBP), for men in the special intervention (SI) and usual care (UC) groups in the Multiple Risk Factor Intervention Trial. For each dietary factor, analyses were done at baseline, for trial years 1-6, and for change from baseline to years 1-6. Analyses were done for all participants and for men receiving or not receiving antihypertensive drug treatment and were controlled for age, race, education, serum cholesterol, smoking, special diet status, and (for specific nutrients) body mass index and alcohol intake. Nutrient data for trial years 1-6, which are based on four or five dietary recalls per man, are more reliable than the baseline or change data, which are based on only one recall. Therefore, this summary focuses on data for trial years 1-6, for SI and UC men pooled. Regression analyses confirmed direct independent relations of body mass index, alcohol intake, sodium, and ratio of sodium to potassium to SBP and DBP, and an inverse relation of potassium to SBP and DBP. Dietary starch was directly related to SBP and DBP; dietary saturated fatty acid and cholesterol and Keys score were directly related to DBP; dietary magnesium, fiber, and caffeine were inversely related to SBP and DBP; and dietary protein, polyunsaturated fatty acids, the ratio of polyunsaturated to saturated fatty acid, and other simple carbohydrates were inversely related to DBP. Method problems, all tending to produce underestimations, are also reviewed.

Low-fat diet practices of older women: prevalence and implications for dietary assessment.

OBJECTIVE: To evaluate the importance of information on low-fat diet practices and consumption of reduced-fat foods for accurate assessment of energy and fat intakes using a semiquantitative food frequency questionnaire (FFQ). SUBJECTS: Subjects were 7,419 women, aged 50 to 79 years, who filled out an FFQ as part of eligibility screening for a diet modification component and/or a hormone replacement trial in a multicenter study of chronic disease prevention in postmenopausal women (Women's Health Initiative). STATISTICAL ANALYSIS: For 26 FFQ questions, we recoded the low-fat diet choices of participants to a high-fat counterpart and recalculated energy and fat intakes. We then determined the decrease in energy and nutrient estimates attributable to adding low-fat options to the FFQ. RESULTS: Low-fat diet practices were widespread in this population. For example, 69% of respondents rarely or never ate skin on chicken, 76% rarely or never ate fat on meat, 36% usually drank nonfat milk, 52% usually ate low-fat or fat-free mayonnaise, 59% ate low-fat chips/snacks, and 42% ate nonfat cheese. These low-fat choices had substantial effects on energy and nutrient estimates. Absolute decreases (and mean percentage decreases) for energy and nutrient measures attributable to adding low-fat diet options to the FFQ were 196 kcal (11.4%) energy, 9 percentage points in percentage energy from fat (22.3%), 23.2 g fat (29.0%), and 9.6 g saturated fat (32.5%). Black and Hispanic women and women of lower socioeconomic status reported significantly fewer low-fat diet practices than white women and women of higher socioeconomic status. CONCLUSION: Failure to collect information on low-fat diet practices with an FFQ will result in an upward bias in estimates of energy and fat intake, and the amount of error will vary by the personal characteristics of respondents.

Cholesterol-lowering intervention program. Effect of the step I diet in community office practices.

BACKGROUND: A randomized study was conducted to test the feasibility of cholesterol lowering in physician office practices using the National Cholesterol Education Program Adult Treatment Panel 1 guidelines. METHODS: Twenty-two physician practices in phase 1 and 23 in phase 2 were recruited from communities in Western Pennsylvania and West Virginia. These physicians treated a total of 450 adults in phase 1 (190 men and 260 women) and 480 adults in phase 2 (184 men and 296 women) with hypercholesterolemia. Three models (Usual Care [phase 1], Office Assisted [phase 2], and Nutrition Center [phase 2]) for implementing the National Cholesterol Education Program Adult Treatment Panel 1 guidelines were tested over an 18-month period. The baseline serum cholesterol levels were as follows: 6.51 mmol/L (252 mg/dL) in the Usual Care Model; 6.80 mmol/L (262 mg/dL) in the Office Assisted Model; and 6.96 mmol/L (269 mg/dL) in the Nutrition Center Model. RESULTS: In the patients who were not taking lipid-lowering medication, the mean cholesterol response was significantly different between the 3 models (P < .01). Serum cholesterol levels declined by 0.14 mmol/L (5.4 mg/dL) in the Usual Care Model; by 0.31 mmol/L (12 mg/dL) in the Office Assisted Model; and by 0.54 mmol/L (20.9 mg/dL) in the Nutrition Center Model. Two factors-length of time to follow-up measurement and change in weight-were independently related to cholesterol response across all models. African Americans demonstrated a significantly smaller response than whites in the Usual Care Model, while men demonstrated greater declines in serum cholesterol levels than women in the Office Assisted Model. Patient satisfaction was very favorable in both enhanced conditions; however, those treated in the the Nutrition Center Model were more satisfied (P < .05) with program components. CONCLUSIONS: The impact of nutrition intervention delivered through physician practices on serum cholesterol levels is less than clinically desirable, and new approaches with more aggressive therapy should be tested and implemented.

Effects of dietary protein restriction on the progression of advanced renal disease in the Modification of Diet in Renal Disease Study.

Patients with advanced renal disease randomized to the very low-protein diet group in the Modification of Diet in Renal Disease (MDRD) Study had a marginally (P = 0.066) slower mean glomerular filtration rate (GFR) decline compared with patients randomized to the low-protein diet group. The objective of these secondary analyses was to determine the relationship between achieved, in addition to prescribed, dietary protein intake and the progression of advanced renal disease. A randomized controlled trial was conducted in patients with chronic renal diseases of diverse etiology. The average follow-up was 2.2 years. Fifteen university hospital outpatient nephrology practices participated in the study, which comprised 255 patients aged 18 to 70 years with a baseline GFR 13 to 24 mL/min/1.73 m2 who participated in MDRD Study B. Patients with diabetes requiring insulin were excluded. The patients were given a low-protein (0.58 g/kg/d) or very low-protein (0.28 g/kg/d) diet supplemented with keto acids-amino acids (0.28 g/kg/d). Outcomes were measured by comparisons of protein intake from food or from food and supplement between randomized groups, and correlations of protein intake with rate of decline in GFR and time to renal failure or death. Comparison of the randomized groups showed that total protein intake from food and supplement was lower (P < 0.001) among patients randomized to the very low-protein diet (0.66 g/kg/d) compared with protein intake from food only in patients randomized to the low-protein diet (0.73 g/kg/d). In correlational analyses, we combined patients assigned to both diets and controlled for baseline factors associated with a faster progression of renal disease. A 0.2 g/kg/d lower achieved total protein intake (including food and supplement) was associated with a 1.15 mL/min/yr slower mean decline in GFR (P = 0.011), equivalent to 29% of the mean GFR decline. After adjusting for achieved total protein intake, no independent effect of prescription of the keto acid-amino acid supplement to slow the GFR decline could be detected. If the GFR decline is extrapolated until renal failure, a patient with a 29% reduction in the rate of GFR decline would experience a 41% prolongation in the time to renal failure. Additional analyses confirmed a longer time to renal failure in patients with lower total protein intake. In conclusion, these secondary analyses of the MDRD Study suggest that a lower protein intake, but not the keto acid-amino acid supplement, retards the progression of advanced renal disease. In patients with GFR less than 25 mL/min/1.73 m2, we suggest a prescribed dietary protein intake of 0.6 g/kg/d.

Nutrition intervention program of the Modification of Diet in Renal Disease Study: a self-management approach.

OBJECTIVE: To characterize the Modification of Diet in Renal Disease (MDRD) Study nutrition intervention program by determining the frequency of intervention strategies used by the dietitians and the usefulness of program components as rated by participants. DESIGN: Dietitians recorded which of 32 intervention strategies they used at each monthly visit. Participants rated the usefulness of 19 program components. SUBJECTS: 840 adults with renal insufficiency. INTERVENTION: Participants were assigned randomly to usual-, low-, or very-low-protein diet groups. Each eating pattern also specified a phosphorus intake goal. Each participant met monthly with a dietitian for an average of 26 months. STATISTICAL ANALYSES: Analyses of variance and chi 2 analyses. RESULTS: Dietitians used the following intervention strategies most often in all groups: providing feedback based on self-monitoring and/or food records, reviewing adherence or biochemistry data, providing low-protein foods, and reviewing graphs of adherence progress. In general, the dietitians used feedback, modeling, and support strategies more often, and knowledge and skills strategies less often, with participants who had to make the greatest reductions in protein intake and those with more advanced disease. In all groups, the dietitians' use of knowledge and skills, feedback, and modeling strategies decreased over time (P < .001), whereas use of support strategies was maintained. The type and frequency of intervention strategies used by dietitians and the usefulness ratings of participants did not vary by educational level of the participant. Both self-monitoring and dietitian support were rated as "very useful" by 88% of the participants. CONCLUSIONS: Three features were central to the MDRD Study nutrition intervention program: feedback, particularly from self-monitoring and from measures of adherence; modeling, particularly by providing low-protein food products; and dietitian support. We recommend the self-management approach.

Registered dietitian time requirements in the Modification of Diet in Renal Disease Study.

OBJECTIVE: To assess time expended by registered dietitians to conduct clinical and research activities during the Modification of Diet in Renal Disease (MDRD) Study. DESIGN: Two randomized, controlled clinical trials among persons with diminished levels of renal function using a factorial design to evaluate effects of dietary protein restriction and blood pressure control on progression of renal disease. In study A, subjects with moderate renal insufficiency were randomly assigned to a diet of usual protein (1.30 g/kg per day) or low protein (0.58 g/kg per day) and to either a usual or low blood pressure level. Study B involved subjects with advanced renal insufficiency who were randomly assigned to the low-protein diet or a very-low-protein prescription (0.28 g/kg per day) with a ketoacid-amino acid supplement (0.28 g/kg per day) and to either the usual or low blood pressure level. A time-log form designed by MDRD Study dietitians was completed for each participant at 36 monthly follow-up visits. SETTING: Fifteen clinical centers throughout the continental United States. SUBJECTS: Eight hundred forty adults aged 18 to 70 years with chronic renal diseases participated in the MDRD Study--585 in study A and 255 in study B. STATISTICAL ANALYSES: One-way analyses of variance and t tests were used to evaluate significant time requirement differences by diet groups, diagnosis, and sociodemographics. RESULTS: Mean total time for all participant visits declined from 183 +/- 1 minutes per visit during months 1 through 4 to 116 +/- 41 minutes per visit during months 25 through 36. Significantly more dietitian time was required for participants consuming the low-protein and very-low-protein diets than for those consuming the usual-protein diet. Age, gender, race, marital status, and renal diagnosis did not influence time requirements. A significant inverse association between education level and dietitian time was apparent. APPLICATIONS: The MDRD Study time-log data should be useful when determining staffing patterns for nutrition management in clinical and research settings.

Evaluating the efficacy of the National Cholesterol Education Program adult treatment guidelines: cholesterol lowering intervention program.

BACKGROUND: A cross-sectional analysis was conducted to test the feasibility of the National Cholesterol Education Program Adult Treatment Panel I Guidelines (ATPI) in physician office practices. METHODS: Twenty-two physician practices in communities from western Pennsylvania and West Virginia were recruited. Using a patient tracking system, 9,171 patients were assessed for cholesterol screening and treatment by their physicians according to the ATPI guidelines. RESULTS: Cholesterol screening was ordered for 1,698 patients or 19% of the population visiting the physician offices. The reasons for not screening included the patient was already under therapy (2,371), screened within the past 5 years (1,714), or acutely ill at the time of the visit (1,691). The frequency of patient refusal for screening was low (444). However, the majority of patient diagnoses were based on a single lipid measurement, and only 817 or 56% of patients evaluated had lipoprotein measures obtained prior to treatment. Follow-up measurement was not performed according to the ATPI schedule, and the magnitude of cholesterol response was inversely related to time to first follow-up measurement. CONCLUSIONS: Many patients in these physician practices had initial cholesterol screening. However, repeat measurements as recommended for initial evaluation were not performed routinely, nor were most patients followed within the recommended 3-month time period. This lack of follow-up is detrimental to effective, long-term patient management since the magnitude of the cholesterol response is related to time of the first follow-up measurement.

Coffee consumption: relationship to blood lipids in middle-aged women.

BACKGROUND: There is controversy about the relationship between coffee intake and blood lipids in women and many studies fail to control for potential confounding factors. METHODS: In 1983 and 1984, 541 randomly selected premenopausal women were recruited from a list of licenced drivers, aged 42-50, within selected areas in Allegheny County, Pennsylvania. They were invited to participate in a 5-year study of biological and behavioural changes associated with menopause. At baseline and the first follow-up visit, lipoprotein, lipid and apoprotein levels, physical activity, dietary intake and coffee consumption were measured. Pearson correlations between coffee consumption and the various lipid values were calculated. Multivariate analyses, which controlled for the potential confounding effects of body mass index, alcohol intake, percent of calories from carbohydrate and fat, number of cigarettes smoked per day, physical activity level, and age in months, were also employed to investigate the relationships. RESULTS: Mean coffee consumption for the group was 3.35 cups of coffee per day at baseline and 3.02 cups per day at follow-up. Results of analyses of correlation between coffee consumption and blood lipids as well as multiple regressions to control for menopausal status at follow-up were non-significant (P > 0.05) for all blood lipid values with the exception of triglycerides, which were inversely related to coffee consumption at follow-up. CONCLUSIONS: These results do not support a relationship between coffee consumption and lipoprotein, lipid or apoprotein levels with the exception of an inverse relationship between coffee consumption and triglyceride level at follow-up.

The effects of dietary protein restriction and blood-pressure control on the progression of chronic renal disease. Modification of Diet in Renal Disease Study Group.

BACKGROUND: Restricting protein intake and controlling hypertension delay the progression of renal disease in animals. We tested these interventions in 840 patients with various chronic renal diseases. METHODS: In study 1, 585 patients with glomerular filtration rates of 25 to 55 ml per minute per 1.73 m2 of body-surface area were randomly assigned to a usual-protein diet or a low-protein diet (1.3 or 0.58 g of protein per kilogram of body weight per day) and to a usual- or a low-blood-pressure group (mean arterial pressure, 107 or 92 mm Hg). In study 2, 255 patients with glomerular filtration rates of 13 to 24 ml per minute per 1.73 m2 were randomly assigned to the low-protein diet (0.58 g per kilogram per day) or a very-low-protein diet (0.28 g per kilogram per day) with a keto acid-amino acid supplement, and a usual- or a low-blood-pressure group (same values as those in study 1). An 18-to-45-month follow-up was planned, with monthly evaluations of the patients. RESULTS: The mean follow-up was 2.2 years. In study 1, the projected mean decline in the glomerular filtration rate at three years did not differ significantly between the diet groups or between the blood-pressure groups. As compared with the usual-protein group and the usual-blood-pressure group, the low-protein group and the low-blood-pressure group had a more rapid decline in the glomerular filtration rate during the first four months after randomization and a slower decline thereafter. In study 2, the very-low-protein group had a marginally slower decline in the glomerular filtration rate than did the low-protein group (P = 0.07). There was no delay in the time to the occurrence of end-stage renal disease or death. In both studies, patients in the low-blood-pressure group who had more pronounced proteinuria at base line had a significantly slower rate of decline in the glomerular filtration rate. CONCLUSIONS: Among patients with moderate renal insufficiency, the slower decline in renal function that started four months after the introduction of a low-protein diet suggests a small benefit of this dietary intervention. Among patients with more severe renal insufficiency, a very-low-protein diet, as compared with a low-protein diet, did not significantly slow the progression of renal disease.