Biomedical subjects

N Van Heel

Publications and source records attributed to N Van Heel.

8 recordsLinked to original sources

PubMed2003

INTERMAP: the dietary data--process and quality control.

The aim of this report is to describe INTERMAP standardized procedures for assessing dietary intake of 4680 individuals from 17 population samples in China, Japan, UK and USA: Based on a common Protocol and Manuals of Operations, standardized collection by centrally trained certified staff of four 24 h dietary recalls, two timed 24-h urines, two 7-day histories of daily alcohol intake per participant; tape recording of all dietary interviews, and use of multiple methods for ongoing quality control of dietary data collection and processing (local, national, and international); one central laboratory for urine analyses; review, update, expansion of available databases for four countries to produce comparable data on 76 nutrients for all reported foods; use of these databases at international coordinating centres to compute nutrient composition. Chinese participants reported 2257 foods; Japanese, 2931; and UK, 3963. In US, use was made of 17,000 food items in the online automated Nutrition Data System. Average time/recall ranged from 22 min for China to 31 min for UK. Among indicators of dietary data quality, coding error rates (from recoding 10% random samples of recalls) were 2.3% for China, 1.4% for Japan, and UK; an analogous US procedure (re-entry of recalls into computer from tape recordings) also yielded low discrepancy rates. Average scores on assessment of taped dietary interviews were high, 40.4 (Japan) to 45.3 (China) (highest possible score: 48); correlations between urinary and dietary nutrient values--similar for men and women--were, for all 4680 participants, 0.51 for total protein, range across countries 0.40-0.52; 0.55 for potassium, range 0.30-0.58; 0.42 for sodium, range 0.33-0.46. The updated dietary databases are valuable international resources. Dietary quality control procedures yielded data generally indicative of high quality performance in the four countries. These procedures were time consuming. Ongoing recoding of random samples of recalls is deemed essential. Use of tape recorded dietary interviews contributed to quality control, despite feasibility problems, deemed remediable by protocol modification. For quality assessment, use of correlation data on dietary and urinary nutrient values yielded meaningful findings, including evidence of special difficulties in assessing sodium intake by dietary methods.

Adult↗

PubMed2000

Accuracy of energy intake data estimated by a multiple-pass, 24-hour dietary recall technique.

OBJECTIVE: This study examined the accuracy of a multiple-pass, 24-hour dietary recall method for estimating energy intakes of men and women by comparing it with energy intake required for weight maintenance. DESIGN: Three-day, multiple-pass, 24-hour recalls were obtained on randomly selected days during a self-selected diet period when subjects were preparing their own meals and during a controlled diet period when all meals were provided by the study. During the dietary intervention, weight was maintained; body weight and dietary intake were monitored closely, thereby allowing estimation of the energy intake required for weight maintenance. SUBJECTS/SETTING: Seventy-eight men and women (22 to 67 years old) from the Dietary Effects on Lipoprotein and Thrombogenic Activity (DELTA) study participated in this study. All 24-hour recalls were collected using a computer-assisted, interactive, multiple-pass telephone interview technique. Energy requirements for each individual were determined by the energy content of the DELTA study foods provided to maintain weight. STATISTICAL ANALYSIS: Paired and independent t tests were conducted to examine differences among study variables. Agreement between recalled energy intake and weight maintenance energy intake was analyzed using the Bland-Altman technique. RESULTS: Compared with weight maintenance energy intake, during the self-selected diet period men and women underestimated energy intake by 11% and 13%, respectively. During the controlled diet period, men underestimated energy intake by 13%, whereas women overestimated energy by 1.3%. APPLICATIONS/CONCLUSIONS: Men had a tendency to under-estimate energy intake irrespective of the recording period. The accuracy of the recalled energy intake of women may be influenced by recording circumstances. Researchers should examine the factors influencing underreporting and overreporting by individuals and their impact on macronutrient and micronutrient intakes. Also, strategies need to be developed to minimize underreporting and overreporting.

Adult↗

PubMed1998

Diet design for a multicenter controlled feeding trial: the DELTA program. Delta Research Group.

OBJECTIVE: To describe the process and results of diet standardization, diet validation, and monitoring of diet composition, which were key components of protocol 1 of Dietary Effects on Lipoproteins and Thrombogenic Activity (DELTA-1), the initial protocol in a program of multicenter human feeding studies designed to evaluate the effects of amount and type of fat on lipoproteins and hemostasis parameters in various demographic groups. DESIGN: DELTA-1 was based on a randomized, blinded, crossover experimental design. Three diets were fed for 8 weeks to 103 healthy men and women aged 22 to 67 years at 4 field centers. Diet A, an average American diet, was designed to provide 37% of energy from fat, 16% of energy from saturated fatty acids (SFAs); diet B (step 1 diet) was designed to provide 30% of energy from fat, 9% of energy from SFA; and diet C (low SFA diet) was designed to provide 26% of energy from fat, 5% of energy from SFA. Key features of diet standardization included central procurement of fat-containing foods, inclusion of standard ingredients, precision weighing of foods--especially sources of fat and cholesterol--and use of standardized written procedures. SETTING: For menu validation, a set of 12 menus for each diet was prepared in duplicate and chemically assayed. For monitoring of diet composition during the study, an 8-day diet cycle (6 weekday and 2 weekend menus) was sampled by every field center twice during each of 3 feeding periods. STATISTICAL ANALYSES: Means (+/- standard error) were calculated and compared with target nutrient specifications. RESULTS: DELTA-1 was able to provide a standardized diet that met nutrient specifications across 4 field centers over 24 weeks of participant feeding spanning a total of 8 months. APPLICATIONS: Prestudy chemical validation of menus and continuous sampling and assay of diets throughout the study are essential to standardize experimental diets and to ensure that nutrient target goals are met and maintained throughout a controlled multicenter feeding study.

Adult↗

PubMed1995

Lifestyle intervention: results of the Treatment of Mild Hypertension Study (TOMHS).

BACKGROUND: Questions regarding the efficacy of nonpharmacologic approaches for the treatment of stage 1 hypertension were addressed as part of the Treatment of Mild Hypertension Study (TOMHS), a 4-year, randomized clinical trial (N = 902). This report describes the lifestyle intervention program used in TOMHS, presents data on the lifestyle changes observed, and focuses on the effect of weight loss on blood pressure and blood lipid levels. METHODS: Participants were randomly assigned to receive either placebo or one of five different antihypertensive medications. All took part in a lifestyle intervention program to reduce weight and sodium and alcohol intake and to increase physical activity. RESULTS: Substantial changes from baseline levels were achieved for all lifestyle intervention variables. Mean weight change was -10.5 lb (-5.6%) at 1 year, -8.5 lb (-4.5%) at 2 years, -7.4 lb (-4.0%) at 3 years, and -5.7 lb (-3.0%) at 4 years. At 4 years, 70% of participants remained below baseline weight and 34% maintained a weight loss of 10 lb or greater. Mean change in urinary sodium excretion was -12.5 mmol/8 hr (-23%) at 1 year, -10.7 mmol/8 hr (-20%) at 2 years, -8.4 mmol/8 hr (-16%) at 3 years, and -4.6 mmol/8 hr (-9%) at 4 years. Alcohol intake declined by 1.6 drinks/week among drinkers at 4 years. Reported leisure physical activity increased by 86% at 1 year and remained 50% above baseline at 4 years. Beneficial changes in blood pressure and serum lipids were associated with these changes. CONCLUSIONS: These results support a role for lifestyle interventions as the initial treatment for stage 1 hypertension and demonstrate that such interventions can be successfully implemented in the clinical setting.

Aged↗

PubMed1987

Nutritional therapy for high blood pressure. Final report of a four-year randomized controlled trial--the Hypertension Control Program.

A four-year trial assessed whether less severe hypertensives could discontinue antihypertensive drug therapy, using nutritional means to control blood pressure. Randomization was to three groups: group 1--discontinue drug therapy and reduce overweight, excess salt, and alcohol; group 2--discontinue drug therapy, with no nutritional program; or group 3--continue drug therapy, with no nutritional program. In groups 1 and 2 patients resumed drug therapy if pressure rose to hypertensive levels. Loss of at least 4.5 kg (10 + lb) was maintained by 30% of group 1, with a group mean loss of 1.8 kg (4 lb); sodium intake fell 36% and modest alcohol intake reduction was reported. At four years, 39% in group 1 remained normotensive without drug therapy, compared with 5% in group 2. Study findings demonstrated that nutritional therapy may substitute for drugs in a sizable proportion of hypertensives or, if drugs are still needed, can lessen some unwanted biochemical effects of drug treatment.

Adult↗

PubMed1987

Do hypertensive patients have a different diurnal pattern of electrolyte excretion?

Studies generally indicate that excretion of sodium, potassium, and water is greater during the day than during the night. To determine whether hypertensive patients exhibit this same pattern of excretion, diurnal variations in excretion of sodium, potassium, creatinine, and water were examined in 107 hypertensive men and women from a clinical trial on control of hypertension by nonpharmacological means--the Hypertension Control Program. Each participant provided two carefully timed 24-hour urine collections divided into daytime and overnight specimens. The median ratios of 24-hour to 8-hour overnight excretion were 2.84, 3.95, 2.99, and 2.77 for sodium, potassium, creatinine, and water, respectively. Thus, more than half of this hypertensive group exhibited a greater rate of sodium and water excretion during sleep than during daytime hours, a reversal of the usual pattern. When the group was subdivided based on age, sex, race, trial randomization group, use of diuretics, and hypertension severity, women had significantly lower ratios of 24-hour to overnight excretion for sodium and water than men and blacks had significantly lower 24-hour to overnight ratios for water and potassium than whites. When the 24-hour to overnight ratios for these hypertensive patients were compared with those for a group of 30 men and women with high-normal blood pressure, those with high-normal blood pressure had significantly larger ratios for sodium and water excretion than the hypertensive group. The results of this study suggest that hypertensive patients may have a different diurnal pattern of sodium and water excretion than normotensive subjects and that further research is needed to clarify this issue.

Adult↗

PubMed1985

Nonpharmacological control of hypertension.

Ability to safely withdraw well-controlled mild hypertensives from drugs is being tested in a three-group randomized trial. Group I (intervention) was removed from drugs after the first 2 months of nutrition counseling. Counseling is continuing through the remaining years of the trial to achieve a minimum weight loss of 10 lb if overweight, reduction of sodium intake to less than 1,800 mg, and reduction of alcohol intake to not more than two drinks per day. Group II (the first control group) was also removed from drugs to see if previous long-term blood pressure control had a carryover effect without dietary change. Blood pressure is monitored frequently in both groups, with return to drug treatment in the event of specified blood pressure rise. Group III (the second control group) has remained on drugs for comparison of blood pressure and biochemical variables. In Group I mean 30-month weight loss was 8 lb, with 35% losing 10+ lb; sodium intake was reduced by 38%. Blood pressure control without drugs was maintained for 47% of Group I patients but only 16% of group II patients (P less than 0.05). These findings indicate it may be possible, after establishing good blood pressure control, to maintain control in a sizable proportion without medication, when reduction of weight, sodium, and alcohol intake is achieved.

Alcohol Drinking↗

PubMed1984

Trial on control of hypertension by nutritional means: three-year results.

Ability to safely withdraw medication from well-controlled mild hypertensives was tested in a 3-group randomized trial. Group I (Intervention): drugs were stopped 2 months after nutrition counseling began. Counselling continued throughout the remaining years of the trial to achieve: a minimum of 10 lb weight loss if overweight; reduction of sodium intake to 1800 mg/day or less; reduction of alcohol intake to not more than 2 drinks per day. Group II (control group 1): drugs were stopped to see if previous long-term blood pressure control had a carryover effect without diet change. Pressure was monitored frequently in both groups with return to treatment if diastolic blood pressure rose to 90 mmHg or above. Group III (control group 2) remained on drugs for comparison of blood pressure and biochemical variables. In Group I mean weight loss at 3 years was 7 lb (3.18 kg) with 39% losing 10 lb (4.55 kg) or more; sodium intake was reduced by 37%. Blood pressure control without drugs was achieved in 44% of Group I patients. This compares with only 15% in Group II. These findings suggest it may be possible after establishing good blood pressure control, to maintain control in a sizeable proportion with less or no medication, when reduction of weight, sodium, and alcohol is achieved.

Antihypertensive Agents↗