Food group and macronutrient intakes, trial years 1-6, in the special intervention and usual care groups in the Multiple Risk Factor Intervention Trial

This chapter presents changes in dietary intake reported by men in the special intervention (SI) and usual care (UC) groups from baseline through 6 y of follow-up in the Multiple Risk Factor Intervention Trial. Changes in nutrients by SI men after 1 y of following the intensive intervention program were as follows: reduced intake of total fat (from 38.4% to 34.3% of energy), saturated fatty acids (14.2% to 10.4% of energy), and cholesterol (448 to 263 mg/d), and increased intake of polyunsaturated fatty acids (from 6.4% to 8.6% of energy). These changes were maintained and did not increase through the remaining 5 y. UC men reported small changes in similar directions. Most of the change in saturated fatty acid intake by SI participants was from high-fat meat and high- and medium-fat dairy products. Reduction in dietary cholesterol was achieved primarily by substantial decreases in intake of eggs and high-fat meats. Several baseline factors were associated with amount of dietary change in SI men. Greater changes were seen in men with higher baseline serum cholesterol concentrations, in those not consuming a special diet, in nonsmokers followed by lighter smokers, in hypertensive than in non-hypertensive men, in older participants, in white than in black men, in moderate drinkers than in nondrinkers or those consuming > or = 22 drinks/wk, and in those with no "stressful life events" than in those reporting one or more life events.

Quality control in the Multiple Risk Factor Intervention Trial Nutrition Modality

One of the principal objectives of the MRFIT was to teach and motivate participants assigned to the SI group to adhere to a fat-controlled dietary regimen over the course of the trial. The magnitude of the trial (with more than 12,000 participants, half of them assigned to the SI protocol, to be followed for at least 6 years in 22 separate centers) presented new challenges for maintenance of quality control over a nutrition intervention program. Collection of data to monitor changes in dietary intake over time in SI and UC groups, as well as information to assess dietary adherence levels in SI participants also presented large-scale challenges in maintenance of quality control. The MRFIT formulated many of its initial nutrition intervention and data collection decisions based on experience of the earlier National Diet Heart Study (NDHS). In order to avoid coding 7-day dietary records by local clinic nutritionists (as in NDHS), the trial opted for collection of 24-hour dietary recalls that were coded centrally at the Nutrition Coding Center. It necessitated extra attention to training and certification of clinic nutritionist-interviewers to be certain that NCC coders had sufficiently precise information about all foods entered on dietary recall forms. Since dietary intake data were collected over a time span of approximately 10 years, procedures for updating the food composition database and coding rules were a necessity. Continuing attention to training and monitoring of performance of clinic nutritionist-interviewers also was important. The MRFIT nutrition intervention program was designed with the need for interclinic comparability of intervention techniques in mind. This required not only development of study-wide nutrition intervention materials, but also necessitated ongoing attention to staff training and monitoring procedures in order to ensure intercenter comparability of efforts. The success of the nutrition intervention modality depended upon the continuing efforts of the nutrition counselors not only to achieve dietary adherence but also to monitor levels of dietary adherence over time. The NDHS experience served as a springboard for designing the MRFIT nutrition intervention and data collection procedures. It is hoped that techniques for maintaining and monitoring quality control over the MRFIT nutrition modality as outlined in this chapter may prove useful to future planners.

A long-term nutrition intervention experience: lipid responses and dietary adherence patterns in the Multiple Risk Factor Intervention Trial

Nutrition counselors in the Multiple Risk Factor Intervention Trial (MRFIT) were able to help middle-aged men who were at high risk for coronary heart disease change their dietary habits, maintain those changes over time, and decrease their serum cholesterol levels. Most of a 7.5% mean serum cholesterol reduction achieved after 6 years of nutrition intervention occurred during the first year of the trial and was thereafter sustained. Total cholesterol and low-density lipoprotein cholesterol fraction decreases indicated improvement in terms of coronary heart disease risk. The food record rating, a numerical, semi-objective adherence technique that assesses a 3-day food record with respect to lipid-lowering potential, was used throughout the trial to measure adherence to recommended food patterns. Participants with lower food record rating scores, which indicate better adherence, demonstrated greater reductions in serum total cholesterol, plasma total cholesterol, and low-density lipoprotein fraction cholesterol determinations on a group basis. Subjective evaluations of the suitability of home and working environments, evidence of deviation from the MRFIT food patterns, and overall nutrition program motivation also showed that as ratings in each category became more favorable, lower food record rating scores and greater blood lipid reductions were consistently observed. The subgroup of participants who were non-smokers and not hypertensive demonstrated greater lipid responses and better dietary adherence. Continued smoking and antihypertensive medications appeared to adversely influence dietary adherence and/or lipid reductions. The MRFIT experience, however, demonstrated for the first time that dietary changes and blood lipid reductions can be achieved after the initial intervention effect, despite a continued emphasis on high blood pressure management and smoking cessation.

Dietary intake in the Multiple Risk Factor Intervention Trial (MRFIT): nutrient and food group changes over 6 years

The Multiple Risk Factor Intervention Trial (MRFIT) was a randomized clinical trial in the primary prevention of coronary heart disease. Middle-aged men determined to be at high risk for coronary heart disease were randomized into either a special intervention (SI) group or a group referred to usual sources of medical care (UC). Twenty-four hour dietary recall data were used to monitor the nutrient intake of the MRFIT population and guide the nutrition education program for the SI group. The SI group of participants decreased intake of dietary cholesterol by 40% and saturated fatty acids by more than one-fourth and increased intake of polyunsaturated fatty acids by one-third. Evaluation of SI dietary intake data by food groups indicates that some dietary changes were relatively easy to implement, whereas others presented more of a challenge. Changes made with relative ease included increasing the consumption of fish and poultry, skim and low-fat milk, polyunsaturated margarines and oils, fruits, and low-fat breads and cereals and reducing the consumption of egg yolks. More difficult changes included eliminating, or even reducing, the intake of high-fat beef and pork, high-fat cheeses, high-fat crackers, snacks, and desserts, and increasing the intake of vegetarian meat alternatives.

Nutrition data collection in the Multiple Risk Factor Intervention Trial (MRFIT). Baseline nutrient intake of a randomized population

Selected preliminary baseline nutrient intake data for volunteers participating in the MRFIT study have been presented. Because of the unique selection criteria applied, nutrient intake trends described may not be generalized to the overall population. Nonetheless, present-day trends in this particular group seem to be toward dietary intakes lower in total fat, saturated fat, and dietary cholesterol and higher in polyunsaturated fat than those documented in earlier studies. Thus, utilizing the dietary methodology which has evolved through NHLBI's ongoing program of research investigations, it appears that the health-conscious men randomized into the MRFIT were already consuming diets somewhat more prudent than those in an earlier generation of studies.

Assessing dietary adherence in the Multiple Risk Factor Intervention Trial (MRFIT). I. Use of a dietary monitoring tool

Participants in the Multiple Risk Factor Intervention Trial (MRFIT) were taught not only how to modify the fat content of their diets but also how to assess their success in doing so. To simplify the process, a food scoring system was developed in which positive points are assigned to high-saturated-fat and high-cholesterol foods and negative points to foods and high-polyunsaturated-fat and low-cholesterol content. Using special forms supplied by MRFIT nutrition counselors, participants were able to self-monitor their dietary regimens. The method is described and forms are illustrated.