Barnardm N., Scialli, A., Turner-McGrievy, G., & Lanou, A. (2004). Acceptability of a low-fat vegan diet compares favourably to a step II diet in a randomized, controlled trial. Journal of Cardiopulmonary Rehabilitation, Vol. 24 (4): 229-235.
Research Purpose
The purpose of the research study was to assess the acceptability, perceived benefits, and the adverse effects of a low-fat vegan diet among menopausal women.
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Review of Literature/Background
The authors provided a “word picture” to guide their study. They stated they will recruit overweight and postmenopausal women and randomly assigned the volunteers to a low-fat vegan diet for 14 weeks. The authors then assessed the volunteers at baseline and again four weeks later. The literature studies reviewed by the authors is relevant to the study's purpose. This is because the literature materials used situates the authors' research focus within the context of the research purpose. More to this is that it identifies a gap within the literature that the authors attempt to address in their study. More specifically, the authors found that prior studies did not address the acceptability of a low-fat vegan diet among overweight or postmenopausal women.
The literature review was logically and clearly organized. However, authors did not review current literature. All the sources reviewed in the study were published more than 5 years ago. Also, the authors used secondary sources only –they used journal articles only.
Research Design and Methods
Prior to the study, the authors sought approval from the Georgetown University Institutional Review Board. More to this is that all the participants gave informed consent. The study was descriptive because the authors used descriptive statistics in their research design. The participants were selected through random sampling. The study was conducted in two replications –the first study was composed of 30 participants, while the second study was composed of 34 participants.
The sampling method used was appropriate. This is because the method used –random sampling –reduces selection bias, given that each member of the population has the characteristic of interest (overweight and postmenopausal women). So, each member had an equal chance of being selected. However, the sample size used was not appropriate because a small sample was used. The sample size is crucial in finding a statistically significant result. For this reason, it appropriate to use a larger sample as it provides more reliable results.
The participants in the study were overweight and obese postmenopausal women with body mass index ranging between 26 and 44 kg/m 2 . The study excluded premenopausal women. The study was conducted in the Washington DC metropolitan area. The study assessed the acceptability, perceived benefits, and the adverse effects of a low-fat vegan diet among menopausal women and overweight and obese adults. The independent variable is overweight and menopausal women, while the dependent variable is the vegan diet given to the volunteers, as compared with a more typical fat-modified diet.
Data Collection, Measurement, and Analysis
For comparison purposes, data for the typical fat-modified diet was retrieved from the National Cholesterol Education Program Step II (NCEP) diet. With regard to the low-fat diet, a food scale and digital weight scales were used to collect data. Different measures were taken at baseline and after 14 weeks. A food scale was used to complete a 3-day dietary record on 2 weekdays and 1 weekend. Rather than food frequency questionnaires, a 3-day dietary record was used because of its reliability and accuracy in estimating macronutrient intake. Nutritionist V (version 2.0) was used to analyze the records.
A digital scale was used to measure the bodyweight of the volunteers. The weights were determined before breakfast. The participants were requested to wear undergarments during the weighing process. The authors also used the Eating Inventory to measure three characteristics –dietary restraint, disinhibition factor, and hunger factor.
The Food Acceptability Questionnaire was used to collect data pertaining to how well the participants like the food, how easy or difficult it has been for them to prepare the foods, the effort they required to stay on a diet, and if they are willing to continue with the diet. The vegan group was asked to compare the vegetarian diet with the unrestricted diet, to rate the acceptability of the vegetarian diet, and if they could stick with the diet. More to this, the questionnaire collected data pertaining to perceived effects or adverse effects during the preceding 2 weeks. Nutritionist V and different statistical tools were used to analyze the data collected.
Findings/Results and Conclusions
The findings of the study was organized logically and presented clearly. The authors found that the dietary restraint increased in the group that received the NCEP diet (P<0.001). This finding shows a greater subjective sense of constraint pertaining to diet requirements. However, the dietary restraint in the vegan group was unchanged. With regard to the data collected using the Eating Inventory, the disinhibition and hunger scores fell in both the NCEP diet group and the vegan group (P<0.001 and p<0.01, respectively). The participants of the study rate the acceptability of both diets high. The vegan group rated the vegan diet as easy prepare (P<0.5), while the NCEP group rated the NCEP diet to be more difficult to continue as when compared to their baseline diet (P<0.5).
The authors concluded the acceptability of a low-fat vegan diet to be high in postmenopausal women. The conclusions are consistent with the results as well as in relation to the conceptual framework. However, the researchers did not place the report in the context of what is already known about the research question. This is because there are prior studies that have addressed the issue. The study did not include males or an untreated control population and, therefore, cannot be used in other settings. The study suggested future research studies to address the approaches presented in their research by considering populations with growing problems of obesity and metabolic syndrome.
Professional Context
The authors did not clearly outline the implications for practice. One of the findings in this article that I will use in my practice is the authors' finding that acceptability of a low-fat vegan diet to be high in postmenopausal women. This will help me prescribe a diet to overweight and postmenopausal women in order to help them live healthy lifestyles.
What is the level of evidence shown for this study?
The level of evidence for this study is 2 –one or more randomized controlled trials.
References
Barnardm N., Scialli, A., Turner-McGrievy, G., & Lanou, A. (2004). Acceptability of a low-fat vegan diet compares favorably to a Step II diet in a randomized, controlled trial. Journal of Cardiopulmonary Rehabilitation, Vol. 24 (4): 229-235.
