Non-soy legume consumption lowers cholesterol levels: A meta-analysis of randomized controlled trials

https://doi.org/10.1016/j.numecd.2009.08.012Get rights and content

Abstract

Background and Aims

Studies evaluating the effect of legume consumption on cholesterol have focused on soybeans, however non-soy legumes, such as a variety of beans, peas, and some seeds, are commonly consumed in Western countries. We conducted a meta-analysis of randomized controlled trials evaluating the effects of non-soy legume consumption on blood lipids.

Methods and Results

Studies were retrieved by searching MEDLINE (from January 1966 through July 2009), EMBASE (from January 1980 to July 2009), and the Cochrane Collaboration's Central Register of Controlled Clinical Trials using the following terms as medical subject headings and keywords: fabaceae not soybeans not isoflavones and diet or dietary fiber and cholesterol or hypercholesterolemia or triglycerides or cardiovascular diseases. Bibliographies of all retrieved articles were also searched. From 140 relevant reports, 10 randomized clinical trials were selected which compared a non-soy legume diet to control, had a minimum duration of 3 weeks, and reported blood lipid changes during intervention and control. Data on sample size, participant characteristics, study design, intervention methods, duration, and treatment results were independently abstracted by 2 investigators using a standardized protocol. Data from 10 trials representing 268 participants were examined using a random-effects model. Pooled mean net change in total cholesterol for those treated with a legume diet compared to control was −11.8 mg/dL (95% confidence interval [CI], −16.1 to −7.5); mean net change in low-density lipoprotein cholesterol was −8.0 mg/dL (95% CI, −11.4 to −4.6).

Conclusion

These results indicate that a diet rich in legumes other than soy decreases total and LDL cholesterol.

Introduction

Worldwide, cardiovascular diseases (CVD) are estimated to be the leading cause of death and loss of healthy life years resulting from disability [1]. In the United States, CVD causes 1 of every 3 deaths [2]. Recent data show that 71.3 million people in the United States have two or more risk factors for heart disease [2]. Studies have consistently shown that risk factor modification can decrease the prevalence of cardiovascular diseases, such as coronary heart disease and strokes [3], [4], [5], [6]. Diet is an important modifiable risk factor for many types of heart disease [7], [8].

Observational epidemiologic studies have strongly indicated an inverse relationship between fruit and vegetable consumption and the incidence of cardiovascular events [7], [9]. So much so that not consuming fruits and vegetables daily may be responsible for up to 13.7% of acute myocardial infarcts in one estimate[10]. Several studies have also shown that persons who consume diets high in whole grains and fiber have lower blood pressure and total cholesterol levels [11], [12]. The Dietary Guidelines for Americans suggest consuming 3 cups of legumes, which are rich in soluble dietary fiber and vegetable protein, per week; however less than a third of the population meets this guideline [13], [14]. Legume consumption has been associated with lower risks of coronary heart disease in observational epidemiologic studies [15], [16] and has been shown to decrease total cholesterol and low-density lipoprotein cholesterol in clinical trials [17], [18]. However, the majority of studies that have evaluated the hypocholesterolemic effects of legume consumption examined soybeans specifically rather than the many non-soy legumes, which are more commonly consumed in the Western hemisphere [19]. Non-soy legumes include a variety of beans such as navy, pinto, kidney, garbanzo and lima beans and peas such as split green peas or lentils. Randomized controlled trials that have examined the potential hypocholesterolemic effects of a diet rich in non-soy legumes have differed in their findings [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], with some finding no effect [22], [24], [31], while other identified a significant cholesterol lowering effect [20], [21], [27]. We conducted a meta-analysis of randomized controlled trials to quantify the direction and magnitude of the potential effect that consumption of non-soy legumes may have on serum cholesterol concentrations.

Section snippets

Study selection

We searched the online databases MEDLINE (from January 1966 through July 2009) using the following terms as medical subject headings and keywords: fabaceae not soybeans not isoflavones and diet or dietary fiber and cholesterol or hypercholesterolemia or triglycerides or cardiovascular diseases. An EMBASE database search (from January 1980 to July 2009) was also performed using the database-specific medical subject headings and keywords: legume or bean not soybean not isoflavone and dietary fiber

Results

Fig. 1 depicts the flow of study selection for the analysis. Of the 140 potentially relevant references identified, 117 were excluded following review of abstract and title. A total of 23 full-text articles were retrieved and reviewed for inclusion. We further excluded 8 articles due to multiple publications from an individual trial, 1 study was shorter than 3 weeks in duration, 1 was excluded due to lack of control diet, 2 articles were excluded because they reported insufficient information

Discussion

CVD remains the leading cause of death in the US and other Western countries despite advances in care [1]. Therefore, modification of risk factors is an essential part of any strategy to decrease the number of CVD events and deaths. Our results indicate that non-soy legume consumption has a significant beneficial effect on serum cholesterol levels, one of the most important risk factors for CVD. Both total and LDL cholesterol decreased, while HDL cholesterol did not change significantly, when

Acknowledgements

The sponsor had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript. Dr. Bazzano had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Dr. Tees and Dr. Nguyen assisted in the abstraction of data and writing of the manuscript. Ms. Thompson contributed to the analysis of the data and editorial

References (43)

  • R. DerSimonian et al.

    Meta-analysis in clinical trials

    Control Clin Trials

    (1986)
  • D. Moher et al.

    Improving the quality of reports of meta-analyses of randomised controlled trials: the QUOROM statement

    Lancet

    (1999)
  • M. Galisteo et al.

    Effects of dietary fibers on disturbances clustered in the metabolic syndrome

    J Nutr Biochem

    (2008)
  • T. Thom et al.

    Heart disease and stroke statistics – 2006 update: a report from the American heart association statistics committee and stroke statistics subcommittee

    Circulation

    (2006)
  • Executive summary of the Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on detection, evaluation, and treatment of high blood cholesterol in adults (Adult Treatment Panel III)

    J Am Med Assoc

    (2001)
  • J. Stamler et al.

    Relationship of baseline serum cholesterol levels in 3 large cohorts of younger men to long-term coronary, cardiovascular, and all-cause mortality and to longevity

    J Am Med Assoc

    (2000)
  • P. Schnohr et al.

    Long-term physical activity in leisure time and mortality from coronary heart disease, stroke, respiratory diseases, and cancer. The Copenhagen city heart study

    Eur J Cardiov Prev R

    (2006)
  • S. Giampaoli et al.

    Favorable cardiovascular risk profile (low risk) and 10-year stroke incidence in women and men: findings from 12 Italian population samples

    Am J Epidemiol

    (2006)
  • A.H. Lichtenstein et al.

    Diet and lifestyle recommendations revision 2006: a scientific statement from the American Heart Association Nutrition Committee

    Circulation

    (2006)
  • L. Palmieri et al.

    Favorable cardiovascular risk profile and 10-year coronary heart disease incidence in women and men: results from the progetto cuore

    Eur J Cardiov Prev R

    (2006)
  • Cited by (235)

    • Nutraceuticals and Functional Foods for Cholesterol Reduction

      2023, Clinical Lipidology: A Companion to Braunwald's Heart Disease
    View all citing articles on Scopus
    View full text