Latest Research
The page features the latest research in dry beans and human health. For other recent studies, please visit our archives.
Bean Consumption and Visceral Fat Accumulation
Hairston KG, Vitolins MZ, Norris JM, Anderson AM, Hanley AJ, Wagenknecht LE. Lifestyle Factors and 5-Year Abdominal Fat Accumulation in a Minority Cohort: The IRAS Family Study. Obesity (Silver Spring). 2011.
The objective of this study was to examine whether lifestyle factors were associated with 5-year change in abdominal fat measured by computed tomography (CT) in the Insulin Resistance and Atherosclerosis (IRAS) Family Study. We obtained abdominal CT scans at baseline and at 5 years, from African Americans (AA) (N = 339) and Hispanic Americans (N = 775), aged 18-81 years. Visceral (VAT) and subcutaneous (SAT) adipose tissue was measured at the L4/L5 vertebral level. Physical activity was documented by self-report of vigorous activity and a 1-year recall instrument. Dietary intake was assessed at follow-up using a semi-quantitative food frequency questionnaire referencing the previous year. Generalized linear models, accounting for family structure, were used to assess the associations between percent change in fat accumulation and smoking, physical activity, total calories, polyunsaturated, monounsaturated, protein, and saturated fat intake, percent of calories from sweets, and soluble and insoluble fiber. Soluble fiber intake and participation in vigorous activity were inversely related to change in VAT, independent of change in BMI. For each 10 g increase in soluble fiber, rate of VAT accumulation decreased by 3.7% (P = 0.01). Soluble fiber was not associated with change in SAT (0.2%, P = 0.82). Moderately active participants had a 7.4% decrease in rate of VAT accumulation and a 3.6% decrease in rate of SAT accumulation versus less active participants (P = 0.003 and P = 0.01, respectively). Total energy expenditure was also inversely associated with accumulation of VAT. Soluble fiber intake and increased physical activity were related to decreased VAT accumulation over 5 years.
Conclusion: In this Hispanic and African American population, there was a statistically significant inverse relationship between the consumption of soluble fiber and visceral adipose tissue.
Bean Consumption and the Metabolic Syndrome
Hosseinpour-Niazi S, Mirmiran P, Sohrab G, Hosseini-Esfahani F, Azizi F. Inverse association between fruit, legume, and cereal fiber and the risk of metabolic syndrome: Tehran Lipid and Glucose Study. Diabetes Res Clin Pract. 2011.
AIMS: To evaluate the association between total dietary fiber and its types and sources with the risk of MetS. METHODS: This population-based cross-sectional study was conducted on a representative sample of 2457 adults (1327 male and 1130 female), aged 19-84 years. Dietary intake was assessed using a validated semiquantitative food-frequency questionnaire. Anthropometrics, blood pressure, and fasting blood glucose and lipids were measured according to standard protocols. The MetS was defined according to definition by Adult Treatment Panel III. RESULTS: Multivariate-adjusted odds ratio of MetS between highest and lowest quartiles was 0.53 (95% CI: 0.39-0.74; P for trend <0.05) for total dietary fiber, 0.60 (0.43-0.84; P for trend <0.05) for soluble fiber, and 0.51 (0.35-0.72; P for trend <0.05) for insoluble fiber. Among sources of dietary fiber, fruit fiber (OR: 0.51; 95% CI: 0.37-0.72), cereal fiber (0.74; 0.57-0.97), and legume fiber (0.73; 0.53-0.99) were inversely associated with the risk of MetS, after adjustment for confounding factors. Intake of vegetable fiber and nut fiber were unrelated to the risk of MetS. CONCLUSIONS: Total dietary fiber, soluble- and insoluble fiber, fruit fiber, cereal fiber and legume fiber were associated with a protective effect for the presence of MetS among this Tehranian population.
Conclusions: Among more than 2,000 male and female adults, the intake of total dietary fiber, total soluble fiber, and fiber from beans was inversely associated with risk of having the metabolic syndrome.
Bean Consumption and Cardiovascular Disease
Mattei J, Hu FB, Campos H. A higher ratio of beans to white rice is associated with lower cardiometabolic risk factors in Costa Rican adults. Am J Clin Nutr. 2011; 94: 869-76.
BACKGROUND: A high intake of white rice is associated with the metabolic syndrome and type 2 diabetes. Costa Ricans follow a staple dietary pattern that includes white rice and beans, yet the combined role of these foods on cardiometabolic risk factors has not been studied. OBJECTIVE: We aimed to determine the association between intake of white rice and beans and the metabolic syndrome and its components in Costa Rican adults (n = 1879) without diabetes. DESIGN: Multivariate-adjusted means were calculated for components of the metabolic syndrome by daily servings of white rice and beans (<1, 1, or >1) and by the ratio of beans to white rice. The OR for the metabolic syndrome was calculated by substituting one serving of beans for one serving of white rice. RESULTS: An increase in daily servings of white rice was positively associated with systolic blood pressure (BP), triglycerides, and fasting glucose and inversely associated with HDL cholesterol (P-trend <0.01 for all). An increase in servings of beans was inversely associated with diastolic BP (P = 0.049). Significant trends for higher HDL cholesterol and lower BP and triglycerides were observed for 1:3, 1:2, 1:1, and 2:1 ratios of beans to white rice. Substituting one serving of beans for one serving of white rice was associated with a 35% (95% CI: 15%, 50%) lower risk of the metabolic syndrome. CONCLUSION: Increasing the ratio of beans to white rice, or limiting the intake of white rice by substituting beans, may lower cardiometabolic risk factors.
Conclusions: Among this Costa Rican population, as the ratio of beans to rice increased HDL-cholesterol increased and diastolic blood pressure decreased.
For Dietitians and Consumers
Three New Studies Support the Benefits of Beans for Preventing the Metabolic Syndrome
One in every four Americans is affected by a group of risk factors called metabolic syndrome, which raises their risk for heart disease, stroke, and type 2 diabetes. The risk factors that contribute to metabolic syndrome are high blood pressure, elevated fasting blood glucose, large waist circumference, low levels of the good HDL-cholesterol, and high blood levels of triglycerides.
The accumulation of fat just beneath the abdominal muscles, called visceral adipose tissue, or VAT, is increasingly recognized as a risk factor for the metabolic syndrome. Even apparently lean people can have a significant accumulation of VAT, which increases their risk for cardiovascular disease and diabetes. And obese individuals who have relatively little VAT can actually have a low risk for these diseases.
Researchers with the Insulin Resistance and Atherosclerosis (IRAS) Family Study examined the effects of lifestyle factors on abdominal fat in 339 African Americans and 775 Hispanic Americans aged 18-81 years over a five-year period. (1). They assessed physical activity and dietary intake, and measured abdominal fat using CT scans. The results showed that the greater the intake of soluble fiber, found in beans, oats, barley, and citrus fruits, and the greater the physical active, the less abdominal fat people had regardless of their overall body weight. More specifically, for every 10 grams of soluble fiber consumed, the rate of VAT accumulation decreased by 3.7 percent. Those subjects who engaged in moderate physical activity had a 7.4 percent decrease in the rate of VAT accumulation. The researchers concluded that consuming more soluble fiber, and engaging in exercise could slow the accumulation of abdominal fat over time.
In a second study, Iranian researchers studied the relationship between dietary fiber and risk of metabolic syndrome in 2457 adults aged 19 to 84 years. (2) Subjects with the highest fiber intakes, which averaged 50 grams per day, were only half as likely to have the metabolic syndrome as those whose average fiber intake was 25 grams per day. However, only fiber from beans, fruit and grains was protective, not from vegetables or nuts
Costa Rican researchers looked specifically at the effect of bean intake, and the ratio of beans to rice in the diet, on risk of metabolic syndrome in 1879 adults. (3). Previous research has shown that a high intake of white rice is associated with the metabolic syndrome and type 2 diabetes. In this study, increased intake of white rice was associated with higher blood pressure, triglycerides, and fasting glucose and lower levels of protective HDL cholesterol. In contrast, increased bean consumption was associated with lower diastolic blood pressure. As the ratio of rice to beans increased, subjects were more likely to have lower HDL cholesterol and higher blood pressure and triglycerides. Substituting one serving of beans for one serving of white rice was associated with a 35% lower risk of the metabolic syndrome.
Taken together, these findings suggest that incorporating beans into diets can lower the risk for the metabolic syndrome and heart disease.