Lentils: The Elite Legume
By William Gamonski
Lentils (Lens culinaris) are indigenous to central Asia and one of the oldest cultivated legumes or pulses. Historians have found archeological evidence of lentil seeds in the Middle East dating back 8,000 years. Lentil seeds spread throughout Europe and Africa before being introduced to India, where they are frequently used in traditional cuisine. Lentils are available in a variety of colors including black, red, green, and brown, with the latter two the most common.1
With their abundance of phytochemicals, vitamins, minerals, and dietary fiber, it’s hardly surprising that numerous studies have reported a strong connection between greater intakes of lentils and a lowered risk of various cancers. In a study published in the International Journal of Cancer, researchers assessed the relationship between dietary flavonol intake and breast cancer risk in more than 90,000 premenopausal women, between the ages of 26 and 46, over an 8-year period.2 Consuming at least two servings of lentils per week was associated with a 24% reduced risk of breast cancer compared with those who ate lentils less than once a month.
In a separate study, Norwegian scientists analyzed legume intake in 3,539 cancer cases and 2,032 controls. They uncovered an association between lentil consumption and cancers of the upper digestive tract. Higher intakes of lentils decreased the risk of mouth/throat, esophagus, and larynx cancers by 51, 48, and 37%, respectively.3
Other research shows that people who consumed more than two servings of lentils per week cut their risk of colon cancer by 47%.4 In the laboratory, scientists fed rats different types of lentils for five weeks before inducing them with the carcinogen azoxymethane, which leads to the formation of lesions known as aberrant crypt foci that precede colon cancer. Compared with the control group, the supplementation of raw split lentils and cooked whole lentils reduced the number of aberrant crypt foci by 36 and 42% respectively.5 Although the mechanisms are not yet clear, it may be related to lentils’ high content of resistant starch.6
During a 6-year study of 14,000 men, researchers found that individuals who ate three or more servings of lentils per week had a 52% lower risk of prostate cancer, according to research published in the journal Cancer.7
Combating Metabolic Syndrome
Up to 34% of Americans have metabolic syndrome, a collection of metabolic abnormalities that increase the risk for heart disease and type II diabetes.8 Metabolic syndrome is defined as having at least three of the following components: central obesity (increased waist circumference); raised blood pressure; insulin resistance; elevated triglycerides; and lowered HDL cholesterol levels.9 Epidemiological evidence published in the Archives of Iranian Medicine indicates an association between the consumption of legumes like lentils and metabolic syndrome, as people with the highest intakes were 75% less likely to develop the condition.10
This positive observational finding is supported by several compelling clinical studies showing that a diet rich in lentils can effectively combat the individual components that contribute to metabolic syndrome. For instance, English researchers found that overweight and obese people consuming two servings of pulses, such as lentils, per day for 18 months reduced their waistlines by 1.5 inches, compared to 0.78 inches in the control group.11 In another study reported in the European Journal of Nutrition, four servings of lentils or other legumes per week as part of a reduced calorie diet for 8 weeks lowered obese subjects’ mean systolic blood pressure reading (top number) by 9 mmHg versus 4 mmHg in the controls.12
To determine the effects of a pulse-dense diet on metabolic syndrome risk factors, scientists at the University of Toronto randomly assigned 40 overweight and obese adults to an ad libitum diet with five cups of pulses per week that included lentils, or a reduced calorie diet with dietary counseling. After 8 weeks, both groups exhibited improvements in several parameters of metabolic syndrome including insulin resistance and fasting glucose levels. However, the pulse group also increased HDL cholesterol by 4.5%, compared with a decrease of 0.8% in the control group.13
In addition to decreasing the risk for metabolic syndrome, lentils show promise for improving blood glucose control in diabetics. In animal research published in the Malaysian Journal of Nutrition, diabetic rats fed cooked lentils daily for 6 weeks had lower blood glucose levels compared to a control group of rats.14
This favorable effect on blood sugar levels was also noted in a recent human study.15 Researchers enrolled 121 type II diabetics and randomly selected them for a low-glycemic index diet with at least one cup of legumes daily or whole wheat products rich in insoluble fiber for 3 months. Hemoglobin A1c (HbA1c) levels, an indicator of blood glucose control over the last approximately three months, along with heart disease risk were the main outcomes studied. The findings revealed that the legume group lowered HbA1c levels by 0.5%, compared to 0.3% in the wheat group. 15 Furthermore, the legume group decreased their risk of cardiovascular disease by 0.8%, which was largely attributed to a reduction in systolic blood pressure by an average 4.5 mmHg.15
The ingestion of lentils in place of saturated fat, omega-6 fat, and high-glycemic carbohydrate foods can help ward off diabetes, cancer, and the deadly metabolic syndrome.
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- Available at: http://www.whfoods.com/genpage.php?tname=foodspice&dbid=52. Accessed November 1, 2012
- Adebamowo CA, Cho E, Sampson L, et al. Dietary flavonols and flavonol-rich foods intake and the risk of breast cancer. Int J Cancer. 2005;114:628-33.
- Aune D, De Stefani E, Ronco A, et al. Legume intake and risk of cancer: a multisite case-control study in Uruguay. Cancer Causes Control. 2009 Nov;20(9):1605-15.
- Singh PN, Fraser GE. Dietary risk factors for colon cancer in a low-risk population. Am J Epidemiol. 1998;148(8):761-74.
- Faris MA, Takruri HR, Shomaf MS, Bustanji YK. Chemopreventive effect of raw and cooked lentils (Lens culinaris L) and soybeans ( Glycine max) against azoymethane induced aberrant crypt foci. Nutr Res. 2009 May;29(5):355-62.
- Liu R, Xu G. Effects of resistant starch on colonic preneoplastic aberrant crypt foci in rats. Food Chem Toxico. 2008;46:2672-9.
- Mills PK, Beeson WL, Phillips RL, Fraser GE. Cohort study of diet, lifestyle, and prostate cancer in Adventist men. Cancer. 1989;64:598-604.
- Mozumdar A, Liguori G. Persistent increase of prevalence of metabolic syndrome among US adults: NHANES III to NHANES 1999-2006. Diabetes Care. 2011 Jan;34(1):216-9.
- Grundy SM, Brewer HB Jr, Cleeman JI, et al. Definition of metabolic syndrome: Report of the National Heart, Lung, and Blood Institute/American Heart Association conference on scientific issues related to definition. Circulation. 2004 Jan 27;109(3):433-8.
- Hosseinpour-Niazi S, Mirmiran P, Amiri Z, Hosseini-Esfahani F, Shakeri N, Azizi F. Legume intake is inversely associated with metabolic syndrome in adults. Arch Iran Med. 2012 Sep;15(9):538-44.
- Venn BJ, Perry T, Green TJ, et al. The effect of increasing consumption of pulses and wholegrains in obese people: a randomized controlled trial. J Am Coll Nutr. 2010 Aug;29(4):365-72.
- Hermsdorff HM, Zulet MA, Abete I, Martinez JA. A legume-based hypocaloric diet reduced proinflammatory status and improves metabolic features in overweight/obese subjects. Eur J Nutr. 2011;50:61-9.
- Mollard RC, Luhovyy BL, Panahi S, Nunez M, Hanley A, Anderson GH. Regular consumption of pulses for 8 weeks reduces metabolic syndrome risk factors in overweight and obese adults. Br J Nutr. 2012 Aug;108:S111-22.
- Al-Tibi AM Jr, Takruri HR, Ahmad MN. Effect of dehulling and cooking of lentils (Lens Culinaris) on serum glucose and lipoprotein levels in streptozotocin-induced diabetic rats. Malays J Nutr. 2010 Dec;16(3):409-18.
- Jenkins DJ, Kendall CW, Augustin LS, et al. Effect of legumes as part of a low glycemic index diet on glycemic control and cardiovascular risk factors in type 2 diabetes mellitus: a randomized controlled trial. Arch Intern Med. 2012 Oct:1-8.
- Available at: http://nutritiondata.self.com/facts/legumes-and-legume-products/4338/2. Accessed November 2, 2012.
- Available at: http://allrecipes.com/recipe/lentil-soup/. Accessed November 2, 2012.