Pulses and Heart Disease

It's a fact... beans and peas are good for your heart!

Nancy Longnecker, Centre for Learning Technology, The University of Western Australia

There is substantial evidence that eating more pulses (chickpeas, beans, lentils, peas and soybeans) can reduce the risk of coronary heart disease. The risk of cardiovascular disease is lower when people eat foods that result in a lower blood cholesterol level.1,2 Diets with less saturated fat are particularly effective in reducing blood cholesterol levels.3,4

Eating pulses more often can reduce blood cholesterol

Pulses are cholesterol free and are low in fat (except soyabean and peanut). And the fats in pulses tend to be 'good' fats; the majority of pulse fatty acids are unsaturated, containing both monounsaturated and essential polyunsaturated fatty acids. With their high levels of fibre, low levels of fat, no cholesterol but some phytosterols, it is not surprising that increasing pulse consumption can reduce blood cholesterol.5-11

Cholesterol and phytochemicals

Cholesterol is a member of the lipid or fat family of compounds. In addition to the cholesterol we eat, our bodies produce cholesterol. It is an essential component of cell membranes and we need it to produce many important hormones (eg oestrogens, testosterone, cortisol). Cholesterol is transported in our bodies by lipoproteins and its behaviour in our bloodstream depends on whether it is being transported by high density lipoprotein (HDL) or low density lipoprotein (LDL). The rule of thumb is that more HDL is good and more LDL is bad as it is cholesterol transported by LDL's that tends to clog up arteries, increasing the risk of cardiovascular disease.

Phytosterols are compounds found in plant foods that have a similar structure to cholesterol. Because their structure is similar, phytosterols can compete with food-based cholesterol and block absorption of cholesterol into the bloodstream. Phytosterols reduced LDL cholesterol by 24% when taken as part of a diet low in saturated fat and cholesterol.12

Large amounts of phytosterols in foods have to be eaten in order for phytosterols to have significant cholesterol-lowering activity. However pulses that are high protein as well as having phytosterols are a vegetable that can substitute for meat in our diets. Eating more pulses in this way can increase phytosterol intake while decreasing cholesterol intake.

Over 50 clinical studies have shown that soy protein decreases blood cholesterol in men, women and children.13 In the USA, the Food and Drug Administration (FDA) has approved the use of a food claim that soy protein reduces the risk of heart disease. It appears that phytoestrogens found in soybeans account for a substantial amount of the cholesterol-lowering effect of soybean. The FDA states that to lower high cholesterol, 25 g soy protein should be consumed each day in conjunction with a diet low in saturated fat and cholesterol.

What level of reduction can be reached?

Reductions in blood cholesterol levels of 10% or more are commonly achieved within two to three weeks on test diets containing either canned beans (69 - 150 g/day) or dry pulses (75 - 200 g/ day).5 The implications of a reduction of this size are significant because a 1% decrease in blood cholesterol can result in a 2% decrease in the risk of coronary heart disease.

Eating pulses can decrease blood cholesterol in healthy people. However the decrease in blood cholesterol has been more pronounced in people whose initial cholesterol levels were highest 5 and are thus at greatest risk of coronary heart disease.3

Eating pulses more often can reduce risk of heart disease

In a large study of almost 10,000 men and women in the USA, those who ate pulses four or more times a week had a 22% lower risk of coronary heart disease and 11% lower risk of cardiovascular events than those who ate pulses less than once a week.14 It appears that this health benefit was independent of other health habits since adjustments of other important confounders of cardiovascular disease resulted in minimal change in the risk estimates.

It is easy to eat pulses four or more times a week once you know how. Find tips for easy incorporation of pulses into your diet.

References

  1. Mann JI. 1987. Clinical trials of cholesterol lowering. Lips Review 1: 26- 34.
  2. Truswell AS. 1994. Review of dietary intervention studies: effect on coronary events and on total mortality. Aust NZ J Med. 24: 98- 106.
  3. Keys A. 1980, Seven countries: a multivariate analysis of death and coronary heart disease. Harvard University Press (Cambridge, MA): pp. 121- 135.
  4. Kris-Etherton PM, Pearson TA, Ying Wan, Hargrove RL, Moriarty K, Fishell V, Etherton TD. 1999. High-monounsaturated fatty acids lower both plasma cholesterol and triacylglycerol concentrations. Am J Clin Nutr. 70: 1009- 1015.
  5. Geil PB, Anderson JW. 1994. Nutrition and health implications of dry beans: a review. J Am Coll Nutr. 13(6): 549- L, Smith BM, Whitis SE. 1990. Dietary fiber and coronary heart disease. Crit Rev Food Sci Nutr 29: 95- 147.
  6. Mathur KS, Khan MA, Sharma RD. 1968. Hypocholesterolaemic effect of Bengal gram: a long-term study in man. Brit Med J 6: 30- 31.
  7. Anderson JW, Gustafson NJ.1988. Hypocholesterolemic effect of oat and bean products. Am J Clin Nutr. 48: 749- 753.
  8. Shutler SM, Bircher GM, Tredger JA, Morgan LM, Walker AF, Low AG. 1989. The effect of daily baked bean (Phaseolus vulgaris) consumption on the plasma lipid levels of young, normo-cholesterolaemic men. Brit J Nutr 61: 257- 265.
  9. Simpson HCR, Lousley S, Geekie M, Simpson RW, Carter RD, Hockaday TDR, Mann JI. 1981. A high carbohydrate leguminous fibre diet improves all aspects of diabetic control. Lancet i: 1-5.
  10. Anderson JW, Deakins DA, Floore TL, Smith BM Whitis SE. 1990. Dietary fiber and coronary heart disease. Crit Rev Food Sci Nutr 29: 95- 147.
  11. Anderson JW, Gustafson NJ, Spencer DB, Tietyen J, Bryant CA. 1990. Serum lipid response of hypercholesterolemic men to single and divided doses of canned beans. Am J Clin Nutr 51: 1013- 1019.
  12. Nestel P, Cehun M, Pomeroy S, Abbey M, Duo Li and Weldon G. 2001. Cholesterol-lowering effects of sterol esters and non-esterified sitostanol in margarine, butter and low-fat foods Eur J Cardio Nurs 55:1084-1090.
  13. Anderston JW, Johnstone BM and Cook-Newell ME. 1995. Meta-analysis of the effects of soy protein intake on serum lipids. N Eng J Med 333: 276-282.
  14. Bazzano LA, He J, Ogden LG, Loria C, Vupputuri S, Myers L, Whelton PK. 2001. Legume consumption and risk of coronary heart disease in US men and women. Arch Intern Med. 161: 2573- 2578.