Eating beans once a day lowers LDL cholesterol by 3% to 5%, according to a review of research findings. The reduction is modest, so beans should be used as a dietary supplement to treatment rather than a replacement for medication, experts said.
Lee Ji-hyun, head of the nutrition team at Ajou University Hospital, outlined this approach to bean consumption for cholesterol management, medical sources said on the 14th. Lee said multiple meta-analyses and randomized controlled trials have consistently shown that legumes lower LDL cholesterol, with larger reductions among people whose baseline levels are higher. High cholesterol narrows blood vessels and reduces their elasticity, raising the risk of heart attack and stroke.
The number of people in South Korea with high cholesterol has risen sharply. According to the 2026 Dyslipidemia Fact Sheet released in September by the Korean Society of Lipid and Atherosclerosis, the prevalence rate climbed more than 2.5-fold, from 11.9% in 2010 to 30.3% in 2024. Over the same period, the treatment rate improved to 64.8% from 35.8% and the control rate to 58.9% from 28.6%, but roughly four in 10 patients still have not brought their levels into the appropriate range.
The size of the effect varies by study. A meta-analysis reported in 2019 found that consuming 25 grams of soy protein a day reduced LDL cholesterol by an average of 4.76 mg/dL, or 3% to 4%. For non-soy legumes such as lentils, chickpeas and kidney beans, a 2014 analysis by researchers at the University of Toronto in Canada — covering 26 randomized controlled trials with 1,037 participants — found a reduction of 0.17 mmol/L at a median intake of 130 grams a day. Converted to mg/dL, that is about 6.6 mg/dL, or roughly 5% of the baseline level.
The evidence is not conclusive. Among the studies reviewed by Health Canada that reported LDL cholesterol results, 81% showed a reduction, but only 33% showed a statistically significant decrease. The agency said the dose-response relationship was not clear and set 25 grams a day as the minimum effective intake.
The U.S. Food and Drug Administration, which approved a heart-disease risk reduction claim for soy protein in 1999, proposed revoking it on Oct. 30, 2017, citing inconsistent research findings. The related final rule has been on the federal regulatory agenda since the fall of 2024. The authors of the CMAJ analysis also said most of the trials were of low quality and that further verification is needed.
Lee explained the mechanism as follows. Dietary fiber in beans, such as beta-glucan and pectin, blocks the reabsorption of bile acids in the intestine. As the liver draws on cholesterol in the blood to replenish the depleted bile acids, levels fall. Plant proteins including glycinin and beta-conglycinin increase the activity of LDL receptors in liver cells, while plant sterols reduce the amount of cholesterol absorbed in the intestine. Evidence for saponins promoting excretion is limited.
Beans should be eaten five to seven times a week, and daily if possible. Lee said there is insufficient clear evidence of a decline in cholesterol levels from eating beans only once or twice a week. The reference amounts are 25 grams of soy protein and 130 grams of non-soy legumes. The first figure refers to protein content and the second to food weight, so consumers should check product nutrition labels. A mix of soybeans, black beans, lentils, chickpeas, kidney beans and peas is recommended. Soybeans have the most evidence for lowering LDL, while black beans contain anthocyanins in their skins.
For preparation, boiling without oil or adding beans to soups and stews is preferable. Soy beans simmered in soy sauce, sweetened soy milk, fried tofu pouches and deep-fried tofu offer less benefit because they are high in sodium, sugar and fat. Among processed foods, tofu, unsweetened soy milk and tempeh are suitable. Doenjang (fermented soybean paste), cheonggukjang (fast-fermented soybean paste) and soy sauce lack direct evidence of improving LDL levels and are high in sodium.
The galacto-oligosaccharides in beans can cause bloating. Symptoms may worsen in people who consume little dietary fiber or who have irritable bowel syndrome. One suggested approach is to spread intake across three meals a day — through soy milk, tofu side dishes and rice cooked with beans — for three to four weeks, check the response, and then increase the amount over two to three weeks. Beans should be soaked thoroughly before boiling, and cutting back on red meat, processed meat and saturated fat while adding whole grains, vegetables and nuts helps improve cholesterol levels.