While the medicinal benefits of alfalfa are poorly understood, the constituents in alfalfa have been extensively studied. The leaves contain approximately 2–3% saponins.14 Animal studies suggest that these constituents block absorption of cholesterol and prevent the formation of atherosclerotic plaques.15 One small human trial found that 120 grams per day of heat-treated alfalfa seeds for eight weeks led to a modest reduction in cholesterol.16 However, consuming the large amounts of alfalfa seeds (80–120 grams per day) needed to supply high amounts of these saponins may potentially cause damage to red blood cells in the body.17 Herbalists also claim that alfalfa may be helpful for people with diabetes. But while high amounts of a water extract of the leaves led to increased insulin release in animal studies, there is no evidence that alfalfa would be useful for the treatment of diabetes in humans.18
Alfalfa leaves also contain flavones, isoflavones, sterols, and coumarin derivatives. The isoflavones are thought to be responsible for the estrogen-like effects seen in animal studies.19 Although this has not been confirmed with human trials, alfalfa is sometimes used to treat menopause symptoms.
Alfalfa contains protein and vitamin A, vitamin B1, vitamin B6, vitamin C, vitamin E, and vitamin K. Nutrient analysis demonstrates the presence of calcium, potassium, iron, and zinc.