Hypercholesterolemia, hyperglycemia, and menopausal symptoms (e.g., hot flashes, poor bone density).
Mechanism of Action
Some of the benefits on lipids and glucose metabolism are believed to occur via mechanisms involving hormonal effects.1 Medicago is a genus of plants in the legume family whose species are high in phytosterols and phytoestrogens, represented by naturally occurring steroid-like molecules such as isoflavones (genistein, daidzein) and coumestans (coumestrol), all of which have all been shown to have estrogen-modulating effects.2
Combined with the calcium, vitamin K,3 vitamins D2 and D3,4 and other nutrients and constituents that the plant naturally contains, Medicago may support bone density and help alleviate menopausal symptoms5 in part because of its phytoestrogenic activity. Genistein has been shown to stimulate bone formation, inhibit bone resorption, and prevent bone loss in ovariectomized rat models.6 Genistein at 54 mg/day for 1 or 2 years has also been demonstrated in a few randomized, double-blind, placebo-controlled studies to be effective in preventing bone loss in postmenopausal women.7
Postmenopause, lipids and blood sugar may elevate and bone density may diminish; therefore, Medicago may offer some protective effects.
One study tested the efficacy of a combination of sage (Salvia officinalis) and Medicago sativa (also known as lucerne or alfalfa) in the treatment of hot flashes and night sweats in 30 menopausal women. It is generally accepted that hot flashes reflect adaptation of the body to estrogen deprivation that affects various central neurotransmitters. Hot flashes and night sweats disappeared in 20 women,
4 women showed good improvement, and the other 6 showed a reduction in symptoms. The authors concluded this herbal combination seemed to have a central, slight antidopaminergic action without side effects, and it was considered an effective agent in the treatment of menopausal symptoms.8 No clinical trials for menopause by using Medicago alone have been reported.
Animal studies have suggested Medicago to be effective in the treatment of hyperlipidemia5,9,10,11 and hyperglycemia; however, more rigorous human studies are required. Saponins found within Medicago are a complex mixture of triterpene glycosides that show a broad spectrum of biological properties. In one study, hyperlipidemic rats given Medicago extract over 7 weeks showed significant improvements in serum lipid levels and total cholesterol, suggesting a possible mechanism with enzymes involved in cholesterol biosynthesis, uptake, and excretion pathways.12
Another animal model using an aqueous Medicago extract in diabetic mice demonstrated stimulation of insulin secretion from pancreatic B-cell lines. Sequential extraction with solvents revealed insulin-releasing activity in both methanol and water fractions, indicating a cumulative effect of more than one extract constituent. The authors concluded the presence of antihyperglycemic, insulin-releasing, and insulin-like activity to be confirmed in Medicago.13
Safety in Pregnancy and Breastfeeding
No human studies or animal studies on Medicago in pregnancy or lactation have been conducted; however, based on the nutritive, food-like nature of the plant, most herbalists consider Medicago to be safe during pregnancy. Farmers do not restrict livestock from feeding on Medicago during pregnancy or lactation; in fact, Medicago is often increased in the feed of pregnant mares as it is more nutritious than grass hay and believed to benefit livestock. One study found that Medicago feed increased milk yield, lowered fat, and increased milk protein in dairy cows.14
Moderate consumption of Medicago leaves in teas and capsules is generally considered safe and without significant side effects. Aggravation of lupus, or promotion of lupus-like symptoms have been reported from the ingestion of large amounts of Medicago seeds and sprouts, an action blamed on the amino acid canavanine.15 Medicago leaves are used by herbalists in teas, tinctures, and encapsulated supplements, and they contain only trace amounts of canavanine. One study found Medicago tablets to contain on average 25.0–33.0 µg of canavanine per tablet.16
Medicago is generally considered safe at doses of 300 mg and up to 1500 mg/day. Traditionally, several grams of powdered Medicago, and even up to 10 g/day of dried leaf powder, have been used.
Medicago sativa (also known as lucerne or alfalfa) is a well-known nutritious herb with a long history of use as a livestock feed, a medicinal herb and food, and more recently, a dietary supplement.
Being a food-like and nutritious plant, the traditional uses for Medicago are extensive, being used to promote diuresis in kidney diseases, improve strength and fertility in livestock, treat diabetes and long-term consequences such as elevated lipids and obesity, and improve chronic inflammatory disorders from allergies to asthma to arthritis. Medicago has also been used in foods, beverages, medicinal drinks, and nutrient blends because of its high content of many important nutrients.
Toxicol Appl Pharmacol. 2014;280(3):455–66. Genistein modulation of streptozotocin diabetes in male B6C3F1 mice can be induced by diet. Guo TL, Wang Y, Xiong T, Ling X, Zheng J.
2 Steroids. 2014;80:37–43. 3D models of human ERα and ERβ complexed with coumestrol. Chandsawangbhuwana C, Baker ME.
3 Methods Mol Biol. 2010;663:229–40. Antithrombotic effects of naturally derived products on coagulation and platelet function. Mousa SA.
4 Arch Biochem Biophys. 1984;231(1):67–71. The isolation and identification of vitamin D2 and vitamin D3 from Medicago sativa (alfalfa plant). Horst RL, Reinhardt TA, Russell JR, Napoli JL.
5 Pharm Biol. 2011;49(2):211–20. Phytochemical and pharmacological potential of Medicago sativa: a review. Bora KS, Sharma A.
6 Nutr Rev. 2009;67:398–415. The effect of genistein aglycone on cancer and cancer risk: a review of in vitro, preclinical, and clinical studies. Taylor CK, Levy RM, Elliott JC, Burnett BP.
7 J Bone Miner Res. 2002;17:1904–12. Effects of genistein and hormone-replacement therapy on bone loss in early postmenopausal women: a randomized double-blind placebo-controlled study. Morabito N, Crisafulli A, Vergara C, Gaudio A, Lasco A, Frisina N, D’Anna R, Corrado F, Pizzoleo MA, Cincotta M, et al.
8 Minerva Ginecol. 1998;50(5):207–11. Treatment of neurovegetative menopausal symptoms with a phytotherapeutic agent. De Leo V, Lanzetta D, Cazzavacca R, Morgante G.
9 Atherosclerosis. 1978;30(1):27–43. Effect of alfalfa meal on shrinkage (regression) of atherosclerotic plaques during cholesterol feeding in monkeys. Malinow MR, McLaughlin P, Naito HK, Lewis LA, McNulty WP.
10 Pak J Pharm Sci. 2008;21(4):460–4. Effects of alfalfa on lipoproteins and fatty streak formation in hypercholesterolemic rabbits. Asgary S, Moshtaghian J, Hosseini M, Siadat H.
11 J Med Food. 2013;16(3):185–98. Nutritional quality of legumes, and their role in cardiometabolic risk prevention: a review. Bouchenak M, Lamri-Senhadji M.
12 PLoS One. 2014;9(2):e88282. The regulation of alfalfa saponin extract on key genes involved in hepatic cholesterol metabolism in hyperlipidemic rats. Shi Y, Guo R, Wang X, Yuan D, Zhang S, Wang J, Yan X, Wang C.
13 Br J Nutr. 1997;78(2):325–34. Pancreatic and extra-pancreatic effects of the traditional anti-diabetic plant, Medicago sativa (lucerne). Gray AM, Flatt PR.
14 J Dairy Sci. 1994;77(4):1003–12. Compressed baled alfalfa hay for primiparous and multiparous dairy cows. Beauchemin KA, Rode LM.
15 Rheum Dis Clin North Am. 1991;17(2):323–32. Dietary amino acid-induced systemic lupus erythematosus. Montanaro A, Bardana EJ Jr.
16 J Chromatogr Sci. 1984;22(10):438–40. Canavanine analysis of alfalfa extracts by high performance liquid chromatography using pre-column derivatization. Weissberger LE, Armstrong MK.