Alfalfa

Scientific Name(s): Medicago sativa L.
Common Name(s): Alfalfa

Medically reviewed by Drugs.com. Last updated on Jul 29, 2022.

Clinical Overview

Use

Alfalfa may be useful in lowering cholesterol and treating menopausal symptoms. It also may have hypoglycemic and anti-inflammatory effects; however, clinical information supporting any of these indications is limited.

Dosing

A general dosing regimen is 5 to 10 g of the dried herb taken 3 times daily. For the treatment of high cholesterol, the seeds may be taken at a dose of 40 g 3 times daily.

Contraindications

The US Food and Drug Administration (FDA) issued an advisory indicating that children, the elderly, and people with compromised immune systems should not consume alfalfa sprouts because they are frequently contaminated with bacteria. Use should be avoided in people with a personal or family history of systemic lupus erythematous (SLE) because of possible effects on immunoregulatory cells by canavanine, a component of alfalfa.

Pregnancy/Lactation

Avoid use. Documented adverse effects of alfalfa during pregnancy include possible uterine stimulation. Although alfalfa has been anecdotally recommended to stimulate milk production, evidence is lacking.

Interactions

None well documented.

Adverse Reactions

Alfalfa seeds and fresh sprouts can be contaminated with bacteria, such as Salmonella enterica and Escherichia coli. The FDA issued an advisory indicating that children, the elderly, and people with compromised immune systems should avoid eating alfalfa sprouts. Ingestion of dried alfalfa preparations is generally safe in healthy adults. Because of its high potassium content, alfalfa may cause hyperkalemia.

Toxicology

Alfalfa tablets have been associated with the reactivation of SLE in at least 2 patients.

Scientific Family

• Leguminoseae (bean)

Botany

The legume alfalfa is cultivated throughout the world under widely varying conditions. Common cultivars include weevelchek, Saranac, team, arc, classic, and buffalo. It is a perennial herb with trifoliate dentate leaves and an underground stem that is often woody. Alfalfa grows to approximately 1 m with 5 to 15 stems. The most common colors of flowers are purple, yellow, white, and cream, which produce spiral-shaped seed pods once pollinated. It is the most cultivated legume in the world, with the United States being the largest producer. California, South Dakota, and Wisconsin are the leading states for alfalfa production.Bora 2011

History

Alfalfa has played an important role as a livestock forage. Its use probably originated in Asia. The Arabians fed alfalfa to their horses, claiming it made the animals swift and strong, and named the legume "al-fal-fa" meaning "father of all foods." Medicinal uses of alfalfa originated from anecdotal reports that the leaves caused diuresis and were useful in the treatment of kidney, bladder, and prostate disorders. Leaf preparations have been touted for their antiarthritic and antidiabetic activity, for the treatment of dyspepsia, and as an antiasthmatic. Alfalfa extracts are used in baked goods, beverages, and prepared foods, and the plant serves as a commercial source of chlorophyll and carotene.Bora 2011, Duke 1985

Chemistry

Dried alfalfa leaves are ground and sold as tablets or powder for use as nutritional supplements. Leaf tablets are rich in protein, calcium, trace minerals, carotene, vitamins E and K, and numerous water-soluble vitamins.Worthington-Roberts 1983 A steroidal saponin fraction composed of several factors (eg, soyasapogenols, hederagenin, medicagenic acid)Massiot 1988, Oleszek 1988 is believed to play a role in the hypocholesterolemic and hemolytic activity of the leaves and sprouts.Malinow 1978 Alfalfa seeds contain the toxic amino acid L-canavanine, an analogue of arginine. Sprouts of certain cultivars of alfalfa contain up to 13 g/kg of canavanine (dry weight). Canavanine levels decrease as the plant matures. The alkaloids stachydrine and l-homo-stachydrine, which are found in the seeds, possess emmenagogue and lactogenic activity.Newsletter 1984 Seeds contain up to 11% of a drying oil used in the preparation of paints and varnishes. The chemistry of alfalfa has been well characterized.Duke 1985

Uses and Pharmacology

Anti-inflammatory effects

Animal/In vitro data

The production of nitric oxide from lipopolysaccharide (LPS)-induced inflammation in RAW264.7 macrophages was reduced in the presence of alfalfa extract. Additionally, LPS-stimulation of interleukin-6 and tumor necrosis factor alpha production was also decreased with chloroform extracts of alfalfa.(Choi 2013)

Pretreatment with a chloroform extract of alfalfa was found to improve 2-day survival rates in mice injected with LPS.(Choi 2013)

Clinical data

There are no clinical data regarding the use of alfalfa for anti-inflammatory indications.

Anxiolytic effects

In a study of mice, a methanolic extract of M. sativa was found to exert anxiolytic effects as noted by the average time spent and number of entries in open arms as part of an elevated plus-maze test.(Singh Bora 2012)

Cholesterol reduction

Alfalfa plant saponins and fiber(Story 1982) bind large quantities of cholesterol in vitro; sprout saponins interact to a lesser degree. In vitro bile acid adsorption is greatest for the whole alfalfa plant, and this activity is not reduced by the removal of saponins from the plant material.

Animal data

Several studies indicate that the ingestion of alfalfa reduces cholesterol absorption and atherosclerotic plaque formation in animals.(Cohen 1990, Malinow 1977, Malinow 1981, Wilcox 1961) In 1 study, the ability of alfalfa to reduce liver cholesterol accumulation in cholesterol-fed rats was enhanced by the removal of saponins. Therefore, alfalfa plant saponins appear to play an important role in neutral steroid excretion, but are not essential for increasing bile acid excretion.(Story 1984) In a study with prairie dogs, the lowest incidence of cholesterol gallstones was obtained with a diet of the higher fiber content (85% alfalfa).(Cohen 1990) In a study of hypercholesterolemic rabbits, alfalfa given for 12 weeks decreased triglycerides, low-density lipoproteins, and glucose. It also increased high-density lipoproteins. A reduction in the formation of fatty streaks in the right and left coronary arteries and the aorta was also noted in animals receiving a diet supplemented with alfalfa.(Asgary 2008)

In addition to demonstrating a cholesterol-lowering effect, alfalfa administration was also found to exert hepatoprotective effects in rats intoxicated by carbon tetrachloride as noted by the ability to suppress increases in glutamic-oxaloacetic transaminase, glutamic pyruvic transaminase, gamma-glutamyl transferase, alkaline phosphatase, and bilirubin contents.(Al-Dosari 2012)

Clinical data

The addition of alfalfa seeds to the diet of 15 patients with type 2 hyperlipoproteinemia helped normalize serum cholesterol concentrations in 1 study.(Mölgaard 1987)

There is no evidence that canavanine or its metabolites affect cholesterol levels.

Hypoglycemic effects

The hypoglycemic effects of M. sativa are believed to be due to its manganese content.(Bora 2011) In streptozocin-induced diabetic mice, lucerne 62.5 g/kg in the diet was found to decrease hyperglycemia. Additionally, the aqueous extract of lucerne was associated with an increase in glucose uptake, carbon dioxide production, and glycogenesis.(Gray 1997)

Menopausal symptoms

Administration of M. sativa and Salvia officinalis was associated with a reduction to a complete resolution of hot flushes and night sweats in 30 menopausal women.(De Leo 1998)

Dosing

A general dosing regimen is 5 to 10 g of the dried herb taken 3 times daily.van Wyk 2004 Seeds for high cholesterol may be taken at a dose of 40 g 3 times daily.Bora 2011

Pregnancy / Lactation

Avoid use. Documented adverse effects of alfalfa during pregnancy include possible uterine stimulation.Brinker 1998, Ernst 2002 Although alfalfa has been anecdotally recommended to stimulate milk production, evidence is lacking.Forinash 2012

Interactions

None well documented.

Adverse Reactions

Alfalfa seeds and sprouts can be contaminated with pathogens such as S. enterica and E. coli.CDC 1997, Christy 1999, Mahon 1997, Van Beneden 1999 Most healthy adults exposed to Salmonella or E. coli will have symptoms such as diarrhea, nausea, abdominal cramping, and fever that are self-limiting. The E. coli infection can lead to hemolytic uremic syndrome with kidney failure or death in children or elderly patients. In 1995, 4 outbreaks of Salmonella infection occurred in the United States because of the consumption of contaminated alfalfa sprouts. In 1995 to 1996, 133 patients in Oregon and British Columbia developed salmonellosis from ingesting alfalfa sprouts contaminated with S. enterica (serotype Newport).Van Beneden 1999 Also in 1995, 242 patients in the United States and Finland developed salmonellosis from ingesting alfalfa sprouts contaminated with S. enterica (serotype Stanley).Mahon 1997

In June and July 1997, simultaneous outbreaks of E. coli 0157:H7 infection in Michigan and Virginia were independently associated with the ingestion of alfalfa sprouts grown from the same seed lot.CDC 1997 The FDA issued an advisory indicating that children, the elderly, and people with compromised immune systems should avoid eating alfalfa sprouts.Christy 1999

Because of its high potassium content, alfalfa may cause hyperkalemia.Munar 2007

Toxicology

Although alfalfa is listed as generally recognized as safe (GRAS) in the United States,van Wyk 2004 there are some concerns. Changes in intestinal cellular morphology were noted in rats fed alfalfa; these effects were more extensive in animals fed whole plant material compared with sprouts. The interaction of saponins with cholesterol in cell membranes may only be partly responsible for these changes.Story 1984 Although their importance in animal intestinal morphology is not clear, it is known that these changes, when observed concomitantly with changes in steroid excretion, may be related to an increased susceptibility to colon cancer.Sprinz 1971

A disease similar to SLE, characterized by hemolytic anemia, decreased serum complement levels, immunologic changes, and deposition of immunoglobulins in the kidney and skin, has been observed in monkeys fed alfalfa seeds.Malinow 1982 Alfalfa ingestion has resulted in pancytopenia and hypocomplementemia in healthy subjects,Malinow 1981 with L-canavanine implicated as the possible causative agent. The toxicity of L-canavanine is mainly due to its structural similarity to arginine; it binds to arginine-dependent enzymes interfering with their action. Arginine reduces the toxic effects of canavanine in vitro.Natelson 1985 Further, canavanine may be metabolized to canaline, an analog of ornithine, that may inhibit pyridoxal phosphate and enzymes that require the B₆ cofactor.Mölgaard 1987 L-canavanine has also been shown to alter intercellular calcium levelsMorimoto 1989 and the ability of certain B- or T-cell populations to regulate antibody synthesis.Prete 1985, Morimoto 1990 Alfalfa tablets have been associated with the reactivation of SLE in at least 2 patients.Roberts 1983

A case of reversible asymptomatic pancytopenia with splenomegaly was reported in a man who ingested up to 160 g of ground alfalfa seeds daily as part of a cholesterol-reducing diet. His plasma cholesterol decreased from 218 mg/dL to 130 to 160 mg/dL.Malinow 1981 His pancytopenia was believed to be due to canavanine.

There is no scientific evidence that self-treatment with alfalfa tablets for asthma and hay fever is effective.Polk 1982 Fortunately, the occurrence of cross-sensitization between alfalfa (a legume) and grass pollens appears unlikely, assuming the tablets are not contaminated with materials from grasses.Brandenburg 1983 One patient died of listeriosis following the ingestion of contaminated alfalfa tablets.Farber 1990

References

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