Alfalfa Side Effects and Warnings

Safety Issues

Alfalfa, in its various forms, may present some health risks. Powdered alfalfa herb, alfalfa sprouts, and alfalfa seeds all contain L-cavanine, a substance that may cause abnormal blood cell counts, spleen enlargement, or recurrence of lupus in patients with controlled disease. However, heating alfalfa may correct this problem.

Researchers investigating alfalfa seeds' ability to lower cholesterol levels discovered that it had another effect on the lab animals used for testing. In some of the monkeys, it caused a disease very similar to lupus. ¹ Further research on this effect revealed that monkeys that had abnormal blood cell counts when eating either alfalfa seeds or sprouts, and then recovered when alfalfa was no longer part of their diet, developed the symptoms again when given an isolated component of alfalfa called L-canavanine. ² Alfalfa seeds and sprouts have a higher concentration of L-canavanine than the leaves or roots.

In a clinical trial of alfalfa seeds for lowering cholesterol involving only 3 human volunteers, one man who participated developed pancytopenia (an abnormally low number of all of the various types of blood cells) and enlargement of the spleen. ³ Additionally, there are two published case reports of patients, who had lupus which was controlled with drug therapy, suffering relapses after consuming alfalfa tablets. Again, L-canavanine is thought to be responsible for these effects.

When alfalfa seeds were autoclaved (heated to extremely high temperatures) and fed to monkeys for a year, no ill effects were seen, and the monkeys' cholesterol levels decreased. ⁴ It may be that the L-canavanine can be destroyed by extreme heat, while the saponins that seem to be responsible for the beneficial effects of alfalfa remain intact. If so, a heat-treated product might prove safe; however, much research remains to be done before we can know this for certain.

At present, it seems prudent that people who have been diagnosed with lupus, or those who suspect a predisposition to it based on family history, should probably avoid alfalfa. This includes the tablets used for supplements and the sprouts on the salad bar (go for the lettuce or the spinach instead).

Because of the estrogenic effects of some of alfalfa's components, alfalfa is not recommended for pregnant or nursing women or young children. In addition, the high vitamin K content in alfalfa could, in theory, make the drug warfarin (Coumadin) less effective.

Finally, a number of cases of food poisoning have been documented from fresh sprouts infected with bacteria that was present on the seeds prior to germination. ⁵ Unfortunately, sprouts can appear fresh and yet host enough bacteria to cause illness in people who eat them. Some healthcare workers recommend that those at higher risk for such infections—young children, those with chronic diseases, and the elderly—avoid eating sprouts altogether.

Interactions You Should Know About

If you are taking warfarin (Coumadin): the high vitamin K content of alfalfa might make it less effective.