Herbs have been credited with many therapeutic properties. Some are thought to help the body fight infection. Others are said to aid digestion, settle nerves, serve as a laxative, or help regulate the glands.
Herbs may have both nutritional and medicinal value. For example, some plants that serve as diuretics, such as parsley, also contain significant amounts of potassium. The potassium in these plants compensates for the loss of this vital element through urination. Likewise, the valerian plant (Valeriana officinalis), long used as a sedative, is high in calcium. The calcium may enhance the herb’s sedative effect on the nervous system.
An encyclopedia on the subject of herbs states: “The unpleasant fact of the matter is that some herbs are downright dangerous. [Regrettably] some people don’t give any herb—dangerous or benign—the appropriate respect.” Chemical compounds in herbs can change heart rate, blood pressure, and glucose levels. Hence, people with cardiac problems, high blood pressure, or blood-sugar disorders such as diabetes must be especially cautious.
Herbs can interact with medicinal drugs in various ways. For instance, they can magnify or reduce a drug’s effect, cause it to be eliminated from the body faster than usual, or increase the risk of side effects. St. John’s wort, often prescribed in Germany for mild to moderate depression, causes many drugs to be eliminated twice as fast as normal, thus lessening their potency. So if you take a prescription drug, including birth-control pills, consult with your doctor before taking herbs.