Rich in color, flavor, and medicinal value
Red raspberries are a popular fruit commonly used in fruit juices, fruit salads, jams and preserves, fruit syrups, breakfast bars, tarts, and other foodstuffs. Red raspberries also contain many health-promoting properties.
The versatile red raspberry, along with the strawberry and blackberry, is loaded with vitamin C and many potent phenolic antioxidants, such as flavonoids, tannins, and anthocyanin pigments. The anthocyanins in the berries have anti-inflammatory activity. The berries also exhibit antiviral and antibacterial activity against a number of viruses and bacteria.
Raspberries and other edible berries strongly impair angiogenesis-the vascularization (abnormal or excessive formation) of tumors needed to sustain their growth. Raspberry fruit extracts have shown the ability to significantly inhibit human liver, breast, and cervical cancer cells.
Do any other parts of the raspberry bush contain health-promoting properties? Absolutely. The pale-green leaves of the raspberry bush, which boast a somewhat harsh and bitter flavor, have long been valued for their medicinal power. A tea made from the leaves of raspberry has been used for centuries as a folk medicine to treat wounds, colic pain, upper respiratory disorders, and difficulties in childbirth.
Raspberry leaf tea is also valued for the treatment of diarrhea. The tea can be prepared by pouring a cup of boiling water over one to two teaspoons of finely cut raspberry leaves and steeping for ten minutes. A cup of raspberry leaf tea can be drunk five or six times a day to control diarrhea. A physician should be consulted, however, when the diarrhea persists beyond two days.
Tannins to the Rescue
Why is raspberry leaf tea an effective remedy for treating diarrhea? Because of its rich content (13 to 15 percent) of tannins. These polyphenolics tend to stop diarrhea by their astringent properties, which help reduce intestinal inflammation.
Raspberry leaf tea may also be used effectively as a mouthwash for sore throat or inflammation of the mouth. The dried leaves or dried root bark of the blackberry plant and the dried leaves and dried fruit of blueberries are also highly recommended to arrest simple diarrhea. Blackberries and blueberries are also rich in tannins.
Tannins that are applied to the mucous membranes or to an abrasion can cause a decrease in vascular permeability and have an anti-inflammatory effect. These effects explain why tannin-rich raspberry leaves are used as a wound treatment, a mouthwash, and a gargle.
But beware. The tannins in raspberry leaves could have some negative consequences. The high content of tannins in raspberry leaves may impair the absorption of dietary minerals, such as calcium, iron, and magnesium. In addition, the absorption of a variety of commonly used drugs, such as sedatives, tranquilizers, and antidepressants, may be impaired.
Help During Childbirth?
Today the use of raspberry leaf tea is fairly popular to facilitate childbirth and lessen labor pains. Raspberry leaf extract apparently contains a component that stimulates contractions of the smooth muscle in the uterine wall.
Researchers in Australia analyzed the safety and effectiveness of raspberry leaf tablets on the duration of labor. In the study of pregnant women, they could not identify any adverse effects for either the mothers or their babies. They did find that women who ingested raspberry leaf might be less likely to receive a Cesarean section, and observed a 35 percent reduction in forceps deliveries for women using raspberry leaf, compared to other women.
In another double-blind, randomized trial, the use of raspberry leaf tablets by women in their last month of pregnancy was associated with a significant shortening of stage-two labor, but not of stage one.
Recently a national survey of 500 certified nurse-midwives was conducted to determine what herbal preparations were being used to stimulate labor. Of the midwives who used herbal preparations, 63 percent used red raspberry leaf, 93 percent used castor oil, and 60 percent used evening primrose oil.
Those recommending the herbal preparations to stimulate labor did so because they felt they were a natural remedy. The most common reason given for not using herbal preparations was the lack of research or experience with the safety of these substances.
The practice of using raspberry leaf tea to facilitate childbirth is by no means universally accepted. More research is needed to determine the safety and effectiveness of raspberry leaf extract. Raspberry leaf should not be taken during pregnancy except under proper medical supervision.
Raspberry leaf, along with peppermint or chamomile, is often recommended for morning sickness. However, there is a dearth of information related to the safety of these substances in pregnancy; hence, they should be used with great caution.
Raspberry leaf is normally considered safe when it is consumed in medicinal amounts. A typical dose for raspberry leaf would be about four to six 0.5g capsules per day. There is, at this time, insufficient reliable evidence available concerning the safety of use of raspberry leaf during pregnancy.
Winston J. Craig is professor of nutrition at Andrews University, Berrien Springs, Michigan.