Rhubarb as a dietary supplement
Rhubarb, particularly the species Rheum rhaponticum, is increasingly recognized as a dietary supplement with a variety of proposed health benefits. Traditionally used in European cooking and Chinese herbal medicine, rhubarb is known for its high fiber content and antioxidant properties, especially vitamin K and polyphenols. The primary proposed use of rhubarb as a supplement is for alleviating menopausal symptoms, supported by a study showing improved symptoms like hot flashes in women. Other potential applications include managing digestive issues, such as constipation and diarrhea, and possibly aiding in conditions like diabetes, kidney disease, and liver disease, though evidence for these uses is primarily from test-tube studies rather than robust human trials.
Rhubarb is considered relatively safe when consumed in moderation; however, caution is advised due to its oxalic acid content, which can lead to kidney issues if consumed excessively. The leaves contain the highest levels of oxalic acid, and standardized extracts are recommended to mitigate this risk. Although rhubarb shows promise for various health benefits, more independent studies are needed to confirm its effectiveness and safety for broader therapeutic applications.
Rhubarb as a dietary supplement
DEFINITION: Natural plant product promoted as a dietary supplement for specific health benefits.
PRINCIPAL PROPOSED USE: Menopausal symptoms
OTHER PROPOSED USES: Allergies, cancer treatment, diabetes, herpes (topical), kidney disease, liver disease, pancreatitis, digestive health, anti-inflammatory, antioxidant, cholesterol, antimicrobial
Overview
The stalk of the intensely flavored rhubarb plant has been used in European cooking since the seventeenth century. Before this time, rhubarb species were utilized medicinally in traditional Chinese herbal medicine. Traditional uses include the treatment of constipation, diarrhea, fever, menstrual problems, jaundice, sores (when applied topically), ulcers, and burns. Although there are many species of rhubarb, the one most studied is Rheum rhaponticum.
Uses and Applications
Rhubarb root contains lindleyin, a substance with estrogen-like properties. On this basis, rhubarb extracts have been tried to control menopausal symptoms. In a twelve-week, double-blind, placebo-controlled trial of 109 women with menopause-related symptoms, the use of a standardized R. rhaponticum extract significantly improved symptoms compared with placebo. Improvements were particularly seen in the rate and severity of hot flashes. While this is meaningful supporting evidence, additional independent trials are necessary to establish that this rhubarb extract is a safe and effective treatment for menopause.
Other potential uses of rhubarb lack reliable supporting evidence. One human trial purportedly found evidence that rhubarb could reduce lung function impairment that may occur when people with lung cancer receive radiation therapy. However, this study had several significant flaws, and its results cannot be regarded as reliable.
In another human trial using a cream containing sage and rhubarb, researchers failed to find more than modest benefits for treating herpes. Additional proposed uses of rhubarb are supported only by test-tube studies. For example, various rhubarb species have shown hints of potential value for treating diabetes, kidney disease, liver disease, and allergies. However, most effects seen in test-tube studies do not recur in human trials.
Rhubarb is high in fiber and was shown in one study to reduce bad LDL cholesterol. The fruit is also high in antioxidants, and especially vitamin K. Rhubarb has been shown to have greater levels of polyphenols than leafy green vegetables such as kale. Diets high in fiber and antioxidants offer many health benefits, such as protecting from free radicals, which can cause oxidative stress and lead to chronic health conditions.
Several other proposed therapeutic uses for rhubarb exist. Rhubarb has been studied for its various digestive benefits, such as relieving constipation, managing diarrhea, and treating stomach ulcers and bleeding. Double-blind, placebo-controlled trials have appeared to support these claims. Its anti-inflammatory properties have shown promise in treating conditions such as pancreatitis. Rhubarb’s antimicrobial properties may also protect from certain bacteria.
Dosage
A typical dosage of rhubarb root is 0.5 to 1 teaspoonful of the root boiled for ten minutes in a cup of water three times daily. In the foregoing menopause study, a standardized extract was used. Such extracts should be used according to label instructions.
Safety Issues
As a widely consumed food, rhubarb is thought to be relatively safe if consumed in moderation. However, the plant contains high levels of oxalic acid, and rhubarb consumption can markedly increase oxalic acid levels in the urine. This could lead to increased risk of kidney stones and other problems. Rhubarb leaf contains the highest oxalic acid content. The roots and stems contain less oxalic acid but higher levels of anthraquinones, laxative substances similar to those found in senna or cascara. It is safest to use rhubarb standardized extracts that have been processed to remove oxalic acid.
Contrary to some reports, consumption of rhubarb probably does not impair calcium absorption. Weak evidence hints that excessive consumption of rhubarb could increase the risk of stomach or colon cancer. Maximum safe doses in pregnant or nursing women, young children, and people with severe liver or kidney disease have not been established.
Bibliography
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