Senna's therapeutic uses
Senna is a natural plant product commonly used as an over-the-counter treatment for occasional constipation, and it is approved by the US Food and Drug Administration for this purpose. Its therapeutic effects stem from the presence of anthranoids, which stimulate bowel movements by interacting with gut bacteria. While senna is generally considered safe for short-term use, concerns have been raised regarding its long-term safety, particularly the potential for cell damage in the colon, which could be linked to an increased risk of colon cancer. However, research findings on this association are mixed, and there is no definitive evidence of causation.
Additionally, chronic use of senna can lead to dependency, where users may find it difficult to have bowel movements without the laxative. There are also reports of rare adverse reactions, such as hepatitis, and caution is advised for individuals with certain medical conditions, particularly those involving significant colonic disease. Pregnant and nursing women are generally advised to avoid senna, especially during the first trimester. Those taking specific medications, including digoxin and diuretics, should be cautious of potential interactions and the risk of potassium depletion from overuse. Overall, while senna can effectively alleviate constipation, its use should be approached with care, particularly concerning duration and individual health circumstances.
Senna's therapeutic uses
DEFINITION: Natural plant product used to treat specific health conditions.
PRINCIPAL PROPOSED USE: Constipation
Overview
Senna extract is an over-the-counter treatment for occasional constipation approved by the US Food and Drug Administration. Because there is no controversy regarding its effectiveness for this purpose, the supporting evidence is not presented here. Rather, this article addresses the concerns that have been raised regarding its safety.
Safety Issues
Senna contains chemicals in the anthranoid family, including dianthrones, which are metabolized by gut bacteria to form rhein anthrones. Related substances are found in various plants used for laxative purposes, such as cascara sagrada, common buckthorn, and turkey rhubarb. The mechanism of action of anthranoids, however, is worrisome: Anthranoids seem to work primarily by damaging the cells lining the colon. In general, cell damage can be a precursor to cancer, and on this basis, concerns have been raised that senna might increase colon cancer risk.
Evaluating this possibility is more challenging than it sounds. The most obvious method is to survey a large population over time to see whether people who use senna have a higher incidence of colon cancer. However, studies of this type (observational studies) are inherently unreliable because they do not show cause and effect. People with colon cancer or other precancerous conditions may become constipated and take senna, and this would cause a statistical association between the use of senna and colon cancer, even if senna did not cause the cancer. In any case, the results of such studies have been mixed, and overall, the association, if any, does not appear to be strong.
Animal studies have generally been reassuring, but a few such trials and test-tube studies have found evidence of possible increased risk with long-term use. Senna does have one potential safety advantage over other herbal anthranoid laxatives: its particular lanthanoids are not very absorbable. This reduces the potential risk of harm deeper in the body.
It appears reasonable to conclude that short-term use of senna is quite safe, while long-term use might or might not be safe. However, senna is not recommended for long-term use anyway. Chronic senna consumption can cause dependency, meaning that the user is unable to have a bowel movement without it. In addition, there have been sporadic reports of unusual reactions to chronic use of senna, such as hepatitis.
As is the case with all laxatives, people with significant colonic disease, such as ulcerative colitis, should not use senna. If senna is taken to the point of diarrhea, the body may become depleted of the mineral potassium. This is particularly dangerous for people using drugs in the digoxin family, which can cause dangerous cardiac arrhythmias if potassium levels in the blood are inadequate. People who additionally use medications that themselves deplete the body of potassium, such as thiazide or loop diuretics, are at special risk of this complication of senna overuse.
Senna's safety during pregnancy has not been established, and pregnant women are advised to avoid it during the first trimester. Nursing women should also avoid using it.
Important Interactions
Persons who are taking digoxin, thiazide diuretics, or loop diuretics should be especially careful not to overuse senna.
Bibliography
Nascimbeni, R., et al. "Constipation, Anthranoid Laxatives, Melanosis coli, and Colon Cancer: A Risk Assessment Using Aberrant Crypt Foci." Cancer Epidemiology, Biomarkers, and Prevention, vol. 11, 2002, pp. 753-757.
"Senna." MedlinePlus, 20 June 2024, medlineplus.gov/druginfo/meds/a601112.html. Accessed 16 Sept. 2024.
"Senna (Oral Route)." Mayo Clinic, 1 June 2024, www.mayoclinic.org/drugs-supplements/senna-oral-route/side-effects/drg-20406012. Accessed 16 Sept. 2024.
"Senna - LiverTox." NCBI, 1 Apr. 2020, www.ncbi.nlm.nih.gov/books/NBK547922. Accessed 16 Sept. 2024.