The laxative senna(Cassia senna L.) is widely used in dietary supplements also available in the form of common supermarket herbal teas. However, this plant can harm theintestines and is among the laxatives placed under surveillance by the European Commission for suspected health damage. We sought clarification from the National Institute of Health (ISS).
Senna, a ‘natural’ laxative with big numbers
In addition to being present in some medicines available without a prescription (e.g., Pursennid, Novartis), senna-the leaves and flowers of Cassia senna L. – is the main ingredient in numerous dietary supplements. From the best-known, such as ‘Fava di fuca,’ ‘Kelemata Herbal Tea,’ to a host of lesser-known brands and blends of the ’10, 20, 100 herbs’ genre that promise ‘relief, balance and lightness.
Senna even appears in herbal teas for sale in supermarkets, registered as supplements, such as Star’s Sogni d’oro Regolarità, Bonomelli Regolarità, Kilocal, etc.
Such wide availability that large segments of the population are exposed to the risk of adverse health effects. Often in the absence of adequate warnings on food supplement labels. With the pious illusion that the ‘natural‘ product is always free of contraindications,.
Suspicions for a decade
Suspicions about the safety of consuming senna and other hydroxyanthracene derivatives as laxatives (chemicals found in many botanical species) have already surfaced in two EFSA scientific opinions over the past decade.
The first opinion dates back to 2013. When questioned about the scientific substantiation of a health claim related to hydroxyanthracene derivatives and improved intestinal function, theAuthority had confirmed these properties.
However, he had ‘advised againstitsuse and prolonged consumption at high doses because of potential safety concerns such as the danger of electrolyte imbalance, deterioration of bowel function and laxative dependence.’
Under surveillance for 4 years
EFSA’s second opinion (2017) on hydroxyanthracene derivatives used as laxatives led to a ban on the use of some parts of aloe, which were found to be carcinogenic and mutagenic, but without reaching sufficient evidence to ban senna. (1)
However, doubts remain. As of 2021, senna is in fact under special surveillance, for four years, along with other hydroxyanthracene derivatives (chemicals found in many botanical species with laxative action).
Meanwhile, Switzerland-where health policy strictly follows the precautionary principle-has already banned the use of the laxative senna in supplements. (2)
Inappropriate use of senna for a prolonged period may also result in increased intestinal sluggishness and further worsening of constipation.
In chronic overdose, liver damage may occur.
In the absence of a prescription, medicines containing senna preparations should not be taken for more than 2 weeks and should not be used in children under 12 years of age or during pregnancy and lactation.
Senna preparations also cannot be taken in cases of inflammatory diseases of the gastrointestinal tract, intestinal obstruction, kidney disease, dehydration, and known hypersensitivity to one or more ingredients.
(Swiss Institute for Therapeutic Agents)
In Italy and other countries, on the other hand, the use of the substance is also widespread in supermarket shelf products, often without warnings to consumers. An abnormal circumstance, about which we asked the National Institute of Health for an explanation.
Responses from the National Institute of Health (ISS).
Researchers Ilaria Ippoliti and Francesca Menniti-Ippolito of ISS’s National Center for Preclinical and Clinical Drug Evaluation and Research, whom we interviewed, basically confirm that the laxative senna is being used inappropriately by consumers.
1 – What is the evidence of harmfulness of Senna for bowel function (doses and duration of consumption)?
‘The senna (Cassia senna L. or Cassia angustifolia) is a plant that contains, among other molecules, the so-called anthraquinone laxatives (called sennosides) that give the effect precisely of laxative with a very intense action so much so that they are referred to as “drastic contact laxatives” and therefore their use is not recommended for prolonged periods of time.
In the EMA (European Medicine Agency) monograph, for example, the use of senna preparations should last a maximum of one week. (3)
If the preparations are taken properly and adequately (not for prolonged periods and only after having already tried other remedies such as a healthy, balanced diet, physical activity or milder laxatives) they are not harmful or toxic.
In the event, however, that they are taken incorrectly (even frequently) or for prolonged use, more or less severe adverse reactions may occur, which could lead, for example, to an effect on the intestinal epithelium and electrolyte imbalances with defects in absorption.
In this regard there are not many human clinical studies available however there is preclinical evidence, considered in the EMA monograph itself’.
Two ISS studies
‘In the past two years, we have carried out two studies concerning a systematic review/metanalysis of literature studies to assess colorectal cancer risk and an analysis of adverse reaction reports to identify possible health risks, respectively.
In both cases the available data did not reveal any particular safety concerns or warning signs however were found to be several cases of prolonged or inappropriate use of senna-containing products; this must therefore be taken into account when assessing the benefit/risk ratio for the health of users’. (4)
2 – Which countries allow the use of senna only in medicines (but not also in supplements), as Switzerland already provides?
‘Each country in the EU independently determines whether to authorize a substance or preparation as a medicinal product, and this is done following a national authorization procedure, so in order to know whether senna-based herbal medicines are authorized in a country reference should be made to the existing legislation of each member state European Union.
Dietary supplements from a legislative point of view are identified as food and follow, like several other commodity categories, Regulation (EU) 2019/515, which establishes and regulates the free movement of goods.
In general, a ban on the marketing of goods lawfully marketed in another member state is one of the most restrictive measures that can be taken and is executed only when other less restrictive measures (e.g., labeling), have not achieved effective results in protecting the public interest. In such cases the state performs the full scientific assessment of the real risk to the population’. (5)
3 – Senna is under observation since 2021, on EFSA prediction. What exactly does ‘under observation’ mean?
‘On November 22, 2017, EFSA issued a scientific opinion on the safety assessment of hydroxyanthracene derivatives (aloe-emodin, emodin, and dantrone) for use in food. Such derivatives were those found in various anthraquinone-containing plants including the leaves or fruits of Cassia senna L.
From these investigations, EFSA found that hydroxyanthracene derivatives, have been shown to be genotoxic in vitro. Therefore, he concluded that these molecules had to be considered genotoxic and carcinogenic unless there were specific data to the contrary.
He also specified that plant extracts containing hydroxyanthracene derivatives also raised safety concerns, however, there were still uncertainties.
EFSA was unable to provide guidance on a daily intake of hydroxyanthracene derivatives that would not raise human health concerns and concluded that the substances considered in the opinion should be banned.’
Senna special observed
‘Following these conclusions The European Commission has taken steps to implement the provisions of Regulation (EC) No. 1925/2006. Therefore, ‘Commission Regulation (EU) 2021/468 of March 18, 2021 amending Annex III to Regulation (EC) No. 1925/2006 of the European Parliament and of the Council as regards botanical species containing hydroxyanthracene derivatives’ was issued.
As a result, the substances aloe-emodin, emodin, dantrone, and aloe preparations containing hydroxyanthracene derivatives were included in Annex III, Part A. 1925/2006 and therefore currently result as “banned substances” in foods and thus in food supplements.
On the other hand, with regard to the plants under consideration, including Cassia senna L., the European Commission has determined that there is still no scientific certainty that these plants (or their preparations) contain the substances listed above (hydroxyanthracene derivatives) therefore they should be subject to European Union surveillance. As a result, these are currently included in Annex III, Part C of Regulation (EC) No. 1925/2006.
In this case, according to the same regulation, food business operators, or any other interested party, may submit to EFSA for its evaluation, A dossier showing the scientific data demonstrating the safety of such substances used in a food or category of food and explaining the purpose of such use.
Within four years after a substance has been listed in Annex III, Part C, the European Commission will make a decision taking into account EFSA’s opinion on any dossiers submitted.
From such a decision may be determined: the use of the substance without restrictions, the use of the substance but with special restrictions, or a ban on the use of the substance’.
Marta Strinati
Notes
(1) Panel on Food Additives and Nutrient Sources added to Food (ANS). Safety of hydroxyanthracene derivatives for use in food. EFSA. 23.1.18. DOI 10.2903/j.efsa.2018.5090
(2) Information on products not allowed as herbal teas or capsules containing senna. SwissMedic. 7.1.22 https://www.swissmedic.ch/swissmedic/it/medicrime/news/warnings/publikation-senna.html
(3) European Union herbal monograph on Senna alexandrina Mill. (Cassia senna L.; Cassia angustifolia Vahl), folium EMA/HMPC/625849/2015
(4) Adverse events related to herbal dietary supplements and over-the-counter medications containing laxatives: a 10-year update from the Italian Phytovigilance and Pharmacovigilance systems. Lombardi N, et al. Ann Ist Super Sanita. 2022;58(2):131-138. doi:10.4415/ANN_22_02_09;
Niccolò Lombardi, et al. Anthraquinone laxatives use and colorectal cancer: A systematic review and meta-analysis of observational studies. Phytotherapy Research. January 17, 2022 https://doi.org/10.1002/ptr.7373.
(5) Application of the Mutual Recognition Regulation to Food Supplements – Training Material for Authorities – Directorate General of Internal Market, Industry, Entrepreneurship and SMEs 2020.
Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
