While many consumers equal 'natural' with 'safe', botanical ingredients and preparations including plant-based supplements and natural food ingredients may contain compounds – such as alkenylbenzenes – that are of concern for human health, say a group of Dutch scientists.
Their study – published in Food and Nutrition Sciences – reveals that whilst many plant-based food supplements contain levels of such compounds in quantities below that of concern, there are supplements on the market that contain potentially dangerous compounds at levels that can lead to cancer in lab animals.
“Plant food supplements generally have a high acceptance by consumers who often consider that ‘natural’ equals ‘safe’. However, this reasoning should be considered with care since several botanicals are known to contain toxic or even genotoxic and carcinogenic compounds,” explained Suzanne van den Berg of Wageningen University – the study’s first author – and her colleagues.
“In total, 30 botanical ingredients were identified as a possible risk for human health based on their genotoxic and/or carcinogenic characteristics. Out of these selected botanical ingredients 18 compounds appeared to be both genotoxic and carcinogenic,” they added.
Dr Robert Verkerk, executive and scientific director at the Aliance for Natural Health (ANH) told NutraIngredients that whilst the research is “without doubt a useful academic contribution to the subject of risk assessment of botanicals,” putting the results of such research into the hands of policy-makers who don't necessarily understand the finer points of the science “could be problematic.”
He added that alkenylbenzenes are found in relatively few species, and represent “a tiny proportion” of botanical food supplements on the market.
van den Berg and her colleagues said that some supplements currently on the market could contain alkenylbenzenes at levels that when taken at the recommended daily dose, may also result in an intake of alkenylbenzenes in the range known to cause malignant tumours in lab animals.
They argued that whilst the use of the alkenylbenzenes estragole, methyleugenol, safrole and β-asarone as flavourings in food products is regulated and prohibited in several countries, their use in supplements is not regulated.
“This is remarkable since the use of plant food supplements might result in high exposures to these compounds,” said van den Berg and her co-workers.
Verkerk noted that whilst it is true that certain common herbs and spices contain potentially carcinogenic or mutagenic alkenylbenzenes, “results from studies of rats, mice and bacteria, using relatively high dosages maintained over a lifetime, don't represent the real world for humans.”
“In fact, some of the plant compounds, like curcumin found in turmeric root, are thought to have exactly the opposite effect in humans, being cancer protective,” he observed.
The research, which forms part of the EU funded PlantLIBRA project, involved screening and selecting botanical compounds that are of possible concern for human health.
The research team reported that analysis of several botanical supplements – containing basil, fennel, nutmeg, sassafras, cinnamon or calamus as major ingredients – revealed that some of these products contain relatively high levels of alkenylbenzenes or pyrrolizidine alkaloids.
They noted that for these botanical ingredients regulatory authorities are aware of the possible risk for human health, and have consequently banned the use of pyrrolizidine alkaloid-containing botanicals in food and botanical supplements in most EU Member States.
van den Berg and her team noted the ban on the use of alkenylbenzenes as flavouring agents in food within the EU, and questioned they restrictions have not yet been made with regard to the presence of alkenylbenzenes in supplements.
As a result, they concluded that the use of such botanical supplements may raise concern for human health, and could be a target of high priority for risk management actions to be taken.
Future studies should place special focus on this subject, they said.
Until these are completed, van den Berg and her team said they must conclude that some - although not all - plant-based food supplements containing the alkenylbenzenes estragole, methyleugenol, safrole or β-asarone might raise a concern for human health, and that this indicates a need for better regulation and quality control of plant-based food supplements containing such compounds.
Source: Food and Nutrition Sciences,
Published online ahead of print, doi: 10.4236/fns.2011.29134
“Levels of Genotoxic and Carcinogenic Compounds in Plant Food Supplements and Associated Risk Assessment”
Authors: S.J.P.L. van den Berg, P. Restani, M.G. Boersma, L. Delmulle, I.M.C.M. Rietjens