Two independent studies have shown that most polyherbal preparations sold in Lagos State are of poor microbiological standards which may be due to poor sanitary and inappropriate hygienic measures; and that the heavy metals content of most poly-herbals sold in Lagos State are below World Health Organisation (WHO)/Food and Agricultural Organisation (FAO) permissible limits and are safe for consumption.
The researchers are from the departments of Plant Biology and Biotechnology, and Science Laboratory Technology, University of Benin, Benin City, Edo State.
The first study titled “Microbial Load of Some Polyherbal Products from Lagos State, Nigeria” was published in International Journal of Ethnobiology & Ethnomedicine 2015, while the second, “Heavy metals contamination of some polyherbal products from Lagos state, Nigeria,” was published in Journal of Ayurvedic and Herbal Medicine 2015.
The researchers led by Prof. MacDonald Idu include: Adeola Jimoh and Oghale Ovuakporie-Uvo.
The first study investigated the microbial contamination of commonly used polyherbal products in Lagos State. 30 polyherbal products were purchased from different vendors.
Using standard microbiological techniques for microbial analysis, the bacteria isolates used included Bacillus sp (100 per cent), Flavobacterium sp (30 per cent), Pseudomonas sp (50 per cent) and Staphylococcus sp (33.3 per cent) while the fungi isolates used were Fusarium sp (10 per cent), Aspergillus flavus (43.3 per cent), Penicilium sp (13.3 per cent), Geotrichum candidum (3.3 per cent), Mucor sp (3.3 per cent), Aspergillus oryzae (23.3 per cent) and Aspergillus niger (3.3 per cent).
The total bacteria counts ranged from 2.5×103 to 6.4×109 cfu/ml while fungal counts ranged from 9.5×103 to 3.5×109 cfu/ml.
The researchers wrote: “This study has shown that most polyherbal preparations sold in Lagos State are of poor microbiological standards which may be due to poor sanitary and inappropriate hygienic measures. Improved hygiene standards of polyherbal products is recommended.”
The researchers concluded: “This work has shown the presence of microbial contaminants in some polyherbal products sold in Lagos State, Nigeria. The 30 polyherbal samples analysed were shown to be heavily contaminated by microorganisms including bacteria and fungi thereby making these products unsafe microbiologically
“Adequate sanitary measures and hygienic practices should be observed during harvesting, handling and processing of herbal product in order to curb microbial contamination of the products.”
Meanwhile a “heavy metal” refers to any metallic element that has a high density and is toxic or poisonous even at low concentration.
The aim of the second study was to investigate the heavy metal contents of 30 used polyherbal products purchased from different vendors in Lagos State.
The researchers used an atomic absorption spectrophotometer, the heavy metals Lead (Pb), Zinc (Zn), Cadmium (Cd), Copper (Cu), Mercury (Hg), Chromium (Cr) and Magnesium (Mg) were tested.
The results showed: Pb, Cd, Hg and Cr were absent in polyherbals analyzed in this study. The concentrations of Zn(0.025- 0.42) ppm, Cu(0.017-0.31 ppm) and Mg (0.02-0.55)were below WHO/FAO permissible limits.
The study has shown that the heavy metals content of most poly-herbals sold in Lagos State is below WHO/FAO permissible limits.
The researchers concluded: “In conclusion, heavy metal poisoning is a serious risk posed to the public by poly-herbal products sold in the market. Thus, proper regulation and screening of heavy metal contents in herbal remedies before they get to their final consumers is recommended.
So, pharmacovigillance of poly-herbals is recommended such that the permissible limits of heavy metals in herbal preparation stay within specification. The absence of Cd, Cr and Pb in poly-herbal products analyzed in thisstudy suggests that the productsare safe for consumption.”
Until now, the use of herbal and traditional medicines raises concerns in relation to their safety, however, there is a wide misconception that “natural” means “safe”.
The contamination of herbal remedies with heavy metals may be due to soil and atmospheric contamination, which poses a threat to its quality and safety. Medicinal plants are normally contaminated with toxic metals during growth, development and processing.
Indeed the issues of safety, efficacy and quality of these medicines have been an important concern for health authorities and health professionals. This could be due to lack of standards for herbal products. To maximize the potential of African traditional medicines as a source of healthcare, the safety, efficacy and quality need to be assessed.
Some of the shortcomings of herbal medicines are scientific proof, imprecise dosage, imprecise diagnosis and unhygienic condition under which the herbal products are produced as well as the contaminated environment (soil and air) where the plants are grown.
Herbal preparations are used in different forms and may carry a large number of microbes originating from soil usually adhering to various parts of herb. The commonly used herbal materials include chewing sticks, herbal pastes, powders, herbal mixtures and suspensions.
Most of these herbal materials are prepared and sold under unhygienic conditions. A number of oral health care materials are hawked when not packaged and this raises the possibility of contamination.
Most of these materials are used directly without further processing (for example chewing sticks) thereby increasing the risk of disease transmission.
Herbal preparations are used in different forms and may carry a large number of microbes originating from soil usually adhering to various parts of herb. The contaminants that present serious health hazard are pathogenic bacteria such as Salmonella, Escherichia coli, Staphylococcus aureus, Shigella species and other Gram positive and Gram negative strains of bacteria.
Biological contamination refers to contamination of herbaceous plants by microorganisms such as bacteria, fungi (moulds), viruses, protozoa, insects (eggs and larvae) and other organisms. The presence of pathogenic microorganisms in herbs might pose a risk to public health and affects the quality of the products.
Pathogenic microorganisms include; Salmonella spp, Escherichia coli, Listeria, Monocytogenes and spore-forming microorganisms such as Bacillus cereus and Clostridium perfringens.
Enterobacteriaceae spp and Pseudomonas spp are the two groups of bacteria found commonly on the harvested plant surface and these can rise to the problem of damage and deterioration in the quality of food. Thus, it’s important to monitor the bacteria contamination in any herbal product  .
The study was carried out in Lagos state, Nigeria. The markets surveyed were Agege market, Ikeja market, Temidire market, Abibatu mogaji market, Alimosho market.
30 polyherbal preparation samples were randomly purchased from different locations in Lagos state. The samples were taken to the laboratory for microbiological analysis.
The researchers wrote: “Herbal medicines especially those containing combinations, are readily used by humans in different parts of the world in general and in particular Lagos State, Nigeria.
This high demand for herbal products is due to the fact that it is natural and no likely to cause serious side effects compared to conventional drugs. Despite these, citizens should not be unaware of the possible contamination of these products by microorganisms especially bacteria and fungi and also heavy metals contamination.
The composition, indication and dosage of the 30 polyherbal samples are enumerated above. The recommended dosage cup was not specific. This research work has focused on the microbiological contamination of different polyherbal preparations sold in Lagos State, Nigeria.”