Several posts on Facebook claim that coriander (or cilantro as it is sometimes known) removes varied amounts of heavy metals from the body. The posts generally say “studies prove that cilantro can remove an average of 87% lead, 91% mercury and 74% aluminium from the body.”
This is incorrect.
The studies we found were primarily experimental animal studies involving rodents. Although some of these did show a reduction in lead levels after coriander use, the studies in humans have not shown the same effects.
There is no good evidence to support coriander as treatment for mercury toxicity in humans and we were unable to find any studies looking at the herb as a treatment for aluminium toxicity in humans. It is unclear where the specific percentages mentioned in the post have come from, but similar claims have circulated for a number of years.
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Heavy metals are a group of chemical substances that mostly occur naturally in the environment and cannot be broken down. They include some substances that are essential for bodily functions but can be harmful if they accumulate in the body.
Exposure to heavy metals can occur in various ways including through food and water consumption, skin contact and also air. A buildup of heavy metals can cause a wide range of issues, including damage to specific organ systems and also the development of diseases.
Heavy metals can be removed by a process known as chelation which allows these substances to be excreted after binding with other molecules. Heavy metal levels in the environment are monitored by the Heavy Metals Network in the UK.
Lead, mercury and aluminium
Lead is a naturally occurring metal which has had many uses over time including being a component in petrol, pipes and pigments. Although some historical uses have now been discontinued, it still has some modern uses such as in car batteries and radiation protection equipment.
Lead exposure can result in its accumulation in the body which can cause many harmful effects, particularly in children. Symptoms of lead poisoning can include abdominal pain, constipation and fatigue. Identifying and removing the exposure is important and chelation therapy can be considered depending on the severity and blood levels.
Mercury is also a naturally occuring metal with different forms and uses. Several factors influence how toxic mercury can be for a person and symptoms can range from mild to severe. Chelation can also be used as treatment for mercury poisoning.
Aluminium is widespread in the environment and has several uses from consumer products to construction materials. The toxic effects of aluminium are extensive. Supportive measures such as maintaining oxygen and fluid levels are important for those who have been overexposed. Chelation is also a recognised treatment for this in certain circumstances.
Does coriander remove these heavy metals from the body?
Recent research has found that coriander may have various benefits for the cardiovascular system. Other studies have suggested that coriander may help conditions such as obesity and other metabolic diseases.
Several experimental studies have shown that coriander can reduce the levels of lead in the blood and tissues of rodents. However, the results have not been the same in humans. A trial in young children found no difference in eventual lead levels in those treated with coriander compared with those that were not. Further research is required to better understand the properties of coriander and potential future clinical use.
There have been some reports of coriander reducing mercury levels. For example, a case report described the reversal of mercury contamination in a dental patient using coriander tablets. Case reports are not normally considered to provide a high level of evidence.
Other examples include coriander preparations reducing mercury levels in batches of groundwater and a different study in rodents showing lower mercury levels in those treated with coriander. However, this does not mean that coriander would be effective in humans and further research is needed, as highlighted by other fact checkers.
A review looking at the evidence for herbal compounds as possible chelation treatments found two studies that suggested it could reduce mercury levels. It was noted that other herbal compounds were more effective than coriander in these studies.
Overall, there is insufficient evidence for using coriander as a treatment for mercury toxicity in humans.
We could only find one abstract which looked at aluminium levels in mice treated with coriander. The researchers reportedly found that the levels of aluminium were reduced after the mice were fed coriander for 25 days. We were unable to find any examples of studies in humans.