“Copper pipes could cause heart disease and Alzheimer's,” says The Daily Telegraph.
This story was based on a narrative review that presents the theory that excess copper from drinking water and supplements may contribute to Alzheimer’s disease and other conditions.
This review was produced by a single author who has presented a small sample of studies from this field of research. While the review discusses the roles of copper and iron in health and disease, most of the evidence is based on studies in animals and cells. No studies presented in this review have directly assessed whether water from copper pipes contributes to Alzheimer’s disease or coronary heart disease. Iron and copper are necessary for a number of biological functions in the body.
Where did the story come from?
This review was written by a single author, George Brewer, from the University of Michigan Medical School. It was published in the peer-reviewed journal Chemical Research in Toxicology.
The Daily Telegraph covered the story but did not indicate that the research behind it was a non-systematic review rather than a piece of primary research, as readers may assume. It is unclear how well the review covers the evidence base on this topic, or whether it has omitted evidence that contradicts the author’s theories on the subject.
What kind of research was this?
This was a narrative review of risks of copper and iron during ageing. Being a non-systematic review means that it may omit some scientific research that may go against the researcher’s hypothesis. This review was written by just one person. However, to ensure a balanced interpretation of the available evidence, several authors are usually required to write a review.
The majority of the studies covered in the review were animal- or cell-based studies, which means that their direct relevance to humans is limited.
What did the research involve?
The review presented studies that had shown an association between disease and exposure to copper and iron. It also proposed and discussed measures that could be taken to limit copper and iron exposure.
What were the basic results?
The author presented a small selection of studies looking at how copper and iron might be associated with cognition problems, artherosclerosis, diabetes, Alzheimer’s and Parkinson’s disease. He presented one study that looked at dietary intake of copper and cognition. It found that people with higher intakes of copper and a high-fat diet had “lost cognition” more rapidly than expected. The procedural details of this study were not given.
The author also discussed a study that looked at how rabbits with a condition similar to Alzheimer’s disease had been affected by copper in their drinking water. The study reportedly showed that in this rabbit model of Alzheimer’s disease, the rabbits given drinking water containing low concentrations of copper had worse symptoms than rabbits given copper-free water. The concentrations of copper in the supplemented water were 10 times lower than the maximum limit of copper in water allowed by the Environmental Protection Agency in the US.
The author discussed the possibility that copper pipes may contribute to the copper levels in the drinking water. The study did not indicate the typical copper concentrations in water that is drawn from copper pipes.
How did the researcher interpret the results?
The researcher concluded that copper and iron contribute to a variety of diseases. Their consumption should be avoided by avoiding supplements containing copper, and by replacing copper pipes. They also recommend that people’s blood copper levels should be monitored.
An immense amount of research has been conducted into the roles of copper and iron in health and disease. In small amounts, these metals are vital for the functioning of many proteins in our body. But their role in disease is still not conclusive. This non-systematic review presented a very small sample of this research. It cited studies that supported the author’s theories that dietary copper and iron are toxic and that further supplementation should be avoided. The majority of studies presented were in animals or cells, and the review has over-extrapolated their results to apply to humans.
The role of copper and iron in health and disease is of great interest to researchers. Copper and iron are present in many foods, and this review does not provide strong evidence that normal dietary intake has any effect on disease. In order to assess whether excess copper or iron intake has an effect on disease, a systematic review representing all of the available evidence in this area would be required.
Analysis by Bazian
Edited by NHS Website
Links to the headlines
The Daily Telegraph, 22 January 2010
Links to the science
Chem. Res. Toxicol.
Bull S. Health Protection Agency. 9 March 2009