Purple fruit health claims are premature

November 12, 2012

Purple fruit health claims are premature

The Daily Telegraph’s story concerning the potential health benefits of purple coloured fruit may or may not be true but it is certainly premature. The newspaper makes the headline that purple coloured berries and fruit “could help ward off Alzheimer’s, Multiple Sclerosis and Parkinson’s” by soaking up harmful iron in the diet. However the iron compounds have yet to be proven as a trigger for Alzheimer’s disease. The author of the report summarises evidence and suggests that some diseases may be affected by certain forms of iron in the body. The summary also says how things could happen, but presently these are only suppositions in support of a theory. There is no proof.

In fairness to The Daily Telegraph the content of the article was well written and balanced, however the headline could easily give false hope to patients, and families of patients of a group of degenerative diseases. The newspaper is also willing to accept that further research and study will have to occur before any certainty can be brought to the situation.

The Real Story

The actual study deals with an investigation into the chemical and biological effects of iron and related chemicals in the body. It was published in the peer-reviewed journal Archives of Toxicology. The writer isProfessor Douglas B Kell of The University of Manchester’s School of Chemistry and Manchester Interdisciplinary Biocentre. The professor has previously written or co written 43 articles dealing with the subject of the chemical and biological actions relating to iron. Funding for earlier studies, which have led to this review, was provided by the Biotechnology and Biological Sciences Research Council, the Engineering and Physical Sciences Research Council and the Medical Research Council.

The central theme to the article is a theory that “some cellular death is caused by a particular chemical form of iron called ‘poorly liganded’ iron”. The author has conducted a study of many documented research articles, papers and reports in this area and has summarised all of his findings. The background to the issue is discussed in terms of systems biology which addresses interaction between all the parts of a biological system. Areas included are biochemistry and toxicology of metabolic pathways, discussing their likelihood of promoting disease within the body.

The theory being challenged was in a previously published work and addressed the chemical and biological behaviour of iron and chemicals that join to it. The assertion that a form of iron may play a role in many different diseases is present in many individual cases of research. The author also gives some simple predictions of why this may be.

The future is also discussed in the paper. Proposed methods to turn the theory into practice and any implications which may present themselves during future research were commented on. In particular the chemical which sticks to metal ions, called chelators was assessed in detail. These chelators remove the positive charge from metal ions which has caused them to be a focus of previous study.

The topic is comprehensively studied from many views. One source addressed diet and some of the sources of chelators found in our food. Pigments called polyphenols and anthocyanins can be found in blueberries, green tea, curry powder and many other fruits and vegetables. Because this has been mentioned in the report it appears that The Daily Telegraph may have chosen to write about this area without giving due consideration to the remainder of the report.

The research presently is unproven, it is still only a theory. Further research is needed to discover if the theory really is true. The central point of the discussion was not that certain foods may react with iron. That was only a very small part of the report. Whether iron can be active in the development of Alzheimer’s disease is still being studied. If the theory is true then further study into foods that may block iron’s negative effects can follow.

The Research Method

This was a document review of articles, research papers and academic studies relating to a theory stating that “some cellular death is caused by a particular chemical form of iron called ‘poorly liganded’ iron”. The author is an expert in this area and reviewed the research literature. He also completed a comprehensive review addressing all aspects before drafting his report.

The article for review was a technical paper and gave detailed descriptions of chemical properties of iron and the processes that occur within the oxygen carrying blood pigment haemoglobin involving the essential iron. It is explained that the ferric form of iron has 3 positive charges (Fe+++) and behaves differently from the ferrous form of iron which has two positive charges (Fe++). How they bond safely is described. Every iron ion has up to six chelation sites allowing other atoms to bind. When all six sites are bound then chelation has occurred.

When an ion is chelated it cannot react with other molecules to stop them interacting with hydrogen peroxide leading to toxic hydroxyl radicals being formed. When only some of the chelation sites are used the term ‘poorly liganded’ is used. The author asserts that poorly liganded ferrous ions modify the “comparatively harmless hydrogen peroxide into the deadly hydroxyl radical”.

The list of neurodegenerative diseases that have been identified as having a possible causal link with poorly liganded iron includes; stroke, Alzheimer’s disease, Parkinson’s disease, multiple sclerosis and Huntington’s disease.

The review further describes poorly liganded iron and chelation in the body, and its effects. It is shown how the amount of the oxidised form of iron can be tested for by using blood or urine samples. The effect of poorly liganded iron on inflammation, and in causing bacteria and virus death is also reported. Discussion related to poorly liganded iron and its association with chemical toxins is present, while dietary and pharmaceutical treatments are also discussed.

What were the basic results?

The author asserts that certain types of iron-chelating natural ingredients found in foodstuffs have protective effects for the body. He believes that these effects are produced by the iron chelating, as well as directly antioxidative properties of the molecules.

He highlights that polyphenols and the pigment anthocyanin found in some fruits have a chemoprotective affect against cancer in mice. He also identifies that polyphenols can be found in green tea and curcumin, which is a constituent of turmeric.

Although the precise molecular mechanisms and their effects are unknown, as are the factors affecting them in many cases, the author asserts that iron’s association with degenerative diseases is difficult to refute because of previous research. He also accepts that a lot of science involves finding patterns in observable data even when no association has been discovered.


Although The Daily Telegraph wrote a balanced piece of journalism and had quotes and input from all sides of the debate including organisations that deal with Alzheimer’s disease, its headline “Eating purple fruit could fend off Alzheimer’s Disease and Multiple Sclerosis” is not known to be true. Presently it is just a theory. Yet The Daily Telegraph wrote it as a fact and in addition added other unproven theories such as “hydroxil radicals cause degenerative disease” as fact too.

The newspaper further stated with certainty that purple coloured foods are helpful by soaking up harmful iron compounds and could help fight off Alzheimer’s disease, multiple sclerosis and Parkinson’s disease.

It is still too early to say with any certainty that poorly liganded iron has an association with a group of neurodegenerative diseases. As a theory to be challenged it has advanced learning and knowledge. An increased understanding generated from such research is crucial. Learning about iron chelation does appear to be a promising route to follow for future research.

The issue now is to find proof that dietary or pharmaceutical intervention could be beneficial to sufferers of neurodegenerative diseases. Further research into whether iron chelations in humans can be affected by elements or compounds found in food, whether purple skinned or not is essential. There are no quick fixes on the horizon, the research is likely to be long term.


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