Iron tablets cause DNA damage in blood vessels

Iron tablets taken by millions of people could damage the body within just 10 minutes, a study has warned.

Tests showed the mineral rapidly causes DNA damage in blood vessels.

While they were carried out in a lab setting, rather than living people, researchers found the levels of iron given in supplements may be too high and harmful.

Iron supplements may contain 10 times more than is necessary for health, the researchers said.

In future, doctors may want to think carefully about prescribing the minimum dose of iron necessary to patients who need it, researchers said.

Iron is an essential element for life. Many women take the supplement after pregnancy and it is used as a treatment for anaemia, a condition caused by low levels of the mineral.

Dr Claire Shovlin, senior author of the study, at the National Heart and Lung Institute at Imperial College London told MailOnline that men need an average of 8.7mg of iron a day, and women who are menstruating need around 14.8mg a day.

A 100g of steak has 3 mg of iron, while the same weight of spinach contains 2.7 mg.

It would be extremely difficult for a person to consume more than 20mg of iron from their diet, Dr Shovlin said.

Low dose supplements that can be bought over the counter at pharmacies and supermarkets typically contain around 14mg - the equivalent of a day's intake.

But if a person develops anaemia they may be prescribed higher dose tablets by their doctor.

These can contain up to 65mg of iron.

Dr Shovlin and her team tested the effect of such high doses of the mineral on human endothelial cells – which line arteries and veins.

She treated the cells with an iron solution comparable to that seen in the blood after taking one prescription iron tablet.

Within ten minutes, she found cells treated with the solution showed signs of damage.

Their DNA repair systems were activated, and were still activated six hours later.  

 'All of the body's cells have DNA repair systems that can fix all sorts of things in cells,' Dr Shovlin explained.

'But when we added iron, we saw that these systems had to work harder than normal.'

It is not yet known whether damage to blood vessels in a laboratory setting would translate to harm to humans' circulatory system, she said.

It does indicate that cells are more sensitive to iron than previously thought, she added.

Dr Shovlin and her team decided to focus on iron after reports that a small proportion of people using iron tablets for the condition hereditary haemorrhagic telangiectasia, which causes abnormalities in the blood vessels reported side effects.

They found their nose bleeds got worse after iron treatment.

She stressed that prescribed iron supplements are essential for many patients and urged people not to stop taking their tablets.

She said: ‘We're not at the stage yet where we would advise doctors to change their approach to prescribing iron supplements. 

'Many people need extra iron - it is crucial to allow our bodies to function properly - and anyone with any concerns about their iron supplements should talk to their healthcare provider.

‘However, this study helps to open the conversation about how much iron people take.

‘At the moment, each standard iron tablet contains almost 10 times the amount of iron men are recommended to eat each day - and these dosages haven't changed for more than 50 years. 

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