Giving blood could have some surprising benefits, including protecting against leukaemia, heart attacks and high iron levels
Giving blood may seem like a selfless act, but some donors could be getting health benefits themselves.
There has long been speculation that giving blood helps protect people from heart attacks and strokes.
Now, research has suggested that people who are frequent blood donors have a lower risk of leukaemia.
Leukaemia is a form of cancer, when cells in bone marrow, which produce the blood’s immune cells as well as oxygen-carrying red blood cells, start multiplying out of control.
Frequent blood donors
The new research involved studying the immune cells of older German men, who had donated blood at least a hundred times in their lives. They were compared with similar men who had rarely given blood.
The immune cells of both groups had undergone genetic mutations, which tend to accrue in all parts of the body as people get older. “As cells divide, they acquire mutations – this is a natural process,” said lead researcher Dr Hector Huerga Encabo, an immunologist at The Francis Crick Institute in London.
The non-donors had mutations that would make leukaemia more likely. But the frequent blood donors had less “pre-leukaemia” mutations. In fact they had mutations that would make their bone marrow better at replenishing red blood cells.
While the findings need to be confirmed by further research, “it is a possibility that blood donation decreases the pre-leukaemia mutations”, said Dr Huerga Encabo. The work has been published in the medical journal, Blood.
Previously, scientists had speculated that giving blood many times might raise the risk of leukaemia, by making bone marrow cells multiply more, which could encourage cancerous mutations.
But it now seems that frequent blood donations actually push bone marrow cells down a route of making more red blood cells instead of a cancerous pathway, said Dr Huerga Encabo.
“This is an interesting paper, though the sample size is small, so further work is needed before conclusions can be drawn,” said Dr Lise Estcourt, NHS Blood and Transplant Medical Director for Transfusion, who was not involved in the research.
“The study suggests that when people give blood on a really regular basis it does not lead to harmful genetic changes, and suggests the changes seen may lead to the production of more healthy red blood cells.
“Further work is needed to know whether donation causes the beneficial genetic changes or whether we are only seeing the ‘healthy donor effect’, where donors tend to be healthier than average because healthier people tend to donate.”
The new findings also support the results from a past Swedish study which found that blood donors experienced the most common kind of leukaemia, called AML, at a 15 per cent lower rate than people who rarely gave blood.
The blood donors did have a 7 per cent higher risk of a less common form of leukaemia called CLL, but put together, the figures suggest that blood donors would have an overall lower risk of leukaemia, said Dr Huerga Encabo.
Heart attacks
Blood donation may also protect people from heart disease and strokes – perhaps by making the person’s remaining blood less prone to clotting.
The theory is not yet confirmed, but in a review of the evidence from 2022, nine studies found blood donors had a lower risk, while in five studies there was no difference.
A definite benefit of blood donation, however, happens with people who have a genetic condition called haemochromatosis, which causes raised iron levels. This can damage the liver, heart and joints and can cause premature death.
The recommended treatment for haemochromatosis is to give blood, as often as every six weeks, which lowers iron levels. People without the condition should only give blood every three months, if they are men, and every four months if they are women, according to NHS guidelines.
In the UK about 1 in 100 people are diagnosed with haemochromatosis but the real figure could be higher, as there is no screening for the condition. Among people who are newly diagnosed, a surprising number are regular blood donors, having unconsciously found that the procedure relieves their joint pains.
For everyone else, the effects of giving blood are usually just temporary tiredness or dizziness, from the slight fall in blood pressure. Blood pressure returns to normal within a few hours.
For those who receive a blood transfusion, however, for instance after surgery, childbirth or illnesses such as cancer, it can be life saving.