You may not feel like one, but technically speaking, you’re a ‘young blood’. No matter how old you are chronologically, no single red blood cell in your body is older than about 4 months.
Your blood is constantly being renewed, and if you look after yourself well and don’t become ill, at the age of 70 you could have a blood profile indistinguishable from that of a healthy 30-year-old.
The Red Cross Blood Service knows this, which is why it is willing to let people donate blood up to the age of 70. It will even take blood from those older than 70 if they have a letter from their doctor confirming that they are in good health. There is no formal cut-off date beyond that.
There is nothing wrong with an older person’s blood, and the routine age limit is there for the protection of the donor, not the recipient. As older people are more likely to have cardiovascular disease, donating blood may be risky for them. Such is the confidence of the Red Cross in older people’s blood that 3 years ago, when blood services were standardised across Australia, some States had their age limits lifted from 65.
Blood has an enormous capacity for self-renewal. Stem cells in the marrow and in the blood have the unique capacity not only to generate new blood but also to renew themselves. Blood does not deteriorate because you age; it deteriorates because diseases that interfere with it become more common with age.
The worst of these are the blood malignancies of leukaemia, lymphoma and myeloma that no-one yet knows how to prevent.
But while the blood in your veins is fresh, it bears many signs of what is going wrong in the rest of the body. From blood you can, for example, determine how low your level of hormones has sunk, how far over the cholesterol safety limit you are and whether you are a candidate for diabetes.
Importantly, you can also tell your body’s iron status. Iron can be a crucial determinant of how well you age. Too much can lead to cancer, while there is now an informed suspicion that too little may be linked to dementia.
If your body keeps accumulating iron and can’t get rid of it, you have what is known as haemochromatosis. There is too much iron in your blood and the excess is deposited in major organs. Australians have an unusually high potential for this disease, which begins insidiously and can end disastrously in liver cancer. Along the way it may cause general malaise, fatigue, joint pain, impotence and diabetes.
A study of the population around Margaret River in Western Australia found that one in seven people carry one gene for this disease. To have hereditary haemochromatosis you must have two genes. One in nineteen people have both genes. Most of them will accumulate excess iron and become unwell as a result. A quarter will develop liver problems. The tragedy of this is that haemochromatosis is easily diagnosed and just as easily treated. Next time you go for a routine health check, it is worth asking for a haemochromatosis blood test. You’ll be tested for the level of iron in your blood and for the gene. If you have the disease, you can control it simply by donating blood regularly. If you are diagnosed before the age of 40, you can avoid the discomfort of having a liver biopsy.
There is a common misconception that menstruation protects women from haemochromatosis for life. It doesn’t. Once past menopause, if they have the genes, women accumulate iron and catch up quickly. Too little iron, on the other hand, is a common cause of anaemia and there is now a suspected link between anaemia and dementia.
An anaemic person has low levels of haemoglobin, the protein that carries oxygen in the blood. This condition can be caused by other factors too, including a poor diet or vitamin B12 and folate deficiency. Even relatively mild long-term anaemia might have serious consequences for the brain. With age, the blood vessels to the brain can ‘harden’ and restrict the flow of blood, thereby depriving the cells of oxygen. This can compromise brain function and leave the person with what is known as vascular dementia. If the person is also anaemic, the problem is compounded. Not only is the volume of blood reaching the brain reduced, but it also carries less oxygen than it could.
About 20 per cent of Australians over the age of 75 are anaemic and often something simple can be done to correct it. However, because anaemia has many different causes, it is important to consult a doctor about which treatments are appropriate.
Current research suggests vascular dementia may be involved in a third or more of all dementia cases in Australia. It is possible that if anaemia could be diagnosed and treated earlier, fewer people would develop dementia. But once a person has dementia, treating their anaemia is not likely to cure it. At best it may relieve some symptoms.
It may be that the risks are greatest for people with cardiovascular disease and related factors such as high blood pressure and high cholesterol. If you are such a person, you could probably benefit from a more aggressive management of your condition so that rather than risking disease and dementia, you allow your perpetually youthful blood to work its miracles and keep you well and functional.
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