• Question: Do we produce less red and white blood cells when we're are older

    Asked by Finn to Carolyn, Peter, Richard, Sara, Siana on 12 Nov 2015.
    • Photo: Richard Unwin

      Richard Unwin answered on 12 Nov 2015:

      We carry around the same number of white cells between the ages of 20 and 70 – about 7,500 per millilitre of blood, although there is some evidence that numbers can decrease slightly after that age.

      It’s a similar story for red blood cells, with about 5-6 million per ml of blood in healthy adults but a slight drop after the age of around 70.

    • Photo: Carolyn Nielsen

      Carolyn Nielsen answered on 13 Nov 2015:

      Good question, Finn! We definitely produce fewer T cells, which are an important type of white blood cell, from the thymus when we get older. The thymus is an organ that’s part of your immune system and it’s where T cells develop before they are released into the blood. This process that’s associated with lower production of T cells during ageing has the fancy name of ‘thymic involution’. We think this is one of the reasons that elderly people are more at risk from infection.

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