Sat, Oct 14, 2017 - Page 8 News List

A rational look at blood donation

By Emilio Venezian

It would be welcome indeed if people providing information and drawing conclusions from it were to provide some of the relevant context, or if reporters were to supply the missing context.

An article on blood donations is a case in point (“Caffeine affecting blood donations,” Oct. 4, page 4). The article attributes to Hou Sheng-mou (侯勝茂), director of the Taiwan Blood Services Foundation, the following information: In 2014, 185,982 people aged 17 to 20 donated blood, a drop of 39 percent from 2005, when 303,595 people in that age group donated blood.

Then the article attributes to Li Lei (黎蕾), public relations director at the foundation, the statement that a decade ago, the stated age group made up 20 percent of all donations, but recently that has dropped to 10 percent, adding that low hemoglobin could be the reason that 14 percent of the donated blood is rejected.

The headline is, at best, misleading. None of the numbers provided have a bearing on the number of donors turned down for low hemoglobin content, changes in the consumption of caffeine in the relevant populations or the role of caffeine.

Yes, there is evidence that one cup of coffee taken at the same time as eating a hamburger reduces iron absorption in “iron replete humans” by 39 percent, but a cup of tea reduces it by 64 percent.

According to the Mayo Clinic, a US nonprofit medical practice and medical research group, the typical cup of regular tea contains from 25mg to 48mg of caffeine and a cup of regular coffee contains from 95mg to 165mg.

That raises two questions. The first is: Should we attribute the reduced absorption to caffeine if one-third of the dose produces twice the reduction? So why mention “coffee and other caffeinated variables” and not mention tea?

The second one is: If young people are drinking more coffee, might they not be drinking less tea, in which case the effect of the shift might have been positive instead of negative?

The statements about changes in the number of donors are not put in any relevant context.

We all know, in a general way, that the birth rate has been declining for some time. We all have read stories about the troubles that is likely to be causing for retirement funds and of the pressures it has already placed on schools and universities. What can we say about the relation of demographic change on blood donations?

The Ministry of the Interior kindly provided me with detailed data of population estimates at the end of 2005 and 2014. Those indicate a very small decrease in the population in the relevant age groups, so the decline in participation is 38 percent, not much different from that cited.

Had the numbers of donations experienced by the foundation been for 2000 and 2010, the decline in participation would have been reduced to 27 percent.

There might be other reasons for the change in participation, one of them being the changes on obligations of young people in relation to military service; such effects might be found with more detailed data.

According to the article, the donation rate urged by the foundation is 10 donations in 104 weeks “to sustain a stable blood supply.” That is an average of 10 weeks between donations.

The Web site www.blood.co.uk/the-donation-process/after-your-donation/how-your-body-replaces-blood/ recommends a minimum wait between donations of 12 weeks for men and 16 weeks for women in order to safeguard the health of the donors.

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