Donating Blood

I read a lot of running blogs. I love them! From the newbies that are discovering running to the super speedy people I wish I could be more like... I read them all :)

Reading all these blogs, I recently realised I don't remember any of them talking about having donated blood. I'm definitely not saying they're horrible people - NO. But I was wondering if they don't donate because it's bad for training.

A one unit blood donation is approx 10% of your body's blood. While the volume of blood is replenished in the next few days after a donation, the red blood cells take longer to replace (almost 3 weeks in some cases).

I know that after I donate blood, I sometimes feel woozy and light-headed. I once blacked out after a donation and the nurses on duty put ice on my face & neck and they said that brings up blood pressure and stopped me fainting.
I also know that in the few days after a donation I feel really sleepy and very different. I can tell that something's wrong if I go to the gym too soon or push myself physically.

It seems my heart rate is affected as well! I took my HR in class, after I had been sitting down for about an hour. I shouldn't have been stressed, but my HR was at about 80 the few times I counted (it is usually 58 or lower).

I wanted to read about the science behind it, so I read a few articles.

1) It seems there's a theory that if you donate regularly, your body gets better at re-generating RBCs (red blood cells) and you can make more, quicker. This would be useful when you're not donating, as it would help to have some extra little red guys while exercising.

2) Regular blood donation does not seem to decrease your iron levels. However, this study did identify that it is important to take supplements to ensure you do not develop anemia.

3) There have been a bunch of studies on elite athletes that show that performance is affected by donating blood. I guess things like VO2 and aerobic levels would be affected, but I remember reading that strength isn't affected too much.

4) Tea affects iron absorption. Did you know that??! I checked out an article and it says that tannins in tea affect the way the body absorbs iron. However, if you drink tea regularly your body has adapted to the tannins and blocks their effect.... so it wouldn't really affect iron absorption. Hmm.

5) Did you know that Vitamin C helps iron absorption?! If you are low on iron you should eat spinach or beans or meats AFTER you eat an orange :)


I'm sorry I forgot to keep the links for your guys' further reading, but take my word that I'm not trying to twist the truth :)
Donating is good for other people, but I don't think it's necessarily good for the donor (unless they take care of themselves!)

Please tell me about your theories on blood donations, effects of it on the body or if you've heard anything different!!