I believe that are we progress in knowledge we will keep rediscovering ancient knowledge. We now have tools that allow us to share knowledge and move closer to the Truth. I will blog more on this topic later (Pyramid of Truth), but right now I would like to speak on the subject for health. In systems theory all things affect all other things in unpredictable ways.
In The 4 Hour Body book, link, he mentions that give blood regular may have additional health benefits, especially for men (women’s menstrual cycle may have a similar effect) since blood have hold toxins that are introduced to the body. The ancients Greeks believed in the balance of the four fluids of the body. And during the dark ages “Blood letting” was a common practice as a cure for a variety of aliments. And during the industrial revolutions till now it was considered barbaric and ignorant. Now we are relearning that maybe there weren’t too wrong.
The bottom line is donate blood is good for the overall society. You might save a life. In addition there are other reasons and it might be healthier for you to give blood. Yes, there are stories about getting infected during blood donation, but I for one believe it to be safe.