Who here has ever taken a new health supplement, seen no effects after a month, and stopped taking it? I have!!! Maybe you've tried Hoodia, or EFA's, or greens, or antioxidants?
Well, I know now, that I shouldn't do that anymore. The reason the lifespan of a red blood cell is important, is that when taking any new supplement, you should give it 4 months before you decide if it's helping, because red blood cells last 4 months before they die, and are replaced by your body. As a red blood cell ages, it becomes more difficult for it to carry oxygen and nutrients to the cells, so that supplement may not be fully delivered to your cells after only 1 month, because only 1/4 of the red blood cells are fully saturated with it.
Now, unfortunately, I can really find any good resources that explain this function on the internet to provide you with a reference. I heard this for the first time from a scientist on a nutrition audio CD, and then I asked my endocrynologist, and my cardiologist, who both confirmed it for me. They both know I take a lot of health supplements. I did find a good link that has a little bit about red blood cells in general though for you:
Red blood cell - Wikipedia, the free encyclopedia