I started a Paleo diet around 3-4 months ago, I've had great external results so far, but I wanted to make sure that I didn't have any internal problems (high blood pressure, cholesterol, etc) so I went to the doctor for blood work this morning.
As the doctor was drawing my blood I noticed that it was particularly dark, much darker than I've seen before. I'm wondering if this has anything to do with my diet or if it is associated with something else (normal fluctuations, dehydration, etc.).
I have INR (prothrombin ratio and international normalized ratio) tests regularly (at least weekly) on my blood... and I have noticed that when my blood has a higher INR number, it is definitely lighter colored. The office I go to is always the same and the lighting is always the same.
High amounts of Vitamin K foods cause your blood to be able to coagulate quicker... that is how I control my blood coagulation is by manipulating Vitamin K intake and with meds.
So maybe you have a high Vitamin K content and have great coagulation... you could get an INR test on your blood to find out... they are cheap.
I am not a doctor, but I understand it like this: When you get a cut and bleed, blood will normally be bright red, being oxygenated or coming in contact with oxygen in the air. When you have blood drawn from your veins it will usually be oxygen depleted (on the way back to get more), and pulled into a vacuum sealed, sterile container, not in contact with oxygen, and appear much darker. In other words, it's normal.