31 Blood Facts That Will Surprise You

By Karin Lehnardt, Senior Writer

Published July 12, 2024

Approximately 7–8% of a person's total body weight is blood._[1]
An average adult has about 4.7 liters, or 5 quarts, of blood. That's equivalent to about 13 cans of soda._[1]
The World Anti-Doping Agency lists blood as a prohibited substance, even if the transfusion is autologous (someone re-infusing his or her own blood) or heterologous (blood from another species)._[3]
Bloodwork is one of three primary diagnostic tools for physicians. The other two tools are imaging and a physical exam._[3]
Adult human bone marrow produces 2 million red blood cells every second._[3]
In the human body, blood travels approximately 60,000 miles a day, which is over twice the circumference of Earth._[3]

After Perseus beheaded Medusa, Pegasus and Chrysaora were born from her blood

Medusa had two types of blood. The blood on her left side was lethal, while the blood on her right side gave life._[3]
A blue whale's heart beats 5 times a minute. A shrew's beats about 1,000 times per minute._[3]
Goethe called blood an "amiable liquid."_[3]
People with type O blood are more susceptible to cholera._[3]
The Nazis believed that type A blood was superior and type B was inferior._[3]
In 1668, when blood transfusions were becoming more common, physicians believed that the spirit of the animal or person was transferred along with their blood._[3]
Shakespeare included the word "blood" over 40 times in his play MacBeth, and it appears at least once in every play._[2]
Maternal blood volume increases by 25% by the 20th week of pregnancy._[9]
American presidents have a limousine nicknamed "The Beast." Inside is a fridge containing a supply of the president's blood type, just in case._[5]
Blood has four main parts: red blood cells, white blood cells, plasma, and platelets._[1]

Blood has four main components: plasma, red blood cells, white blood cells, and platelets

Plasma makes up half of your blood. Plasma is about 90% water, which helps plasma move through the body easily._[3][6]
Platelets are the smallest of the blood particles. Platelets are originally shaped like little plates, but when they are exposed to air, they start to stretch and block blood flow to an injury._[6]
Because blood is more than just a liquid and contains living cells, it is actually considered a tissue._[6]
A centrifuge is a machine that spins blood to separate it into its three main parts. The top half (55%) is plasma, the bottom segment (45%) is hemoglobin, and the middle is white blood cells and platelets (1%)._[6]
In the human body, blood is always red and never blue, as some people think. It might look blue because some veins look blue under our skin._[6]
The human heart pumps the equivalent of two thousand gallons of blood a day._[6]
The medical community agrees that drinking raw blood has no health benefits. It does, however, pose severe health risks, including contracting blood borne illnesses, such as hepatitis C, HIV, norovirus, and more. Ingesting large amounts of iron can also be toxic._[6]

Lamashtu is often associated with blood

In 5000 BC, people in Mesopotamia (modern-day Iraq) believed in Lamashtu, a female goddess who stole babies from women and sucked their blood._[6]
Red blood cells live for about 4 months, platelets for 9 days, and white blood cells range from a few hours to a few years._[6]
Humans have 4 major blood types (A, B, AB, O). Cows have 11 groups, with one group containing over 60 subtypes._[6]
When Pope Innocent VIII was dying at the end of the 15th century, his physicians allegedly bled three young men to death and fed their blood to the pope. They believed the blood would pass on their youthful health._[6]
The cornea has no blood supply, which helps keep it clear for vision. Cartilage also has no blood supply._[10]
Canadian surgeons were surprised when they cut into a patient and found he had green-black blood. It was due to his migraine medication._[7]
Most major cities in the world have a vampire community that feasts on blood._[8]
After Bayer realized they had HIV and Hepatitis C contaminated blood supplies in the 1980s, they pulled it from the American market and sold it to Asia and Latin America._[4]