Dietary Factors Affecting Red Blood
The availability of two B-complex vitamins—vitamin B
folic acid—signiF cantly inﬂ uences red blood cell production.
These vitamins are required for DNA synthesis, so they are
necessary for the growth and division of all cells. Cell divi-
sion is rapid in hematopoietic tissue, so this tissue is espe-
cially vulnerable to deF
ciency of either of these vitamins.
Lack of vitamin B
is usually due to a disorder in the stom-
ach lining rather than to a dietary deF ciency, because pari-
etal cells in the stomach secrete a substance called
required to absorb vitamin B
Iron is required for hemoglobin synthesis. Although
much of the iron released during the decomposition of hemo-
globin is available for reuse, some iron is lost each day and
must be replaced. Only a small fraction of ingested iron is
absorbed. Iron absorption is slow, although the rate varies
with the total amount of iron in the body. When iron stores
are low, absorption rate increases, and when the tissues are
becoming saturated with iron, the rate greatly decreases.
summarizes the life cycle of a red blood cell.
summarizes the dietary factors that affect red
blood cell production.
Low blood oxygen
Red bone marrow
Low blood oxygen causes the kidneys and liver to
release erythropoietin. Erythropoietin travels to red bone marrow and
stimulates the production of red blood cells that carry oxygen to tissues.
Globin + Heme
Red blood cells
about 120 days
Iron + Biliverdin
Life cycle of a red blood cell. (
) The small intestine absorbs essential nutrients. (
) Blood transports nutrients to red bone marrow.
) In the red bone marrow, red blood cells arise from the division of less-specialized progenitor cells. (
) Mature red blood cells are released into the
bloodstream, where they circulate for about 120 days. (
) Macrophages destroy old red blood cells in the liver and spleen. (
) Hemoglobin liberated
from red blood cells is broken down into heme and globin. (
) Iron from heme returns to red bone marrow and is reused. (
) Biliverdin and bilirubin
are excreted in bile.