Like any part of the body, the blood can also be afflicted with
diseases and disorders that can compromise your health. Disorders of
the blood range from mild, with no symptoms, to life-threatening
medical emergencies.
The majority of the blood is plasma, which accounts for about half
of the blood volume. Plasma is mostly water and contains dissolved
salts and proteins, as well as hormones, electrolytes, fats, sugars,
minerals, and vitamins. The other components of blood include:
- Red blood cells—Red blood cells are responsible
for carrying oxygen from the lungs to all other cells in the body, and
for transporting carbon dioxide back to the lungs. Red blood cells are
produced in the bone marrow. Each red blood cell has a life cycle of
about 120 days, at which point they wear out and are destroyed in the
spleen. Red blood cells are able to transport oxygen because of
hemoglobin, an iron-containing molecule that binds to oxygen. About 90
percent of each red blood cell is hemoglobin, and each molecule of
hemoglobin can carry four molecules of oxygen (Eastern Kentucky
University 2005).
- White blood cells—White blood cells are the
backbone of the immune system. They fight infection by engulfing
invading organisms or abnormal cells. There are five basic kinds of
white blood cells: neutrophils, monocytes, lymphocytes, eosinophils,
and basophils. Neutrophils are the most common form of white blood cell
and are responsible for fighting infection.
- Platelets—Platelets are responsible for
blood clotting. They circulate constantly in the bloodstream. In the
event of an injury, platelets gather (aggregate) at the injured site
and touch off a chemical reaction that results in a blood clot.
Abnormal platelet function may result in increased bleeding or the
formation of dangerous blood clots where they don’t belong, which can
cause a heart attack or stroke.
In this chapter, we will review three blood disorders—anemia (low
red blood cells), leukopenia (low white blood cells), and
thrombocytopenia (low platelets). We will address how these disorders
are diagnosed and conventionally treated and how to support the health
of your red blood cells, white blood cells, and platelets with
nutrition.
What Is Anemia?
Anemia is a common blood disorder characterized by a decrease in the
amount of red blood cells, or a decrease in the capacity of red blood
cells to transport oxygen. This results in a lack of oxygen reaching
the body’s cells and tissues. Referred to as the “hidden hunger” by the
World Health Organization, anemia poses significant health risks
worldwide. It affects between 2 percent and 15 percent of people in the
United States (Abrahamian FM et al 2005). Women are about twice as
likely to be anemic as men. This is especially true of premenopausal
women; between 4 percent and 8 percent of premenopausal women have iron
deficiency anemia (Abrahamian FM et al 2005; Conrad ME 2005).
Anemia is associated with poor health outcomes. In patients who have
had a heart attack, anemia sharply increases mortality (Wu RC et al
2001), and it is a strong predictor of overall mortality in the
elderly. Over a 5-year period, anemic people aged 70 to 79, 80 to 89,
and 90 to 99 were 28 percent, 34 percent, and 48 percent, respectively,
more likely to die than people of the same ages who were not anemic.
Stroke is commonly associated with anemia (Kikuchi M et al 2001).
Anemia is associated with the following symptoms (Abrahamian FM et al 2005):
- Weakness and fatigue
- Irritability
- Shortness of breath
- Headaches
- Sore tongue and bleeding gums
- Pallor
- Nausea and loss of appetite
- Faintness and dizziness
- Confusion and dementia
- Increased heart rate
- Heart failure (in severe cases)
Depending on its cause, anemia is generally classified in three
ways: excessive bleeding, decreased red blood cell production, or
increased red blood cell destruction.
Excessive bleeding
This form of anemia occurs when someone loses too much blood, either
because of an injury (acute anemia) or a chronic disease. When the body
loses a large amount of blood, the body reacts by pulling water from
surrounding tissues into blood vessels to maintain a healthy blood
pressure. This dilutes the blood, lowering the proportion of red blood
cells.
Excessive bleeding can result in very serious anemia, depending on
the nature of the injury. Acute anemia that involves the rapid loss of
great volumes of blood can result in heart attack or stroke (Beers MH
2003). However, anemia related to chronic conditions, such as recurrent
nosebleeds or ulcers in the stomach, develops more slowly and may not
be as obvious. This type of anemia sometimes occurs as a result of
cancer, especially colon cancer.
Chronic blood loss can cause a deficiency in iron. Iron deficiency
anemia is the most common form of anemia (Leung AK et al 2001; Rasul I
et al 2001), affecting about 2 billion people worldwide (Lynch SR
2005). It results in decreased red blood cell production.
Because it can take several months to deplete the body’s supply of
iron, it might take a long time for symptoms to develop. Iron
deficiency anemia caused by blood loss is one of the most common forms
of anemia in the United States (Beers MH 2003). In women, this
condition is frequently related to excessively heavy menstrual
bleeding; in men, it is often related to gastrointestinal bleeding.
Decreased red blood cell production
Red blood cells are manufactured in the bone marrow. This process
relies on various nutrients, including iron, vitamin B12, and folic
acid, as well as smaller amounts of vitamin C, riboflavin, and copper.
Also, the production of red blood cells is stimulated by a hormone
called erythropoietin. Deficiencies in any of these nutrients or in
erythropoietin can result in anemia. Besides iron deficiency anemia
caused by bleeding, other forms of anemia include:
- Pernicious anemia (vitamin B12 deficiency)—It is
estimated that 300,000 to 3 million people in the United States have a
vitamin B12 (cobalamin) deficiency (Diamond AL et al 2004). Vitamin B12
deficiency is rarely related to a dietary deficiency. Rather, vitamin
B12 relies on intrinsic factor, a protein generated by cells in the
stomach, to be bound to vitamin B12 and then absorbed in the ileum, the
last segment of the small intestine. People who lack intrinsic factor
cannot use the available vitamin B12, meaning that anemia can develop
even if large amounts of vitamin B12 are consumed. Besides a lack of
intrinsic factor, pernicious anemia can be caused by Crohn's disease,
stomach surgery, or a strict vegetarian diet. Breast-fed infants of
vegan mothers are particularly at risk of vitamin B12 deficiency.
- Folic acid deficiency anemia—Folic acid is
abundant in green leafy vegetables. Because many people in
industrialized countries don't eat enough vegetables, folic acid
deficiency is more common than pernicious anemia. Folate deficiency is
found in malnourished individuals (especially alcoholics), infants who
are fed only cows’ milk, pregnant women, and adults over age 60. It can
also be caused by diseases that affect absorption in the small
intestine, including Crohn's disease.
- Anemia of chronic disease—Anemia is
associated with various chronic diseases and conditions, including
infections, inflammatory diseases, and cancers that affect the ability
of the body to produce red blood cells (Brill JR et al 2000; Bron D et
al 2001). Diseases or conditions that are associated with anemia
include cancer (Gillespie TW 2003; Knight K et al 2004), HIV/AIDS
(Sullivan PS et al 1998), and testosterone deficiency (Bain J 2001;
Zitzmann M et al 2000). In patients with cancer or HIV/AIDS, anemia is
associated with increased mortality (Buskin SE et al 2004; Caro JJ et
al 2001). Testosterone deficiency can cause anemia because the hormone
helps stimulate kidneys and bone marrow to produce erythropoietin and
stem cells. Symptoms of testosterone deficiency include decreased
libido, impotence, infertility, fatigue, and decreased muscle mass and
strength (Baker HWG 1995).
Additionally, aplastic anemia is a rare form of anemia that occurs
when bone marrow fails to produce all three types of blood cells: red
blood cells, white blood cells, and platelets. Causes of aplastic
anemia include autoimmune diseases, viruses, or chemicals (e.g.,
benzene or pesticides). Symptoms include frequent infections (white
blood cells are reduced), fatigue (red blood cells are reduced), and
bleeding (platelets are reduced).
Increased red blood cell destruction
If the rate of red blood destruction is more rapid than the creation
of new red blood cells, hemolytic anemia occurs. This form of anemia is
less common than the other two. Hemolytic anemia can result from
infection, certain drugs, autoimmune disorders in which the body
attacks and destroys its own red blood cells, and inherited disorders
such as sickle cell anemia or thalassemia.
Additionally, an enlarged spleen can result in anemia. The spleen is
responsible for destroying old red blood cells; an enlarged spleen can
increase the rate of red blood cell destruction beyond the body’s
ability to manufacture new red blood cells.
Sickle cell anemia is the most common inherited blood disorder in
the United States, affecting 1 in 500 African Americans and 1 in 2000
Hispanics of Caribbean or South or Central American descent (Pegelow C
et al 2004). In this disease, the red blood cells are abnormally shaped
(they resemble boomerangs), and their blood carrying capacity is
reduced. These cells are fragile and break up as they travel through
blood vessels, resulting in a reduced red blood cell count.
Thalassemia occurs when there is an imbalance in the production of
one of the amino acid chains that makes up hemoglobin. Many people who
have thalassemia also have mild anemia.
Autoimmune disorders can cause anemia if the body identifies red
blood cells as invader pathogens and attacks them. In most people, the
cause of autoimmune anemia is unknown (Beers MH 2003).
Diagnosing Anemia
Anemia is typically diagnosed with a complete blood count (CBC)
test. Anemia is defined as a decreased number of red blood cells, a
decrease in the quantity of hemoglobin, or a lowered hematocrit (the
ratio of red blood cells to whole blood). The following Table shows the
reference ranges for these measurements.
Reference Ranges for Blood Indicators*
|
Indicator |
Men |
Women |
|
Red blood cell count |
4.10-5.60 (×106/µL) |
3.80-5.10 (×106/µL) |
|
Hemoglobin |
12.5-17.0 (g/dL) |
11.5-15.0 (g/dL) |
|
Hematocrit |
36%-50% |
34%-44% |
|
*µL=microliter; g/dL=grams per deciliter. |
If initial blood tests analyzing hemoglobin, red blood cell count,
or hematocrit indicate anemia, additional testing should be done to
determine the cause of anemia (Brill JR et al 2000). Additional tests
may include:
- Stool tests—If a person has symptoms of anemia and
has noticed bleeding, a physician may test for the presence of blood in
the stool, which can indicate chronic bleeding that would cause anemia.
- Iron deficiency tests—Iron deficiency is
best diagnosed by blood testing (Uthman E 2005). Additionally,
physicians may test for levels of transferrin (a protein that carries
iron) or for ferritin (a protein that stores iron).
- Other tests—Laboratory tests for vitamin
B12 anemia are usually based on low serum vitamin B12 levels or
elevated serum methylmalonic acid and homocysteine levels (Baik HW et
al 1999). Similarly, folic acid levels can be measured to detect a
deficiency in folic acid.
Managing Anemia
Management of anemia depends on the cause. If anemia is caused by
chronic bleeding, for example, the goal is to stop the bleeding; the
anemia may then resolve on its own. For instance, in patients with
HIV/AIDS, anemia can be treated by temporarily suspending treatment
with the antiretroviral drugs used to attack the virus. In extreme
cases of acute blood loss, a transfusion may be necessary to raise the
red blood cell count.
In some cases, anemia is treated by prescribing erythropoietin, a
hormone that stimulates red blood cell production. Erythropoietin is a
very expensive drug that is sometimes used to treat severe anemia
caused by chemotherapy, certain anti-HIV drugs, testosterone
deficiency, or chronic kidney failure. Erythropoietin, taken along with
iron, may help reduce the need for a red blood cell transfusion. It is
particularly important to supplement erythropoietin with iron because
erythropoietin causes the iron to be utilized to form new red blood
cells. A poor result may occur if an iron supplement is not prescribed
concurrently with erythropoietin.
If the anemia is caused by a genetic disorder (such as sickle cell
anemia), blood transfusions may be used to raise the red blood cell
count while other drugs are prescribed to treat the genetic disorder
itself.
Nutritional Support
Some forms of anemia respond well to nutritional therapy, including anemia caused by iron deficiency or folic acid deficiency.
Iron
In the United States, dietary iron
deficiency is rare because of a diet high in iron-rich foods such as
red meat, beans, egg yolks, whole-grain products, nuts, seafood,
iron-fortified cereals, dark green leafy vegetables, and dried fruit.
However, some people in the United States have a higher need for iron,
including children, pregnant or menstruating women, strict vegetarians,
and long-distance runners.
Oral iron supplements are available to treat iron deficiency anemia.
However, gastrointestinal malabsorption syndromes may require the
intramuscular or intravenous injection of iron dextran (Imferon) by a
physician. Iron protein succinate (sold as a drug in Germany) may be
the most effective oral treatment of iron deficiency anemia. This form
of iron has been evaluated in multicenter clinical trials to determine
efficacy and tolerability (Kopcke W et al 1995). The following effects
were seen in anemic adults after only 60 days:
- 23 percent increase in percentage of red blood cells (hematocrit)
- 30 percent increase in blood oxygen-carrying capacity (hemoglobin)
- 6 percent increase in total number of red blood cells
One new and novel approach to iron supplementation is the use of
ferritin, a protein that is involved in the storage of iron and can be
found naturally in foods like beans. Newer studies have shown that
ferritin supplementation may be able to boost iron levels without the
side effects associated with iron supplementation (Theil EC 2004). In
one study, a ferritin complex was shown to be effective in children who
had anemia that was caused by hemodialysis (Warady BA 2005).
Folic acid
The recommended daily requirement of
folate is difficult to obtain from food sources alone. Symptoms of
folic acid deficiency may include diarrhea and other gastrointestinal
problems. Because supplementation with folic acid can mask a vitamin
B12 deficiency, folic acid and vitamin B12 should be taken together.
Anemia caused by folic acid deficiency normally responds quickly to
oral folic acid and vitamin B12 supplementation. Anticonvulsants,
antituberculosis drugs, alcohol, and oral contraceptives have been
associated with low serum levels of folate (Lambie DG et al 1985).
Vitamin B12
In pernicious anemia, the body lacks
intrinsic factor, which is needed to carry vitamin B12 from the
digestive tract into the bloodstream. This condition often affects the
gastrointestinal tract and the nervous system, with symptoms that range
from weakness to vertigo to angina. Vitamin B12 is available as a
supplement in multiple forms, including cyanocobalamin and
methylcobalamin. The conventional treatment for pernicious anemia is an
intramuscular injection of cyanocobalamin, often followed by lifelong
supplementation with vitamin B12.
One study, however, showed that subjects given 1500 micrograms (mcg)
of methylcobalamin orally daily for 1 to 3 months experienced prompt
correction of their anemia, with recovery of neurological disturbances
observed after 1 month and recovery of hemoglobin and serum
concentrations within 2 months. These results imply that orally
administered methylcobalamin may be as effective as traditional vitamin
B12 injections for treatment of pernicious anemia (Takasaki Y et al
2002). If, however, red blood cell levels fail to respond to treatment
with methylcobalamin, conventional treatment should be sought.
Copper, zinc, and selenium
Trace minerals can be
an adjunctive nutritional therapy to reduce the effect of anemia on
normal red blood cell function. Copper, zinc, and selenium are used in
biochemical processes such as cellular utilization of oxygen, DNA and
RNA reproduction, maintenance of cell membrane integrity, and
sequestration of free radicals (Chan S et al 1998).
L-carnitine
Patients with anemia caused by
end-stage renal disease respond to therapy with L-carnitine. In one
study, L-carnitine therapy increased hematocrit and decreased
resistance to erythropoietin (Horl WH 2002).
Testosterone therapy
Anemia associated with
testosterone deficiency can be addressed with testosterone replacement
therapy, which can stimulate erythropoietin production and increase
hematocrit. Potential candidates for testosterone replacement therapy
should undergo a complete physical examination including a complete
medical history and a hormone profile (Morales A et al 2000).