What Foods are Good for My Immune System?

Topics
Introduction
What is my immune system?
Maintaining a healthy gastrointestinal barrier is
essential for optimal immune function
What nutrients support my immune system cells?
Protein and your immune system
The essential vitamins for healthy immune function
Minerals that support your immune system
Antioxidants and phytonutrients that promote
healthy immune function
Are there foods that are bad for my immune
system?
How do I keep a healthy 'balance' in my immune
system?
Weight-management, nutrient dense foods and the
immune system
What can I do to support and maintain a healthy
immune system?
Discussion
Introduction
Your ability to interact with the world around you
and remain healthy is dependent to a large extent
on the healthy functioning of your immune system.
Your immune system is responsible for fighting
foreign invaders to your body, like pathogenic
bacteria and viruses, and also for destroying cells
within your body when they become cancerous.
Poor nutrition has been shown to result in increased
infections, to slow healing from injury and
infections, and to increase susceptibility to
symptoms and complications from immune system
dysfunction. Science has shown that immune
function often decreases as we age, and recent
research suggests this decrease is also related to
nutrition and may be slowed or even stopped by
maintaining healthy nutrition.
Medical science has established that one of the
most important factors in supporting a healthy,
balanced immune system is good nutrition.
Research studies show that healthy eating can help
in keeping your immune system ready and capable
of functioning properly when necessary. The
World's Healthiest Foods provide the kind of
nutrition that supports your immune functions to
their fullest, while minimizing the agents that may
induce or activate your immune response when it
should not be active. Let's take a look at how the
World's Healthiest Foods support optimal immune
function.
What is my immune system?
Your immune system is like a finely tuned orchestra
whose purpose is to defend your body from
unhealthy insults from the world around you. Like
an orchestra, your immune system contains many
different instruments that work harmoniously
together with one goal, protecting you from foreign
insults that can cause damage to your body. And,
like an orchestra, the different parts of your
immune system must be present, play their part at
the right time, and then stop when they have
completed their function. The main parts of your
immune system are the immune cells, the structural
barriers in your body in which the majority of these
cells are localized, and the specific messenger
molecules that call the cells to action or tell them to
stop.
The cells of your immune system are quite varied,
and include the lymphocytes, or T-cells , which fight
invading molecules directly, and the B-cells , which
form antibodies that can respond to invading
molecules or toxins. The antibodies produced by
the B-cells can bind with a potentially damaging
molecule or to the surface of a virus or bacteria,
thereby targeting it for removal by other immune
cells. Your immune system also includes the
phagocytic cells, such as macrophages and
neutrophils , which remove the debris created from
destroying cells and tissue at the site of an
infection.
The cells of your immune system are found
circulating in your bloodstream or in the lymph
nodes, which are located throughout your body;
therefore, the immune cells themselves are spread
throughout your tissues and can travel quickly when
called upon. This way, your immune system is
positioned so that it can minimize the entrance into
your body of foreign invaders that can cause
infection and disease and can quickly respond to
any invaders that do manage to gain entrance into
your body.
Your immune system also relies upon specific
structures in your body that provide a foundation for
defense. The most important structures are the
barriers between the inside of your body and the
outside. These barriers keep unwanted organisms
and molecules from entering your body where they
can do damage. Since your skin is in contact with
the outside world, it is probably not surprising that
your skin is an important barrier; however, it is only
one part of your defensive barrier. Your
gastrointestinal tract is actually the largest barrier
between you and the outside world.
Your immune system also includes molecules called
soluble factors . These are molecules that can
recognize when your barrier has been compromised
by a foreign invader or toxin and then try to heal the
area of damage and remove the insult from your
body rapidly. Factors such as the complement
cascade , a complex group of proteins, can form an
immediate response to an insult. Your immune
system also can deploy signaling molecules, which
are soluble factors that send messages to the
immune cells located further inside the tissue that
has been compromised, or into your bloodstream.
These messenger soluble factors call immune cells
to the site of damage and activate the cells,
bringing them in full force to the infected area.
These messenger molecules are called cytokines .
Your cytokines not only signal immune cells to take
up action, but they also often promote an
inflammatory response. The inflammatory response
at a site of infection is one way your body secludes,
or walls-off, an infected area. For example, if you
have ever had poison ivy, or gotten a rash from
eating a food to which you are allergic, you may
have noticed the signs of inflammation -- redness
and swelling -- surrounding the affected area. So,
when we talk about the immune system, it is not
one organ; it is really the types of immune cells,
structures, and soluble factors, like cytokines, which
are present throughout all your organs that
constitute the immune system. And, your immune
system gets help from your inflammatory response.
Nutritionally supporting your immune system means
supporting all these sections in the orchestra.
Maintaining a healthy
gastrointestinal barrier is essential
for optimal immune function.
Of the physical barriers between your internal
organs and the outside world, your gastrointestinal
tract is of primary importance. The gastrointestinal
tract is like an internal skin, but it has about 150
times more surface than does your outside skin. It
also contains the largest number of immune cells of
your whole body, constituting approximately 60% of
your entire immune system.
It may be surprising that the gastrointestinal tract
has more of your immune system localized within it
than any other organ in your body; however, it has
a very difficult role. Your gastrointestinal tract
comes into contact with the largest amount and
number of different molecules and organisms of
any organ in your whole body. Just as an example,
the average person ingests more than 25 tons of
food over his or her lifetime.
And, unlike your skin or even your lungs, your
gastrointestinal tract must figure out how to keep
out damaging molecules and pathogenic organisms,
while still letting in the nutrients and food
components your body needs to survive. So, it has
to be selective in its protection. The gastrointestinal
mucosal layer has the unique role of keeping out
damaging molecules and organisms, like harmful
bacteria and viruses, while allowing in only the
health-promoting nutrients, molecules and
substances. In a perfect scenario, only the
beneficial nutrients and phytonutrients are absorbed
into the body, while non-beneficial substances and
organisms never make it across this barrier and are
excreted from your body.
The foods you eat can provide support for this
barrier or cause damage to it. For instance, alcohol
consumption is known to irritate the gastric
(stomach) mucosal barrier. Some drugs, for
example, the non-steriodal anti-inflammatory drugs
like aspirin and ibuprofen, also can harm this
barrier. Many nutrients in the World's Healthiest
Foods help to support a healthy barrier. Foods that
are high in phosphatidylcholine or its precursor,
choline, are particularly beneficial in supporting a
healthy gastrointestinal barrier since
phosphatidylcholine is one of the components of
the protective mucosa that lines your intestinal tract
and provides the first barrier defense. Studies have
shown that diets low in choline result in low levels
of phosphatidylcholine.
Maintaining healthy cells within the tissues that
constitute your barriers, including your
gastrointestinal tract is also vital for optimal health.
Vitamin A plays an important role in supporting the
cells of the skin, gastrointestinal tract and lungs '
the epithelial cells ' which constitute the main
barriers that separate you from the external
environment, plus vitamin A promotes the formation
of the protective mucous in your gastrointestinal
tract. Phosphatidylcholine is a component of your
cell membranes, and therefore choline-rich foods
also support healthy cell membranes. Essential fatty
acids, such as those found in cold-water fish, and a
healthy range of monounsaturated fatty acids, such
as those in olive oil, can also support healthy
gastrointestinal cells by promoting healthy
membranes.
Finally, foods high in fiber , such as whole, fresh
fruits and vegetables, promote a healthy
gastrointestinal system in several ways. They are
fermented by the friendly bacteria in your colon to
short-chain fatty acids (SCFAs), which are used as
a fuel by gastrointestinal tract cells. Studies have
shown that fibers that promote SCFAs also promote
a healthy gastrointestinal barrier. Fiber also
promotes the removal of toxins that can adversely
affect your gastrointestinal tract cells and supports
healthy digestive function overall.
What nutrients support my immune
system cells?
Research over the past ten years has shown that
nutrition plays a major role in supporting the
production and action of both the cells and the
soluble factors of the immune system. Protein,
antioxidants, essential fatty acids, and certain
vitamins, and minerals are all key to a healthy
immune system.
Protein and your immune system
Much research has shown that protein malnutrition
can have a variety of untoward effects on the
immune system. In fact, protein malnutrition may be
an important contributing factor in HIV
seroconversion (the process by which a person with
primary exposure to Human Immunodeficiency
Virus becomes infected with that virus). Research
studies have show that deficiency of high-quality
protein protein can result in depletion of immune
cells, inability of the body to make antibodies, and
other immune-related problems. In addition, animal
studies have shown that the immune system can be
significantly compromised with even a 25%
reduction in adequate protein intake.
Protein is composed of the 20 amino acids your
body needs for growth and repair, and some of
these amino acids appear to be particularly
important for immune functioning. For example, the
amino acids called glutamine and arginine are being
considered as nutrition therapy in pre-surgery
patients because of their ability to stimulate the
immune system. Interestingly, it is not just
deficiency of these amino acids that can
compromise the immune system, an imbalance in
the ratios among amino acids can also affect the
immune response.
Therefore, a diet that supports a healthy immune
system should contain foods providing high-quality,
complete protein, such as that found in eggs, fish,
and shellfish. Many vegetables and grains are also
excellent sources of many of the immune-
stimulating amino acids and, together with other
protein sources, are particularly beneficial. The
recipes on this web page provide many excellent
menus for a meal with complete protein, such as
the Baked Seafood with Asparagus , or Poached
Fish with Chinese Cabbage .
The essential vitamins for healthy immune
function
As discussed above, your body uses a variety of
responses to maintain its defense against harmful
pathogenic organisms in the environment; therefore,
it may not be surprising that nearly all of the
vitamins are necessary to maintain and promote
some aspect of your immune function. Some
vitamins have received more attention in the
research literature since they are particularly
important to a healthy immune system.
Much has been written about the role of vitamin C
in supporting the immune system, in part because it
has been promoted as an immune stimulant by the
noted scientist and Nobel Prize Laureate, Linus
Pauling. Vitamin C appears to support a decrease in
the length of time and severity of symptoms
associated with upper respiratory viral infections,
promote phagocytic cell functions, and support
healthy T-cell function. Vitamin C also provides
antioxidant activity to support healing at sites of
inflammation. An excellent source of vitamin C is
citrus fruit. Many vegetables are also excellent
sources of vitamin C, such as broccoli, kale, bok
choy, turnip greens, beet green, mustard greens,
collard greens, Swiss chard, and asparagus.
Many of the B-vitamins are also very important in
supporting a healthy immune system. For example,
vitamin B5 (pantothenic acid) promotes the
production and release of antibodies from B-cells,
and deficiency of vitamin B5 results in reduced
levels of circulating antibodies. Folic acid deficiency
leads to a decrease in T-cells and can result in
reduced effectiveness of the soluble factors as well.
Vitamin B6 deficiency consistently impairs T-cell
functioning and results in a decrease in blood
lymphocyte counts. Deficiencies in vitamins
B1( thiamin ) and B2 ( riboflavin ) may impair normal
antibody response, and low vitamin B12 appears to
inhibit phagocytic cells and possibly T-cell function.
Almost all whole grains, vegetables and fruits can
serve as excellent sources of at least some of these
vitamins, but some vegetables are particularly
beneficial since they are excellent sources of many
of these immune-supporting vitamins. In particular,
Romaine lettuce is a rich source of vitamins B1, B2,
C, and folate. Turnip greens and spinach are
excellent sources of folate, vitamin B6 and vitamin
C. Cauliflower happens to be an excellent source of
vitamin C, folate, vitamin B6, and pantothenic acid.
Crimini mushrooms are also an excellent source of
vitamin B2, niacin, and pantothenic acid. Red bell
peppers are an excellent source of vitamin B6.
Excellent sources of vitamin B12 include sardines,
salmon, tuna, cod, lamb, scallops, shrimp, and beef.
The fat-soluble vitamins, vitamin A , vitamin E and
vitamin K are also important to overall health.
Vitamin A deficiency has been shown to impair
antibody function and T-cell activity. Vitamin E is an
important antioxidant and supports a healthy
inflammatory response. Vitamin E is also an
important component of all cell membranes and
promotes healthy cellular functioning overall. T-cells
and B-cells from vitamin E-deficient animals show
depressed responses, and tumors have been shown
to grow faster in vitamin-E deficient animals.
Vitamin K supports a healthy blood-clotting ability in
your body, and this is necessary for seclusion of
areas of infections and injury in the healing
process. Turnip greens, Swiss chard, and mustard
greens are excellent sources of vitamin E and
vitamin A (in the form of carotenoids). Other
excellent sources of pro-vitamin A carotenoids
include many vegetables such as leafy greens,
carrots, sweet potatoes, winter squash, asparagus,
and bok choy. Concentrated sources of vitamin K
include cauliflower, as well as most green
vegetables such as spinach andasparagus.
Minerals that support your immune system
Zinc is one of the minerals in food that has received
the most attention for its ability to support immune
function. Zinc is a potent immunostimulant, and its
deficiency can result in profound suppression of T-
cell function. Children with severe zinc deficiencies
show signs of growth retardation and susceptibility
to infections. However, an excess of zinc has also
shown negative effects on immune function and
can inhibit the phagocytic cells ( macrophages and
neutrophils ). So, maintaining adequate but not
excessive levels of zinc is important. This is one
reason food is such an excellent source of
obtaining nutrition versus supplementation; food
contains a balanced variety of the micronutrients
whereas supplementation with individual nutrients
can lead to too much of some and not enough of
others. Very good sources of zinc include spinach,
asparagus, shiitake mushrooms and crimini
mushrooms. Good sources include sesame seeds,
pumpkin seeds, garbanzo beas, lentils, cashews,
and quinoa.
Many other minerals are important in supporting
immune function. Clinical research studies have
shown that iron deficiency results in impaired
response to antibodies, and defective phagocytic
cell functioning. Copper deficiency is associated
with an increase in infections and may impair
development of immune cells such as T-cells and
the phagocytic cells. Selenium and manganese are
important for supporting healing from inflammation
and may be immunostimulants. Selenium can be
obtained from fish and shellfish , as well as tofu and
whole grains. Excellent sources of copper include
sesame seeds, cashews, soybeans, mushrooms,
turnip greens, beet greens, spinach, asparagus,
Swiss chard, mustard greens, kale, and summer
squash. Spinach, Swiss chard, cumin, and turmeric
are excellent sources of iron while beet greens,
collard greens, bok choy, asparagus, mustard
greens, turnip greens, leeks, and romaine lettuce are
very good sources..
Antioxidants and phytonutrients that
promote healthy immune function
Reactive oxygen species, free radicals and other
damaging molecules are generated at sites of
infection and inflammation. Your body needs these
molecules at the site of infection to help kill
unhealthy cells; however, when your antioxidant
systems are not functioning, or when not enough
antioxidants are present in your diet, these
molecules are not disarmed after they have done
their jobs and can become damaging to healthy
tissue as well. Many fruits and vegetables provide
antioxidants and phytonutrients that help maintain
healthy tissue around the sites of infection and
support healing. Fruits and vegetables, especially
colored foods like strawberries , cherries, carrots ,
and tomatoes contain many beneficial
phytonutrients with antioxidant potential. More
detailed information on the health benefits of
phytonutrients can be obtained from the FAQ: 'What
is the Special Nutritional Power Found in Fruits and
Vegetables'.
Are there foods that are bad for my
immune system?
Your immune system is not just involved in fighting
invaders like bacteria, but also becomes activated
when you eat foods to which you are intolerant or
allergic. Reactions to allergic foods can be quick,
like the anaphylactic reaction often seen with
peanut or shellfish allergies, but food allergy
reactions can also be delayed and cause a number
of symptoms like headaches, fatigue, muscle aches,
rashes and other systemic (whole body) effects.
The most common allergenic foods include peanuts
and shellfish, cow's milk, wheat, and soy; however,
everyone is unique in their food intolerances and
allergies.
Processed foods and foods produced with
pesticides or not grown organically may also be
problematic for your immune function. Toxic metals
such as cadmium, lead and mercury are
immunosuppressive. Some pesticides and
preservatives can negatively effect the
gastrointestinal lining. Food additives can also have
untoward effects on the nutrient content of the
food. For example, sulfites destroy thiamin-vitamin
B1 in foods to which they have been added.
How do I keep a healthy 'balance' in
my immune system?
Your immune system is developed to be able to kill
cells, such as bacteria cells or viruses; your
immune cells can act against cancer cells within
your body as well if it is able to tell that these cells
are unhealthy to you. However, without proper
control and the ability to differentiate healthy from
unhealthy cells, your immune system can
mistakenly kill your own healthy cells. Your
inflammatory response is also developed to support
healing, but when this response becomes overly
active, it can become destructive. Autoimmune
system diseases like rheumatoid arthritis and
multiple sclerosis, susceptibility to infections, and
wounds that won't heal are some of the
repercussions of immune system imbalance and
dysfunction. Therefore, healthy immune and
inflammatory responses must maintain a delicate
balance to achieve protection without causing self-
destruction.
Your body has a complex means of recognition on
your cells' membranes to help your immune
system. Some specific soluble factors of your
immune system are also involved in turning-off your
immune response. How well these responses
function is defined in part by your genes; however,
recent research has suggested that diet plays a
much larger role in autoimmune system dysfunction
than was once thought. For example, research has
shown an association with low levels of vitamin D
and increased risk of some autoimmune diseases,
such as multiple sclerosis. Concentrated sources of
vitamin D include cow's milk eggs and shellfish
such as shrimp and fish such as cod .
The omega-3 fatty acids, which are produced in
your body from the essential omega-3 fat ' alpha-
linolenic acid ' have been studied for their effects
on the immune system and inflammatory response.
Diets low in omega-3 fatty acids are associated with
chronic inflammatory conditions and autoimmune
diseases. In order to achieve a more beneficial ratio
of omega-3 fatty acids in your body, it is important
to decrease the amount of omega-6 fatty acids in
your diet, while increasing the amount of omega-3
fatty acids. This can be accomplished by reducing
your consumption of meats, dairy products, and
refined foods, while increasing consumption of the
omega-3 rich foods such as wild-caught cold-water
fish like salmon , flaxseed oil , walnuts , and leafy
green vegetables.
Weight-management, nutrient-dense
foods and the immune system
Research and clinical observations suggest that
obesity is associated with immune dysfunction. For
example, increases in the incidence of infectious
illness and infection-related mortality are found in
obese people. An increase in inflammation has also
been seen with an increase in weight in individuals.
Some studies have shown an association between
high cholesterol and susceptibility to infections as
well. Therefore, maintaining a healthy weight and
healthy cholesterol levels may also be beneficial to
your immune system's functioning.
Eating nutrient-dense whole foods is one way to
provide your body with the full spectrum of
nutrients it needs while keeping calorie intake to a
healthy level. The World's Healthiest Foods are
analyzed for their nutrient density. Foods such as
cooked turnip greens , boiled Swiss chard, raw
crimini mushrooms , boiled mustard greens , boiled
asparagus and Romaine lettuce provide a broad
spectrum of the key micronutrients that support
healthy immune function and are therefore
recommended as part of an immune-enhancing
diet.
What can I do to support and
maintain a healthy immune system?
Provide support for the physical barriers in your
body.
Support a healthy digestive process. In particular,
the acidic environment provided in your stomach
and the presence of digestive enzymes can destroy
some bacteria and viruses that you ingest in food,
and therefore, provides protection for your body.
Consume adequate protein and healthy fats.
Provide for balanced immune and inflammatory
functions. Clinical studies have shown that
maintaining a healthy balance between omega-3
and omega-6 fatty acids is one way to support
balance in your immune and inflammation
responses system. Research indicates a ratio of
omega-3 to omega-6 fats of 1:4 is health-promoting.
Provide micronutrients and phytonutrients that
support healthy immune function.
Decrease intake of allergens and toxins. Eating
whole grains, fresh, organically grown fruits and
vegetables, wild-caught fish, and meat and eggs
from organically raised animals is one way to
minimize the intake of toxins and unhealthy
molecules that can inhibit your immune system's
ability to protect your health.
Maintain healthy weight and cholesterol levels.
Basing your diet on nutrient-dense foods, such as
those found in the World's Healthiest Foods
nutrient-dense food list, is one way to decrease
calorie consumption while consuming optimal levels
of micronutrients and immune-supporting
phytonutrients.