Immune Function and Diet
by Connie Guttersen, RD PhD,
author of the Sonoma Diet
In recent years, the effect of diet on the different aspects
of immune function has become increasingly apparent. However,
research in this area is limited by the lack of information,
which is predictive for the effects in humans. Research has
explored the use of herbs as a medicinal agent, as well as
micro and macro nutrients, ranging from vitamins, to phytochemicals,
to the actual types of dietary fats we consume.
When we speak of immune function, it is necessary to understand
that there are many different aspects to address. For example,
immune function pertains to
the body's ability to fight infection, heart disease, cancer,
conditions related to oxidation, inflammation, and auto-immune
diseases such as arthritis and type I diabetes. It is difficult
to compare the broad or general impact of various nutrients
or diets on immune function since much of the research completed
tends to select single aspects or indexes of immune response.
These indexes of immune response include delayed type hypersensitivity
skin tests, antibody production, lymphocytes, cytokine production,
and numbers of the specific white blood cells. The amount and
specific type of dietary fatty acids we consume in our diets
can have an affect on all of these indexes.
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Table 1: Dietary Fatty Acids and
their Metabolism
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n-9
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n-6
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n-3
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n-3
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Fatty Acid
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Oleic Acid
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Linoleic Acid
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Alpha Linolenic
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Eicosapentaenoic
docosahexaenoic
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Sources
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Olives and olive oil,
canola oil, avocados, nuts, peanuts
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Soy, Corn, Safflower,
Cottonseed Oils
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Flaxseed Oil, Canola Oils
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Cold Water Fish: Salmon,
Mackerel, Tuna, Herring
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Formation of:
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Eicosatrienoic Acid
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Arachadonic Acid
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Eicosapentaenoic Acid
(not as efficiently as
from fish sources)
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Eicosapentaenoic Acid
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 Recently,
there has been a growing interest in the role of specific
fatty acids for their effect on inflammation (For more
information on the background of these specific fatty acids,
see my past article on Dietary
Fats & Health). The anti-inflammatory effect
of n-3 fatty acids has been studied extensively. The research
consistently finds that the higher the ratio of n-6 to n-3
fatty acids in platelet phospholilids, the higher the rate
of inflammation. Inflammation is not only characterized by
pain, redness and swelling, but is also associated with the
development of atherosclerosis. Among the key promoters of
inflammation are the n-6 derived eicosanoids, prostaglandin
E2 (PGE2) and leukotrienes B4 (LTB4), which are derived from
the n-6 polyunsaturated arachadonic acid. Nutritional therapy
can be guided to improve and change the balance of fatty acids
consumed so as to reduce the physiological parameters, which
promote inflammation. For example, increasing the intake of
the n-3 and n-9 fatty acids, while decreasing the intake of
the n-6 fatty acids is a basic approach. This is applicable
since in the typical Western diet, as much as 20 times more
n-6 fats from linoleic acid than the omega 3 fatty acids are
consumed. This is a far reach from the medically suggested
2:1 ratio. This imbalance we see today is a result of the
increase use of vegetable oils and cereal grains to feed livestock.
The predominance of the n-6 fatty acids are due to the abundance
of linoleic acid which is present in soy, corn, safflower,
and sunflower oil. By contrast, there is a low intake of the
n-3 fats from leafy green vegetables, flaxseed, canola oil,
and cold water fish such as salmon. The balance between the
n-6 and n-3 fatty acids influence the type of eicosanoids
and prostaglandins that are produced, thus ultimately affecting
inflammation and other factors which influence disease. The
eicosanoids derived from the n-6 fatty acids have opposing
properties as
those derived from the n-3 fatty acids. Essentially, there
is competition between these type types of fatty acids for
the formation of the different series of eicosanoids. Formation
of the eicosanoids from the n-3 fatty acids decreases the
factors that are responsible for increasing inflammation.
While the n-6 fatty acids produce factors which mediate or
promote inflammation. Monounsaturated fats or n-9 fatty acids
are important because they do not appear to compete with the
n-3 fatty acids for the production of beneficial eicosanoids
and can improve the ratio of n-6 to n-3 fatty acid intakes.
Also, olives and olive oil have been found to decrease the
production of leukotrienes B4, a key promoter of inflammation.
By substituting vegetable oils with monounsaturated fatty
acids and including more natural sources of monounsaturated
fat (olives, nuts, avocados), a healthier balance of fatty
acids can be achieved to produce less inflammatory factors.
Hydrogenated fats, found in many processed and fried foods,
are yet a separate and growing concern among health professionals.
A recent study also found that consumption of a diet high
in hydrogenated fat increases the production of inflammatory
cytokines. These cytokines have also been associated with
the development of atherosclerosis. Hydrogenated fats have
also been found to have negative effects on the function of
white blood cells. This is primarily influenced by the amount
of hydrogenated fat which accumulates within the cellular
membranes.
Since many nutrients interact with one another, understanding their combined
effects on immune response becomes more important for communicating
the results of current research. The n-3 and n-6 fatty acids,
due to their structural forms, are considered a highly unsaturated
fatty acid. Another way to interpret this statement is that
the structure of n-3 and n-6 fatty acids contain many double
bonds as opposed to monounsaturated or saturated fats. The
increased number of double bonds makes the fat more susceptible
to the negative effects of oxidation in the body. Therefore,
dietary antioxidants become important for the stability of
these fatty acids. Monounsaturated fatty acids, (n-9), are
more stable but will also benefit from the individuals antioxidant
intake. Common antioxidants, which are easily recommended
from foods, include Vitamins E, C, Beta Carotene and the many
phytochemicals present in fruits, vegetables, olives, nuts,
and whole grains.
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n-6 &
Hydrogenated Fatty Acids
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n-3 and
n-9 fatty acids
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Metabolism
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Metabolism
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Pro-inflammatory
Mediators
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Inhibitors of pro-inflammatory
mediators
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Interested
in what chefs are learning about immune function and menu
planning? This less technical information may also
be good to pass along to patients.
A Primer On Immune Function and Diet
With cold and flu season upon us, now is a good time to help
your clients understand how proper diet can help their immune
systems. And believe us, there is no need to sacrifice taste
when it comes to nutritious eating. Here's a little primer
and some recipe suggestions to pass along (or use yourself!).
Looking for some new recipes that'll please your palate and
your immune function?
1. Bright colored fruits and vegetables
 These
foods contain powerful antioxidants, which protect the immune
system against free radical damage. Yellow, orange and red
pigments contain nutrients such as vitamin C and Beta carotene.
Vitamin C helps prevent and speed up the recovery time from
a cold. Beta carotene, found in carrots, spinach and sweet
potatoes, is also a strong antioxidant that has been specifically
found to improve the immune system's function. Vitamin A,
also made from beta carotene, has its own and different
immune boosting qualities and is crucial for immune defense.
It enhances white blood cell function, increases the resistance
to infection and helps maintain skin and mucus defenses
to infection. Fresh and canned tomatoes contain another
type of antioxidant, lycopene. Lycopene enhances the function
of the immune system by
having a positive effect on the production and maintenance
of our natural killer cells or also referred to as white blood
cells. White blood cells are powerful immune factors; they
have the capability of destroying more than 100 types of viruses
/ bacteria and many different types of cancer cells. Other
foods with bright colors such as cranberries, blueberries,
and strawberries all contain a wide variety of antioxidants,
which also protect immune cells from the environmental stresses.
Here are some to get you started: Chicken Tagine,
Moroccan Roast Chicken Breast, Ancient
America Grain Salad and Mediterranean Chickpea
Soup.
2. High Quality Protein
Your immune system is dependent on a constant supply of
high quality amino acids - the building blocks of protein.
So, both calories and high quality protein become an important
issue for strengthening the immune system when you are sick.
When infections invade the body, it reacts by calling upon
the immune system to produce antibodies, also referred to
as immunoglobulins. Antibodies, which are proteins made
from certain amino acids, bind to different types of infections
in order to neutralize, destroy and eliminate them from
your body. The recent increase in vegetarian styles of eating
has made the quality of protein a greater issue. It is important
that a healthy diet provide the 8 essential amino acids.
These 8 essential amino acids are found in " complete
proteins" such as animal sources, soy and quinoa or
also found in plant
A Wider Variety of Grains
and Beans for Plant Proteins
Grains
Amaranth, Buckwheat, Jobs Tears, Millet, Quinoa
(a complete protein), Wild Rice, Teff, Triticale,
Wheat Berries, Bulgur Wheat, Cracked Wheat,
Kamut, Spelt
Beans
Adzuki, black beans, butter beans, chick peas,
borlotti, cannelloni, Dutch brown, flageolets,
great northern, lentils, split peas, soybeans,
white beans, haricot beans
Here are some recipes that pack
a grain, bean or old-fashioned meat protein
punch:
Chunky Quinoa Chili, Egyptian
Lentils with Olives and Tomatoes, Gingered
Beef and Olive Salad and Autumn
Lamb Stew.
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sources, or "incomplete proteins". "Incomplete
proteins" refer to plant sources such as grains, beans,
legumes and nuts, which are missing one or two of these 8
essential amino acids. Since these individual sources of plant
proteins typically do not contain the 8 essential amino acids,
combinations of grains with legumes and beans or eating a
wide variety of these foods on daily basis will provide the
body with the 8 essential amino acids. The most popular style
of "vegetarian eating" is the semi vegetarian diet.
The recent growth of this style is mostly inspired by health
reasons and the emergence of the many global cuisines, which
do not focus on meat as the primary ingredient. Most semi-vegetarian
diets will include moderate amounts of fish and poultry, but
focus on the plant sources for protein. The advantages of
incorporating plant sources of protein in the diet is that
grains, legumes, beans and nuts all contain fiber, antioxidants
from vitamins and phytochemicals, as well as healthy oils
from the monounsaturated and polyunsaturated group.
The table to the right contains interesting grains and
heirloom beans, which will expand your selection of nutrient
dense plant proteins.
3. Healthy Fats and Oils
There are several categories of fats and oils in our diets.
They include saturated fats
(primarily from animal products, tropical oils and hydrogenated
fats), monounsaturated fats (olives, nuts, avocados and
canola oil) and polyunsaturated fats (vegetable/seed oils,
and fish oils). It has been well documented that olives
and olive oil boost the immune system against
Dietary
Sources of Fats and Oils
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Saturated Fats:
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Animal products, coconut and
palm oils, Hydrogenated fats, Processed
Foods, Fried Foods |
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Monounsaturated Fats:
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Olives, olive oil, nuts, avocados,
canola oil |
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Polyunsaturated:
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Omega 6: Oils from corn, soybeans,
safflower, cottonseed
Omega 3: Salmon, herring, tuna,
flaxseed, walnuts, canola oil, pursulane,
tofu
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attacks from microorganisms, bacteria, and viruses. Our
immune system is greatly affected by
the different types and amounts of fats and oils we eat. A
healthy variety and balance of fats can be achieved by increasing
the monounsaturated sources: olives, nuts, avocados, and canola
oil as well as increasing the omega 3 oils found primarily
in cold water fish, such as salmon or from plant sources such
as flaxseed. Dieting, a long time common way of life for many
Americans, may be what is behind the frequent bouts of the
flu and cold. Low calorie and low fat diets, especially those
that result in rapid weight loss, have been shown to impair
the immune function. Low fat diets have also been linked to
an increased incidence of depression. This is significant
since it is well documented that depression decreases the
immune system. The best types of fats to prevent depression
are the omega three oils and monounsaturated fats.
Consider diving into these recipes: Salmon
with Pinenut Crust, Triple S Seafood Stew,
Bouillabaisse Under Wraps, Tortilla
Toasts with Avo-Olive Salsa, Quinoa Pinenut
Pilaf and Tuna Melt Sandwich.
4. Garlic and Onions
 The
folk remedy of drinking the juice of onions for coughs may
be more accurate than what was perceived by many. Garlic,
also a member of the onion family, has been used medicinally
for 5000 years by the ancient Egyptians, Greeks, Romans
and Chinese. Historically, its role was believed to hold
a cure for infections, epilepsy, and heart disease. Recent
medical studies appear to conclude that a clove a day may
keep the doctor away. There was also the discovery that
sulfur-containing compounds in both onions and garlic act
as the body's disinfectant, clearing away toxins and germs,
and thus, warding off many common infections in the body.
Garlic and onions stimulate the body's immune system by
boosting the activity of the natural killer cells (white
blood cells) and T helper cells, both essential to a strong
immune response. Numerous medical studies, such as the Iowa's
Women's Health Study have confirmed garlic's immune enhancing
properties and benefits to work against cancer and heart
disease. Some of the major functions of garlic in enhancing
the immune system are listed to the right.
What gives garlic and onions their medicinal properties?
The answer is related to the group of sulfur-based phytocHemicals
they contain. The active component of garlic is a sulfur
compound, which is converted to allicin when garlic is crushed
or chopped. It is one of the most important compounds in
garlic's nutritional makeup. Yet, it is not the only phytochemical
contained in garlic. Others include allylic sulfides, mono-terpenes,
tri-terpenes, and phbenolic acids. Cooking with garlic may
alter the activity of some of the phytochemicals in garlic.
For example, studies have shown that heating in a microwave
or oven can minimize garlic's cancer fighting benefits.
However, if the garlic is minced or crushed and allowed
to stand for at least 10 minutes before heating, there is
little or no loss of the phytochemical, allicin. The 10
minute standing time allows for enzymes present in garlic
to start producing allicin. As we experience more of the
global cuisine flavors, we find an abundance of garlic,
onions, and leeks within the recipes.
Garlic adds fine flavor to these recipes: California
Ripe Olive Rainbow Chard and Tomatoes, Chicken
with Ripe Olives in Pepper Salsa, Chipotle
Turkey Wrap and Galician Style Dumplings.
5. Vitamin E
One in three Americans do not get enough vitamin E in their
diets. This immune-boosting nutrient is commonly regarded
as a powerful antioxidant with benefits beyond heart disease
and  cancer.
Vitamin E has been found to also boost T- cells (immune
function related) and antibody responses in individuals
who are exposed to high levels of stress. A recent study
found that daily intake of vitamin E as a mega supplement
may not be such a good idea for elderly people, especially
those who are already taking in a well-balanced and adequate
diet. In this study, which was released this year in the
Journal of the American Medical Association, the results
showed that adults (60 years and plus), who had a respiratory
infection and also took vitamin E supplements were sick
for a longer period of time than those adults who did not
take the Vitamin E supplement. In explaining the results,
the researchers suggested that an increase in the symptoms
may reflect an enhanced immune activity or perhaps an immune
imbalance. In conclusion, adults should be cautious about
taking mega doses of Vitamin E. However, a different perspective
is reported by Tuft's scientist, Simin Meydani ,who states
that it is very difficult to obtain the amount of vitamin
E necessary for an immune response through diet alone--especially,
if one is dieting on a low fat / low calorie diet. Good
sources of vitamin E include plant oils, almonds, hazelnuts,
peanut butter, soybeans, wheat germ, dark green leafy vegetables
and olives. When cooking with these ingredients, take note
that vitamin E is a fat soluble nutrient. This means that
it is best absorbed and utilized in the body when accompanied
by healthy fats. In the same perspective be careful to not
lose vitamin E in discarded cooking liquids or sauces that
are oil based. Although supplementation may help or enhance
Vitamin E's immune benefits in individuals who are deficient
in the nutrient, it is necessary to recognize that over
supplementation can suppress immune function caused by the
effects of the supplement on other nutrients and their ability
to be absorbed in the body. (In other words, over supplementation
may create a competition for other nutrients, which in turn
may create a nutrient deficiency.) The best advice is to
obtain the nutrients from nutrient dense foods in order
to promote a proper balance and variety among all nutrients.
Here are some "E"xcellent recipe selections:
California Ripe Olive Briks, Grilled
Orzo Salad, Grilled Chicken Penne, Lemon
Salmon Linguini and California
Ripe Olive Rainbow Chard.
Sugar is not sweet to immune system
Any attempt to add fresh fruits, vegetables, whole grains
and limiting the amount of red meat, refined sugars and highly
processed foods will be an improvement and an important to
step to strengthening the immune system. A key food to avoid
is refined sugars, as they actually decrease the effectiveness
of the immune system by limiting the capacity of the natural
killer cells (white blood cells) ability to fight infection
in the body.
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