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 You
Are What You Eat
by Connie Guttersen, RD PhD,
author of the Sonoma Diet
The saying, "you
are what you eat" holds absolute truth. A closer look
within our body, and the cells of which we are made-up, reflects
the actual types of fats we typically eat. These fats or fatty
acids make up the outer covering of our cells, known as cell
membranes. There
are several types or categories of fats. 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 oil and fish oils).
Our immune systems
are affected by the types of fatty acids we consume. This
is because different families of compounds known as eicosanoids,
are produced based on the amounts, balance and types of fatty
acids in our diets. These different eicosanoids play a role
in the body's ability to fight infection, hypertension, heart
disease, diabetes, rheumatoid arthritis, and ulcerative colitis.
 The
primary source of the production of the eicosanoids comes
from polyunsaturated oils. Within this category, the omega
6 (vegetable oils) and the omega 3 (fish and some plant oils)
are the parent fatty acids for the formation of different
types of eicosanoids.
These two
groups, omega 6 and omega 3, actually compete for the production
of their own specific groups of eicosanoids. When there is
too high of an intake of omega 6--as compared to the omega
3--a shift in the production of eicosanoids occurs and the
body is more inclined towards cardiovascular disease and inflammation.
On the other hand,
the proper balance of omega 3 eicosanoids (primarily those
coming from fatty fish sources) helps immune function and
has a beneficial effect on heart disease and inflammation.
Recent studies recommend a ratio of 2.3 : 1 for omega 6 to
omega 3 fatty acids. Today, our ratio of omega 6 to omega
3 fatty acids is approximately 10 : 1--with some parts of
the United States as high as 20 : 1.
This is a far cry
from what scientists say we were eating about 10,000 years
ago. Back then we consumed equal amounts of omega 6 and omega
3 fats-- and had a low intake of saturated fats. We had great
sources of omega-6 and omega-3 acids from wild plants, animals
and fish.
The onset of the
industrial revolution saw a marked shift in the way we ate.
The balance between omega 6 to omega 3 changed considerably,
as we increased our use of vegetable oils and changed the
way we feed livestock. We've also increased the amount of
saturated fats and hydrogentated fats in our diets. (Just
read the ingredient lists on processed foods.)
 One
way to achieve a healthier ratio of omega 6 to omega 3 is
by increasing our intake other types of healthy fats, like
those found in monounsaturated oils, olives,
nuts, avocados, and canola oil), in place  of
the seed / vegetable oils. You can also consume more fish
and other plant sources of omega 3, and minimize excessive
intakes of saturated fats.
How does the immune system work?
The immune system is the most incredible system in the body
for our key defense against infection and disease. From the
common cold to heart diseases and other serious ailments,
the immune system generates compounds capable of recognizing
and eliminating invaders. The immune system is a network of
organs called lymphoid organs. These organs are distributed
throughout the body and produce the body's disease fighting
agents.
Our immune system
has two basic lines of defense: the natural or innate immunity;
and, the acquired immunity. The first, our natural or innate
immunity, is the line of defense we are born with. The basic
barriers such as skin, internal body temperature and mucous
membranes are included, as well as the macrophages, monocytes,
and neutrophils that can engulf, kill, and digest whole microorganisms.
Our second line of defense, also referred to as acquired immunity,
provides the immune system with a memory bank of special reactions
to different infections one has experienced. In some cases,
once you have been exposed to a particular microorganism,
the body develops a natural resistance for it by creating
antibodies. This is quite similar to the basis of how vaccines
work.
Lymphocytes are
the primary cells of this system. The response of the lymphocytes,
in particular the T lymphocytes or T-cells, are a factor involved
in acute infections, aging, rheumatoid arthritis, type I diabetes,
cancer, and cardiovascular disease.
As the scientific
world continues to learn more, there is continuous confirmation
for the importance of good nutrition and a healthy lifestyle
for a strong immune response. A balanced diet with a wide
variety of foods in moderation is the advice we have been
given for many years. Some nutrients for maintaining function
are zinc, selenium, beta carotene, vitamin C and E, as well
as some of the phytochemicals.
All of these nutrients are primarily found in fruits, vegetables,
whole grains, and nuts.
Benefits
of Antioxidants
 Dietary
antioxidants play a key role for preventing diseases and minimizing
the metabolic effects due to the aging process and oxidative
damage. Aging is associated with a decline in immune status.
This is partly due to the life-long exposure to free radicals
and the resulting damage which occurs in the cells, as well
as to a decrease in T-cells. It is not uncommon for T-cells
to lose approximately 50% of their power by the time people
reach their 70's. Nutrients such as Vitamins C, E, beta carotene,
zinc, selenium, and phytochemicals decrease the oxidative
damage within the body, which simply comes from normal life-long
metabolic function as well as free radicals obtained via smog,
excessive sunlight, cigarettes and other pollutants. As we
understand more about the balance between dietary antioxidants
and the processes which contribute to oxidative damage, it
appears that the amounts of dietary antioxidants required
for normal function of the immune system in elderly populations
are higher than what is recommended in the current RDA. There
are many foods which provide good sources of dietary antioxidants.
 Studies
have found interesting news on the benefits of antioxidants
for immune function. In one study, long term supplements of
beta carotene (50 mg every other day, for 10-12 years) were
associated with an enhanced activity of natural killer cells.
Researchers from the University of Nottingham found that adults
who consumed the most vitamin E had fewer allergy related
antibodies in their blood. High levels of these antibodies
are associated with asthma and allergies. Asthma may also
be related to DNA damage occurring from oxidation. It is known
that vitamin E protects DNA from oxidative damage and thus
may reduce asthma risk. Meydai et al.
(please refer to the recommended reading to the left) also
found beneficial results using vitamin E supplements. In his
study, he investigated the long term effect of vitamin E supplements
in healthy older adults, ages greater than 65 years. The supplement
doses of vitamin E consisted of 60, 200, or 800 IU for 235
days. All three doses improved immune function, however, individuals
taking the 200 IU dose showed the best immune response. This
study concluded that 200 IU per day was the optimal amount
of vitamin E to increase immune response in elderly populations.
This study also found that individuals taking the vitamin
E supplements had 30% less self reported infections than did
the placebo group. This is an important study since more than
40% of older Americans have a vitamin E intake below the RDA.
In looking at dietary sources of vitamin E, nuts, seeds, oils,
and whole grains, it would be difficult to reach a daily intake
of 200 IU from diet alone. A vitamin E supplement in addition
to a healthy diet is the best approach.
Zinc also plays
a key role in immune function and also acts as an antioxidant.
A dietary zinc deficiency results in a depressed immune system
and in skin problems such as dermatitis. Several studies have
demonstrated the ability of zinc supplements to reduce infectious
diseases, with one reporting a 45% reduction in the incidence
of acute lower respiratory infections. Zinc supplements also
have beneficial effects when administered during infections--for
example, zinc lozenges for the common cold. Skin dermatitis
has also been shown to improve with zinc supplements. Studies
with pre-school children showed that zinc supplementation
during gastro-intestinal infections reduced the duration of
the illness by 30%. Short term intakes of zinc, which are
2-3 times the RDA, are generally considered safe in preschool
children and adults; however additional studies suggest that
supplements higher than these levels may result in anemia
and depressed immune function. As for any nutritional supplement,
caution should be taken for any excessive doses.
Benefits
of Physical Activity
Exercise has a positive effect on the immune system
within minutes of starting the activity. During this initial
time period, the body's first line of defense, the white blood
cells, increase in number and make the immune system more
efficient. Regular exercise also prevents the natural decline
in immune function that comes from aging. Research has found
that regular exercise can bring T-cell levels of a 65 year
old to levels as high as people in their 30's.
Evidence is also
accumulating that shows regular exercise is associated with
a reduced risk of some cancers--particularly colon cancer.
The risk of colon cancer was reduced by 40 to 50% s as compared
to those who were least active. Regular exercise can keep
the colon in shape by maintaining the specific muscles involved
in peristalsis, (the intestinal muscular action which aids
in digestion) and thereby speeding the passage of food through
the intestines. Breast cancer risk can also be decreased by
regular exercise. This is primarily due to a hormonal effect
since exercise decreases the levels of estrogen in the body
and also decreases excessive body fat stores which contribute
to elevated estrogen levels.
But, as mentioned
earlier, balance is the key. Strenuous and prolonged exercise
may actually impair health and depress the immune system.
It is especially important to have an adequate supply of dietary
antioxidants since exercise requires extra oxygen and produces
a higher level of free radicals. Dr. Neiman, who has conducted
studies of exercise and the immune system, found that after
numerous periods of strenuous exercise, there was an increase
of damaged white blood cells as a result of free radical damage.
Vitamin C and E may be the most important antioxidants involved
in maintaining the balance for health in exercising individuals.
So as we look to
the foods we eat--and the foods you prepare for others-- it's
important to remember balance. A wide variety of foods in
moderation is the basis, but you can also focus on certain
key nutrients that may enhance immune function and overall
health.
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Table 3.
Tips for achieving balance in fatty acid intakes
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- Do not
overly restrict dietary fats. You may not get enough
essential fatty acids. Fats such as omega 3 from fish
and monounsaturated fats are actually beneficial to
health and immune function.
- Replace
sources of linoleic acid, primarily omega 6, with
oils that are rich in linolenic acid like canola oil,
and flaxseed oil - and with monounsaturated rich oils
like olive oil.
- Limit
intake of trans fatty acids by decreasing use of margarine
and other processed food.
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