Diet, Exercise, Stress, and the Immune System
The immune system and its role in chronic fatigue syndrome (CFS)
The immune system is our body's protective network designed to fend off
invasion by harmful substances, including bacteria, viruses, and harmful chemicals, and to
act as a surveillance system against the development of cancer.
Under normal circumstances, the immune system is highly efficient, providing multiple
defenses against the onslaught of outside invaders. These defenses include physical
barriers (such as skin); the non-specific inflammatory response, which is brought about by
changes in blood flow that bring chemical substances to the injured area; and specific
immune responses, in which the body learns to recognize specific invaders and destroy them
after subsequent exposures.
In many diseases, ranging from autoimmune diseases to AIDS and CFS, there is evidence of mild to severe dysfunction of the immune system. An impaired
immune system weakens the body's ability to fend off infection and malignancy, but the
immune system can also produce symptoms such as fever, weight loss, musculoskeletal pain
and fatigue. In fact, many of the symptoms of the flu (such as achy muscles and joints,
fever, and headache) are caused by the immune system's response to the infection.
Functions of the immune system suspected to be impaired in CFS include those of the B-lymphocytes (B cells) and T-lymphocytes (T cells), as well as
those of the phagocytic and complement systems. B cells and T cells carry out specific
immune responses. B cells, a type of white blood cell, can recognize foreign proteins
(antigens) and make specific proteins (antibodies) to destroy the antigens (humoral
immunity). T cells, other types of white blood cells, do not produce antibodies, but can
perform a number of functions, including recognizing foreign antigens, attaching to them
and destroying the invader cells (cell-mediated immunity).
The phagocytic and complement systems bring about non-specific inflammatory responses.
In the phagocytic system, numerous types of white blood cells (phagocytes) engulf and
digest foreign particles. The complement system is a group of proteins that become
activated when they come into contact with antigen/antibody complexes, the combination of
the antibody attached to the antigen. Once activated, these proteins attach to the invader
and destroy it. The complement system can bring about a host of non-specific inflammatory
How can I strengthen my immune system?
While it is difficult to enhance a normal functioning immune system, there are
things that you can do to protect and strengthen your immune system during periods of
illness or in the face of chronic disease. The three areas that are most important in
protecting and bolstering the immune system are diet and nutrition, exercise, and
Diet, nutrition, and immunity
There have been many excellent books written about the relationship between
diet, nutrition, and immunity. (Please refer to the reading list below.) There are two major changes you can make in your diet to help your immune system. First, you can enrich your diet with antioxidants and, second, you can make sure you are getting enough nutrients and micronutrients.
Antioxidants are vitamins and minerals, found in foods and available as
supplements, that remove harmful oxidants from the bloodstream. Oxidants, also known as
free radicals, are the toxic byproducts our bodies make when we turn food into energy.
They are also byproducts of cigarette smoke, pollution, sunlight exposure, and other
environmental factors. Free radicals are capable of damaging DNA and suppressing the
body's immune system.
Free radicals also play an important role in the development of many human diseases. In
fact, there are several journals now dedicated to their study and investigation. Nearly
all types of cancers have been related to diets that are poor in antioxidants. Data from
some research also suggest that a diet high in antioxidents might also protect against
Heart disease and atherosclerosis (hardening of the arteries) are also brought about,
in part, by free radicals. Certain diseases of the central nervous system — such as
dementia and some forms of kidney, gastrointestinal, and skin disease — also involve free
radicals. You cannot prevent these diseases simply by taking antioxidants. You can,
however, ensure that you are doing everything possible to lessen their effects. Most
importantly, you should eliminate environmental factors that promote the production of
Nutrients and micronutrients
Marginal nutrient deficiencies in the diet can also weaken the immune system.
Marginal deficiency is a state of gradual vitamin loss that can lead to a general lack of
well being and impairment of certain biochemical reactions. Marginal deficiencies of
micronutrients (nutrients required only in a small amount) do not cause obvious symptoms
of disease, but they can affect your mental abilities, your coping abilities, and your
body's ability to resist disease and infection. They might also slow your recovery from
Marginal nutrient deficiencies are very common in both younger and older individuals.
The typical American diet is often deficient in a variety of nutrients including calcium,
iron, vitamin A, and vitamin C. Furthermore, the recommended daily allowance (RDA) for many
nutrients might be well below what is needed to optimally protect the immune system. For
this reason, vitamin and mineral supplements are used to protect us against micronutrient
You can further modify your diet by eating less saturated fat and animal protein
(particularly red meat), by limiting dairy products (particularly those with fat), by
modifying your use of oils and fats, and by eating more fresh fruits, vegetables, and whole
Take a minute to examine your diet. How many times a week do you eat fried foods or red
meat? What types of oils do you use in your cooking? Do these oils include cooking oil as well
as butter and margarine? What types of garnishes and sauces do you use? Do they contain egg
yokes or oils? What types of dairy are you consuming? If you drink milk, which is good
for you, is it anything less than skim or 1%? Do the yogurts and cheeses you eat contain
a lot of fat?
- Try eliminating red meat from your diet or, if necessary, eat it no more than once every
10 days. Also eliminate or reduce your intake of fried meats. Try to replace the meats in
your diet with servings of fish, particularly oily fish such as salmon. Salmon contains a
rich form of an oil known as omega-3 fatty acids, which has natural anti-inflammatory
- Use only olive oil in your cooking. Olive oil is rich in mono-saturated fats. All other
oils, with the possible exception of canola oil, have unfavorable types of fats for the
immune system. Avoid excessive use of margarine. Though most margarines are unsaturated in
their fat content they are artificially prepared and the long-term effects of their use
are not known. Try to minimize the use of all fats, but wherever possible use olive oil in
cooking and for dressing salads.
- Eat more fruits and vegetables. Green leafy vegetables such as broccoli are very rich in
antioxidants. Add several servings a week to your diet. Do not overcook them and think of
creative ways to prepare them. Add more servings of other fruits and vegetables to your
diet, as they are rich sources of antioxidants as well.
- Add fiber to your diet. Fiber can be found in many types of whole grains. If you are
going to add rice, which is healthy, try to add brown rice. Brans and cereals are also
helpful, but avoid those with any form of artificial sugar.
- Drink plenty of water.
If you follow these guidelines, you will move your diet in the proper direction
toward protecting your immune system. As an added benefit, you will be following a diet
that is also good for your cardiovascular system. (These recommendations are similar those
of the STEP II diet promoted by the American Heart Association.)
Ideally, fat should account for less than 30 percent of your total calories. Less than 7
percent of your total calories should come from saturated fats. In addition, you should try to eat
less than 200 milligrams (mg) of cholesterol per day.
Much has been said about nutritional supplements and their ability to enhance or
protect health. While there is a lot of debate in the medical literature, and many
doctors do not discuss their use with their patients, some CFS specialists believe that nutrients can provide a measure of protection for the immune system.
No matter how well you design your diet for nutrition, you can still augment it with
supplemental antioxidants. Some of the best studied and most readily available as
supplements are beta carotene, selenium, vitamin C, vitamin E, and vitamin A.
Supplementing your diet with a balanced multivitamin is essential. To do this, you should
add beta carotene in a dose of 25,000 international units (IU) twice per day. In
addition, vitamin C in doses of at least 500 to 1000 mg a day is recommended. Why these vitamins?
Beta carotene is one of the most potent nutrients and can protect the body from oxidative
stress. Populations that have diets high in beta carotene have a lower incidence of
certain forms of cancer.
Several studies have shown that beta carotene supplements can do little to reduce
cancers in people who smoke cigarettes. This fact should not be surprising. Dietary
modifications are made to bring back a failing immune system or to protect a healthy
immune system, not to overcome overwhelming toxic effects of activities such as smoking.
Vitamin C is also an extraordinarily important antioxidant. While many studies have
shown that daily ingestion of vitamin C does little to protect you from the common cold,
it can reduce the severity of colds. Furthermore, there are several controlled studies
performed in populations of people working under heavy stress that have shown a profound
protective effect of vitamin C in terms of common colds and pneumonia.
Other nutrients that might be helpful include selenium in doses of 200 micrograms (mcg)
per day and vitamin E in doses of 400 IU per day. Many over-the-counter vitamins with
similar doses are available. There is no difference between natural vitamins and synthetic
Exercise and immunity
Even more so than nutrition, exercise has the capacity to protect and even
enhance the immune response. Experimental studies have shown that a regular exercise
program of brisk walking can bolster many defenses of the immune system, including the
antibody response and the natural killer (T cell) response.
Fortunately, the intensity and duration of exercise needed to support the immune system
is less than that needed to provide the best cardiovascular training. Thus, even
relatively low levels of aerobic exercise can protect your immune system. Twenty to 30
minutes of brisk walking five days per week is an ideal training program for maintaining a
healthy immune response.
Exercise can also improve your mental wellness. Regular aerobic exercise can help
relieve mild to moderate degrees of depression and anxiety. People who exercise also have
less loneliness and anger, and are better able to control their own destiny. It is not
clear whether exercise boosts the immune system directly or works through a link with the
brain and nervous system.
Stress and immunity
The final component for fine-tuning your immune system is reducing the stress
in your life by achieving a higher level of spiritual harmony. Altered mood states such as
depression, anxiety, and panic are harmful to the body in many ways. Secondary symptoms
such as fatigue, difficulties with memory and concentration, aches and pains, and problems
with sleep are common in people with mood disorders. Mood disorders also harm the immune
There are many techniques you can use to reduce stress and anxiety in your life. Guided
imagery involves focusing on mental images, such as a serene setting. You can also try
yoga or tai chi, which combine both mental and physical exercise, and can help heal the
mind and the body. You might consider using biofeedback, a process in which you monitor
certain functions of the body, such as blood pressure, and learn to alter these functions
through relaxation. Other simple techniques include breathing exercises or taking a walk
and appreciating the beauty in the world around you.
For people who have severe mood disorders, antidepressants and other psychotropic
medicines, as well as counseling, are essential.
Putting it all together
Diseases such as chronic fatigue syndrome, fibromyalgia, and many other poorly
understood illnesses should no longer be viewed as disorders of either the mind or the
body. The mind and body act as one unit and thus we must approach them together.
To maintain the strongest immune system possible, you must have a nutritious diet, get
regular exercise, and reduce stress in your life. You must attend to all three of these
areas to achieve your optimum health.
Some people eat a nutritious diet and exercise regularly, but are so keyed up in their
lives that their stress levels overcome all of the success they achieve in the first two
areas. Other people might have successfully modified their mental and spiritual state but
are eating unhealthy diets or are sedentary. Others might make significant advances in all
three areas, but are doing foolish and harmful things to their bodies, such as smoking or
using excessive alcohol, which take away from their achievements.
Dr. Andrew Weil, noted author and director of the program in integrative medicine at
the University of Arizona, has written extensively about the body's ability to heal
itself. Many health care providers have witnessed people overcome complex medical
illnesses without the assistance of medicine. Though medicines are vital for overcoming
many acute illnesses, they might be less important in overcoming chronic diseases.
You can take advantage of the body's inner ability to heal by eating well, exercising
regularly, and striving for spiritual well-being. Eliminate other negative factors such as
drugs, alcohol, tobacco, and other insults to the your body. Only you can put it all
together and it cannot be achieved overnight. There is no better time to start than now.
Simone C. Cancer and Nutrition. Garden City, New York: Avery Press; 1992.
Wyle A. Eight Weeks to Optimum Health. New York: Alfred A. Knopf: 1997.
Selected articles on exercise, nutrition and stress
Calabrese Leonard H: Exercise, immunity and infection. Journal of the
American Osteopathic Association. 1996:166-176.
Hemial H: Vitamin C and common cold incidence. A review of studies with subjects under
heavy physical stress. International Journal of Sports Medicine. 1996: Vol 17, p
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