Immunity-A Mighty Defense against Aging

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Immunity-A Mighty Defense against Aging

JoAnn Guest

Jan 10, 2004 10:43 PST

 

Immunity-A Mighty Defense against Aging

--

Somewhere in your body, right at this moment, your immune system is

choreographing a deadly waltz with viruses, bacteria, fungi and any

other unwelcome intruders.

 

Like a professional dance troupe, a healthy immune system seems to

have

perfect timing and synchronization. At its best, it is an aggressive

age

fighter that helps keep you feeling good, looking good and brimming

with

energy,

says Terry Phillips, Ph.D., director of the immunogenetics and

immunochemistry laboratories at George Washington University Medical

Center in Washington, D.C.

 

" If the immune system is doing its job, and you have good health,

you

don't even think about it, " Dr. Phillips says.

 

" The best way to keep it that way is to do all the things that are

going to keep it naturally strong like exercising, eating right and

coping with stress as best you can. "

 

But as we age, our immune system, like an aging dancer, loses some

of

its dexterity. This incredibly complex defensive system gradually

weakens and is less able to pounce on and destroy invading

organisms.

 

" The immune system certainly ages and clearly functions less

optimally

as we get older.

 

We believe that loss of immune system function is related to the

onset

of cancer, autoimmune diseases like rheumatoid arthritis and the

frequency and severity of infectious diseases. At 27, for example,

pneumonia is a nuisance, but at 70 it can be life threatening, " says

Michael Osband, M.D., adjunct professor at Boston University School

of

Medicine.

 

A Look at the All-Star Cast

 

The immune system actually consists of millions of cells that have

many

specialized roles. Some play starring roles, while others are

stimulated

to act only in specific situations.

 

Among the key performers are B-cells and T-cells, which are types of

white blood cells.

 

B-cells hang out in the spleen and lymph nodes waiting for specific

invaders, also known as antigens.

 

Once a B-cell identifies an invader, it releases antibodies into the

bloodstream.

 

These Y-shaped proteins latch on to the antigen and tag it for

destruction by various cells.

 

T-cells mature in the thymus--a small gland in the throat--and are

one

of the most important parts of the immune system.

 

They are among the few cells in the body that can distinguish normal

cells from foes like cancer cells, viruses, fungi and bacteria, says

John Marchalonis, Ph.D., professor and chairman of the Department of

Microbiology and Immunology at the University of Arizona College of

Medicine in Tucson.

 

How T-cells learn to do that is complicated. But basically, on the

surface of each T-cell is a receptor, a chemical molecule that

recognizes one of the ten million known antigens.

 

So when a T-cell detects an antigen, not only does it seek out and

attempt to destroy that intruder, but it also sends out signals to

the

other parts of the immune system that determine how aggressively the

body will attack the invader.

 

T-cells, for example, can activate " macrophages " , amoeba-like cells

that

literally gobble up the intruder or signal the B-cells to crank up

their

production of antibodies.

 

A Slow Decline

 

The immune system reaches its prime just about the time that you

enter

puberty. Then the thymus begins to wither away, and your T-cell

production and function drop considerably.

 

Although you may continue to make T-cells throughout your life,

these

cells don't identify invaders and choreograph the defensive effort

of

the immune system as well as the ones produced when the thymus was

at

its peak, Dr. Osband says.

 

Why the thymus shrinks remains a mystery, but some researchers

suspect

that the hormones that trigger puberty also may turn off the thymus.

 

" You generally don't make a lot of T-cells after the thymus goes

away.

 

The thymus is important because that's where T-cells learn to

recognize

antigens, " Dr. Osband says. " Clearly, that learning process doesn't

stop

when the thymus goes, but your T-cells are left to learn on their

own.

It's like trying to educate yourself by reading an encyclopedia

instead

of going to college. "

 

Genetics and free radicals--chemically unstable oxygen molecules

that

cause havoc through the body--also contribute to the decline of the

immune system, says Marguerite Kay, M.D., professor of microbiology

and

immunology at the University of Arizona College of Medicine.

 

In addition, some invaders like HIV (human immunodeficiency virus),

the

virus that causes AIDS, attack the immune system directly and

destroy

it.

 

Keeping Your Immunity Strong

 

While some declines in immune power may be a natural part of aging,

researchers including Dr. Phillips say that making just a few

lifestyle

changes can keep your immunity vigilant long into your life.

 

" In the end, " Dr. Phillips says, " it's how well we look after

ourselves

that decides how well our immune systems look after us. " Here are

some

ways to boost your body's natural defenses.

 

Soothe stress. Researchers have long suspected that stress

suppresses

the immune system, and emerging evidence supports that theory.

 

Researchers at Carnegie Mellon University in Pittsburgh, for

example,

gave cold viruses in the form of nasal drops to 400 volunteers.

Placebo

drops were given to 26 subjects. The researchers then identified

stress

levels in both groups and watched for new infections.

 

The highly stressed volunteers ended up being twice as likely to

develop

colds as the low-stressed volunteers. None of the 26 people who

received

the placebo got a cold.

 

Scientists believe that steroids produced by the adrenal glands are

released during stress

and suppress the activity of immune system cells, Dr. Phillips says.

 

How you ease stress is an individual choice, but for starters, you

could

play with your kids or pet, participate in a hobby like gardening or

woodworking, do meditation or yoga, watch a funny movie or

television

program or just read an enjoyable book.

 

Get some Zzzs.

 

" Sleep is the repair shop for the immune system, " Dr. Phillips says.

During sleep, your brain and body rest but your immune system

doesn't.

So when you're snoozing, your immune system has less competition for

the

nutrients needed to strengthen your disease-fighting mechanisms.

 

Without enough rest, your immune system will suffer. In a study of

23

people, for example, researchers at the University of California,

San

Diego, School of Medicine found a 30 percent decrease in immune

response

after these people missed three or more hours of sleep in a night.

 

Try to get at least six to eight hours of sleep a night, Dr.

Phillips

suggests.

 

Stop smoking.

Tobacco smoke contains formaldehyde, a chemical that can paralyze

macrophages in the lungs and make you more susceptible to upper

respiratory ailments, including colds and flus, Dr. Phillips says.

So if

you smoke, quit.

 

Sweat it out.

Moderate exercise helps prevent bacteria from gathering in the lungs

and

strengthens the vigilance of the immune system by increasing

circulation

of antibodies in the blood, says William H. Adler, M.D., chief of

clinical immunology at the National Institute on Aging in Baltimore.

 

After a 15-week study of 18 women in their thirties who were asked

to

walk 45 minutes a day, five days a week, researchers at Appalachian

State University in Boon, North Carolina, found that the walkers had

half as many colds and flus as a group of sedentary women.

 

To keep your immune system at its best, do aerobic exercise like

walking, jogging, swimming or bicycling at least 20 minutes a day as

often as possible.

 

Shoot Down the Sniffles

---

-----------

 

Eat, Drink and Be Immune

 

" The role of diet in immunity is very direct, " says Jeffrey

Blumberg,

Ph.D., associate director of the U.S. Department of Agriculture

Human

Nutrition Research Center on Aging at Tufts University in Boston.

 

" Specific nutrients play very particular roles in pushing immunity

up

and down. "

 

Here's an A-to-zinc guide to some vitamins and minerals that could

help

keep your immunity in high gear.

 

Get on the A list.

Vitamin A fortifies the top layer of skin against cracks through

which

invaders can enter and fights cancer tumors, possibly by boosting

white

blood cell activity.

It's probably a good idea to get your daily requirements from food

rather than high-dose supplements, says Ranjit Chandra, M.D.,

research

professor at Memorial University of Newfoundland in St. John's and

director of the World Health Organization Center for Nutritional

Immunology.

 

The Recommended Dietary Allowance (RDA) is 800 micrograms retinol

equivalents (or 4,000 IU).

 

One medium sweet potato has more than double your daily requirement

of

vitamin A. Other foods rich in vitamin A are carrots, spinach,

broccoli,

lettuce, apricots and watermelon.

 

Boost your beta-carotene.

An antioxidant, beta-carotene, which is converted to vitamin A in

the

body, also combats free radicals and may strengthen the immune

system's

ability to prevent cancer.

 

Like vitamin A, beta-carotene is found in foods such as carrots,

spinach, broccoli and lettuce. But, unlike vitamin A, beta-carotene

can

be taken in large doses. Dr. Osband suggests taking six to nine

milligrams a day.

 

Don't forget B6.

" When older people were fed diets deficient in vitamin B6, their

immunity was lowered substantially, " Dr. Blumberg says. " When their

intake was then increased one step at a time, immunity gradually

returned to normal--but only after intake of more than 1.6

milligrams

(the RDA) was provided. "

 

You can get the RDA of 1.6 milligrams of vitamin B6 by eating two

large

bananas.

Other good dietary sources are free range chicken, fish, rice,

avocados,

walnuts, wheat germ and sunflower seeds.

Vitamin B6 can be toxic in extremely large doses (1,000 to 2,000

milligrams per day), Dr. Blumberg says.

 

Supercharge with C.

From keeping viruses from multiplying to stimulating tumor-attacking

cells, vitamin C gives almost every part of the immune system a

boost,

Dr. Blumberg says.

Fruits and vegetables like organic oranges, strawberries, broccoli

and

red bell peppers are good sources of this nutrient. It appears that

optimal dosages range from 500 to 1,000 milligrams a day, says Dr.

Blumberg.

 

The sun shines on D.

Although scientists know that vitamin D is an immunity booster, they

are

mystified by its role.

 

They do know that vitamin D is needed for strong bones, which is

significant because immune system cells are formed in the bone

marrow.

 

Fortunately, most people get their fair share.

 

It's abundant in organic yogurts and oily fish such as herring, tuna

and

alaskan salmon. You can get vitamin D from sunlight, since

ultraviolet

radiation triggers a vitamin D­ making substance in the skin. In

summer,

about 10 to 15 minutes of sun a day will give you all the vitamin D

you

need. Vitamin D is toxic in large amounts, so doctors say it should

never be taken in supplements.

 

Eat your E.

A real powerhouse, vitamin E can boost your immunity across the

board.

 

In particular, it prevents free radical damage to cells, improves

white

blood cell activity and increases interleukin-2, a substance that

promotes the growth of T-cells.

 

It also turns off prostaglandin E2, a naturally occurring substance

that suppresses the immune system.

 

Vitamin E--also considered an antioxidant--

can be found in nuts and seeds, but it's difficult to get a

health-promoting or immune-boosting dose through food alone, says

Dr.

Blumberg. Healthy diets generally provide only 20 IU a day. Optimal

dosages appear to be between 100 to 400 IU a day, he says.

 

Ax the fat.

In animal studies, a diet consisting of 40 percent of calories from

fat--the typical American diet--had a detrimental influence on the

immune system, says Dr. Chandra. So try to reduce your fat

consumption

to 25 percent of calories.

 

To do it, eliminate dairy products, trim skin or visible fat from

meats

and eat no more than one three-ounce serving (about the size of a

deck

of cards) of free range poultry, cold water fish or organic red meat

a

day. Be sure to eat at least six servings of beans and rice and at

least

five servings of fruits and vegetables like apples, pears, broccoli

and

spinach daily.

 

Maximize your magnesium.

Some studies suggest that magnesium deficiency can cause the immune

system to run amok, attack normal cells in the body and trigger

autoimmune diseases like rheumatoid arthritis, Dr. Phillips says.

 

Taking a magnesium supplement may be a good idea for women on water

pills (diuretics) or high blood pressure drugs.

Both make you lose this mineral. So does drinking excessive amounts

of

alcohol. The rest of us can get the RDA of 280 milligrams without

supplements by regularly eating leafy vegetables, organic potatoes,

whole grains, milk and seafood.

 

Stock up on selenium.

This nutrient, an antioxidant that's a known cancer fighter, may be

required to fire up your immune system's infection-fighting team.

You

should be getting plenty in your normal diet.

 

The RDA of selenium for women is 55 micrograms, and you'll get 138

micrograms from a tuna sandwich alone. All fish, and whole-grain

cereals

and breads are selenium rich.

Very high doses can impair immune responses, however, so supplements

should not exceed 200 micrograms a day, Dr. Chandra says.

 

Try zinc, the missing link.

" Of all the minerals, zinc is probably the most important for

maintaining immunity, " Dr. Phillips says. A shortage can cause a

drop in

production of the white blood cells that surround and destroy

microscopic invaders.

 

Zinc also helps the body process vitamin D, another important

nutrient

that bolsters immunity. To get the RDA of 12 milligrams from your

diet,

eat lean organic red meats, oats, whole grains, organic eggs and

free

range poultry. Avoid supplements providing more than 40 milligrams.

_________________

JoAnn Guest

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DietaryTi-

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