HomeHealthArchivesApr 2007



What is the immune system?

The immune system is the policing and protection system of the body.

What do you mean by policing?

Important to the function of an army is the correct identification of the enemy. The policing function of the army or the surveilance function is a complicated system that enables the body to more accurately identify potentially harmful things in the body.

What is included in "things"?

Some of the functions of protection that our immune systems give to us have to do with identifying harmful bacteria and destroying them. Viruses are another disease that the immune system identifies and attacks. Cancer cells can often be destroyed by the immune system. And sometimes other substances such as wood chips or abnormal other objects may be attacked by the immune system.

Where does the attack begin?

The defense systems of the body help to prevent harmful substances from entering in the first place. The skin and mucus membranes provide a major barrier to harm coming in from outside the body.

The body also has protective substances in the tears, and defense around body openings to help to defend the entries.

What happens after abnormal substances enter the body?

The body has responders such as natural killer cells to attack the offender. Also, if the problem has been encountered before, an antibody memory response may enable the body to more effectively deal with the offender. This is the principle behind vaccines.

How do vaccines work?

Often, a part or more than one part of bacteria or viruses are injected into a person. The body recognizes the abnormal substances and builds antibodies to them. When faced with a similar problem in the future (although perhaps the future exposure will be to the actual disease) the body has prepared for this and is much more able to defend itself.

Are there abnormal responses that the immune system makes?

A common term used is "autoimmune diseases" these diseases are a group of diseases in which it appears that the immune system is attacking the body.

Why would the body attack itself?

The body would not normally attack itself, but it does build up antibodies to foreign invaders. At least some, and perhaps many autoimmune diseases appear to develop because the body has detected a foreign substance and builds an antibody response to the foreign substance. The problem is that the antibody is designed to attack a substance too similar to a substance in the body. So there appears to be cross reaction where, although the body may indeed attack an invader; it also attacks itself.

What is the effect of this attack?

If there is a cross reaction affecting heart valves, then the body may wind up using the immune system to damage heart valves. There are multiple diseases that may have a similar mechanism of disease.

What can I do about this to prevent autoimmune disease?

While it would at first appear that those who have the strongest immune systems would be those with the greatest risk for autoimmune disease, this has not been my experience. In fact those who strengthen their immune systems with healthful lifestyles may see immune system disease improve dramatically sometimes.

Does alcohol affect the immune system?

Alcohol impairs their normal function of the B-lymphocytes. They produce antibodies in the blood. It takes only two drinks to reduce antibody production by two-thirds.

A group of white blood cells called Natural Killer cells (NK cells) are also weakened by alcoholic drinks.

Rats were injected with breast cancer cells.

Some drank alcoholic drinks to produce a blood alcohol level of 0.15% about equal to a human adult drinking four or five drinks per hour.

Others drank more producing a 0.25% blood alcohol level.

A third group drank no alcohol.

Those that drank at the lower level had twice as many cancerous tumors as the non-drinking rats.

The higher level drinkers had 8 times as many tumors.

Can you give me a possible explanation for how healthful living might affect the immune system?

One possibility is that the multiple antigens entering through the digestive system of an individual who has not cared for his digestive system properly may stimulate more antibody responses than those in a person who has allowed the digestive tract to be a more secure barrier to antigens entering the blood stream. This gives the blood borne immune system a greater challenge.

Also this same individual who has not cared for his digestive tract may not be eating the whole plant foods that strengthen the immune system and so the immune system is not as capable of defending itself as well. This may increase the chance of stray "bullets".

What should I eat to have a good immune system?

In Neil Nedley, M.D. Proof Positive:

Both human epidemiology and animal research suggest that vitamin A is important for reducing our risk of cancer. One classic Norwegian study, published in 1975, reported five years of research on over 8000 men. Dr. Bjelke found that, for any given level of smoking, low vitamin A intake increased lung cancer risk. For the total population, which includes smokers and nonsmokers, those who had low levels of vitamin A intake had over double the risk of lung cancer. More impressively, those who ever smoked had over four times the risk of developing the most common smoking-related lung cancers if their vitamin A intake was low.

A more recent Japanese study also found that low blood levels of vitamin A increased the risk of lung cancer. Those with serum vitamin A levels in the lowest third had nearly six-times the risk of lung cancer as those with levels in the upper third. Not all lung cancers are developed in smokers. Up to 15 percent of lung cancers can occur in those who do not actively smoke, but may be exposed to varying levels of second-hand smoke. Those nonsmokers with a higher beta carotene intake from fruits and vegetables had only 70 percent of the risk of lung cancer as those eating less beta-carotene.

Are there relatives of beta carotene that are helpful?

A host of other beta-carotene relatives occurs in plants. These are called carotenoids and can also be converted into vitamin A. Some of these carotenoids include beta cryptoxanthin, lutein, and lycopene. Lycopene causes the red color in strawberries and tomatoes. Foods that are particularly rich in lycopene have been associated with prostate cancer prevention. Harvard's Health Professionals Follow-up Study found that men who ate tomato sauce as little as once per week had prostate cancer risks 23 percent lower than those who never ate it. Those men eating tomato-based products ten or more times per week were up to 35 percent less likely to develop prostate cancer. The study's lead author, Dr. Edward Giovan-nucci, believes that lycopene may be the key ingredient that causes this risk reduction.

Those with the lowest lycopene blood levels also have a significantly increased risk of developing pancreatic cancer. Lycopene, like most of the helpful beta carotene relatives, cannot be found in pills but only in fruits and vegetables.

Why do vitamin A related compounds protect seem to protect us?

First, they act as antioxidants. In this role, they help the body dispose of chemicals called free radicals that can genetically damage normal cells and set the stage for cancer. (Free radicals are explained in the next section).

Second, vitamin A-related compounds appear to be capable of stimulating the immune system. Mice given additional vitamin A have an improvement in the function of their T lymphocytes, which are a variety of white blood cells that destroy cancer cells. Third, vitamin A compounds help body tissues to differentiate, that is, develop in a normal, orderly fashion. Since cancer is characterized by a lack of differentiation, some theorize that vitamin A may help to reverse early cancerous changes by helping those abnormal tissues to move into a more orderly state of growth.

Is there any other vitamin that we should look into?

Vitamin C is another cancer-protective food. Its main effects are also likely due to its role as an antioxidant, similar to vitamin A, thus decreasing exposure to toxic "free radicals."

Vitamin C also tends to prevent the formation of carcinogenic nitrosamines from nitrites in the diet.

It does more than protect the person himself from cancer. Recent research suggests that vitamin C may help to protect sperm from genetic damage. There is evidence that genetically damaged sperm may cause inherited diseases such as cancer in the next generation. Vitamin C provides protection through its role as an antioxidant. Certain childhood malignancies such as leukemia and cancer of the kidney and brain have their roots in the father's genetically damaged sperm. Such sperm abnormalities may represent a combination of factors such as cigarette smoking (which appears able to actually oxidize the sperm and genetically damage it), a poor diet (less than 250 mg of Vitamin C a day) and low consumption of other antioxidants), and exposure to occupational toxins. Thus a man's lifestyle, including eating habits, from a few weeks prior to conception up to the time of conception is vitally important in determining the integrity of his offspring's DNA.

What about vitamin E?

Vitamin E appears to help protect against cancer for similar reasons that vitamin C does. It is an antioxidant and a free-radical scavenger. It also has a role in blocking the formation of carcinogenic nitrosamines and nitrosamides from foods containing nitrite.200,201,202

As an example of the power of antioxidant vitamins to reduce cancer risk, consider the following study. Researchers obtained a hairless strain of rabbits that were prone to skin cancer and exposed them to ultraviolet light for 24 weeks to accelerate the development of cancer. For rabbits with the regular diet, 24% got skin cancer, for the rabbits that were given the regular diet plus vitamins C and E 0% got skin cancer.

Are there benefits to eating foods in addition to that acquired from vitamins A, C, and E?

Some anitoxidant rich fruits and vegetables include:

Fruits: Strawberry, Plum, Orange, Red grapes, Kiwi fruit, Pink grapefruit, White grapes, Bannana, Apple, Tomato.

Vegetable: Garlic, Kale, Spinach, Brussels sprouts, Alfalfa sprouts, Broccoli, Beets, Red Bell Pepper, Onion, Corn

Each of these foods has much more antioxidant activity than the sum of the antioxidant content of vitamins A, C, and E. For example, one cup of cooked kale has as much antioxidant activity as about 800 mg of Vitamin C or 1100 IU of Vitamin E. However, the kale only contains about 50 mg of Vitamin C and 13 IU of Vitamin E. What accounts for the difference? A whole host of other antioxidants in the kale that we often do not measure. It is well established that many fruits and vegetables have powerful antioxidant effects far beyond what an assessment of conventional vitamin contents would reveal.

We have heard about phytochemicals. Do they influence disease risk?

Most of the research on the effects of phytochemicals on humans comes from nutritional epidemiologists. These researchers study the dietary habits of people and then draw conclusions as to which dietary factors are protective and which are harmful. Most of us do not sit down to a meal of supplement pills that consist of isolated phytochemicals. We obtain these protective compounds in the fruits, grains, nuts, and vegetables that we eat. As a result, research tends to show connections between foods that are rich in phytochemicals and cancer risk.

One group of foods that are loaded with cancer-protective factors are the cruciferous vegetables. These members of the cabbage family include brussels sprouts, cauliflower, broccoli, kale, turnips, kohlrabi, bok choy, collards, and cabbage. One study showed that those who ate cabbage at least once per week had two-thirds less colon cancer than those who ate it once per month or less. Indoles are among the cancer-protective phytochemicals in these plants. These compounds work as blocking agents by increasing colon enzymes that can deactivate carcinogens.

A large study from the Netherlands involved over 120,000 men and women. Researchers there made a connection between another phytochemical-rich food and cancer prevention, the simple onion. The cancer it prevented was stomach cancer. Those eating the most onions (one or more onions every other day) had half the stomach cancer risk of those who never ate onions.

Garlic has been shown to protect against developing cancer; in mice, it is effective in treating cancer. The amount of 50 milligrams of garlic administered in 3 ounces of drinking water to mice with bladder cancer led to significant shrinking of the tumors, while 500 milligrams of garlic not only reduced the cancer size but actually decreased the mortality rate from the cancer. All of this occurred without side effects. The researchers believe that the garlic may have stimulated the mice's immune systems, helping them to combat the cancer.

How does exercise relate to the immune system?

Harvard Alumni found that those who burned only 500 calories or less per week in exercise had 35 percent more cancer deaths than those expending greater than 2,000 calories per week.

Researchers at the Cooper Clinic in Dallas have found that those who exercise moderately have only about three-quarters of the prostate cancer risk experienced by their inactive peers. The high exercise group fared by far the best; they had only about 30 percent of the risk faced by those getting little or no regular exercise.

Why would exercise lower cancer risk?

Why does exercise reduce cancer risk? There are several possible reasons-many of them center around the immune system. For example, strenuous, sustained exercise stimulates white blood cells to release a compound called interleukin 1. We could expect any vigorous exercise to accomplish this effect, whether it is gardening, brisk walking, or dozens of other activities. This is good news because interleukin-1, in and of itself, is a natural chemotherapy agent. Beyond this, interleukin-1 stimulates the release of interleukin-2, which also aids the immune system. These interleukin chemicals from our white blood cells serve as modulators of the whole immune system.

Another way that vigorous exercise helps the immune system is by doubling the blood plasma interferon levels. Interferon is another chemotherapy agent that acts against certain types of cancer such as hairy-celled leukemia. It also fights chronic viral infections such as hepatitis B and hepatitis C.

Exercise also increases other critical immune substances, the natural killer cells. Natural killer cells are certain white blood cells that seem to have a natural instinct to detect abnormal cells and destroy them. They seem to be especially important in defending us from cancer. Finally, the blood lymphocytes, which are a broad group of white blood cells that are very prominently involved in the immune system itself, are increased with exercise.

Exercise also has the ability to modulate hormonal mechanisms. This may be important in both sexes at all ages, but has been particularly noted in young women who exercise vigorously. It is common knowledge that the hormonal changes from exercise in that group can be so profound that menstrual cycles can cease.

Does sun exposure affect the immune system?

Probably, sun exposure may help prevent colon cancer. Researchers at the University of Washington studied cancer rates in nine areas of the United States. They discovered that men from Southern states had much less colon cancer than Northerners.