En excerpt from the book :
IN CANCER THERAPY"
by Ross, R.Ph. Pelton, Lee Overholser
FROM CANTALOUPES to broccoli and carrots to zucchini, when your mother urged you to eat your fruits and vegetables, she was really helping to protect you from cancer. Beta-carotene, a nutrient that occurs naturally in many fruits and vegetables, is rapidly gaining recognition as an important nutrient in the prevention and treatment of cancer.
Cancer of the epithelial cells accounts for nearly 90 percent of all cancers. The epithelial cells make up the skin, the lining of the intestines, and other thin tissues throughout the body. Some of the studies in this chapter show that beta-carotene helps to prevent cellular mutation and cancer formation while at the same time strengthening the immune system. The evidence comes from a number of sources, including cell culture studies, animal model systems, and, more recently, human population studies.
Responsible treatment of cancer is more than a matter of removing the current cancerous cells. Preventing a recurrence of the cancer is just as important, and beta-carotene appears to be an important nutrient in this effort.
Beta-carotene, like most of the substances used in alternative cancer therapies, occurs naturally. It's also one of nature's immune-system boosters and part of the protective anticancer systerns that are naturally found in plants, animals, and humans.
An important principle of many alternative approaches to cancer is that there is not much difference between treatment and prevention. This principle also applies to preventing the reappearance of a treated cancer. One researcher suggested, in the American Journal of Clinical Nutrition, that beta-carotene should be studied for its ability to prevent a recurrence of primary tumors in patients who have been cured of their initial cancer, but have an increased risk of developing new cancers. (29)
Beta-Carotene and Vitamin A
Vitamin A and beta-carotene arc chemically related. All the vitamin A in our diets comes from animal sources, and all the beta-carotene comes from fruits and vegetables. Beta-carotene, which is also called provitamin A, is really just two molecules of vitamin A linked together. Whenever the body needs more vitamin A, intestinal enzymes split a molecule of beta-carotene in half. (9)
Chemically, vitamin A is called retinol, and its many analogs are called retinoids. Beta-carotene is the most important carot-enoid, since it is found in abundance in so many vegetables and has the highest level of biological activity.
A large body of evidence suggests that both carotenoids and retinoids play an important role in the prevention and treatment of cancer. Several published studies provide comprehensive reviews of this research. (10, 14, 30) Much of the interest in these compounds stemmed from the knowledge that vitamin A exerts profound effects on the healthy development of epithelial tissues, helping to prevent cancers of the skin, mouth, esophagus, stomach, lungs, mammary glands, cervix, bladder, colon, rectum, et cetera. (22)
The idea that retinoids and carotenoids could be used to prevent cancer dates back to 1922, when it was reported that a deficiency of vitamin A led to precancerous changes in epithelial cells of the respiratory tract. (18) Solid evidence linking retinoids and cancer was published in 1926, when Japanese researchers observed the development of stomach cancer in rats fed diets deficient in vitamin A. (6)
In the 1960s Drs. Leonida Santamaria and Amalia Bianchi concluded that a number of studies demonstrated vitamin A's ability to prevent cancer in cell and organ cultures, as well as in various chemically induced tumors in animals. (24) Many subsequent studies have shown that when beta-carotene is administered on the skin, injected, or added to the diet of laboratory animals, it is capable of inhibiting various types of experimentally induced cancers. (12) In 1977, in a study with animals prone to develop tumors, it was shown for the first time that beta-carotene is capable of significantly delaying the appearance of tumors and also reducing tumor growth rate. (5)
Another study assessed the effect of antioxidant nutrients on chemically induced liver tumors. Vitamin E caused a 60-percent reduction in the appearance of tumors. Glutathione caused an 80-percent reduction. Vitamin C, selenium, and uric acid each individually caused an 87-percent reduction in the appearance of liver tumors. However, the most impressive result was that beta-carotene TOTALLY inhibited the development of liver tumors. (19)
In 1982 a study demonstrated that beta-carotene has anti-tumor action in animals with transplanted tumors. Beta-carotene decreased tumor growth and extended animal survival time; in addition, when beta-carotene was fed to animals that had already developed palpable tumors, it slowed tumor growth and increased animal survival time. (23)
Trials in Humans
The Basel study (1971-73) was one of the first large-scale trials that showed the relationship between beta-carotene and cancer in humans. (27) During the twelve-year follow-up, cancer mortality was highest in subjects with the lowest plasma levels of beta-carotene. The plasma concentration of beta-carotene was significantly lower in people who developed lung cancer and stomach cancer, and for all cancer cases combined. (28) Many other studies have been published since, which consistently show decreased rate of cancer in subjects with high levels of beta-carotene. (16, 32)
Fill up your plate with those green and yellow fruits and vegetables. Over twenty studies have been published showing a diet high in vitamin A and carotenes lowers the risk of cancer. A study conducted at Harvard University found that elderly individuals who reported the highest consumption of green and yellow fruits and vegetables had a significantly decreased risk of developing cancer. (4)
A large Japanese study showed that vegetable eaters had a decreased risk of developing lung and stomach cancer. This twenty-year ongoing study also indicates that damage from poor dietary and life-style habits is reversible. For example, ex-smokers who ate a daily dose of vegetables reduced their risk of lung cancer. Also, just eating more vegetables produced a 25-percent reduction in stomach cancer. (25)
Premalignant lesions are areas of abnormally developed cells that are statistically known to be associated with the eventual development of cancer. The most commonly occurring sites for pre-malignant lesions include the skin, stomach, esophagus, cervix, oral cavity, lungs, bladder, and colon. .
The study of premalignant lesions offers an ideal opportunity to identify and evaluate substances that actually inhibit the development of cancer. Studies of premalignant lesions are limited in number, but cervical dysplasia and oral leukoplakia are two types of precancerous lesions that have been well researched.
PRECANCEROUS LESIONS OF THE MOUTH
Millions of people throughout the world indulge in the daily habit of chewing either tobacco or betel nut leaves. These people frequently develop precancerous cells in the skin that lines the mouth. (29) This condition is called oral leukoplakia and is characterized by persistent white spots or areas inside the mouth.
Some studies have shown that the consumption of foods rich in beta-carotene reduces the risk of developing this type of oral cancer. (7, 15) Other studies have shown that supplementation with beta-carotene has produced complete or partial regression of this precancerous condition in the oral cavity. (8)
THE CERVICAL CANCER LINK
Cervical dysplasia is a premalignant lesion of the uterine cervix. It has been repeatedly shown that women with cervical dysplasia have a significantly higher probability of developing cervical cancer. (26) Ten different studies have been published showing that women with low dietary intakes and/or low blood levels of beta-carotene have significantly increased risks of cervical dysplasia and cancer of the cervix.
One of these studies reported that women consuming beta-carotene in amounts below the study's median intake had a risk two to three times greater of developing cervical dysplasia or localized cervical cancer than women with the highest dietary beta-carotene intake. (31) In another study, women with the highest plasma beta-carotene levels had approximately an 80-percent reduction in the risk of developing cervical cancer. (1)
One of the most consistent findings in nutritional research has been the association between beta-carotene and reduced risk of lung cancer—particularly, the reduced risk of squamous cell carcinoma. (17) Bronchial metaplasia is a premalignant lesion that is considered to be an indicator of risk for lung cancer in smokers.
The Immune Systemm] Recent studies have begun to explore how vitamin A and beta-, carotenes inhibit cancer. Their effect on the immune system in ;animals has been well known, but more recently there have been studies on how they affect cells in the human immune system. (21) Vitamin A compounds produce increases in T-helper s cells, whereas beta-carotene produces significant increases in natural killer (NK) cells.
I Both nutrients also produce modest increases in other cellular ¦markers in the immune system. Both retinoids and carotenoids ¦can produce major changes in the human immune system at doses that are appropriate to take as daily nutritional supplements. (33)
Beta-Carotene: A Powerful Antioxidant
Earlier anticancer studies tended to focus on vitamin A, but recent evidence indicates that beta-carotene is a more powerful anti-cancer agent. This stems from the discovery that beta-carotene is a powerful antioxidant nutrient capable of neutralizing potential cancer-causing free radicals. (2,11) It has been well established that free-radical damage to DNA and cellular membranes can lead to cancer. (3)
Although vitamin A is an important essential nutrient, it does not possess the same antioxidant, anticancer properties that beta-carotene does. Since the body converts beta-carotene into vitamin A as needed, taking beta-carotene provides the body with its vitamin A while providing an extra level of antioxidant cancer prevention.
In 1981 research was published that proposed it was beta-carotene and not dietary vitamin A that was responsible for significantly reducing the risk of lung cancer in humans in previous studies. (20) This claim stimulated research on beta-carotene and other carotenoids as possible diet-related antitumor agents. /
Beta-Carotene: An Unusual Antioxidant
By the mid-1980s it was established that beta-carotene is an unusual and previously unknown type of antioxidant. It is capable of deactivating two of the most damaging types of unstable cancer-causing free radicals, polyunsaturated fatty-acid radicals and the singlet-oxygen free radical. The toxicity of oxygen free radicals is known to be a primary factor in the initiation phase of cancer. (2)
The singlet-oxygen free radical is one of the most damaging types of oxygen radicals. It is formed during regular metabolic processes, and also as a result of exposure to direct sunlight (ultraviolet rays) or ozone.
Our bodies have developed enzymes to deal with most free radicals, but we have not developed an enzyme system to neutralize the singlet-oxygen radical. Beta-carotene is important because it is the only known substance that can neutralize the singlet-oxygen radical. (13)
Preventing a Second Primary Malignancy
Tumor metabolism generates tremendous amounts of oxygen free radicals. Two Italian physicians, Leonida Santamaria and Amalia Bianchi, theorized that complete removal of a tumor with no lymph node involvement or even successful removal of a tumor and all cancerous lymph nodes cannot reverse or prevent change in the remaining epithelial tissue. The cells in the remaining tissue may already have undergone free-radical-induced genetic change, which can enable a second primary malignancy b grow in the same site. (24)
The expression "we got it all," after successful cancer surgery, pay not accurately describe the situation. Prevention of further change is as important as eliminating the existing cancer cells.
First Clinical Case Report [ 4980-88}
Drs. Santamaria and Bianchi decided to use "saturation" dosages of two carotenoids after surgery, both with and without chemotherapy and radiation, in an effort to prevent the eventual development of a second primary malignancy. Although only eleven subjects were studied, a survey of these clinical cases after eight years provided highly promising results. There were two breast cancers, one lung cancer, five urinary bladder cancers, and three nose and throat cancers. (24)
The use of saturation dosages of two carotenoids in this clinical trial, beta-carotene and canthaxanthine, provided total prevention of second primary tumors far exceeding the expected disease-free intervals for these cancers. It should also be noted that three of these patients were initially considered to be hopeless.
Although the Santamaria-Bianchi trial is the first clinical case report of its kind, the authors report that their convincing results appear to be confirmed by another case history, which was personally reported to them. The patient was a middle-aged man who, five and a half years previously, underwent removal of a kidney due to cancer.
Soon after surgery, dysplasias (precancerous cells) of the bladder mucosa were detected. The patient began beta-carotene supplementation, and the abnormal cells completely disappeared after only two months. This tends to confirm that beta-carotene can prevent the recurrence of cancers that so often eventually follow surgery.
In their concluding remarks, Santamaria and Bianchi state that the overall picture emerging from their clinical trials, although preliminary, is extremely encouraging with regard to current and future intervention trials.
A significant body of research shows that beta-carotene can provide substantial benefit in the prevention and treatment of cancer. It is a nutritional supplement that is safe, inexpensive, and easy to obtain, and that does not interfere with any conventional treatments.
Norman I. Krinsky from Tufts University School of Medicine has researched the beta-carotene-cancer connection extensively. He concludes, "The implications are obvious: carotenoids may prove to be a very important, non-toxic chemopreventive agent in the war on human cancer." (12) The research reviewed in this chapter indicates that beta-carotene may also have a significant role to play in the treatment of cancer.
Side Effects and Toxicity
Although both vitamin A and beta-carotene have well-documented anticancer properties, beta-carotene has become the preferred therapeutic supplement in cancer therapy for several reasons. One of the most important aspects of treatment with beta-carotene is that it has no known toxicity and lacks any serious side effects.
Daily high doses of vitamin A can be dangerous, including damage to the liver and, in extreme cases, death. The side effect of an overdose of beta-carotene is called carotenosis, which means the skin begins to turn yellowish-orange, like a carrot. However, this condition is not dangerous.
A typical dosage of between 75,000 IU to 150,000 IU of beta-carotene daily is prescribed for cancer patients at clinics that use nutritional approaches. This is equivalent to 1 or 2 capsules (25,000 IU each) at each meal.
I personally take 150,000 IU of beta-carotene daily. From time to time my patients at the hospital will tease me when my skin color starts to become yellow-orange. This occasional teasing is my feedback mechanism, which tells me to decrease my dosage from 150,000 IU daily to 75,000 IU daily for a few weeks.
However, I want to stress that the slight skin-coloring effect from high-dose beta-carotene intake is not harmful. It simply means that I have optimum anticancer protection in all the body's skin and cellular membranes.
En excerpt from the book :
IN CANCER THERAPY"
by Ross, R.Ph. Pelton, Lee Overholser