November 2004, Volume 31, Number 6

Online Exclusive
Herbs or Natural Products That Protect Against Cancer Growth Part Three of a Four-Part Series
Muriel J. Montbriand, PhD, RN

Abstract

Purpose/Objectives: To provide evidence-based research information about 47 herbs and natural products that have the potential to protect against the development of cancer.

Data Sources: Natural Medicines Comprehensive Database and Lawrence Review of Natural Products-Monograph System. Information about these herbs has been found in evidence-based studies cited in the references.

Data Synthesis: Early research shows that some herbs and natural products appear to have the potential to prevent cancer growth.

Conclusions: This preliminary evidence may be useful to healthcare professionals or patients who are concerned about cancer.

Implications for Nursing: Oncology nurses who receive this information can become resources for patients or other healthcare professionals.

Key Points

• Some herbs and natural products may protect against cancer growth.
• The best protection against cancer may be a dietary pattern that emphasizes fruits, vegetables, grains, and beans and limits meats, dairy products, and high-fat foods.
• Oncology nurses can become better resources for healthcare professionals and patients regarding herbs and natural products.

Consumers and patients with cancer take numerous alternative products to protect themselves from cancer. Evidence indicates that use of alternative products is as high as 89% among all patients and consumers (Eisenberg et al., 1993, 1998; Ernst, 2000a, 2000b; Ernst & Cassileth, 1998; Montbriand, 1994, 1995a, 1995b, 1997, 2000b; Perlman, Eisenberg, & Panush, 1999; Sparber et al., 2000; Spar-ber & Wootton, 2001; White, 2002). Yet research has shown that only 3% (4 of 150) of nurses, doctors, and pharmacists believed that they had adequate information to give to patients about alternative products (Montbriand, 2000a, 2000b). Conversely, 97% (146 of 150) of these healthcare professionals indicated a willingness to be resources if they could have evidence-based information that was available, succinct, and in one place. This review article provides evidence-based information from preliminary research to assist healthcare professionals' endeavors as resources for patients as well as others.

This is the third article in a four-part series dedicated to providing information about herbs and natural products for healthcare professionals in clinical oncology. The target herbs and natural products are those that may protect against cancer growth. The target group for this article is individuals who do not have cancer but are concerned about its development.

As indicated in previous parts of this series, some overlap in categories should be expected because early evidence (especially in vivo and in vitro evidence) often shows contrary results. In Part I (Montbriand, 2004a), fish oils containing vitamins A and D and omega-3 fatty acids are indicated to have a potential role in decreasing cancer growth. In this article, vitamin A and D are indicated for their potential to protect against cancer. The same will be found for soy in Part II (Montbriand, 2004b), which is focused on products with the potential to increase cancer growth. Soy also appears in this article because it has the potential to protect against cancer. This overlap occurs because this series targets two specific groups, individuals who have cancer (Parts I and II) and individuals who do not have cancer (Part III). For each target group, the aim is to identify herbs and natural products with the potential for or against cancer growth. For example, if a woman with breast cancer takes soy, she increases her risk of cancer growth. If a woman who does not have cancer takes soy, she protects herself against cancer.

For this article, the names of herbs and natural products have been selected from listings in the Natural Medicines Comprehensive Database (2004) and Lawrence Review of Natural Products-Monograph System (Facts and Comparisons, 2001). Evidence about these herbs has been found in the studies cited in the references. Other products that interact positively with cancer may exist; however, this review includes only herbs and natural products recognized by the authors, professionals, or advisory boards of these two sources.

Most of the studies cited are in vitro studies, performed in glass on tissue from a living organism, or in vivo studies, performed on tissue not removed from a living organism (animal studies). Most studies have not advanced to clinical trials on humans. The few human studies cited are preliminary clinical trials. Therefore, although results seem favorable or unfavorable, treat these findings with caution.

Neither the author nor publisher makes any medical claims for any of the herbs or natural products in this review or the tables. This is informational literature. Note that some of the herbs described are deadly poisons and some are extremely dangerous.

The American Cancer Society (ACS) 1996 Advisory Committee on Diet, Nutrition, and Cancer Prevention (1996) recommended the dietary intake of more fruits and vegetables to lower the risk of cancer. ACS also indicated that no evidence supports the use of additional vitamin supplements to protect against cancer. Remarkably, many of the herbs and natural products currently investigated and indicated in this article are common foods, reinforcing ACS's stance and providing an update to the society's work.

Table 1 provides names of herbs and natural products discussed in the text. Common names as well as brand names and manufacturers are included. Some products have numerous brand names, making a complete listing prohibitive. The number of brand names found also is included in the table. When a brand name contains only one ingredient, it often bears the product's common name. Single-ingredient products are identified in Table 1. Other brands with numerous ingredients also are indicated. Products with single ingredients should be favored over those with multiple ingredients because as the number of ingredients increases, so does the number of possible side effects. Table 1 can be used as a quick reference to find product names or equivalent common names. The following provides additional information on each herb or natural product.

Herbs and Natural Health Products

Alpha-linolenic acid, which has the same scientific name, is used to treat numerous conditions such as renal disease, migraine headaches, and skin cancer. Individuals also use it to prevent cardiovascular disease and other cancers (Klein et al., 2000; Simopoulos, 1999). Women with higher levels of alpha-linolenic acid in breast adipose tissues have a lower risk of cancer, leading researchers to propose that this acid may have a protective effect (Klein et al.). However, high intake of this acid may cause prostate cancer (Colditz, 2000; De Stefani, Deneo-Pellegrini, Boffetta, Ronco, & Mendilaharsu, 2000; Freeman et al., 2000; Gann et al., 1994; Giovannucci et al., 1998; Harvei et al., 1997; Ramon et al., 2000). Kolonel, Nomura, and Cooney (1999) and Ramon et al. have speculated that prostate cancer may be attributed to high animal fat intake and consumption of red meat and dairy products, which contain alpha-linolenic acid. Patients and consumers should not be concerned about moderate dietary intake of alpha-linolenic acid. A daily diet containing 1.2-2 g of alpha-linolenic acid seems to prevent coronary heart disease (Ascherio et al., 1996; Christensen, Christensen, Toft, Dyerberg, & Schmidt, 2000; Hu et al., 1999). Self-medication beyond 1.2-2 g of alpha-linolenic acid to prevent breast cancer may impart a risk. See Table 2 for adverse effects.

American pawpaw has a scientific name of Asimina triloba, which is synonymous with Annona triloba. According to Gruenwald, Brendler, and Jaenicke (1998), this herb is used to treat fever, vomiting, and oral inflammation. Highly cytotoxic acetogenin constituents have been found in American pawpaw, and preliminary studies show that some acetogenins have activity against certain lung and breast cancers (He et al., 1997). Adverse reactions include nausea and urticaria (Gruenwald et al.). No standard dosage is available (Natural Medicines Comprehensive Database, 2004).

Apple has a scientific name of Malus sylvestris. Individuals use apples for many conditions from cleaning their teeth to treating diarrhea, constipation, fever, and cancer. The antioxidant flavonoid quercetin in apples seems to have a protective property against lung cancer. This finding was reported by Butland, Fehily, and Elwood (2000), who examined 2,512 individuals' lung functions and diets, and by another group of researchers who compared diet items of 582 individuals with lung cancer to diet items of 582 control participants (LeMarchand, Murphy, Hankin, Wilkens, & Kolonel, 2000). Although apples are considered safe when taken as a dietary fruit source, the seeds contain hydrogen cyanide that is released, generated, or liberated when mixed with saliva. Duke (1987) reported the death of a man who ingested a cup of apple seeds. Stones and seeds of fruit naturally contain two parts glucose, one part benzaldehyde (mildly poisonous), and one part cyanide (Herbert, 1981). The most common dose for self-medication appears to be 500 mg apple pectin capsules (Natural Medicines Comprehensive Database, 2004).

Asparagus has a scientific name of Asparagus officinalis. People often self-medicate with this vegetable for urinary conditions (Blumenthal et al., 1998). Fibers from asparagus have a mutagen-absorbing (cancer-preventing) activity (Leung & Foster, 1996). Asparagus can cause mucous membrane irritation (Tyler, Brady, & Robbers, 1981). A typical dosage is prepared as a tea using 40-60 g of cut asparagus root (Blu-menthal et al.). Self-medication doses have not been made available.

Barley, with a scientific name of Hordeum distychum or Hordeum vulgare, is used to prevent cancer. Barley also is used for bronchitis, diarrhea, and gastrointestinal conditions and to lower blood sugar, cholesterol, and lipid levels (Facts and Comparisons, 2001). Studies show a reduction of colon cancer risk in barley-fed rats (Facts and Comparisons). Barley and barley dust can cause asthma and allergic reactions for sensitive individuals (Natural Medicines Comprehensive Database, 2004). Gruenwald et al. (1998) indicated that medicinal preparations and combination products are made from barley malt extract. No suggested dosage is available.

Beta-sitosterol has scientific names of 22,23-dihydrostigmasterol; 24-beta-ethyl-delta-5-cholesten-3beta-ol; 24-ethyl-cholesterol; and 3-beta-stigmast-5-en-3-ol. Self-medication with beta-sitosterol is for numerous conditions from asthma and allergies to preventing colon or cervical cancer, the common cold, and tuberculosis (Natural Medicines Comprehensive Database, 2004). In vitro, beta-sitosterol can inhibit human colon cancer cells (Awad, Chen, Fink, & Hennessey, 1996; Awad, von Holtz, Cone, Fink, & Chen, 1998). Beta-sitosterol typically is well tolerated, but it can cause nausea, indigestion, flatulence, diarrhea, or constipation (Berges, Windeler, Trampisch, & Senge, 1995; Klippel, Hiltl, & Schipp, 1997; Micromedex Inc., 2004). Typical doses of beta-sitosterol used for benign prostatic hyperplasia and prostatitis are 60-130 mg divided into two or three daily doses (Martindale, 1999; Micromedex Inc.).

Bifidobacteria has scientific names of Bifidobacterium adolescentis and Bifidobacterium bifidum. Bifidobacteria is used to replenish normal flora of the bowel when patients have diarrhea during radiation, chemotherapy, or antibiotic therapy, for example. Preliminary research shows that bifidobacteria may protect the body against cancer by decreasing fecal enzymes that metabolically activate some mutagens and carcinogens (Roberfroid, 2000). No adverse effects have been reported (Natural Medicines Comprehensive Database, 2004). The strength of the preparation is dependent on the number of living organisms per capsule. The typical dose is 1 billion-10 billion viable cells daily, divided into three or four doses (Murray & Pizzorno, 1998).

Black seed, with a scientific name of Nigella sativa, is used in self-medication for gastrointestinal conditions and as an immunoprotectant against cancer (Facts and Comparisons, 2001). Preliminary studies show that black seed is an anticancer agent, inhibiting stomach tumors, carcinoma, and Ehrlich ascites carcinoma (Badary, Al-Shabanah, Nagi, Al-Rikabi, & Elmazar, 1999; Salomi, Nair, Jayawardhanan, Varghese, & Panikkar, 1992). Other in vitro studies examined the potent enzyme glyceraldehyde-3-phosphate dehydrogenase from Ehrlich ascites carcinoma cells (Bagui, Ray, & Ray, 1999) and concurred with Badary et al.'s and Salomi et al.'s findings. No typical dosage is given in Natural Medicines Comprehensive Database (2004). No adverse effects from oral use of black seed have been reported. In use for at least 1,400 years, black seed was found in King Tutankhamen's tomb (Facts and Comparisons).

Blond psyllium has the scientific name of Plantago ovata, which is synonymous with Plantago decumbens and Plantago isphagula. People self-medicate with blond psyllium for numerous gastrointestinal disorders, hypercholesterolemia, hyperglycemia, and cancer (Natural Medicines Comprehensive Database, 2004). Initial research has indicated that psyllium seems to preserve normal colon cell proliferation and possibly decrease absorption of carcinogens and unconjugated estrogens (Alabaster, Tang, Frost, & Shivapurkar, 1993; Gerber, 1996). Commonly used doses for laxative properties range from 7-40 g per day, taken in two or three doses (Blumenthal et al., 1998; Gruenwald et al., 1998). Individuals self-medicating with blond psyllium should start with the lowest dose and gradually increase the dose as needed. They should consume at least 240 ml of water for every 5 g ingested (Schneider, 1989). Blond psyllium may cause allergic symptoms such as rhinitis, sneezing, conjunctivitis, urticarial rash, and asthma (Freeman, 1994; Suhonen, Kantola, & Bjorksten, 1983). Caution patients against using blond psyllium found in the wild. Chewing or crushing psyllium wild seeds releases a pigment that can damage renal tubules (Leung & Foster, 1996).

Blueberry has a scientific name of Vaccinium angustifolium. People self-medicate with blueberry for eye conditions, ulcers, urinary tract infections, multiple sclerosis, fever, varicose veins, hemorrhoids, and constipation (Duke, 1997; Robbers & Tyler, 1999). The antioxidant effects of blueberry extracts may have anticancer activities, according to preliminary research (Bomser, Madhavi, Singletar, & Smith, 1996). Blueberry seems to have no adverse effects (Natural Medicines Comprehensive Database, 2004). Blueberry must not be confused with bilberry, which has a scientific name of Vaccinium myrtillus (Robbers & Tyler). Three tablespoons of dried blueberries or a decoction of crushed fruit is a typical dose for diarrhea (Natural Medicines Comprehensive Database).

Cabbage has a scientific name of Brassica oleracea. Although cabbage has a history in self-medication for gastrointestinal disorders, asthma, morning sickness, and preventing osteoporosis, individuals also use it to prevent lung, stomach, colorectal, breast, and other cancers (Natural Medicines Comprehensive Database, 2004). Constituents in cabbage are released when it is chewed, and these constituents may change the way that estrogen is metabolized. Therefore, cabbage may have anticarcinogenic properties (Bradlow, Michnovicz, Telang, & Osborne, 1991; Grubbs et al., 1995; He, Friesen, Ruch, & Schut, 2000; Michnovicz, 1998; Michnovicz & Brad-low, 1990; Yuan et al., 1999). As an augmentation to diet, cabbage has been pressed into juice, and as much as 1 L has been consumed daily with no adverse effects (Gruenwald et al., 1998).

Canthaxanthin has scientific names of 4,4-diketo-beta-carotene and Beta, beta-carotene-4,4-dione. Individuals ingest canthaxanthin to produce an artificial tan (Martindale, 1999; Micromedex Inc., 2004). In several in vivo and in vitro animal studies, canthaxanthin inhibited tumor growth and transformation of tumor cells (Huang, Odeleye, & Watson, 1992; Vainio & Rautalahti, 1998). However, large amounts of canthaxanthin can cause orange discoloration of body secretions and skin (Natural Medicines Comprehensive Database, 2004) as well as diarrhea, nausea, and stomach cramps (Micromedex Inc.). One death from ingestion of canthaxanthin for tanning purposes has been reported (Bluhm, Branch, Johnston, & Stein, 1990). A typical dose for tanning is 120 mg per day for several days (Micromedex Inc.). Canthaxanthin is in nonprescription drugs sold in Canada for tanning purposes.

Chaparral has two scientific names, Larrea divaricata and Larrea tridentata, which are synonymous with Larrea mexicana and Zygophyllum tridentatum. Chaparral is used to treat conditions such as arthritis, cancer, the common cold, tuberculosis, and venereal disease (Newall, Anderson, & Philpson, 1996). Preliminary research has found that a constituent of chaparral, nordihydroguaiaretic acid, has the potential for anticarcinogenic and antimutagenic activity (Anesini, Ferraro, Lopez, & Borda, 2001; McDonald et al., 2001).

Chaparral is considered unsafe, causing serious poisoning, acute hepatitis, liver and kidney damage, and irreversible renohepatic failure. Multiple reports have cited liver and kidney damage requiring at least two liver transplants (Batchelor, Heathcote, & Wanless, 1995; Estes et al., 2003; Gordon, Rosenthal, Hart, Sirota, & Baker, 1995; Katz & Saibil, 1990; Newall et al., 1996; Sheikh, Philen, & Love, 1997). These researchers also indicated chaparral's potential interaction with hepatotoxic herbs and drugs and liver function tests and exacerbation of liver disease. No typical dose is available for this toxic herb. Chaparral and red clover are components of Jason Winters tea, a popular alternative therapy cancer remedy. The manufacturer of Herp-Eeze™ (Olympian Labs, Scottsdale, AZ) claims that its chaparral product is rendered nontoxic by the manufacturing process (Natural Medicines Comprehensive Database, 2004); however, no studies have substantiated this claim.

Choline has scientific names of Trimethylethanolamine and beta-hydroxyethyl trimethylammonium hydroxide. Individuals are known to self-medicate with choline for many psychological and brain-related conditions such as schizophrenia, dementia, and Tourette syndrome. Some athletes take choline for endurance (Natural Medicines Comprehensive Database, 2004). Preliminary research has found that choline has a potential role in cancer prevention (Albright et al., 1997; Yen, Mar, & Zeisel, 1999; Zeisel, 1992). The typical North American diet supplies 200-600 mg of choline daily (Covington, 1996) in liver, muscle meats, fish, nuts, beans, peas, and eggs (Gennaro, 1995). Adults self-medicating with doses exceeding 3.5 g per day put themselves at risk for adverse effects (Yates, Schlicker, & Suitor, 1998), such as sweating, a fish-like body odor, vomiting, and diarrhea (Covington).

Chrysanthemum has several scientific names: Anthemis grandiflorum, Anthemis stipulacea, Chrysanthemum morifolum, Dendranthema morifolium, and Matricaria morifolia. Initial tests show that a product called hua-sheng-ping (chrysanthemum, licorice, and Panax notoginseng) may reverse precancerous gastrointestinal lesions (Yu, 1993). However, chrysanthemum causes photosensitivity and contact dermatitis (Bleumink, Mitchell, Geismann, & Towers, 1996; de Jong, Vermeulen, van Wijk, & de Groot, 1998; Kuno, Kawabe, & Sakakibara, 1999; Paulsen, Sogaard, & Andersen, 1998). To make an extract of chrysanthemum, 300 mg of the dried flower in 500 ml water are allowed to concentrate by condensation (time is not given). A typical dose of 25 ml can be taken up to three times daily (Huang, 1999).

Conjugated linoleic acid has scientific names of cis-9, trans-11 conjugated linoleic acid and trans-10,cis-12 conjugated linoleic acid. Individuals self-medicate with conjugated linoleic acid for atherosclerosis, bodybuilding, cancer, obesity, and other conditions (Natural Medicines Comprehensive Database, 2004). Conjugated linoleic acid seems to enhance immune function and inhibit cyclooxygenase and lipoxygenase pathways in tumor cells (O'Shea, Stanton, & Devery, 1999; Sebedio, Gnaedig, & Chardigny, 1999). This acid may modulate cellular response to tumor necrosis (Pariza, Park, & Cook, 1999). Gastrointestinal disturbances and fatigue are the most common adverse effects (Blankson et al., 2000). A typical dose is 2-7 g per day (Blankson et al.).

Cranberry has numerous scientific names such as Vaccinium macrocarpon, which is synonymous with Oxcycocus macrocarpos. Additional species have either genus name. Popular as a self-medication in preventing urinary infections or as an antibiotic in treating urinary infections (Harkins, 2000; Jackson & Hicks, 1997), cranberry also is used to treat or prevent cancer (Natural Medicines Comprehensive Database, 2004). Cranberry's proanthocyanide fraction may have anticarcinogenic activity (Bomser et al., 1996). Animal models show that cranberry products and juice can reduce the number of breast cancer tumors, delay tumor development, and slow metastases of cancer to lungs and lymph nodes (Natural Medicines Comprehensive Database). Oral intake of cranberry usually is well tolerated. Chronic ingestion of more than 1 L of cranberry juice per day can increase the risk of renal calculus (Jackson & Hicks).

Folic acid has scientific names of Pterolglutamic acid, Pte-roylmonoglutamic acid, and Pterolpolyglutamate. Often used in self-medication to prevent folate or vitamin B12 deficiency, it also is used to prevent colon cancer (McKevoy, 1998; Mic-ro-medex Inc., 2004). Folic acid also is known as vitamin B9. Early studies indicate that folic acid may protect patients with ulcerative colitis against cancer (Lashner, 1993). Excessive amounts of folic acid can exacerbate or precipitate neuropathy for patients with a vitamin B12 deficiency (Natural Medicines Comprehensive Database, 2004). The recommended daily dose for individuals older than age 13 is 400 mcg (Yates et al., 1998). Health and Welfare Canada (1990) advised a dose of 217 mcg for a 70 kg man and 170 mcg for a 55 kg woman.

Forskolin has scientific names of 17beta-acetoxy-8,13-epoxy-1alpha and 6beta,9alpha-trihydroxylabd-14-en-11-one. Individuals self-medicate with forskolin for gastrointestinal, urinary, and cardiac conditions, as well as cancer. Preliminary studies show that the product has the potential for blocking tumor cell-induced human platelet aggregation, preventing growth of tumor cells, and preventing metastases (Agarwal & Parks, 1983; Tzanakakis, Agarwal, & Vezeridis, 1990). No adverse effects have been reported for oral use of forskolin, and no typical dose has been made available.

Fructo-oligosaccharides have the scientific name of Beta-D-fructofuranosidase. A self-medication for constipation, fructo-oligosaccharides appear to protect against colon cancer (Pierre et al., 1997). Side effects of abdominal pain, belching, bloating, and flatulence tend to be more severe when fructo-oligosaccharides are taken in amounts of 10 g or more daily (Circosta et al., 1984; Stone-Dorshow & Levitt, 1987).

Garlic has a scientific name of Allium sativum. Self-medication with garlic is for the treatment of numerous conditions including cardiovascular atherosclerosis, HIV drug-induced lipid disorders, cancer prevention, colds and the flu, and tick bite prevention (Bloch, 2000; Blumenthal et al., 1998; Micromedex Inc., 2004; Newall et al., 1996). Humoral and cellular immunity seems to be stimulated by garlic (Sato & Miyata, 2000). Another constituent in garlic seems to be active against erythroleukemia as well as breast and prostate cancer cells (Efendy, Simmons, Campbell, & Campbell, 1997; Ide & Lau, 1997, 1999; Imai et al., 1994; Moriguchi, Saito, & Nishiyama, 1996; Sigounas, Hooker, Anagnostou, & Steiner, 1997; Zhang, Moriguchi, Saito, & Nishiyama, 1998). Anticoagulant properties of garlic call for caution in its use with other anticoagulant and antiplatelet herbs and products such as ginkgo, ginseng, and vitamin E and with anticoagulant and antiplatelet agents such as warfarin sodium. Most clinical studies use a standardized dose of garlic powder containing 1.3% alliin (Auer et al., 1990; Holzgartner, Schmidt, & Kuhn, 1992; Jain, Vargas, Gotzkowsky, & McMahon, 1993; Sato & Miyata; Silagy & Neil, 1994). Alliin is the medicinal ingredient in garlic. Four grams of fresh garlic contain 1% alliin (Natural Medicines Comprehensive Database, 2004).

Glucomannan, a polysaccharide, is found in the tubers (underground stems) of a plant with the scientific name of Amorphophallus konjac. Self-medication with glucomannan is usually for constipation, control of blood glucose, or reduction of serum cholesterol (Facts and Comparisons, 2001). A Chinese study (Luo, 1992) found that glucomannan protected mice against clinically induced lung cancer. The tablet form of glucomannan has caused esophageal and gastrointestinal obstruction (Luo; Martindale, 1999). Typical doses are approximately 3 g daily (Walsh, Yaghoubian, & Behforooz, 1984).

Green tea has the scientific name of Camellia sinensis, which is synonymous with Camiellia thea. Individuals self-medicate with green tea for headaches, for gastrointestinal conditions, to maintain remission of Crohn's disease (Alic, 1999), and to prevent prostate, colon, and gastric cancers (Gupta, Ahmad, & Mukhtar, 1999; Taylor & Wilt, 1999; Tsubono et al., 2001). Green tea also is used to prevent skin cancer or damage from ultraviolet radiation (Katiyar, Ahmad, & Mukhtar, 2000). Catechins in green tea, especially epigallocatechin-3-gallate, seem to reduce the risk of some cancers by preventing blood vessel growth in tumors (Cao & Cao, 1999; L'Allemain, 1999). Green tea also seems to reduce oxidative DNA damage, lipid peroxidation, and free radical generation, which appears to decrease mutigenic activity for smokers (Lee et al., 1997). In addition, green tea appears to prevent ultraviolet radiation-induced immunosuppression and protect against skin cancers (Katiyar et al.).

Alternatively, heavy consumption of green tea has been linked to esophageal cancer (Facts and Comparisons, 2001) because of the caffeine constituent of tea. Adverse reactions include headache, diuresis, anxiety, insomnia, tremor, tachyrhythmias, premature heartbeat, nausea, vomiting, diarrhea, ringing in the ears, elevated blood sugar, delirium, and convulsions (Facts and Comparisons; Gruenwald et al., 1998; Hardman & Limbird, 1996; Schulz, Hansel, & Tyler, 1998). Doses of green tea vary but often range from 1-10 cups daily (Fetrow & Avila, 1999). Table 1 shows brand names of green tea in tablet and capsule form. According to the Natural Medicines Comprehensive Database (2004), these tablets contain standardized extracts of as much as 97% polyphenols, which is equivalent to drinking four cups of green tea. No typical or safe dose is available, except to follow Tyler's (1993, 1994) guide to consume no more than 250 mg of caffeine per day. A 6 oz cup of tea has 10-50 mg of caffeine.

Indole-3-carbinol has a scientific name of indole-3-methanol. Individuals self-medicate with indole-3-carbinol to prevent all types of cancer, including breast and colon cancers. Self-prescription is carried out to maintain hormonal balance, detoxify the bowels and liver, and boost the immune system (Natural Medicines Comprehensive Database, 2004). Researchers suspect that indole-3-carbinol is one of several vegetable components that may be protective against breast, cervical, endometrial, and colorectal cancers (Grubbs et al., 1995; He et al., 2000; Kojima, Tanaka, & Mori, 1994; Wong et al., 1997; Yuan et al., 1999). Research findings are controversial; some research has shown that indole-3-carbinol may be helpful against hormone-dependent cancers such as breast cancer (Bradlow et al., 1991; Grubbs et al.; Kojima et al.; Michnovicz, 1998; Michnovicz & Bradlow, 1990; Yuan et al.). However, other research raises concerns that indole-3-carbinol may increase the carcinogenicity of certain toxins (Bailey et al., 1991; Dashwood, 1998; Kim et al, 1997; Pence, Buddingh, & Yang, 1986). Whether indole-3-carbinol increases or decreases cancer risk may depend on duration and timing of exposure to this component in addition to dietary factors. High doses of indole-3-carbinol (i.e., more than 400 mg per day) can result in dysequilibrium symptoms, tremor, and nausea (Rosen, Woodson, Thompson, Hengesteg, & Bradlow, 1998). Bell et al. (2000) reported the use of 200 mg for cervical dysplasia. Rosen et al. reported the use of 300 mg per day for breast cancer prevention. Typically, 20-120 mg of indole-3-carbinol are in a daily dietary intake (Natural Medicines Comprehensive Database).

Jiaogulan has a scientific name of Gynostemma pentaphyllum, which is synonymous with Gynostemma pedatum. Jiaogulan is used for the self-medication of numerous conditions such as cardiovascular and gastrointestinal disorders, cancer, diabetes, and obesity, as well as strengthening the immune system. It also is used as an anti-inflammatory agent, antioxidant, or detoxifying agent (Natural Medicines Comprehensive Database, 2004). This herb seems to have anticancer activity and immunostimulatory abilities (Facts and Comparisons, 2001); however, severe diarrhea and nausea have resulted from oral use of jiaogulan (Facts and Comparisons). An extract of 10 mg three times daily is noted by Natural Medicines Comprehensive Database, but this is not indicated as a safe or typical dose.

Lavender has the scientific name of Lavandula angustifolia, which is synonymous with Lavandula officinalis. Individuals self-medicate with lavender to treat cancer and numerous other conditions such as insomnia, loss of appetite, gastrointestinal disorders, headache, and nervousness. In vitro and animal studies have shown some anticancer activity for this herb (Facts and Comparisons, 2001). Considered a safe food additive (Leung & Foster, 1996), the typical oral dose is one cup of tea several times a day (Bisset & Wichtl, 1994).

Lutein has a scientific name of beta, epsilon-carotene-3, 31-diol. Individuals self-medicate with lutein to prevent age-related macular degeneration and colon cancer (Natural Medicines Comprehensive Database, 2004). Epidemiologic studies by Slattery et al. (1997) and Steinmetz and Potter (1991) have indicated that carotenoids seem to decrease the risk of cancer. Lutein typically is present in two carotenoids, stereoisomer and zeaxanthin; both are found in a pigment of human macula and retina (Snodderly, 1995). No adverse reactions have been noted when lutein is ingested. Chasan-Taber et al. (1999) and Pratt (1999) indicated that 44 mg of lutein are in a cup of cooked kale, 26 mg are in a cup of cooked spinach, and 3 mg are in a cup of broccoli. Corn, orange peppers, kiwi fruit, grapes, orange juice, zucchini, and some squashes also are rich in lutein and other carotenoids (Sommerburg, Keunen, Bird, & van Kuijk, 1998).

Lycopene has scientific names of all-trans-lycopene and psi-psi-carotene. Self-medication typically is intended for preventing atherosclerosis and cancer. The red color of fruits and vegetables comes from the pigment lycopene (Rao & Agarwal, 1998, 2000). Lycopene has no vitamin A activity, yet it is a carotenoid (Rao & Agarwal, 1998, 2000). Rao and Agarwal (1998, 2000) have studied lycopene's potential in cancer prevention. Some evidence shows that when serum or tissue lycopene concentrations are low, the risk of prostate cancer is increased (Clinton et al., 1996; Gann et al., 1999; Giovannucci, 1999; Giovannucci et al., 1995; Tzonou et al., 1999). No adverse effects have been reported (Natural Medicines Comprehensive Database, 2004). At least 6 mg of lycopene per day from food is needed to protect against prostate cancer (Giovannucci et al., 1995), and at least 12 mg of lycopene per day from food is needed to protect against lung cancer in nonsmoking men (Michaud et al., 2000). A cup of tomato juice contains about 23 mg of lycopene.

MGN-3 has no scientific name, but it also is known as biobran hemicellulose complex with arabinoxylane. Individuals self-medicate with MGN-3 to treat and prevent cancer and to treat AIDS, hepatitis, diabetes, and chronic fatigue syndrome (Natural Medicines Comprehensive Database, 2004). MGN-3 is produced by hydrolyzing rice bran using enzymes from mycelia of shitake, kawaratake, and suehirotake mushrooms. Some studies show that MGN-3 can increase natural killer cell activity and production of tumor necrosis factor-alpha (Natural Medicines Comprehensive Database). Small studies comparing healthy individuals and individuals with cancer suggest that use of MGN-3 increases the activity of natural killer cells (Ghoneum, 1998). No adverse effects have been reported, but the dose used in human tests was 3 g per day (Natural Medicines Comprehensive Database).

Microalgae has scientific names of 3,3'-dihydroxy-4,4'-diketo-beta-carotene; 3S, 3'S-astaxanthin; 3'R-astaxanthin; and 3R,3'S-astaxanthin. This product is used in self-medication to protect against cancer, reduce cholesterol, aid in stroke recovery, and prevent macular degeneration in the eyes (Natural Medicines Comprehensive Database, 2004). A constituent of microalgae, astaxanthin (a reddish carotenoid pigment) is a powerful antioxidant that stimulates immunity (Chew, Park, Wong, & Tong, 1999; Chew, Wong, Park, & Wong, 1999) and has the potential to protect against mammary, liver, bladder, or oral cancers (Chew, Wong, et al.; Gradelet, Le Bon, Berges, Suschetet, & Astorg, 1998; Tanaka et al., 1994, 1995). Adverse reactions have not been reported, and the typical dose is 2.5 mg per day (Natural Medicines Comprehensive Data-base).

MSM has scientific names of methylsulfonylmethane and Dinethylsulfone. Individuals self-medicate with MSM for numerous conditions, such as breast and colon cancer, chronic pain, arthritis, scar tissue, wrinkles, eye inflammation, allergies, gastrointestinal and cardiovascular conditions, obesity, Alzheimer disease, snoring, headaches, and hangovers (Herschler, 1986). O'Dwyer et al. (1988) found that MSM delayed the onset of chemically induced colon cancer in animals. MSM also delayed the onset of chemically induced mammary tumors in rats (McCabe et al., 1986). If taken orally, MSM can cause nausea, diarrhea, and headaches (Natural Medicines Comprehensive Database, 2004). Typically, MSM is taken in oral doses of 1,000-3,000 mg daily with meals or 250-500 mg daily as a dietary supplement (Natural Medicines Comprehensive Database).

Olive oil has a scientific name of Olea europaea. People self-medicate with olive oil to prevent cardiovascular conditions (Trevisan et al., 1990) or treat diabetes (Keys et al., 1986). Although some individuals take it to treat breast cancer (la Vecchia et al., 1995), others take it to prevent colorectal cancer (Stoneham, Goldacre, Seagroatt, & Gill, 2000). Ingestion of olive oil seems to reduce a bile acid, deoxycholic acid, involved in mucosal changes and polyp formation prior to colon cancer (Stoneham et al.). Individuals with gallstones may experience biliary colic if they consume olive oil (Blumenthal et al., 1998; Brinker, 1998; Gruenwald et al., 1998). A dose of 30-40 g per day (1.2-1.6 oz) of extra virgin olive oil is used as a diet supplement therapy for hypertension (Ferrara et al., 2000).

Peanut oil has a scientific name of Arachis hypogaea. Peanut oil often is used to lower cholesterol, aid in weight loss, or prevent heart disease or cancer (Natural Medicines Comprehensive Database, 2004). Beta-sitosterol and resveratrol may contribute to the cardiovascular and cancer protective activity of peanuts (peanut oil) (la Vecchia et al., 1995). However, severe allergic reactions can result from ingestion of peanut products (Eigenmann, Burks, Bannon, & Sampson, 1996). The typical dosage for peanut oil is not available (Natural Medicines Comprehensive Database).

Propolis has no scientific name. The resinous material from poplar and conifer buds, propolis is used to treat numerous infections such as tuberculosis and those of bacteria, fungal, and protozoal origins. Individuals also self-medicate with propolis for nasopharyngeal carcinoma (Foster & Tyler, 1993). Propolis contains caffeic acid phenethyl ester, which is thought to have cancer chemopreventive activities (Lee et al., 1999). Allergic reactions to propolis are possible, especially in those who are allergic to bees or bee stings. Oral ulcerations may occur from propolis-containing lozenges (Facts and Comparisons, 2001; Hay & Greig, 1990). No typical doses have been reported.

Quercetin has a scientific name of 3,3',4'5,7-Penthydoxyflavone. Individuals self-medicate with quercetin to treat allergies, atherosclerosis, cataracts (Li, Blacklock, & Garside, 1985), coronary heart disease, diabetes (Lean et al., 1999), inflammation, asthma, gout, and viral infections and to prevent cancer (Natural Medicines Comprehensive Database, 2004). The antioxidant and anti-inflammatory activities of this product seem to inhibit division and growth of T cells and some cancer cells (Shoskes, Zeitlin, Shahed, & Rajfer, 1999). Quercetin may inactivate malignant precursors or inhibit carcinogenesis (Li et al.). According to a preliminary study conducted by El Attar and Virji (1999), various kinds of cancers, including breast, leukemia, colon, ovary, oral squamous cell, endometrial, gastric, and non-small cell lung, may be inhibited by consuming this product. Quercetin also has an antiestrogenic effect in cultures of breast cancer cells (Miodini, Floravanti, Di Fronzo, & Cappelletti, 1999). Huang, Fasco, and Kaminsky (1997) found that quercetin inhibits estrone sulfatase and estrogen synthesis in liver cells. If taken orally, this product can cause headaches and tingling in the extremities (Shoskes et al.). A common dose is 400-500 mg three times daily (Natural Medicines Comprehensive Database).

Rice bran has a scientific name of Oryza sativa. Rice bran is taken to treat diabetes and hypertension, induce weight loss, and prevent cardiovascular disease or cancer (Natural Medicines Comprehensive Database, 2004). Increasing fecal bulk appears to decrease the risk of bowel cancer because secondary bile acids are eliminated from the body more quickly (Weisburger et al., 1993). Rice bran has the ability to increase stool size, but it can cause flatulence, abdominal discomfort, and erratic bowel habits (Covington, 1996). McKevoy (1998) indicated that the use of rice bran may result in a tendency to slow or reduce absorption of some prescription drugs, herbs, or supplements. Typical doses range from 12-84 g of rice bran per day or 4.8 g of rice bran oil per day (Gerhardt & Gallo, 1998; Ohkawa, Ebisuno, Kitagawa, Morimoto, & Miyazaki, 1983; Ohkawa et al., 1984; Watkins, Geller, Kooyenga, & Bierenbaum, 1999).

Shark cartilage has a scientific name of Squalus acanthias. Individuals self-medicate with shark cartilage to prevent and treat cancer (Hunt & Connelly, 1995; Lane & Comac, 1992; Miller, Anderson, Stark, Granick, & Richardson, 1998). Some preliminary evidence shows that shark cartilage may have some anticancer properties. Researchers hypothesized that this cartilage may prevent the new vessel growth that is required for solid tumor proliferation (Hunt & Connelly). Preliminary research has revealed that shark cartilage has possible antimutagenic, antioxidant, anti-inflammatory, and analgesic activities (Fontenele, Araujo, de Alencar, & Viana, 1997; Fontenele, Viana, Xavier-Filho, & de-Alencar, 1996; Gomes, Souto, & Felzenszwalb, 1996). Adverse effects include nausea, vomiting, dyspepsia, constipation, hypotension, dizziness, hyperglycemia, hypercalcemia, altered consciousness, decreased motor strength, general weakness, and fatigue (Lane & Comac; Miller et al.). Other adverse effects found by Ashar and Vargo (1996) are signs of acute hepatitis, including low-grade fever, jaundice, yellowing of the eyes, right upper-quadrant tenderness, and elevated liver enzymes. Typical doses suggested by commercial product manufacturers range from 500 mg-4.5 g, divided into two to six doses per day (Fetrow & Avila, 1999). These doses cannot be considered as recommended or safe.

Soy has a scientific name of Glycine max, which is synonymous with Glycine soja. Some people use soy products as a substitution for cow's milk in diets, but soy also is taken for numerous illness conditions, as well as prevention of breast or prostate cancer. Soy also is used commonly to treat hot flashes caused by breast cancer treatments. Diets that are high in soy products appear to be related to a reduced risk of prostatic disease and cancer (Evans, Griffiths, & Morton, 1995). However, a controversy about the action of soy exists. Some scientists have reported that soy may increase the risk of breast cancer, whereas others believe that soy may have some protective effect for breast cancer (Hakkak et al., 2000; McMichael-Phillips et al., 1998; Petrakis et al., 1996). Women with breast cancer or with a history of breast cancer should avoid therapeutic doses of soy products especially if they are taking tamoxifen (Facts and Comparisons, 2001; Massey, Palmer, & Horner, 2001; Montbriand, 2004b; Smolinske, 1999). Two or more glasses of soy milk daily have been suggested to reduce the risk of prostate cancer (Jacobsen, Knutsen, & Fraser, 1998). Safe therapeutic doses of soy vary from 20-60 g per day for adults (Natural Medicines Comprehensive Database, 2004).

Spinach has a scientific name of Spinacia oleracea. People self-medicate with spinach to treat gastrointestinal complaints and fatigue, induce blood building, and stimulate the appetite (Blumenthal et al., 1998). Ahn (1997) found that consumption of fresh spinach, not supplements that include spinach, is associated with a decreased risk of human stomach cancer. Notably, more than 60 products were found with spinach as an ingredient. No adverse reactions or typical doses have been found (Natural Medicines Comprehensive Database, 2004).

Tragacanth has a scientific name of Astragalus gummifera. Tragacanth is used to treat diarrhea (Facts and Comparisons, 2001); conversely, it also is used as a laxative (Gruenwald et al., 1998). Early studies indicate that tragacanth may inhibit cancer cell growth (Leung & Foster, 1996). If this herb is taken with insufficient amounts of fluids, obstruction of the ileum or esophagus can occur (Gruenwald et al.). No typical dose has been identified.

Turmeric has the scientific name of Curcuma longa, which is synonymous with Curcuma domestica. Individuals self-medicate with turmeric to ease gastrointestinal discomfort and to treat colorectal cancer (Gruenwald et al., 1998). This herb may have bile-stimulating, liver-protectant, antioxidant, and anticancer effects (Facts and Comparisons, 2001; Gruenwald et al.). Its overuse may cause gastrointestinal complaints (Gruenwald et al.; Robbers & Tyler, 1999). A typical dose is as much as 1.5-3 g per day, according to Blumenthal et al. (1998).

Vitamin A has no scientific name. People self-medicate with vitamin A for numerous conditions such as cataracts, acne, cold sores, diabetes, and gastrointestinal disorders, as well as the treatment or prevention of cancer (McKevoy, 1998; Micromedex Inc., 2004). Vitamin A is made up of a 20-carbostructure molecule with various chemical groups at 15 carbon positions. Different forms of vitamin A, called retinoids, are formed at variations of these 15 positions. Several in vitro studies have suggested that retinoids in vitamin A may help prevent cancer (Sporn, 2000; Widschwendter et al., 2000). High doses or chronic use of vitamin A can cause blood cell changes, anemia, and liver damage among other less severe symptoms (McKevoy; Micromedex Inc.). The recommended daily dose of vitamin A is 800-1,000 retinol equivalents for adults aged 19 and older (Health and Welfare Canada, 1990).

Vitamin D has scientific names of calcifediol; 25-hydroxycholecalciferol; calcitrol; 1,25-dihydroxycholecalciferol; cholecalciferol; dihydrotachysterol; ergocalciferol; calcipotriene; paricalcitol; and alfacalcidol. Vitamin D is used to build bones, protect against bone loss and muscle weakness, promote strong teeth, and decrease the risk of breast, colon, and prostate cancers (McKevoy, 1998). Preliminary negative evidence suggests that vitamin D may be associated with increased risk of colon, breast, and prostate cancers (McKevoy). However, Gesensway (2000) reported that vitamin D may have an antiproliferative effect on colon, breast, or prostate cancer. Symptoms of vitamin D toxicity are similar to those of hypercalcemia: osteoporosis, serum electrolyte imbalances, cardiac dysrhythmias, and irreversible calcification of soft tissues (McKevoy; Micromedex Inc., 2004). The recommended nutritional dose for vitamin D is 400 units or 10 mcg daily (Micromedex Inc.; Yates et al., 1998). Health and Welfare Canada (1990) recommended a nutritional dosage of 5 mcg for individuals aged 13 or older.

Vitamin K has scientific names of phytonadione (K1), menaquinone (K2), menadione (K3), menadiol acetate (K4),and 4-amino-2methyl-1-naphthol (K5). Self-medication is based on the vitamin's number. For example, vitamin K1 is used for vitamin K deficiency or to decrease bleeding or hemorrhage. Vitamin K2 is used to treat osteoporosis or lower cholesterol in patients on dialysis. Vitamin K3 is used in combination with vitamin C to treat or prevent breast and prostate cancers. Vitamin K4 is used to treat poor absorption of vitamin K. Natural Medicines Comprehensive Database (2004) reported that recent evidence has shown that a combination of vitamins K3 and C may have potential in the treatment of prostate and breast cancers. Few adverse effects have been reported for oral use of vitamin K (McKevoy, 1998; Micromedex Inc., 2004). No typical dose has been identified (Health and Welfare Canada, 1990). McKevoy suggested that doses be individualized and used under medical supervision.

Wheat bran has a scientific name of Triticum aestrivum. Individuals self-medicate with wheat bran to prevent colon cancer and other colon conditions (Foster & Tyler, 1993). Some people use it to prevent breast cancer ("Consensus Statement on Cereals, Fibre and Colorectal and Breast Cancers," 1998). Wheat bran may reduce the risk of cancer by lowering plasma estrogen levels. This action seems to involve interference with enterohepatic circulation and an increase in the rate of fecal estrogen excretion (Bouhnik et al., 1992). Digestion of grains and starches reduces ammonia produced by fermentation of foods high in fat and sugar; this possibly prevents cell damage and reduces the risk of colon cancer (Govers, Gannon, Dunshea, Gibson, & Muir, 1999). Wheat bran has a tendency to cause flatulence and gastrointestinal discomfort; however, McRorie et al. (2000) found no gastrointestinal discomfort in a carefully controlled study with participants taking 20-40 g of wheat bran daily. This result also was found by Sauvaire et al. (1998).

Whey protein has no scientific name. Individuals self-prescribe whey protein to prevent colon cancer (McIntosh, 1993), to treat metastatic carcinoma (Kennedy, Konok, Boun-ous, Baruchel, & Lee, 1995; Papenburg, Bounous, Fleis-zer, & Gold, 1990), or as a substitute for milk if they are lactose intolerant. Whey protein also is known as bovine whey protein concentrates. Researchers are interested in whey protein as a potential cancer prevention because when gamma-glutamylcsteine, a component of whey protein and a precursor of glutathione (GSH), is introduced to tissue, GSH substrates increase (Bounous, Batist, & Gold, 1991). Kennedy et al., who used a dose of 30 g in their study, postulated that whey protein may exert antitumor effects on cells by increasing GSH, thus making cells more vulnerable to chemotherapy. Other researchers have reported that dietary whey protein may protect against certain cancers (Hakkak et al., 2000; McIntosh; Papenburg et al.). Whey protein usually is well tolerated, but with high doses (i.e., 2-6.5 g/kg daily), consumers should expect increased stools, nausea, thirst, bloating, cramps, reduced appetite, fatigue, and headache. Whey protein also increases blood urea nitrogen (Natural Medicines Comprehensive Database, 2004).

Yucca has a scientific name of Yucca glauca. Yucca is used to treat arthritis, hypertension, headaches, diabetes, and gastrointestinal conditions (Leung & Foster, 1996; Newall et al., 1996). The polysaccharides in yucca exhibit antitumor activity against B16 melanoma but not against L1210 and P388 leukemias in mice (Facts and Comparisons, 2001; Foster & Duke, 1990; Leung & Foster; Newall et al.). Yucca can cause stomach irritation, nausea, and vomiting, and it has a bitter taste (Gruenwald et al., 1998). No typical dosage has been identified (Natural Medicines Comprehensive Database, 2004).

This review article provides information about 47 herbs and natural products that have the potential to protect humans against cancer. The majority of these herbs and natural products are fruits, vegetables, animal or fish products, grains, and molecular components of plants or herbs that are found in human diets. Therefore, findings in this review are similar to the ACS 1996 Advisory Committee on Diet, Nutrition, and Cancer Prevention's (1996) conclusions that the best protection against cancer is a dietary pattern that emphasizes fruits, vegetables, grains, and beans and limited amounts of meat, dairy, and high-fat foods.

Another one of the ACS 1996 Advisory Committee on Diet, Nutrition, and Cancer Prevention's (1996) conclusions was that no conclusive evidence is available to support taking supplements to reduce the risk of cancer. Alternately, consider the healthy food choices available that give protection against cancer. Notice the choices in this review. Alpha-linolenic acid is found in red meat and dairy products. Choline is abundant in liver, muscle meats, fish, nuts, beans, peas, and eggs. Eggs and fatty fish such as herring, mackerel, sardines, and tuna are rich in vitamin D. Many foods are fortified with vitamin D. Vitamin D also is available to the body when the skin is exposed, in moderation, to the sun. However, McKevoy (1998) indicated that excessive sun exposure results in photodegeneration of vitamin D. Vitamin K2 is available in meat and cheese.

Several grains such as barley, rice bran, and wheat bran (outer hull of wheat found in whole wheat bread) protect against cancer. Various vegetables, fruits, and plants also show promise as protection against cancer: apple, asparagus, blueberry, cabbage, cranberry, green tea, lavender tea, olive oil, peanut oil, and spinach.

Molecular components available in vegetables and animal products have the potential to protect against cancer. For example, folic acid is available in all vegetables and animal products, especially liver, leafy vegetables, fruit, pulses, and yeast. Indole-3-carbinol is found in vegetables such as brussels sprouts, cabbage, collards, cauliflower, kale, kohlrabi, mustard greens, rapeseed, turnips, and rutabagas. All red-colored fruits and vegetables contain the pigment lycopene, a protection against cancer. Corn, orange peppers, kiwi fruit, grapes, orange juice, zucchini, and some squashes are rich in lutein. Green and yellow vegetables, especially carrots, are rich in vitamin A. Brussels sprouts, plant oil, and margarine also are rich in vitamin K1, a possible protection against cancer.

Individuals who are concerned about cancer have a rich array of potential cancer protection available to them in a healthy diet. More importantly, the risk of overdose or adverse side effects is considerably less or nonexistent when individuals seek cancer protection through a healthy diet. Conversely, the potential for adverse health risks and side effects are high when taking supplements. Table 1 provides numerous instances when supplements contain other ingredients along with the herb or product found potentially useful in this review. When additional ingredients are in the supplement, the potential for adverse effects is even higher.

Healthcare professionals will find exceptions in this review that are not in the human diet. Some herbs and natural products are only available in plant form or supplements. Furthermore, some individuals will continue to take supplement forms of products instead of dietary forms. When individuals approach healthcare professionals about these products, the information about possible dosage may be useful. In some cases, such as chaparral, advise potential users of the herb or product's toxicity and encourage avoidance.

Questions for healthcare professionals to ask consumers include the following. Why seek protection from cancer by taking supplements that have not shown the potential to decrease the risk of cancer in evidence-based research? Why take products with the potential for many adverse side effects that may destroy your present good health? Why take supplements when enjoying a nutritious diet that is rich in fruit and vegetables can be your best protection against the risk of cancer? With the information available in this review article, healthcare professionals have an opportunity to encourage safer and healthier ways to protect against cancer.

The author gratefully acknowledges the continuing support of Carl D'Arcy, PhD, director of applied research/psychiatry at the University of Saskatchewan in Saskatoon, Canada.

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Muriel J. Montbriand, PhD, RN, is an associate professor in the College of Nursing and a research associate in applied research/psychiatry in the College of Medicine at the University of Saskatchewan in Saskatoon, Canada. During this work, the author was a recipient of two Health Services Utilization and Research Commission, Socio-Health Grants, in Saskatoon. (Mention of specific products and opinions related to those products do not indicate or imply endorsement by the Oncology Nursing Forum or the Oncology Nursing Society.)

Author Contact: Muriel J. Montbriand, PhD, RN, can be reached at montbriand@skyway.usask.ca, with copy to editor at rose_mary@earthlink.net.

American Cancer Society: Complementary and Alternative Therapies

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