Natural Strategies For Boosting Resistance to Cancer
Prevention of Cancer Development and Progression
Natural strategies known to prevent the development and progression of cancer include:
Calcium. In clinical studies involving more than 1000 colorectal cancer patients, calcium supplements reduced the risk of recurrence of colon polyps(Shaukat A et al 2005). Other studies show that calcium supplements generally reduce the risk of developing colorectal cancer in the first place (Flood A et al 2005; Sandler RS 2005). This beneficial effect of calcium was noted for calcium obtained from both dietary sources and nutritional supplements (Flood A et al 2005).
Carotenoids. Clinical studies have found that supplementing with lycopene, a carotenoid that is abundant in tomatoes and tomato-based products, can protect against cancers of the prostate (Campbell JK et al 2004; Jian L et al 2005; Kucuk O et al 2002), colon (Nair S et al 2001), pancreas (Nkondjock A et al 2005), ovaries (Huncharek M et al 2001), breast (Toniolo P et al 2001), and bladder (Schabath MB et al 2004).
According to the American Journal of Clinical Nutrition, individuals seeking broad spectrum colon protection should also include foods rich in lutein (another type of carotenoid) in their diet (Slattery ML et al 2000). These include spinach, broccoli, lettuce, tomatoes, oranges, carrots, celery, and greens.
Curcumin, extracted from the spice turmeric, has preventive and therapeutic anti-cancer properties (Aggarwal BB et al 2003; Sharma RA et al 2004).
Curcumin can stop the growth of cancers of the prostate (Dorai T et al 2000; Dorai T et al 2004), colon (Narayan S 2004), and breast (Inano H et al 2000).
In a phase I clinical study of colorectal cancer patients, curcumin in doses of up to 3.6 grams a day improved some clinical markers and was not associated with any toxicities (Sharma RA et al 2004). Clinical studies have shown that curcumin in doses of up to 10 grams a day had no adverse effects in humans (Aggarwal BB et al 2003).
Garlic has long been known to have anti-cancer properties (Das S 2002; Khanum F et al 2004) due to its ability to disrupt the function of cancer-causing agents (Das S 2002).
Garlic consumption lowers the risk of developing a range of cancers, including those of the stomach, colon, mammary glands, cervix (Khanum F et al 2004; Sengupta A et al 2004), and prostate (Hsing AW et al 2002). Garlic-derived allitridum, taken in combination with selenium, protects against the development of gastric cancer (Li H et al 2004).
Various other garlic extracts, including aged garlic extract, allicin, and ajoene, have a range of cancer-preventive and therapeutic capabilities (Oommen S et al 2004; Tanaka S et al 2004; Xu B et al 2004).
Green and Black Teas. Catechins and theaflavins, compounds found in green and black teas, have anti-cancer properties (Yang CS et al 2005).
Clinical studies have shown that consuming five or more cups a day of green tea reduces the risk of developing breast cancer, and may help reduce the risk of recurrence in breast cancer survivors (Seely D et al 2005).
Consumption of green tea also significantly improves the survival of ovarian cancer patients (Zhang M et al 2004) and reduces the risk of developing cancers of the lung, breast, and prostate (Bonner MR et al 2005; Doss MX et al 2005).
Such is the strength of data demonstrating green tea’s potential in preventing cancer that Japanese researchers are trying to develop a strategy, based on green tea consumption, for delaying cancer onset in the Japanese population, as well as reducing the risk of recurrence in cancer survivors (Fujiki H 2005).
Folic Acid. The use of folic acid dietary supplements, or the adoption of diets rich in fruits and vegetables containing folate, is associated with a reduced risk of developing cancer, particularly colorectal (Martinez ME et al 2004; Strohle A et al 2005) and lung cancers (Shen H et al 2003). Sufficient intake of folic acid is also thought to protect against breast cancer (Zhang SM 2004) because folic acid guards against DNA damage and promotes gene stability (Strohle A et al 2005).
Melatonin. The hormone melatonin, produced by the pineal gland during night-time hours, has anti-cancer properties (Anisimov VN 2003; Sainz RM et al 2005).
The use of melatonin (20 mg a night) during chemotherapy improves survival and quality of life in lung cancer patients (Lissoni P et al 2003). Melatonin also reduces the growth potential of prostate and breast cancer cells (Sainz RM et al 2005; Shiu SY et al 2003).
Further evidence supporting melatonin’s role as a cancer-preventive agent comes from studies showing an elevated risk of breast cancer in night-shift workers and others who have lower levels of melatonin due to the disruption of their waking and sleeping cycles (Anisimov VN 2003). Interestingly, blind people, who generally have higher melatonin levels, have lower rates of cancer (Coleman MP et al 1992; Feychting M et al 1998).
Selenium supplements have cancer-preventive properties (Combs GF, Jr. 2005), particularly in reducing the occurrence of lung, colorectal, esophageal, and prostate cancers (Mark SD et al 2000). Indeed, low selenium levels are associated with a four- to fivefold increase in the risk of developing prostate cancer (Brooks JD et al 2001). Higher selenium levels are associated with a reduced risk of prostate cancer (Brooks JD et al 2001). Because selenium levels decline with age, selenium supplements may be of particular benefit to elderly men (Brooks JD et al 2001).
However, the benefits of selenium supplements in preventing cancer appear to be cancer-specific, as some clinical studies have shown supplementation to be ineffective in protecting against basal and squamous cell carcinomas of the skin (Clark LC et al 1996). Indeed, selenium supplements may increase the risk of squamous cell carcinoma (Duffield-Lillico AJ et al 2003b).
In addition to their cancer-preventive potential, selenium supplements may enhance the effectiveness of conventional chemotherapy treatment (Vadgama JV et al 2000) and improve quality of life for patients undergoing radiation therapy (Hehr T et al 1997).
Silymarin, a milk thistle extract, demonstrates anti-cancer properties against prostate cancer cells and may be useful in preventing and treating prostate cancer (Singh RP et al 2004; vis-Searles PR et al 2005).
Vitamin A derivatives, known as retinoids, protect against the development of various cancers, including those of the skin, breast, and lung (Clarke N et al 2004; Khera P et al 2005). Dietary supplementation with synthetic vitamin A for 12 months in liver cancer survivors prevented recurrence of this cancer (Takai K et al 2005). In addition to preventing cancer, vitamin A derivatives have been used to cure acute promyelocytic leukemia (Clarke N et al 2004).
Vitamin C. Long-term human studies have shown that vitamin C dietary supplements, when used in conjunction with other antioxidants, can reduce the risk of developing cancer (Hercberg S et al 2004). Similar results were found for cancers of the prostate (Meyer F et al 2005) and lung (Mooney LA et al 2005; Wright ME et al 2004).
Vitamin D. Moderate sun exposure causes the synthesis of vitamin D in the skin. This micronutrient is known to play a role in cancer prevention (Holick MF 2004; Kimlin MG et al 2004). Indeed, medical literature dating back more than 50 years affirms that regular sun exposure is associated with a substantial decrease in death rates from certain types of cancers (Ainsleigh HG 1993). It is estimated that moderate sun exposure without sunscreen—that is, enough to stimulate vitamin D production but not enough to damage the skin—could prevent 30,000 cancer deaths in the United States each year (Ainsleigh HG 1993). The sun’s most damaging rays occur between 10 a.m. and 3 p.m., the hours demanding the greatest watchfulness.
Insufficient vitamin D levels are particularly associated with increased risk of developing breast, colon, and prostate cancers (Chen TC et al 2003; Studzinski GP et al 1995). Increased vitamin D levels, obtained through sun exposure, are associated with a reduced risk of non-Hodgkin’s lymphoma (Hughes AM et al 2004). Vitamin D causes bones to release calcium and can thus lead to excessively high calcium levels (hypercalcemia); however, scientists are developing synthetic versions of natural vitamin D (deltanoids) that lack this adverse side effect (Agoston ES et al 2006; Guyton KZ et al 2003).
Vitamin E. Clinical studies have shown that vitamin E can reduce the risk of prostate and lung cancers, particularly when used in combination with selenium supplements (Helzlsouer KJ et al 2000; Woodson K et al 1999). Regular and long-term (over 10 years) use of vitamin E reduces the risk of death from bladder cancer (Jacobs EJ et al 2002). Similarly, the use of vitamin E supplements for longer than three years slightly reduces the risk of recurrence among breast cancer survivors (Fleischauer AT et al 2003).
In addition, animal studies indicate that vitamin E may have activity against colon cancer and melanoma (Barnett KT et al 2002; Malafa MP et al 2002b; Malafa MP et al 2002a).
Larger clinical studies are currently underway to further assess vitamin E’s protective role against prostate cancer (Fleshner N et al 2005; Lippman SM et al 2005).
has been shown in laboratory and animal studies to have anti-cancer properties (Lamson DW et al 2003). Results from a small clinical study indicate that vitamin K may protect women with viral liver cirrhosis, a known risk factor for liver cancer, from developing the disease (Habu D et al 2004).