Cancer and nutraceuticals
Cancer has emerged as a major public health problem in developing countries. According to the World Cancer Report the cancer rates are increasing and it would be 15 million new cases in the year 2020 that is, a rise in 50%. A healthy lifestyle and diet can help in prevention of cancer. Carotenoids are a group of phytochemicals responsible for different colors of the foods. They have antioxidant activities and are effective on cancer prevention. Recent interest in carotenoids has focused on the role of lycopene in human health, especially in cancer disease.
Plants rich in daidzein, biochanin, isoflavones and genistein, also inhibit prostate cancer cell growth. Because of the unsaturated nature of lycopene it is considered to be a potent antioxidant and a single oxygen quencher. Lycopene concentrates in the prostate, testes, skin and adrenal where it protects against cancer. The linkage between carotenoids and prevention of cancer and CAD, heightened the importance of vegetables and fruits in human diet.
Lycopene contained vegetables and fruits exert cancer-protective effect via a decrease in oxidative stress and damage to DNA. Lycopene is one of the major carotenoids and is found exclusively in tomatoes, guava, pink grapefruit, watermelon and papaya.
?-carotene has antioxidant activity and prevents cancer and other diseases. Among the carotenes, ?-carotene has the most antioxidant activity. Alpha-carotene possesses 50–54% of the antioxidant activity of ?-carotene, whereas epsilon carotene has 42–50% of the antioxidant activity.
Chronic inflammation is associated with a high cancer risk. Chronic inflammation is also associated with immune-suppression, which is a risk factor for cancer. Ginseng is an example of an antiinflammatory molecule that targets many of the key players in the inflammation-to-cancer sequence.
Nowadays, phytochemicals with cancer-preventive properties have been on high attention. Chemopreventive components in fruits and vegetables, among other beneficial health effects, have potential anticarcinogenic and antimutagenic activities. A broad range of phyto-pharmaceuticals with a claimed hormonal activity, called “phyto-estrogens,” is recommended for prevention of prostate and breast cancers.
Citrus fruit flavonoids are able to protect against cancer by acting as antioxidants. Soyfoods are a unique dietary source of isoflavones, the polyphenolic phytochemicals exemplified by epigallocatechin gallate from tea, curcumin from curry and soya isoflavones possess cancer chemopreventive properties. Soybean seems to offer protection against breast, uterine, lung, colorectal, and prostate cancers. ?-carotene found in yellow, orange, and green leafy vegetables and fruits such as tomatoes, lettuce, oranges, sweet potatoes, broccoli, cantaloupe, carrots, spinach, and winter squash has anticancer activity.
Saponins are reported to possess antimutagenic and antitumor activities and might lower the risk of human cancers, by preventing cancer cells from growing. Saponins are phytochemicals which can be found in peas, soybeans, and some herbs with names indicating foaming properties such as soapberry, soapwort and soapbark. They are also present in tomatoes, potatoes, alfalfa, spinach, and clover. Commercial saponins are extracted mainly from Yucca schidigera and Quillaja saponaria
Tannins also scavenge harmful free radicals and detoxify carcinogens. Tannins present in grapes, lentils, tea, blackberries, blueberries and cranberries is a proven anticarcinogen is used in alternative medicine and to prevent cancer. Ellagic acid, present in walnuts, pecans, strawberries, cranberries, pomegranates and red raspberry seeds, is an anticancer agent.
Pectin is a soluble fiber found in apples has been shown to prevent prostate cancer metastasis by inhibiting the cancer cells from adhering to other cells in the body. Several studies have shown that pectin decreases serum cholesterol levels. Naturally occurring phenolic acid derivatives are reported to possess potential anticancer properties. Phenolic compounds such as curcumin, gallic acids, ferulic and caffeic acid are reported to possess anticancer activity.
Glucosinolates and their hydrolysis products, including indoles and isothiocyanates, and high intake of cruciferous vegetables has been associated with lower risk of colorectal and lung cancer. Bio-transformation products of glucosinolates include dithiol thiones, isothiocyanates, and sulforaphane. They block the enzymes that promote tumor growth, particularly in liver, colon, lung, breast, stomach and esophagus.
The sulfur compounds in garlic have been found to boost the immune system and reduce atherogenesis and platelet stickiness and cancer. Sulforaphane rich in broccoli is a potent phase 2 enzyme inducer. It produces D-glucarolactone, a significant inhibitor of breast cancer. Sulforaphane is an antioxidant and stimulator of natural detoxifying enzymes. Sulforaphane has been reported to reduce the risk of breast cancer and prostate cancer.
Curcumin is a polyphenol derived from the plant Curcuma longa, commonly called turmeric. Curcumin has been reported to possess antioxidative, anticarcinogenic, and antiinflammatory properties.
Consumption of fruits and vegetables having cysteine, glutathione, selenium, Vitamin E, Vitamin C, lycopene, and various phytochemicals elevates the levels of antioxidative capacity. However, more investigations are needed to determine their beneficial effects in cancer prevention or treatment.
Large scale clinical trials suggest that some agents such as green tea, Vitamins D and E, selenium, lycopene, soy, anti-inflammatory and inhibitors of 5a-reductase are effective in preventing prostate cancer. Cancer was not prevented by ?-carotene, N-acetylcysteine, ?-tocopherol, retinol, retinyl palmitate, or isotretinoin in smokers. Ongoing trials may help define new avenues for chemoprevention.
Several studies have shown the values of alternative and complementary medicine as adjuvant to chemotherapy or radiotherapy. Complementary therapy may be a reliable and useful supportive measure for prostate cancer patients. Majority of the studies have shown a preventive role for nutraceuticals in cancer, however more elaborate studies are needed.