Fruits and vegetables

Fresh or frozen fruits and vegetables are both good, and contrary to common thought, frozen produce is just as nutrient dense as fresh produce, while dried produce is often sweetened, causing some of the nutrients to be broken down. Studies have shown produce consumption is effective in reducing cancers, especially in the gastrointestinal tract, lowering cancer rates by 22% and mortality to dietary related cancer by 11%.[8] Berries have been causing a lot of commotion and promise in the world of cancer research. The darker the berry, the better in terms of being more packed with nutrients that is better at warding off cancer. Research has been putting the spot light on black raspberries and their ability to reduce oxidative stress and gastroesophageal reflux disease, each of which causes damage to the esophageal cells.[9] Close runner-ups to the black raspberry are blueberries, blackberries, strawberries, and cranberries. These berries are high in vitamin C, fiber, and ellagic acid, which can prevent skin cancer.[4] In addition to these nutrients, the American Association for Cancer Research found that berries are extremely high in polyphenol phytochemicals, and some research is suggesting that these phytochemicals are what is inhibiting tumor growth, more so than vitamins and minerals. These phytochemicals have the ability to interfere with tumor development, probably due to their natural job of protecting plants and their structures, as well as maintaining their vibrant colors (2007). Beta-carotene and lycopene are two prevalent nutrients that have shown a lot of promise in their capabilities to slow tumor growth.[6]

Flavonoids
[2] Flavonoids and catechins are nutrients that give foods a bitter taste, but they also are emerging as great anticancer agents. After looking into these nutrients further, Abdulla et al. found the best sources to be green and black teas, chocolate, wine, and grapes (2000). He also found that catechins are a powerful form of antioxidant that act as a powerful inhibitor of cancer growth. In fact, catechins are 100 times more powerful than vitamin C and 25 times more powerful than vitamin E in their antioxidant/growth inhibitor powers. The flavonoids and catechins together have proven the ability to protect cells from x-ray damage, block the progression of the cell cycle, and inhibit mutations (2000). Other foods high in flavonoids are garlic, onions, shallots, and leeks, which also contain vitamin C, selenium, and sulfur compounds that together, increase the metabolic disposal of chemical carcinogens[2] , thus lowering the risk of cells turning cancerous.

Probiotics
Probiotics are bacteria that live in our gastrointestional tract and aid us in digestion as well as provide other benefits for its host. Ruize suggests that one of these benefits is their ability to eliminate procarcinogenic substances before they can turn carcinogenic. The probiotics are capable of altering certain enzymes (such as b-glucuronidase and nitro-reductase) that turn procarcinogens into carcinogenic agents by neutralizing the bad bacteria enzymes. Essentially, the good bacteria is cleansing the GI tract of harmful substances, such as poisonous bacteria and extraneous pollutants, found in the environment and our food chain. Without the probiotics, the immune system would be left to clean the body alone, causing a work overload and probably not as thorough, thus the probiotics are good because they help the immune system to keep toxins out of our intestines.[10]

Reducing-risk factors
Increasing evidence suggests that diets high in foods containing fibre (or fiber) are associated with a reduced risk for cancer, especially cancer of the colon.[11]
A few studies have also shown a reduced risk for cancers of the breast, rectum, oral cavity, pharynx, stomach, and other sites with diets rich in fruits, vegetables and grain products.[12] Numerous studies have found evidence that carotenoids reduce the risk of some cancers. The evidence is particularly strong for lung cancer,[13] even after taking smoking into account. Vitamin C is found in fruits, particularly citrus fruits and juices, and in green vegetables, as well as in some fortified foods. Of a group of epidemiologic studies investigating the role of vitamin C, three-quarters found that vitamin C, or fruit rich in vitamin C, provides significant protection.[14]
A leaner diet is believed to lower cancer risk. Tomatoes, calcium, agaricus blazei mushrooms[1], other minerals, saponins, sausage tree, sea mat, cat's claw, and licorice are believed to prevent or suppress different kinds of cancerous tumors.[citation needed] Currently there is not enough evidence for using mushrooms or mushroom extracts in the treatment of cancer, but there is significant potential for research in the area and future clinical trials, due to the numerous scientific studies which have shown they may offer a beneficial effect.[15]

Mushrooms
Main article: Medicinal mushrooms
Main article: Polysaccharide-K
Some mushrooms offer an anti-cancer effect, which is thought to be linked to their ability to up-regulate the immune system. Some mushrooms known for this effect include, Reishi,[16][17] Agaricus blazei, [2], Maitake,[3] and Trametes versicolor[4]. Research suggests the compounds in medicinal mushrooms most responsible for up-regulating the immune system and providing an anti-cancer effect, are a diverse collection of polysaccharide compounds, particularly beta-glucans. Beta-glucans are known as "biological response modifiers", and their ability to activate the immune system is well documented. Specifically, beta-glucans stimulate the innate branch of the immune system. Research has shown beta-glucans have the ability to stimulate macrophage, NK cells, T cells, and immune system cytokines. The mechanisms in which beta-glucans stimulate the immune system is only partially understood. One mechanism in which beta-glucans are able to activate the immune system, is by interacting with the Macrophage-1 antigen (CD18) receptor on immune cells.[18]
A highly purified compound isolated from the medicinal mushroom Trametes versicolor, known as Polysaccharide-K, has become incorporated into the health care system of a few countries, such as Japan.[19] Japan's Ministry of Health, Labour and Welfare approved the use of Polysaccharide-K in the 1980s, to stimulate the immune systems of patients undergoing chemotherapy