Avocados are a rich source of antioxidant glutathione (GSH). This powerful antioxidant attacks free radicals in the body by blocking intestinal absorption of certain fats and also prevents damage to important cellular components.

Avocadoes are an excellent source of beta-carotene and supply more potassium than bananas. It is also believed by scientists that avocados may be useful in treating viral hepatitis (a cause of liver cancer), as well as other sources of liver damage

Carrots contain a lot of beta-carotene, which helps reduce a wide variety of cancers which includes the lung, mouth, throat, stomach, intestine, bladder, prostate and breast.

Although some research has indicated that beta-carotene may actually cause cancer, this does not mean to say that eating carrots daily can cause cancer, unless a very large quantity such as 2 - 3 kilograms a day are consumed.

A substance called falcarinol present in carrots has been found to reduce the risk of cancer. Researchers at Danish Institute of Agricultural Sciences (DIAS). Kirsten Brandt, head of the research department, explained that isolated cancer cells were observed to develop at a slower rate when exposed to falcarinol. This substance is a polyacethylen, therefore it is important not to cook the carrots.

Tomatoes contain lycopene, an antioxidant that attacks roaming oxygen molecules, known as free radicals. These free radicals have been attributed to triggering cancer. It appears that the hotter the weather, the more lycopene tomatoes produce. They also have vitamin C, an antioxidant which can prevent cellular damage that leads to cancer.

Watermelons, carrots, and red peppers also contain these substances, but in lesser amounts.
It is concentrated by cooking tomatoes.
Scientists in Israel have shown that lycopene can kill mouth cancer cells. An increased intake of lycopene has already been linked to a reduced risk of breast, prostate, pancreas and colorectal cancer. (Note: Recent studies indicate that for proper absorption, the body also needs some oil along with lycopene

Figs apparently have a derivative of benzaldehyde. According to researchers at the Institute of Physical and Chemical Research in Tokyo, benzaldehyde is highly effective at reducing the size of tumors, though I haven't seen this report.

In addition, the U.S. Department of Agriculture states that figs, which are a rich source of vitamins A & C & minerals calcium, magnesium & potassium, may actually curtail appetite and improve weight-loss efforts. Fig juice is also a potent bacteria killer as seen in test-tube studies.

Flax contains lignans, which may have an antioxidant effect and block or suppress cancerous changes.

Flax is also high in omega-3 fatty acids, which are thought to protect against colon cancer and heart disease

Garlic has dialyl sultides, an immune-enhancing allium compound that appears to elevate the activity of immune cells that combat cancer. It has also be shown to indirectly assist in the break down of cancer causing substances by assisting in blocking carcinogens from entering cells as well as retard the progression of tumors.

Diallyl sulfide, a component of garlic oil, has also been shown to render carcinogens in the liver inactive. Studies have linked garlic, as well as onions, leeks, and chives, to lower the risk of stomach and colon cancer.

Grapefruits, like oranges and other citrus fruits, contain monoterpenes which are believed to assist in cancer prevention by sweeping carcinogens out of the body.

Some studies show that citrus fruits especially the grapefruit may inhibit the proliferation of breast-cancer cells in vitro.

Grapefruits are a rich source of vitamin C, beta-carotene, and folic acid.

Grapes, Purple or red with seeds contain bioflavonoids, powerful antioxidants that work as cancer preventives. Grapes are also a rich source of resveratrol, which inhibits the enzymes that can stimulate cancer-cell growth and suppress immune response. They also contain ellagic acid, a compound that blocks the enzymes that are necessary for cancer cells thereby assisting in slowing the growth of tumors.
Studies show that consumption of green and yellow leafy vegetables has been associated with lower levels of stomach cancer.

Kale has indoles, nitrogen compounds which may help stop the conversion of certain lesions to cancerous cells in estrogen-sensitive tissues. 

In addition to indoles, isothiocyanates, phytochemicals found in kale, are thought to suppress tumor growth and block cancer-causing substances from reaching their targets.

Licorice root has a chemical called glycyrrhizin. This chemical essentially blocks a component of testosterone which may have the effect of preventing the growth of prostate cancer.

This should be an essential component of every man's diet, especially men in their 40s and above.

Taken in excessive amounts however, can lead to elevated blood pressure.

Mushrooms - There are a number of mushrooms that appear to help the body fight cancer and build the immune system. These include: Shiitake, maitake, reishi, Agaricus blazei Murill, & Coriolus Versicolor. These mushrooms contain polysaccharides, especially Lentinan, powerful compounds that help in building immunity.

They are also a good source of Beta Glucan. Mushrooms also contain a protein called lectin, which attacks cancerous cells and prevents them from multiplying. Thioproline is another protein found in mushrooms. These mushrooms can stimulate the production of interferon in the body.

Extracts from mushrooms have been successfully tested in recent years in Japan as an alternative to chemotherapy. PSK is made from the Coriolus Versicolor. Maitake mushroom extract is PCM4

Nuts contain the antioxidants quercetin and campferol which may suppress the growth of cancers. Brazil nut contains 80 micrograms of selenium, which is important for those withprostate cancer.

Many people are allergic to the proteins in nuts, so if you have any symptoms such as itchy mouth, tight throat, wheezing, etc. after eating nuts, stop. Instead, consider taking a selenium supplement or work with someone on how to eliminate this allergy.

Oranges and lemons contain Iimonene which stimulates cancer-killing immune cells (lymphocytes, e.g.) that may also break down cancer-causing substances

Papayas contain vitamin C that works as an antioxidant and may also reduce absorption of cancer-causing nitrosamines from the soil or processed foods.

Papaya contains folacin (also known as folic acid), which has been shown to minimize cervical dysplasia and certain cancers.

Raspberries contain many vitamins, minerals, plant compounds and antioxidants known as anthocyanins that may protect against cancer.

According to a recent research study reported by Cancer Research 2001;61:6112-6119, rats fed diets of 5% to 10% black raspberries saw the number of esophageal tumors decrease by 43% to 62%. A diet containing 5% black raspberries was more effective than a diet containing 10% black raspberries.

Research reported in the journal Nutrition and Cancer in May 2002 shows black raspberries may also thwart colon cancer. Black raspberries are rich in antioxidants, thought to have even more cancer-preventing properties than blueberries and strawberries.

Rosemary may help increase the activity of detoxification enzymes. An extract of rosemary, termed carnosol, has inhibited the development of both breast and skin tumors in animals. We haven't found any studies done on humans.

Rosemary can be used as a seasoning. It can also be consumed as a tea: Use 1 tsp. dried leaves per cup of hot water; steep for 15 minutes.

Seaweed and other sea vegetables contain beta-carotene, proteins, vitamin B12, fiber, and chlorophyll, as well as chlorophylones, important fatty acids that may help in the fight against breast cancer. 

Many sea vegetables also have high concentrations of the minerals potassium, calcium, magnesium, iron, and iodine.

Sweet potatoes contain many anticancer properties, including beta-carotene, which may protect DNA in the cell nucleus from cancer-causing chemicals outside the nuclear membrane.

Teas: Green Tea and Black tea contain certain antioxidants known as polyphenols (catechins) which appear to prevent cancer cells from dividing.

Green tea is best, followed by our more common black tea (herbal teas do not show this benefit).