Vegetables
Allium species, such as garlic (the Russian penicillin), onions and leeks – are rich in sulphur phytochemical compounds. They are among the richest sources of flavonoids and contribute to a large extent to the overall dietary intake of flavonoids. They have been shown to prevent cancer cells growth and protect cells against carcinogenic substances, thus reducing the risk of several common cancers. For example a study conducted in Italy on large-scale data from southern Europe showed that consumption of onions and garlic is inversely correlated with cancer incidence; similar findings were provided by studies conducted in China and the USA. Furthermore, onions have strong blood-sugar lowering properties similar to prescription drugs phenformin and tolbutamide, thus helping with insulin-peak management.
Consumption recommendations: When cutting onions a compound responsible for producing tears is released. To decrease such release, chill the onions in the fridge for 1 hour prior to cutting. When cutting or chopping garlic a substance called allicin gets released. Allicin is believed to be responsible for garlic’s health benefits. It is preferable to eat garlic raw and freshly chopped – some studies suggest that peeling the garlic and waiting for 15min prior to cooking it may preserve its anticancer properties. Leeks need to be eaten in larger quantity to provide similar benefits to garlic and onions. Please note that onions and leeks contain small amounts of oxalate and therefore it is best if consumed in moderation by people with a history of oxalate-containing kidney stones.
Artichokes (Cynara) – are rich in anticancer compounds, such as silymarin, a powerful hepatoprotective and antioxidant. For example in vitro and in vivo studies showed that they reduce proliferation and induce apoptosis in liver cancer and leukaemia cells.
Consumption recommendations: Fresh artichokes are low in calories. They have been traditionally used to treat liver diseases and recent scientific studies have demonstrated such property. To prevent darkening when cooking add lemon juice or vinegar.
Beetroot – has potent cancer chemopreventive compounds, such as betacyanin. For example, in mice models it showed lung and skin cancer chemopreventive effects, the latter were shown even at a very low dose. In a human study on stomach cancer, beet juice inhibited the formation of nitrosamines (cancer-causing compounds ingested primarily through the consumption of smoked and cured meat) and cells mutation.
Consumption recommendations: When selecting beets make sure the greens are fresh and intact. If you are planning to store the beets for a few days make sure you remove the greens so that they will not decrease the beet moisture. Beet greens are usually eaten gently steamed to avoid loosing their anticancer properties. Beetroots are usually boiled or oven cooked. Please note that beet greens and, to a lesser extent, roots contain high levels of oxalate and therefore it is best if consumed in moderation by people with an history of oxalate-containing kidney stones
Carrots – are rich in compounds with anticancer properties such as flavonoids, like luteolin, and retinoids. For example luteolin anticancer properties have been associated with apoptosis, decrease cell proliferation, metastasis and angiogenesis. Luteolin has been associated with a decrease in gastric, prostate, colon and lung cancer. In a clinical trial (phase III) conducted in Italy feretinide (a retinoid found in carrots) consumption induced significant reduction of second breast cancer in pre-menopausal women and of ovarian cancer. Retinoids have also been found to have chemopreventive and chemotherapeutic effect on cancerous and pre-cancerous cells of the uterine cervix. In a US study it was observed that consumption of carotenoids lowered the risk of lung cancer.
Consumption recommendations: Eating raw carrots enhances the bioavailability of its active compounds. Please note that ingesting large quantities of carotene can produce carotenodermia, a yellowing of the skin – which is not a serious condition. Consumption of very large quantities of carrots (0.45 to 1kg per day) for several years has been associated with a decrease in white blood cells count as well as menstrual disorders.
Celery – has cancer chemopreventive compounds such as the flavonoid luteolin (see carrots).
Consumption recommendations: As pesticides are often found on celery it is best to use organic celery.
Cruciferous, or cabbage, family of vegetables – “Cancer hates cabbage” (Prof Richard Beliveau and Dr Denis Gingras, “Foods to fight cancer”, Dorling Kindersley, Great Britain 2007) – are rich in anticancer phytochemical compounds such as isothiocyanates (like sulphoraphane) and indoles (like indole-3-carbinol). They have potent anti-cancer and anti-inflammatory properties. They contain many anticancer molecules (particularly Brussels sprouts and broccoli). They initiate the elimination of pre-cancerous cells thus preventing them from developing into cancer. They stimulate the detoxification of certain carcinogenic substances, such as pulmonary carcinogens. They trigger cancer cells suicide (apoptosis) and block their proliferation and metastasis. For example, they have shown anticancer activities against prostate, colon, breast, cervix and lung cancer.
Consumption recommendations: Please note that the above mentioned anticancer compounds, isothiocyanated and indoles, are released by molecules (glucosinolate) which are very sensitive to heat and soluble in water. It is advisable to eat cruciferous vegetables regularly (also recommended by the American Cancer Society), particularly broccoli and Brussels sprouts, cook them as little as possible in minimum water (prefer steaming or quick stir-frying, avoid boiling) and chew them well. Broccoli sprouts contain between 30 to 100 times the concentration of anticancer compounds found in mature broccoli plants.
Dark chocolate (>70% cacao) – has anti-inflammatory and anticancer properties. Cocoa is rich in flavonoids such as epicatechin. For example cocoa reduces carcinogenesis in animals studies and inflammation in human studies - in an Italian population based study daily consumption of small doses of dark chocolate was associated with decreased inflammation.
Consumption recommendations: It is advisable to eat dark chocolate (>70% cacao) in moderation, 20gr every 3 days. Please note that dark chocolate has about half the glycemic index of white bread; this is not the case for milk chocolate. A square of dark chocolate has similar polyphenol amounts to a cup of green tea and about twice as much of a glass of red wine.
Extra-virgin olive oil – is unique amongst vegetable oils as it has high levels of phenolic compounds and has been shown to have excellent anticancer properties. Extra virgin olive oil (EVOO) may partly explain the health promoting effects of the “Mediterranean diet”. For example EVOO lignans, flavonoids and secoiridoids were found to have anticancer effects on breast cancer cells; EVOO oleic acid also enhanced the inhibitory effects of trastuzumab (Herceptin) drug. Furthermore, extra virgin olive oil contains oleocanthal, the compound responsible for the stinging sensation in the throat, which has anti-inflammatory properties similar to ibuprofen. In a human study high consumption of extra virgin olive oil was associated with a significant decrease in inflammatory markers. Up to 80% of EVOO is composed of monounsaturated fatty acids which are less likely to become oxidised (process of fatty acids degradation) than other oils – it is believed that only oxidised cholesterol adheres to vessel walls. The EPIC-Greece cohort human study showed a negative correlation between depression and monounsaturated lipids and a positive correlation between depression and polyunsaturated lipids. According to Trichopoulos D, an epidemiology professor at Harvard University in Cambridge (Massachusetts) EVOO is the only dietary lipid that has not been associated with an increase in cancer risk. In a human study individuals were asked to substitute all fats and oils used with 50g daily of olive oil for 8 weeks; the study showed a reduction in DNA damage. EVOO is also a dietary source of luteolin (see carrots).
Consumption recommendations: Prefer it to other fats and oils for seasoning and cooking. To make sure you maximise the anticancer compounds present in olive oil it is advisable to consume only cold pressed extra-virgin olive oil. It is best to store it in a glass container away from light and heat.
Licorice – is one of the most frequently utilised ingredients in traditional herbal medicine, it is often added to herbal preparation to reduce the toxicity of other herbs, and it is also utilised as a natural sweetener. Its flavonoids, such as isoliquiritigenin, and other components have shown anticancer properties in a variety of human cancers, including estrogen dependent breast cancer.
Consumption recommendations: Licorice has shown to improve antitumor effects of certain chemotherapeutic agents, such as cyclophosphamide, and to reduce their induced toxicity, such as in the case of Doxorubicin, however it appears to inhibit the effects of cisplatin. Please note that licorice increases blood pressure and therefore it is advisable that individuals suffering from hypertension avoid it.
Soy – main phytochemical compounds are isoflavones which have a chemical structure very similar to the sex female hormone estrogen. Isoflavones can enhance or inhibit the activity of estrogen depending on the type of cell estrogen receptor. When taken from puberty soy is believed to reduce hormone dependent cancers risk, such as breast and prostate cancer, and it has been suggested that soy consumption within Asian populations is an explanation for their lower incidence of such type of cancers.
Consumption recommendations: It is advisable to consume soy as whole food, such as tofu. It is best to avoid soy consumption in the presence of estrogen-receptor positive cancers and when undergoing taxol based chemotherapy or taking tamoxifen. Avoid isoflavone supplements as potentially linked to increased cancer risk.
Spinach and watercress – are rich in anticancer compounds, such as retinoids and lycopene (see carrots and tomatoes), which protect against carcinogenic substances and reduce their intake, suppress cancer growth and inhibits its proliferation.
Consumption recommendations: It is preferable to eat organic spinach as it is one of the vegetables with highest pesticide found on it. Please note that spinach contains high amounts of oxalate and therefore it is best if consumed in moderation by people with a history of oxalate-containing kidney stones.
Squash (summer and winter) – are rich in carotenoids, such as lycopene and lutein, which are responsible for their anticancer properties (see tomatoes).
Consumption recommendations: Please note that summer squash contains high amounts of oxalate and therefore it is best if consumed in moderation by people with an history of oxalate-containing kidney stones.
Tomatoes – carotenoids, such as lycopene, are responsible for their anticancer properties. For example daily consumption of tomato juice has been associated with decreased DNA damage in lymphocytes under oxidative stress.
Consumption recommendations: To maximise tomatoes anticancer properties it is advisable to cook them with olive oil. Please note that tomatoes contain moderate amounts of oxalate and therefore it is best if consumed in moderation by people with a history of oxalate-containing kidney stones.
Fruits
Apples – phytochemical compounds, such as quercetin, have anticancer properties. For example in vitro and in vivo experiments have shown that apples have potent antioxidant and antiproliferative activity against different cancers, such as skin, breast, colon, and lung.
Consumption recommendations: Epidemiological observations indicate that regular consumption of one or more apples a day may decrease the risk of cancer.
Avocado – phytochemicals, such as alpha-carotene, have shown to inhibit cancer growth and induce apoptosis in vitro.
Consumption recommendations: Once chopped you can add a little bit of lemon to prevent from darkening.
Berries (blueberries, cranberries, raspberries and strawberries) – are a great source of anticancer polyphenols such as anthocyanins, anthocyanidins, proanthocyanidins and ellagic acid. For example anthocyanins and anthocyanidins have shown to inhibit cancer development, such as those of the colorectal tract, leukaemia, cancer of esophagus, cervix, breast, stomach, prostate and intestine.
Consumption recommendations: Eat fresh or frozen all year round. Please note that berries contain moderate amounts of oxalate and therefore it is best if consumed in moderation by people with a history of oxalate-containing kidney stones.
Cherries – contain anthocyanidins which have been found to inhibit the growth of certain types of cancers (see berries).
Consumption recommendations: Cherries are susceptible to the growth of Aspergillus moulds, which have carcinogenic effects, therefore make sure you check for signs of decay and mould.
Citrus fruit – main anticancer phytochemical compounds are polyphenols and terpenes. They inhibit cancer cells growth and proliferation.
Consumption recommendations: It is preferable to eat the whole fruit as hesperdin concentration, an important flavonoid with anti-inflammatory and anticancer properties, is higher in the white pulp of the citrus fruit. Please note that grapefruit contains high levels of naringin, a flavonoid, which can inhibit the liver capability to break down some drugs thus potentially increase their toxicity; if on prescription drugs, please ask your doctor about consuming grapefruit.
Mango – contains magiferin and lupeol compounds which have shown to possess chemopreventive and chemotherapeutic effects against cancer (for example against lung, prostate and skin cancer) both in vitro and in vivo.
Consumption recommendations: If possible choose mangoes grown in Florida or Hawaii to avoid exposure to pesticides banned in USA and Europe. Mango peel can be irritating to the skin when the fruit is unripe.
Papaya – has several anticancer compounds such as benzylisothiocyanate enzyme and lycopene. Benzylisothiocyanate has shown to induce cancer cell apoptosis, for example in prostate, pancreatic and leukemic cells.
Consumption recommendations: It can be eaten alone or added to salads and other dishes.
Peaches, nectarines, plums – are good sources of flavonoids such as lycopene and lutein which help in preventing and fighting cancer. For example extracts of peach has shown to inhibit the growth of colon carcinoma and protective effects against cisplatin-induced nephrotoxicity (poisonous effect on the kidneys) in animal studies. MK615 compound isolated from Japanese apricots inhibits pancreatic and breast cancer cells growth in vitro.
Consumption recommendations: Since peaches are one of the most pesticide rich fruit it is recommended that only organically grown ones are consumed. Also they contain moderate amounts of oxalates, therefore it is best if people with a history of kidney stones containing calcium oxalates limit peaches intake.
Pomegranate – is rich in polyphenolic phytochemicals, such as punicalagin, with cancer cells antiproliferative and apoptotic properties. For example, pomegranate juice (pj) has shown to inhibit colon, prostate and oral cancer cells proliferation by 30% to 100% in vitro. In human trials pj consumption determined a decrease in the rate of rise of prostate specific antigen following radiation or surgery treatment.
Consumption recommendations: Delicious as a freshly squeezed juice.
Red wine and grapes - have shown to stop tumor growth and provide protection against several types of cancer.
Consumption recommendations: Moderate consumption of red wine is recommended (note that more than 1 glass per day is associated with increased cancer risk). If eating grapes it is advisable to choose organically grown ones. Please note that grapes contain variable amounts of oxalate and therefore it is best if consumed in moderation by people with a history of oxalate-containing kidney stones.
Watermelon – is rich in lycopene and thus has important anticancer properties (see tomatoes, peaches and papaya).
Consumption recommendations: As watermelons rest on the ground it is advisable to wash them with additive-free soap or commercial produce wash, to avoid its flesh contamination when cutting it. It is recommended to eat organically grown watermelons as high quantities of pesticides have also been found on them.
Nuts (Almonds, brazilian nuts, cashew nuts, sunflower seeds, walnuts) – have anticancer properties.
Herbs and spices
Most of the commonly used spices and herbs have anticancer properties, some example are anise, basil, capers, chilli pepper, cloves, coriander, dill, fennel, mint, mustard seeds, oregano and majorama, parsley, piperine, rosmary, saffron, sage, thyme and particularly curcumin (principal active ingredient of turmeric) and ginger. When using herbs it is usually better to utilise them in their fresh form.
Curcumin (principal active ingredient of turmeric) – is an important component of Indian and Chinese traditional herbal medicine. It is believed to be the reason for the difference in certain cancers occurrence between India and Western countries. It has several properties such as anti-inflammatory, antioxidant, chemopreventive and chemotherapeutic. It has been shown to be the most potent natural anti-inflammatory agent, with effects similar to drugs such as hydro-cortisone. It is a potent immunomodulatory agent. Furthermore, it has several anticancer properties such as helping the body destroy cancer cells and inhibiting cancer angiogenesis, metastasis and proliferation. More than 2600 research studies on its effects on human disease treatment have been published in english journals and is currently in human clinical trials for a variety of conditions including pancreatic cancer, colon cancer, multiple myeloma and Alzheimer’s disease.
Consumption recommendations: the effects of curcumin are substantially increased by the presence of piperine (pepper) – absorption of curcumin is increased by a factor of 1000 when consumed with piperine. Turmeric can be used in curries, soups, pasta, or as a salad dressing. Indians consume on average 1.5gr to 2gr of turmeric per day.
Ginger – anti-inflammatory compounds, gingerols, have been associated with anticancer and anti-inflammatory activities. As an anti-inflammatory, several human studies have reported significant improvement in arthritis rheumatoid (up to 75% of patients), including pain and stiffness reduction; most of these studies utilised 1gr of ginger-root powder per day.
Consumption recommendations: Ginger is an excellent analgesic and very helpful while undergoing chemotherapy to decrease nausea, for example by drinking a cup of ginger tea.
Miscellaneous
Green Tea – is rich in polyphenol compounds such as epigallocatechin gallate (EGCG) and retinoic acid (RA). These compounds have been shown to prevent oxidative damage in healthy cells, induce apoptosis, and prevent cancers from developing a blood supply that allows them to grow bigger. The types of cancer which appear to be most responsive to green tea are: cancers of the gastrointestinal tract (including pancreas, colon, stomach and small intestine); estrogen-related cancers, such as most breast cancers and adenocarcinoma of the cervix; and prostate cancer.
Consumption recommendations: In general prefer Japanese green tea (Sencha, Gyokuro, Matcha, etc.) as they are richer than Chinese green tea in anticancer molecules. Brew tea for 8-10 minutes, as brewing time affects the polyphenol content, and drink within 1 hour. Obviously better quality green tea has higher polyphenol count. Drinking several cups of green tea daily (about 6) allows to reach the necessary concentration of cancer receptor inhibitors. Please note that Darjeeling is one of the few black teas containing significant levels of catechins flavonoids. Avoid drinking very hot tea as hot beverages have been associated with increased cancer risk.
Mushrooms – are an essential ingredient of traditional Asian medicine. Many types of mushrooms provide health benefits: button, shiitake, maitake, reishi, chanda, enoki, portabella, oyster, agaricus blazei and coriolus are the most popular and all contain anticancer compounds, although their effectiveness varies. They have traditionally been used in Japan for their anticancer properties. Their polysaccharides, such as beta-glucans, have shown important anti-cancer activities because of their ability to activate and power the immune system. Beta-glucan components have been shown to protect cells from carcinogenic substances, to enhance immune system activity (by binding to white blood cells outer membranes, including natural killer cells, and stimulating the bone marrow white blood cells production), to induce apoptosis and block cancer cells proliferation in several types of cancer, such as ovarian, breast, lung and colon cancer. For example lentinan (a form of beta-glucan found in shiitake) is known to have life prolonging effects in combination with chemotherapy on some cancers. In a case control study conducted in China, higher mushrooms intake decreased breast cancer risk.
Consumption recommendations: Shiitake mushrooms lentinan assimilation appears to be dampened when administered orally. On the other hand maitake seems to be quite effective when administered orally. Furthermore a study conducted in the USA to evaluate the effectiveness of compounds from portabella, enoki, shiitake and oyster mushrooms on breast and colon cancer cells growth, showed that oyster mushrooms compounds were the most potent. Please note that while the above mushrooms have a good record of safety, high consumption may induce severe side effects such as hepatic dysfunction.
Seaweed – is rich in phytochemicals compounds, such as fucoxanthins. These compounds have antiproliferative and apoptosis-inducing effects on different cancers, such as hepatic carcinoma, bladder and prostate cancer.
Consumption recommendations – the Food Standard Agency in the UK advises to avoid hijiki as they found high levels of arsenic in some samples.
Grains
Oat – beta-glucan has shown to inhibit the initiation and growth of cancer.
Consumption recommendations: It is preferable to eat organic oat (see Diet for more details).
Barley – ursolic acid suppresses cancer formation and proliferation.
Consumption recommendations: It is preferable to eat organic barley.
Omega-3s fatty acids
Omega-3s fatty acids - reduce inflammation and prevent cancer proliferation. Excellent sources of omega-3s are fish (long-chain), such as salmon, herring, mackerel, anchovies and sardines, and flaxseeds (short-chain). For example omega-3s have been inversely correlated with the risk of breast cancer and in a clinical trial on prostate cancer, cancer was growing at a significantly slower rate (30%-40%) in men who where given a daily dose of 30gm of flaxseed.
Consumption recommendations: As they are highly unstable it is recommended that they are consumed as whole foods as opposed to supplements. Eating fatty fish once or twice a week provides a good source of omega-3s to our diet. There are concerns about the risk of chemical, bacterial, viral, etc. fish contamination. The FSA (Food Standard Agency, UK) and FDA (Food and Drug administration) issue fish consumption limit recommendations and warnings on a regular basis, for more details please visit their websites (www.food.gov.uk www.fda.gov). Be aware that the longer a fish lives the more mercury it accumulates. Avoid eating endangered fish species. Grounded flaxseeds can be eaten with cereals in the morning or used as a salad dressing. Note that you can also use flaxseed oil but its anticancer molecules concentration is lower.