Introduction
Hippocrates (460-377BC), the father of modern medicine, made this famous quote : "Let food be thy medicine and medicine be thy food!" And Louis Pasteur (1822-1895), a French microbiologist who is remembered for his remarkable breakthroughs in the causes & preventions of diseases such as vaccination & pasteurisation, once said : "Nature is the best physician; she heals three-quarters of all diseases and never badmouths her colleagues."
Eating fruits & vegetables has long been known as a way to help reduce the risk of cancer. Historically, cultures that consume a low-fat diet that includes a variety of fruits, vegetables, legumes and whole grains have lower rates of certain cancers and heart disease. Among the many anticancer components that fruits & vegetables contain, research studies have shown that plant compounds called phytochemicals have an amazing ability to inhibit cancer growth. A diet based on a regular intake of foods containing high levels of phytochemicals is vital in preventing cancer.
In nutritional terms, the foods we eat are generally divided into two categories : macronutrients & micronutrients. Macronutrients include carbohydrates, proteins and lipids (fats). Micronutrients include vitamins, minerals, fibres and phytochemicals.
What are Phytochemicals? (sources : see “References”)
Phytochemicals refer to a wide variety of compounds produced by plants that have protective or disease preventive properties. They are found in fruits, vegetables, beans, grains and other plants.
Phytochemicals are the molecules responsible for the colour and organoleptic properties (properties that affect the organs & the senses such as taste, texture, astringency & aroma) of fruits & vegetables. For example, the brilliant red colour of the strawberry, the characteristic smell of garlic and the bitter taste of bitter gourds are due to the presence of different phytochemical compounds in these foods.
Plants produce phytochemicals to protect themselves from bacteria, viruses and fungi. Recent research demonstrates that phytochemicals can also protect humans against diseases. Scientists have identified about 10,000 different phytochemicals in plants that are considered beneficial in the prevention of chronic diseases such as cancer, stroke & heart disease. Some of the well-known phytochemicals are lycopene in tomatoes, isoflavones in soy and flavanoids in fruits.
Phytochemicals & Anticancer (sources : see “References”)
There is some evidence that certain phytochemicals may help prevent the formation of potential carcinogens (substances that cause cancer), block the action of carcinogens on their target organs or tissue, or act on cells to suppress cancer development. Many experts suggest that people can reduce their risk of cancer significantly by eating more fruits & vegetables. Phytochemicals are present in virtually all of the fruits, vegetables, legumes (beans and peas) and grains we eat, so it is quite easy for most people to include them in their diet. For instance, a carrot contains more than a hundred phytochemicals.
A research done by Prof Beliveau & Dr Gingras, two of the world’s top researchers, revealed that some foods have shown potential to help prevent cancer. In a book they co-authored, they wrote, “Until recently, vitamins, minerals and fibres were considered the only substances responsible for the beneficial effects of fruits & vegetables in the prevention of chronic diseases such as cancer. However, results obtained in the last few years have cast these conclusions into doubt. It now seems more and more probable that the protection against cancer that is offered by fruits & vegetables is due mostly to their phytochemical content.”
The researchers added, “It is the high levels of different classes of phytochemicals present in certain foods that allow them to act as agents in cancer prevention & thus be considered as nutraceuticals. A nutraceutical is any food (fruit, vegetable, beverage or product of fermentation) that contains a large quantity of one or more molecules with anticancer potential. Although all fruits & vegetables contain phytochemicals, many of the phytochemicals showing the highest levels of cancer prevention activity are present only in a few very specific foods.”
Nutraceuticals - Foods with Anticancer Phytochemicals
It's good to eat a variety of fruits & vegetables to benefit from the thousands of phytochemicals present in plants.
According to the research done by Prof Beliveau & Dr Gingras, the following foods (nutraceuticals) have shown high levels of anticancer phytochemicals so you should try to include these foods regularly in your diet to help you fight cancer :
• Cruciferous veggies – cabbage, broccoli, cauliflower, brussels sprouts, etc
• Garlic, onions, shallots & members of the Allium family
• Soya-based foods - tofu, miso, soya beans, soya milk (dou-nai), etc
• Turmeric
• Green tea
• Berries – raspberry, strawberry, blueberry, cranberry
• Omega-3 fatty acids - fresh walnuts, soya beans, tofu, sardines, mackerel, etc
• Tomatoes
• Citrus fruits – orange, grapefruit, lemon, mandarin orange
• Grapes & grape juice (red wine)
Whole Foods or Supplements?
Someone may say, "I've no time to juice or cook, can I take supplements?" My answer is "No". A lot of people think that popping a pill can make up for the lack of a healthy meal. I would say that nothing can substitute for a balanced diet made up of fresh, whole foods.
On the American Cancer Society website it says, "Many of the better-known phytochemicals are now available as dietary supplements. Examples are beta-carotene, ascorbic acid (vitamin C), vitamin E, folic acid, curcumin, etc. However, most available evidence suggests that these single supplements are not as beneficial as the foods from which they are derived." This is because phytochemicals cannot be found in supplements and are present only in whole foods.
Therefore I would suggest that you eat whole foods and NOT food supplements which often come in the form of ready-to-swallow capsules or pills OR ready-to-drink mixture or satchet. Eating whole foods, instead of taking supplements, allows the body to benefit from the wide range of phytochemical compounds they contain.
Foods with high levels of anticancer phytochemcials
You can eat the foods in their natural form (as juices or salads) or you can cook the food. I like to eat my food raw & uncooked so as to preserve its God-given natural nutrients. Many nutrients in food tend to be destroyed by the high heat of cooking so I consume some veggies in the form of juices. But I also include cooked vegetables in my daily balanced meals (purely for their fibres content, and also because some foods are best eaten cooked eg tomatoes). You too can eat your foods raw or cooked to enjoy the full benefits that nature provides.
You can include the following foods regularly in your anticancer diet.
1. Cruciferous Vegetables
Members of the cabbage family are known as crucifers or cruciferous vegetables and belong to the Cruciferae or Brassicaceae family. This family takes its name from the shape of their flowers whose four petals resemble a cross (crucifer). Cruciferous vegetables have a unique ability to fight against the development of cancerous cells in the body. Eaten regularly, they are an easy & inexpensive way to help prevent cancer.
Members of the crucifer or cabbage family include the following :
• Brocolli & broccoli sprouts
• Brussels sprouts
• Cauliflower
• Cabbages – green cabbage (with smooth green-white leaves), red cabbage (with purple-red leaves), savoy cabbage (with curly crinkled leaves), Chinese celery or napa cabbage (or wong-bok)
• Non-head-forming cabbages – bok choy (or pak choy, peh chai, bai-cai, Shanghai qing-cai), Chinese broccoli or Chinese kale (kai-lan), collard greens, kale, kohlrabi, mustard, radish, rutabaga, spring greens, turnips, wasabi, watercress
Phytochemicals in Cruciferous Veggies
Cruciferous vegetables are unique in that they are rich sources of sulphur-containing compounds called glucosinolates that impart a pungent aroma and spicy, bitter taste. Glucoraphanin and isothiocyanate sulforaphane are two major types of glucosinolates. Chopping or chewing cruciferous vegetables results in the formation of bioactive glucosinolate hydrolysis products such as isothiocyanates and indole-3-carbinol.
“In food-bearing plants, glucosinolates act as natural pesticides and are stored in the plant’s cells, ready to be released upon tissue damage. Similarly, when consumed by humans, the action of chewing releases the glucosinolates into the body where they are transformed into bioactive compounds believed to have anticancer properties. These anticancer compounds operate on several fronts --- triggering the body’s own detoxification systems, slowing cancer cell growth and supporting DNA repair.” (source : sharecare.com)
“Research suggests that glucosinolates can stimulate the body’s own natural antioxidant systems. As such, glucosinolates act as indirect antioxidants triggering the liver to produce detoxifying enzymes that block free-radical attack on DNA. Once this process occurs, a cascade of antioxidant activity actually cycles over and over within the body, continuing to protect your system for up to four days after the glucosinolate-containing food was initially eaten.” (source : sharecare.com)
Anticancer effects
• Of all edible plants, cruciferous vegetables contain the largest variety of phytochemical compounds with anticancer activity.
• Cruciferous vegetables contain important quantities of many anticancer compounds that slow the development of cancer by preventing carcinogenic substances from causing damage to cells.
• Many studies have found that eating a diet rich in cruciferous vegetables has been associated with a decrease in the risk of many cancers such as lung cancer, breast cancer, prostate cancer and gastrointestinal cancers such as stomach, bladder & colorectal.
• Isothiocyanates, such as sulphoraphane (American spelling : "sulforaphane"), may help prevent cancer by promoting the elimination of potential carcinogens from the body.
• “Certain isothiocyanates show more powerful anticancer activity than others; this is the case of the sulphoraphane in broccoli. Sulphoraphane accelerates the body’s ability to flush out toxic substances linked to cancer. Sulphoraphane also seems capable of acting directly at the level of the cancerous cells & bringing about their demise.” (source : Beliveau & Gingras)
• “Broccoli & broccoli sprouts are by far the best source of sulphoraphane; one serving of broccoli contains up to 60mg while one serving of broccoli sprouts can contain up to 100 times more. This makes broccoli one of the most important foods in the prevention of cancer through diet.” (source : Boliveau & Gingras)
• Sulphoraphane can be found in all cruciferous veggies but highest in broccoli & broccoli sprouts. Broccoli, broccoli sprouts and Brussels spouts are exceptional sources of these anticancer molecules and should be eaten regularly.
• “Despite all the beneficial properties associated with sulphoraphane, it would be wrong to assume that eating regular helpings of broccoli is the only way we might prevent cancer. The isothiocyanates and indoles present in other cruciferous vegetables also possess anticancer properties that contribute to their protective effect on health.” (source : Beliveau & Gingras)
• “Among these molecules, two deserve special mention : phenethyl isothiocyanate (PEITC) & indole-3-carbinol (I3C). Studies have shown that PEITC, present in large amounts in watercress & Chinese cabbage, not only can prevent the development of tumours but it may also play a protective role in fighting existing tumours.” (source : Beliveau & Gingras)
• “I3C is a type of glucosinolate that is found in most cruciferous vegetables and especially broccoli & Brussels sprouts. Research on the chemopreventive role of I3C has shown its impact on oestrogen metabolism & its ability to interfere with cancers dependent on oestrogens such as breast, cervical and uterine cancers.” (source : Beliveau & Gingras)
Basic facts you should know (source : Beliveau & Gingras)
Several factors must be considered in order to maximise the active isothiocyanate & indole content in cruciferous vegetables.
(1) The anticancer molecules in cruciferous vegetables are present in a latent state in the vegetables themselves; it is only when these vegetables are actually chewed & eaten that the active anticancer compounds are released.
(2) Glucosinolates are very soluble in water so cooking a cruciferous veggie for 10 min in a large volume of boiling water reduces by half the quantity of glucosinolates present in the veggie. This is a cooking method best avoided.
(3) Myrosinase activity (definition below) is very sensitive to heat. A prolonged cooking time substantially reduces the amount of isothiocyanates. Cruciferous veggies should therefore be cooked as little as possible, in a minimum of liquid, to reduce the loss of myrosinase activity & glucosinolates.
What is Myrosinase? (source : whfoods.com)
Did you know that cutting the broccoli florets into smaller pieces and the stems into thin slices and letting them sit for 5 to 6 minutes before cooking will enhance their cancer protective properties? Cutting broccoli into smaller pieces breaks the cells and activates an enzyme called myrosinase. The myrosinase converts some of the sulphur-containing chemicals found in broccoli (called glucosinolates) into other sulphur containing chemicals (called isothiocyanates) which research has shown to contain cancer preventive properties not found in the glucosinolates . Studies have actually pinpointed specific mechanisms, like changes in cellular genetic processes, which are involved in increasing cancer protection.
Cooking Tips
• Avoid boiling cruciferous veggies as boiling will destroy sulphoraphane & indo-3-carbinols.
• Cruciferous vegetables should be lightly cooked and thoroughly chewed when eaten in order to maximise their anticancer potential.
• Rapid cooking techniques, such as steaming or stir-frying in a wok, are simple & effective ways of maximising the quantity of anticancer molecules delivered by cruciferous veggies. Cover & steam briefly (steam for 2-3 min after water in steamer has boiled) or stir-fry rapidly in a wok with a little olive oil & some garlic.
• Steamed veggies taste delicious even without any seasoning. Give it a try, you will love its original natural sweetness & flavour. Lightly cooked veggies have a bright green colour.
• Don’t overcook cruciferous veggies as they will turn yellow and can produce a strong sulphur odour which can be unappealing. Overcooking the veggie will also decrease its nutritional value.
• When buying fresh broccoli, look for firm florets with a purple, dark green or bluish hue on the top. These are likely to contain more beta-carotene and vitamin C than florets with lighter green tops. If it has yellow in it or is limp and bendable, the broccoli is old --- don’t buy it.
Caution : Goitrogens present in cruciferous vegetables
People who suffer from hypothyroidism and who are on thyroid hormone replacement treatment should consider limiting the consumption of cruciferous vegetables. This is because cruciferous vegetables contain thyroid inhibitors known as goitrogens. (Generally, there are two categories of foods that have been associated with disrupted thyroid hormone production in humans : soybean-related foods and cruciferous vegetables.)
Goitrogens are substances that suppress the function of the thyroid gland by interfering with iodine uptake, which can, as a result, cause an enlargement of the thyroid, that is, a goitre. Goitrogens can cause difficulty for the thyroid in making its hormone. Isothiocyanates appear to reduce thyroid function by blocking thyroid peroxidase and also by disrupting messages that are sent across the membranes of thyroid cells.
“Although research studies are limited in this area, cooking does appear to help inactivate the goitrogenic compounds found in food. Both isoflavones (found in soy foods) and isothiocyanates (found in cruciferous vegetables) appear to be heat-sensitive and cooking appears to lower the availability of these substances. In the case of isothiocyanates in cruciferous vegetables like broccoli, as much as one third of this goitrogenic substance may be deactivated when broccoli is boiled in water.” (source : whfoods.com)
“Although for many people goitrogens do not seem to pose a health concern, certain individuals who have thyroid problems may be advised by their healthcare practitioner to limit excessive consumption of foods that contain these compounds. As cooking seems to help to inactivate the goitrogenic compounds found in food, it seems reasonable to conclude that for individuals with deficient thyroid hormone production, steaming of cruciferous vegetables like broccoli makes good sense, as does consumption of tofu in cooked versus raw form.” (source : whfoods.com)
(more to come)
Eat right. Exercise daily. Rest adequately.
shuqin
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References
Phytochemicals
American Cancer Society
http://www.cancer.org/Treatment/TreatmentsandSideEffects/ComplementaryandAlternativeMedicine/HerbsVitaminsandMinerals/phytochemicals
Book : "Foods to fight Cancer" by Prof R Beliveau & Dr D Gingras (2007)
Book : "Anticancer" by Dr D Servan-Schreiber (2011)
ShareCare.com
How do glucosinolates in vegetables protect me from cancer?
http://www.sharecare.com/question/glucosinolates_protect_cancer
Wikipedia
http://en.wikipedia.org/wiki/List_of_phytochemicals_in_food
Cruciferous vegetables
Wikipedia
http://en.wikipedia.org/wiki/Cruciferous_vegetables
Cook’s Thesaurus
http://www.foodsubs.com/Cabbage.html#bok
Cruciferous Vegetables Diet
http://www.cruciferousvegetablesdiet.com/
The World’s Healthiest Foods
http://www.whfoods.com/genpage.php?tname=george&dbid=47
How to prepare broccoli to retain its nutritional value (must read)
http://www.whfoods.com/genpage.php?tname=george&dbid=64
