Some other changes to vegetable and fruit quality are more deliberate. Many of the plant compounds that have both interested cancer researchers and repel plant pests are bitter, acrid, or astringent. Consumers do not generally appreciate these qualities. It also had been assumed that natural chemical insect repellants in plants are toxic to us – in all concentrations. However, recent research is revealing that some compounds toxic in high concentrations may actually be beneficial at lower levels. Many modern crop varieties have been purposefully selected by plant breeders to contain reduced amounts of such compounds9. Not only are the blander tasting highly bred crop varieties possibly not as good for us, they may also be less able to ward off attack by plant pests, leading an increased reliance on chemical pesticides to produce them. The loss of beneficial plant chemicals also occurs after crops are harvested, as the food industry removes still more through de-bittering agents during food processing10. For example, cocoa beans contain an abundance of flavanols thought to have anti-cancer activity11, but because these compounds impart a bitter taste, they have been largely removed from the milk chocolate that most people eat. While aversion to excessive bitterness is to us an important cue for avoiding poisonous plants, by removing any hint of bitterness, we may have gone too far.

In order to increase the chances of my own body being able to destroy remaining melanoma cells that might still be floating around and also to possibly help prevent formation of any additional skin cancers, I am eating more foods shown to have anti-cancer properties. When possible, I am also eating organic produce – the more holes chewed by bugs the better - and am attempting to eat wilder foods that have not been extensively altered by plant breeders and therefore maintain more of their natural phytochemicals – for example, black walnuts instead of English walnuts, flax seeds (this crop was bred mostly for fiber – the content of the seeds is more a byproduct), assorted leafy greens like collards, mustard greens, or dandelion leaves, and wild berries.

Below is a list of foods that melanoma patients may wish to incorporate into their diet, based on information from studies published in the scientific literature. Wherever possible, I have included foods that have been studied in relation to melanoma, but many have also generated interest for the prevention or treatment of other cancers as well.

Soy

Soybeans contain an abundance of phytoestrogens, including isoflavones, which are believed to protect against certain cancers. In a study on mice, adding soy protein to the diet dramatically reduced the extent of melanoma metastasis12. Mice were intravenously injected with live melanoma cells and some were fed a diet high in soy protein while others received regular mouse food. After a period of time on this diet, it was discovered that 80 percent of the standard diet/control mice had more than ten distinct areas of melanoma growing in their lungs, while only 22 percent of the soy fed mice contained more than ten metastases. In addition, the median number of tumors in mice where soy protein comprised 0%, 10%, 15% and 20% of their diet was 53, 2, 2, and 1, respectively. A follow up study where mice were fed the soybean isoflavones genistein and daidzein showed a similarly dramatic reduction in tumor number and size13.

How much soy to eat? It is hard to say since the same studies that have been done on mice have so far not been done on humans. What works for mice may not work for us. However, the amount that was shown to be effective in mice would equate to a lot of soy. While tofu and soymilk are good sources of isoflavones, I am also trying to eat soy products that are less processed, such as edamame or soynuts. Both make great snacks.

Flax

Flax seed is a rich source of lignans, a natural plant phytoestrogen compound with cancer fighting properties. Lignans are found in many plants, but the concentration in flax is particularly high. Researchers have investigated the effect of dietary supplementation of flax on mice with melanoma, finding a substantial reduction in tumor occurrence compared to mice not fed flax14. The median number of tumors in mice fed diets supplemented with 2.5%, 5%, and 10% flax was 32%, 54%, and 63% lower than that of mice fed no flax, respectively. The addition of flaxseed to the diet also resulted in reduced tumor size and volume.

Flax seed can be easily ground into a coarse meal and added to cereal and smoothies. The whole raw seeds make an interesting nutty-tasting snack on their own as well. Eating the whole seeds requires quite a bit of chewing though… without chewing, the whole seeds mostly pass through the body undigested. Flax seed oil is convenient and widely available, but not all of the good things about flax end up in the oil - lignans are most abundant in the hulls of flax seed. Some flax seed oil blends include more hull particles and are labeled "high-lignan".

Carrots, yams, sweet potatoes, beets and other orange and red vegetables

Carotenoids such as beta-carotene and lycopene found in yellow and red vegetables are powerful antioxidants that can protect cells from free radicals that damage DNA and potentially lead to cancer. The beneficial effects of beta-carotenes to the skin have been shown in studies linking beta-carotene consumption with reduced reactions to sunburns15. In addition, one recent study showed that mice with melanoma fed a diet supplemented with beta-carotene had 71% fewer tumors than mice not fed beta-carotene16. Some carotenoids are vitamin A precursors and vitamin A supplements have also been shown to reduce melanoma tumor size and extent of metastases in mice17. [Note: vitamin A supplements can be very toxic when taken in large amounts – so be careful.]
One great way of ingesting a large quantity of beta-carotene (and vitamin A precursors) is by drinking lots of fresh carrot juice. When making juice, I sometimes also add a beet, celery stalks, a few collard green leaves, or even broccoli stalks and kale stems that might otherwise be thrown away, to the mix. Lycopene -another type of carotenoid that gives tomatoes their red color - has been shown to reduce the risk of prostrate cancer. A diet consisting of one tomato product serving a day or five servings a week has been recommended for protection against prostate cancer and other malignancies18.

Turmeric

The active ingredient in the spice turmeric (curcumin) was shown to reduce melanoma growth and increase survival time in mice19. A recently published study by researchers at the M.D. Anderson Cancer Center found a similar result, with curcumin suppressing the viability of human melanoma cell lines in the lab and even causing cell death20. The authors state that clinical trials to investigate the effects of curcumin on melanoma are planned. The turmeric spice is heavily used in Indian food - so eat lots of curry! The whole turmeric root is also available in some specialty stores (it looks a bit like orange-colored ginger root) and has a very potent taste.

Cruciferous vegetables

Studies have associated diets high in cruciferous vegetables with lower risk for breast, lung, stomach, colorectal, prostate, and bladder cancers in humans21. Isothiocyanates and other plant phytochemicals with cancer fighting properties are very abundant in this vegetable group which includes broccoli, brussel sprouts, cabbage, cauliflower, kale, bok choy, kohlrabi, collard greens, mustard greens, turnips, and water cress. Several laboratory studies have suggested that cruciferous vegetables help regulate a complex system of bodily enzymes that defend against cancer. Isothiocyanate compounds have been shown to arrest cell growth and even kill melanoma cells in culture in the laboratory22,23. In the body, these compounds are thought to exert their anti-cancer effects by activating detoxifying proteins that scavenge for cancer-causing molecules. The more bitter the aftertaste may possibly mean the better for you – mustard greens, collard greens, and brussel sprouts contain among the highest levels of several of these beneficial compounds.

Fruit

Many fruits contain phytochemicals including flavonoids such as anthocyanins. Anthocyanins, like other antioxidants, help neutralize the negative by-products of metabolism called free radicals, which can damage DNA molecules and lead to cancer. Antioxidants also counteract environmental carcinogens, protect against cardiovascular disease, fight sun damage to skin and may thwart the effects of Alzheimer's and other age-related diseases. Not all fruits are created equal. Wild blueberries apparently contain some of the highest levels of anthocyanins of any fruit. One study showed that isoprenoids found in fruits (and vegetables) actually suppressed the proliferation of mouse melanoma cells24. A great way to get plenty of fruit in the diet is to make smoothies using frozen and/or fresh fruit. To enhance intake of phytoestrogens and lignans as well, I use soymilk when making smoothies and add a few tablespoons of ground flax seed to the mix.

Green tea

Green tea is rich in polyphenols such as catechins that have generated considerable interest among cancer researchers. Studies have linked regular green tea consumption with reduced cancer risk25 and there is some evidence that green tea might prove to be effective for cancer treatment as well. Compounds found in green tea are believed to be especially effective at preventing skin cancers. In one study, extracts of green tea applied to the skin of rats inhibited the development of skin cancer in response to exposure to carcinogens including ultraviolet light26. Green tea has also been shown to inhibit some of the cellular changes that result in melanoma metastases27, and even directly reduce the incidence of lung metastases in mice28.

Whole grains

Whole grains are rich in antioxidants and phytoestrogens and studies have shown that diets high in whole grains are protective against cancer29, 30. In addition, the beta-glucan found in whole grains such as barley and oats may play a role in enhancing immune response by stimulating macrophages to attack foreign bodies such as viruses and cancer cells. One study showed that treatment with beta-glucan increased the survival of mice with metastatic liver disease31. Unfortunately, many of the grains we get in our diet are highly processed and have reduced levels of beneficial compounds. My sister passed a simple cereal recipe on to me which calls for putting ½ cup of whole oat groats in a thermos, adding two cups of boiling water, closing the lid and leaving overnight. Served with honey, it makes for a healthy and tasty way to start the day.

Nuts

It is believed that vitamin E confers protection against some types of cancers32 and nuts contain particularly high concentrations of this vitamin. In addition, compounds found in black walnuts, such as ellagic acid and juglone have been shown to reduce tumor growth rate in mice33. Almonds also contain many phenolic compounds that act as antioxidants34.

What to avoid

The only "food" for which I could find evidence about a positive association with melanoma was alcohol2,35. In a study of a limited number of Australian women, those consuming two or more drinks a day had 2.5 times the risk of developing melanoma35. This was only an observational study with many other possible confounding lifestyle factors. However, researchers have hypothesized that alcohol reduces the bodies’ ability to repair certain types of cell damage that can lead to cancer36. Heavy drinking is probably something to avoid.

While many of the foods listed above are thought to help prevent certain cancers, their efficacy as cancer treatment has not been demonstrated, at least in humans. Studies on mice provide tantalizing clues that at least some plant phytochemicals may eventually prove useful in the treatment realm. Until much more is known, what we eat should be viewed as a supplement to other medical treatment, and not a substitute. However, with the adjuvant therapies available for melanoma today having only a limited apparent benefit to survival, the proportional impact of eating the right foods, even if it not great, may still be important. For me, changing diet to include different cancer fighting foods has also had a beneficial psychological impact. Doing something to assist in one's own treatment reduces the feeling of helplessness that can accompany a cancer diagnosis. Besides, people who take an active role in their treatment and maintain an optimistic outlook generally lead a better quality of life and may even have a higher rate of survival37. Eating healthy certainly can’t hurt.

I compiled these research findings, along with my own thoughts and ideas in case it might inspire other melanoma patients to further explore the dietary path as one aspect of their treatment. Since www.mpip.org posted the first version, melanoma patients have contacted me with more great suggestions of foods to try, or asking for advice and information. So, I feel it is important to disclose that although a scientist, I am not a medical doctor and no expert in this field. The research I've read in the past few years is all new information to me too. Please also keep in mind that these foods are by no means the only ones researchers are studying. Quite a few who have contacted me also seem be interested in supplements… I did not mention supplements due to my own biases that compounds in foods act synergistically and even the non- "active" substances within foods may be important. I also enjoy eating LOTS of unusual vegetables and fruits… some others might feel they need supplements to get the volume. Comments or additional ideas welcome.

Good health and happy eating! -Eric Knapp (eeknapp2000 (at) yahoo.com)

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