Food for cancer prevention and support
(Originally published in Cancer Care Centre’s Healthy Living Magazine)
In recent years nutritional medicine research has helped our understanding of the healing qualities of natural foods. Diet does matter and many foods are actually “anti-cancer” foods in that they have compounds which act to “turn-off” the processes by which cancer gets established and spreads. These compounds, referred to as phytochemicals, are found in all edible plants but are particularly concentrated in a relatively small number of “medicinal foods”. Consumption of these foods as part of an “anti-cancer” diet may assist the body to fight cancer more effectively.
Some of these phytochemicals act mainly to protect normal cells from damage which can lead to cancer initiation. At this level the main phytochemicals identified to date are sulforaphane (broccoli), indole-3-carbinol (cabbage), diallyl sulfide (garlic) and ellagic acid (strawberries). Other phytochemicals block the promotion and progression of cancer including: curcumin (turmeric), epigallocatechin (green tea), resveratrol (red grapes), lycopene (tomatoes), anthocyanidins (blueberries), Omega-3 fatty acids (oily fish/flaxseed oil), limonene (citrus) and proanthocyanidins (cinnamon, cranberries, blueberries). Specific mechanisms by which these foods act include inhibition of tumor cell growth (green tea, turmeric, soy, cruciferous veggies, garlic and onion, grapes and berries, citrus, tomatoes, omega-3, dark chocolate); induction of tumor cell death (turmeric, soy, cruciferous, garlic and onion, grapes and berries); and interference with new blood vessel formation required for cancer spread (green tea, turmeric, soy, grapes and berries, omega-3). Immune boosters include turmeric, citrus and omega-3.
What about soy? Soy has a phytochemical called genistein which has multiple anti-cancer actions however, there is controversy regarding the potential for soy to stimulate estrogen receptors as it is a strong phytoestrogen. Therefore it is recommended that soy not be consumed by people dealing with an estrogen dependent cancer.
In addition to increasing “medicinal foods” in the diet it is important to maximise the availability of the phytochemicals through proper preparation of these foods. For example, the medicinal quality of broccoli and cabbages will be vastly reduced if it is cooked in too much water. Traditional use often points the way to maximal benefit and the Asian tradition of stir frying broccoli and cabbage quickly maximises its benefits. Similarly for tumeric – it is not well absorbed “neat” but absorption is increased if heated with oil (or ghee) and black pepper – the way tumeric is traditionally cooked in Indian food. A third example of “traditional wisdom” is the preparation of tomatoes, garlic and onion. The Italian tradition of cooking all three together liberates the healing compounds in these foods!
Besides the “medicinal foods” what else should one consider when undertaking an “anti-cancer” diet? Certainly there is no one diet that is recommended for cancer patients however, there are certain guidelines that I recommend to my patients including avoiding foods that are associated with an increased risk for cancer, using a variety of whole natural foods, and having a “plant-based” diet.
Foods that are associated with an increased risk of cancer include dairy, red meat, pork, processed foods especially processed meat, sugary or very sweet foods and inflammatory fats. Dairy, red meat and pork are high in saturated fats. Dairy is also high in estrogens (the cows are pregnant). Grain fed meat is full of saturated and inflammatory fats. Inflammation in the body is a cancer promoter. Anti-inflammatory protein sources such as oily fish are a better choice and remember Omega 3’s found in oily fish are “anti-cancer” agents.
Sugary foods and processed carbohydrate foods increase the blood glucose levels dramatically. Cancer cells love blood sugar – they need glucose to survive and unlike normal cells cannot use other substrates for energy production. In order to avoid the sugar problem I recommend sticking mainly to lower GI fruits like apples, pears and berries and when eating fruit try to have some fat or protein along side it. So for example a few nuts and seeds will help stabilise blood sugar.
Using a variety of foods that are natural and unprocessed is one way to ensure you are getting as many health-promoting phytochemicals as possible. Since most of those identified so far are found in brightly colored fruit and vegetables my recommendation is that we “eat a rainbow” and try to have at least 5 different colours of vegetables and fruit per day. The number of serves of “rainbow foods” should be between 8 and 10. Juicing is one way to get a lot of colors in one glass – consider taking the juicing class here at Cancer Care Centre which provides great information about juicing for cancer support.
Finally, I recommend a plant based diet. This is not to say that everyone should be a vegetarian but rather that the majority of food on our plates should be plant based. For those that do follow the low or non-animal product path be conscious of getting sufficient protein in your diet through nuts, seeds, lentils and beans (rather than dairy). Protein is an essential requirement for the liver detoxification pathways and we must have sufficient protein to run these pathways. The body will “waste” its own muscles if inadequate protein is consumed contributing to the weight loss problem associated with both cancer and its medical treatment.