12 Dietary Changes to Lower Cancer Risk
Some foods actually contribute to the development of cancer; other foods lessen the risk. Follow these dietary changes to lower cancer risk. More specifically, these dietary guidelines target lowering the risk of colorectal cancer as well as preventing cardiovascular disease. For people with a genetic tendency toward colorectal cancer, it is not just an option, it’s a lifesaving necessity.
1. Keep your diet low in total fat and very low in saturated fats
There are at least two ways in which dietary fat contributes to cancer risk. First, tumor cells need low density lipoproteins (LDL’s) to grow. Therefore, a diet that helps to lower LDL levels could keep potentially cancerous cells from growing. Eating fat also stimulates the production of bile, which is needed to digest fat. If a lot of bile is allowed to stagnate in the large intestine for a long period of time, it’s converted into apcholic acid, a proven carcinogen. Here are tips for eating not only less fat, but eating the right fats:
Eat less total fat
Limit your daily fat intake to no more than 20 percent of your total food calories. This means that if you average 2,500 calories a day, fat should provide no more than 500 of these calories. This means you should eat around 55 grams of fat per day, maximum. (On a 2,000 calories per day diet, you would eat about 45 grams of fat.)
Eat the right fat
Eating the wrong kinds of fat may be even more cancer-causing than eating too much fat. Cancer researchers became aware of this fat fact when they noticed that the incidence of most cancers is less in some cultures who actually have a high-fat diet, such as Eskimos (who eat a lot of seafood rich in omega 3 fatty acids) and the Mediterranean diet (which is plant-based, but high in monounsaturated oils). Some fats don’t contribute to cancer and may in fact have some anticancer properties:
- Unsaturated fats, found in plant foods, such as legumes
- Vegetable oils that are high in monounsaturated fats, such as olive (Greek women who tend to eat a diet rich in olive oil have a very low incidence of breast cancer) and canola oil. A 1998 study showed that men who eat less animal fat and more vegetable fat in their diets had less prostate cancer.
- Seafood, such as salmon and tuna, that is high in omega 3 fatty acids
- Oils that contain more omega 3 than omega 6 fatty acids, such as flaxseed, pumpkin seed, canola, soybean (not hydrogenated), walnut, safflower, sunflower, sesame, and virgin olive oils. (Heating vegetable oils at high temperatures can change fatty acids and make them carcinogenic. Peanut oil and extra virgin olive oil stand up best to cooking, but try not to boil them. It helps to keep stirring stirfrys so the oil doesn’t get burnt.)
Studies in experimental animals have shown that fish-oil-supplemented (high in omega 3 fatty acids) animals had significantly fewer colorectal tumors. Omega 3 fatty acids (such as those found in fish oils and flax seed oil) are not only the heart-healthiest fats, but they may have anticancer properties. Eskimo women who have a high concentration of omega 3 fatty acids in their diet have a lower incidence of breast cancer. (It is thought that omega 3 fatty acids may block the effect of estrogen on breast cells, thus lowering the risk of them becoming cancerous.) Omega-3 dha supplements from Dr. Sears can be added to the morning oatmeal for added health benefits.
Don’t eat bad fats
Avoid oils high in saturated fats, such as palm, palm kernel, coconut, and cottonseed oils. Hydrogenated fats (those that have been chemically changed from unsaturated to saturated fats), are potentially carcinogenic. Adding hydrogen to a fat molecule may enable the molecule to interfere with the normal metabolism of cells in the body, setting the cell up for cancerous changes. So get used to reading labels because if any food contains “hydrogenated” or “partially hydrogenated” fats, leave it on the shelf. Most fast-food outlets use hydrogenated fats. Ask, and if they do, don’t eat the food. Since hydrogenated fats allow for a longer shelf life, nearly all packaged foods, such as potato chips, contain hydrogenated fats.
MORE LEAN – LESS CANCER
2. Increase Your Fiber Intake to Lower Cancer Risk
In all the research linking food to cancer, the evidence for a relationship between a high fiber diet and lower chances of colorectal cancer is the most conclusive. It follows common sense as well. Fiber moves potential carcinogens through the intestines faster, decreasing the contact time between carcinogens and the intestinal wall. The less exposure to carcinogens, the less chance of colon cancer. Besides pushing them through faster, fiber binds carcinogens, keeping them away from the intestinal wall. Fiber also absorbs bile acids, keeping them from acting on bacteria to produce fecapentanes, the cancerous substances that are formed by decaying foods within the colon. There are about 20 of these compounds that can mutate colon cells into cancerous cells. Fiber also promotes the growth of healthy bacteria in the intestines, which crowd out the undesirable bacteria that produce fecapentanes. A high fiber diet seems particularly protective against cancer in persons who have a hereditary risk of developing precancerous colorectal polyps. In a study of persons who were at high risk for developing colorectal cancer, those who ate at least 13 grams of wheat bran fiber a day (All-Bran is a good source) for eight weeks showed less growth of potential cancer cells in the colon. Besides lowering the risk of colorectal cancer, a high fiber diet can lower the risk of breast cancer by binding estrogen in the bowels, thereby lessening the estrogen effect in the cells of breast tissue. Based on both of these scientific and common sense findings, we suggest you eat at least 25 grams of fiber a day. The best anti-cancer fiber sources are: wheat bran, kidney beans, garbanzo beans, navy beans, whole wheat, whole grains, legumes, whole grain bread, and prunes. Get used to looking at the package label to find the fiber content of foods. Simple modifications in your diet can increase the amount of fiber you eat. Use whole grain breads instead of white bread (white bread is junk bread). Eat beans regularly (try a salad composed of kidney beans, garbanzo beans, broccoli, and other raw vegetables). Have a big bowl of high fiber bran cereal for breakfast.
NUTRITIP: An Apple a Day May Keep the Cancer Doctor Away
3. Eat lots of raw fruits and vegetables
Again, the consensus of the hundreds of studies exploring the link between diet and cancer is that eating more fruits and vegetables reduces all kinds of cancer risks. Eating more fruits and vegetables decreases your appetite for fatty foods- which increase the risk of cancer. Plants also contain phytochemicals; substances that may help your body fight cancer. The five major classes of compounds that occur in fruits and vegetables as natural blocking agents against carcinogens are: phenols, indols, flavones, cumines, and isothiocyanates. These neutralizing agents prevent carcinogens from reaching critical target sites within the cell. The vegetables most important to reducing your cancer risk are the cruciferous vegetables: broccoli, cabbage, Brussel sprouts, mustard greens, kale, and cauliflower. These vegetables contain three cancer-protective biochemicals: sulforaphane, which not only boosts immunity but blocks enzymes that draw carcinogens into healthy cells; compounds that prevent the formation of carcinogenic nitrosamines in the intestines; and indoles, which lessen the risk of breast cancer. Researchers estimate that eating lots of cruciferous vegetables could lower your risk of breast and colon cancer by 40 percent. Making your main meal, such as lunch, a huge salad (with no more than a tablespoon of vegetable oil as a dressing) would be one of the healthiest habits you could get into. Best salad sources of anti-cancer nutrients are: dark green leafy spinach (instead of iceberg lettuce, which is nutritionally useless), broccoli, tomatoes, red peppers, kidney beans, and garbanzo beans. As an added benefit, sprinkle your salad with a bit of garlic because it’s been shown to have health-promoting and possibly anti-cancer properties. In addition, phytoestrogens from plant foods, especially cruciferous vegetables, can lower the risk of estrogen-dependent cancers, such as breast cancer. The phytoestrogens fill estrogen receptor sites on cells, keeping the cancer-causing estrogen from promoting the growth of malignant cells.
NUTRITIP: An Anti-Cancer Salad
4. Switch from red meat to seafood
People who eat the most red meat and fat in their diet have the highest incidence of colon cancer. My 50 years of eating steaks, cheeseburgers, and french fries were not worth the price of getting cancer. Instead of red meat being the main course, let it be an accent in a dish based on vegetables or grains, such as stir fry or pasta. Beginning in 1976, a group of researchers at the Harvard School of Public Health set out to study the role of dietary factors in colon cancer and test some of the theories suggested by earlier studies. They followed 88,000 healthy women, ages 34 to 59 years old, and discovered these correlations:
- The risk of colon cancer was 2.5 times higher in women who ate beef, pork, or lamb as a main dish every day, as compared with those eating it less than once a month.
- The risk of developing colon cancer correlated with the amount of animal fat in the diet.
- Eating meat, especially processed meats, was highly associated with increased risk of colon cancer. Eating fish and chicken without skin decreased the cancer risk.
- A low intake of fiber also increased the risk of developing colon cancer.
No association was found between the risk of colon cancer and vegetable fat or linoleic acid (the most abundant polyunsaturated fat) in the diet.
The reason for the red meat-colon cancer connection is still being studied. Current research suggests a combination of factors. High fat diets increase the excretion of intestinal bile acids, which act as tumor promoters. Some processed meats contain nitrosamines, which can be carcinogenic to the colon. Also, compared with vegetarians, meat-eating persons have different colonic flora. The effects of the meat may cause intestinal bacteria to transform bile acids into potential carcinogens.
In a 14-year study of 16,000 Swedish men and women, the foods that were associated with the highest risk of colon cancer were beef and lamb. As a lambchop lover, I took this study personally. Whenever our local meat market got in a shipment of lambchops, I stocked up. A month after my colon cancer was diagnosed, Martha took the 30 pounds of lambchops that were in our freezer back to the market and traded them in for salmon.
Not only can red meat itself be carcinogenic, but how you prepare it can also elevate the cancer risk. Grilling under high heat (such as searing or flame-cooking meat to well- done) can release carcinogens into the meat called heterocyclicamines, which can damage cellular DNA. Poaching, stewing, microwaving, or slow low-heat cooking releases fewer carcinogens.
5. Switch from an animal-based diet to a plant-based diet
The most compelling research linking diet to cancer risk are studies of people who have primarily plant-based diets such as vegetarians and Seventh Day Adventists. One of the theories on the high incidence of cancer in modern times is the belief that the switch from plant- based to animal- based diets correlates with the increase in cancer risk. Plant food/ less cancer correlation is primarily due to three health-promoting factors: Plants have less fat, more fiber, and more phytonutrients. Besides providing the anti-cancer properties of fiber, legumes (such as seeds, rice, soy beans, beans, and chick peas) contain anti- cancer properties called protease inhibitors, which have been shown to reduce the growth of breast, colon, and skin cancers in experimental animals.
6. Eat more soy products to lower cancer risk
Soy is a more healthful source of protein than meat. The primary anti- cancer value of soy seems to come from phytonutrients (for example, isoflavones) which inhibit the growth of new blood vessels necessary for tumor survival. Soy also protects against colon cancer by blocking the carcinogenic effects of bile acids (a process called angiogenesis). Isoflavones also help regulate the production of sex hormones, which could affect the risk of prostate and breast cancer. Studies have shown that women who eat more soy foods have less risk of breast cancer. Don’t rely on highly-processed soy foods, such as soy burgers, soy sauce, and soy beverages to contain a lot of cancer-fighting isoflavones. American women, especially those whose diets are low in soy products, are four times more likely to die of breast cancer than Japanese women whose diets are plentiful in soy. The reason this reduced risk is contributed mainly to the soy and not to the genes is that even in their own country, those Japanese who eat the most soy foods lower their cancer risk. Soy seems to protect against the most common types of cancer including lung, rectal, colon, stomach, prostate, and breast. Experimental animals who are fed high soy diets and then given a chemical that causes cancer, develop fewer tumors than the animals who are not fed soy. And you don’t need to eat much to reap the benefits. One serving of soy (equal to a 1/2 cup of cooked soybeans, tofu, tempeh, or one cup of soy milk) a day can lessen your cancer risk.
GENISTEIN CONTENT IN SOY
The isoflavone in soy that has the most potent anti- cancer properties is genistein. The highest content of genistein is found in these soy foods, rated from highest to lowest:
|Soy Food||Genistein Content (milligrams/100 grams)|
|Soy protein isolate||56|
|Soy burgers||20 (varies)|
Be sure to consume soy products from a manufacturer that uses a water extraction process and not alcohol extraction, which can remove much of the genistein from the soy. Check the label or call the manufacturer.
7. Change your oils
Oils that are rich in omega-3 fatty acids (i.e., fish and flax oils) have anti-cancer properties. Studies in experimental animals have shown that fish-oil-supplemented animals develop significantly fewer colorectal tumors. Omega 3 fatty acids, such as those found in oily fish and flax seeds, help produce cancer-fighting phytochemicals. Flax oil also contains the anti- cancer phytonutrient lignans. Best protection against cancer is a diet that contains more omega 3 than omega 6 fatty acids, just the reverse of the typical American diet. Coldwater fish, such as salmon and tuna, are high in omega-3 fatty acids. Most vegetable oils (except flax oil) contain little omega 3 fatty acids and a lot of omega 6 fatty acids. I take one tablespoon of flax seed oil a day, which mixes beautifully in a yogurt shake or as a salad dressing. Monounsaturated oils, such as olive oil, also play a role in cancer prevention. Populations with an olive oil- rich diet, such as Mediterranean cuisine, have a lower incidence of cancer. Greek women, who tend to have an olive oil- rich diet, have a much lower risk of breast cancer. One study found that the incidence of breast cancer correlated with the amount of hydrogenated oils in a woman’s diet. As much as possible, avoid saturated and hydrogenated oils. (For more information, see All About Oils)
8. Eat foods containing calcium
Studies have shown that populations with a high intake of calcium (e.g., people in Sweden) have a lower incidence of colorectal cancer. Calcium controls the multiplication of epithelial cells lining the colon. When these cells proliferate at a fast rate, the risk of cancer increases. Calcium also binds cancer-producing bile acids and keeps them from irritating the colon wall. One study showed that an average intake of 1,200 mg. of calcium a day was associated with a 75 percent reduction in colorectal cancer. In another study of persons with an increased risk of colorectal cancer, a daily supplement of 2,000 mg. of calcium carbonate significantly decreased the risk by suppressing the uncontrolled growth of the cells that line the colon. To lower your risk of colorectal cancer, consider taking between 500 and 1,000 milligrams of calcium carbonate or calcium citrate daily, depending on how much calcium you get from food each day. Best sources of calcium are dairy products, such as yogurt, and bony fish.
9. A diet high in antioxidants can lower cancer risk
While there are many unsubstantiated claims about the benefits of antioxidants, there is reliable scientific evidence that beta carotene, vitamin C and vitamin E definitely lower the risk of colorectal cancer. Fruits and vegetables are the main sources of these naturally occurring antioxidants. Antioxidants protect against cancer in several ways:
- They protect the membrane of intestinal cells.
- They prevent free-radical reactions that can cause bowel contents to be carcinogenic.
- They prevent faulty metabolism in the cell, which can predispose a cell to becoming carcinogenic.
Beta carotene fights against cancer by both boosting the immune system and releasing a specific chemical called tumor necrosis factor. Beta carotene can block the growth of potentially cancerous cells. The recommended cancer prevention dose of beta carotene is 15 to 25 mg. per day (around 30,000 IU). This is about ten times the amount in the average American diet, but it’s actually easy to get enough beta carotene in your diet without taking supplements. Best sources of beta carotene are sweet potatoes, carrots, cantaloupe, pumpkins, butternut and other types of winter squash, spinach, broccoli, mango, and papaya. Eating pink grapefruit (which contains beta carotene) instead of white grapefruit gives you a beta carotene boost. You could get enough protective beta carotene each day by eating: half a sweet potato, half a cup of pumpkin, two medium-size carrots, 1.5 cups of cooked spinach, or two medium-size mangos. Best sources of beta carotene are these:
- carrots – 1 carrot contains 4.4 milligrams
- sweet potatoes – 1 medium contains 12 milligrams
- butternut and other types of winter hard-shell squash – 1/2 cup contains 2.4 milligrams
Tomatoes contain lycopene, which enhances the absorption and utilization of beta carotene, so eating tomatoes with beta carotene-rich foods provides an added boost. Carrots and tomatoes are a good combination.
A big dose of vitamin C fights the big “C.” Studies have shown that persons with the highest intake of vitamin C have the lowest incidence of intestinal cancers. Vitamin C blocks the formation of nitrosamines in the gut. These are potent carcinogens made from nitrates and nitrites found in food, especially processed meats. Vitamin C also boosts the immune system by increasing the production of lymphocytes. Best sources of vitamin C are fresh fruits and vegetables. Taking 1,000 to 2,000 milligrams of vitamin C daily may have anticancer benefits.
The anti-cancer properties in vitamin E are similar to vitamin C. In a ten-year study that followed 21,000 men, those with high levels of vitamin E in their diet showed a 30 percent lower risk of all types of cancer. Women with low blood levels of vitamin E and selenium had ten times the risk of breast cancer in one study. In another study at the University of Toronto, researchers gave colon cancer patients vitamin C and E supplements after surgery and found two years later that the supplements reduced the recurrence of precancerous colon polyps by 20 percent. Studies suggest a dose of 200 to 400 IU a day, which is nearly impossible to get from foods. You may get less than ten percent of this amount from even the best diet.
NUTRITIP: Natural vs. Synthetic E
10. Don’t forget your flax
Flaxseeds contain two cancer-preventive compounds: omega 3 fatty acids and lignans, which may reduce the risk of breast cancer and colon cancer. Ground flaxseeds, because they contain both the fiber and the oil, have more potent anticancer properties than flax oil alone. Cancer researchers suggest 25 grams of ground flaxseeds a day. You can grind your own in a coffee grinder or purchase pre-ground flaxseed meal, which mixes well in smoothies or sprinkled like bran flakes over yogurt and cereal.
11. Drink less alcohol
Alcohol consumption slightly increases the risk of colorectal cancer, and the alcoholic beverage with the strongest link to colon cancer is beer. Beer is thought to contain nitrosamines, a carcinogen or pre-carcinogen that is activated in the intestines. Tannins are a carcinogenic compound that is found in red wine and some coffee and tea. While red wine is touted to have health-promoting properties, due to the natural phytonutrients that are found in the grape skin, you’re better off simply eating the grapes.
12. Eat other anti-cancer nutrients
Increasing several other daily nutrients can also lower your risk of cancer:
Vitamin D, which you get from exposure to sunshine (around 10 to 15 minutes a day) and from vitamin D-fortified milk and other foods, has anticancer properties. It suppresses angiogenesis, the formation of new blood vessels that nourish the growth of tumors. The rates of breast, prostate, and colon cancer are lower in climates that have the most sunshine. Low levels of vitamin D have been found in some people with colon cancer. Women whose diets are high in vitamin D have a lower risk of breast cancer.
This overlooked mineral is a potent antioxidant or scavenger of carcinogenic free radicals. Studies have shown a lower incidence of colon cancer in people taking selenium supplements in the range of 100 to 200 mcg a day. Studies have shown that persons who have lower levels of selenium in their blood are more likely to have colon polyps, and those with higher levels of selenium have much less of a chance of getting cancer. Selenium is most effective when taken along with foods or supplements that are high in vitamin E. Consider taking 100 mcg of selenium a day as a supplement. Best sources of selenium in food are fish (especially red snapper) lobster, shrimp, whole grains, and vegetables, depending on the selenium content of the soil they’re grown in. Other sources include: brown rice, cottage cheese, lambchops, chicken (white meat), sunflower seeds, and garlic.
These intestinal-friendly bacteria have been shown to have anti-cancer properties. They promote the growth of healthy bacteria in the colon and reduce the conversion of bile acids into carcinogens. Studies have shown that consuming dietary supplements of lactobacillus acidophilus greatly diminishes the level of colon enzymes that produce carcinogenic decomposition products from food. In studies on experimental animals, 75 percent of the animals tested showed slower tumor growth when fed yogurt containing live bacterial cultures.Populations such as the Finns who have a diet relatively high in fat but who also eat a lot of fiber and a lot of yogurt, have a relatively low incidence of colon cancer. In an experiment in which carcinogens were given to rats, the animals that were fed large amounts of lactobacillus acidophilus developed less colon cancer compared with those who were not given doses of these health-promoting bacteria. Take 1 to 2 teaspoons of live lactobacillus daily, the one that is in the refrigerated section of the nutrition store. This can be added to a smoothie or a shake. Or, eat yogurt with the L.A.C. (live active cultures) seal.
Whether or not garlic has health-promoting and anticancer properties is still controversial, but it’s possible that garlic may have some anti-cancer benefits. The Kyolic brand of garlic supplements seems to be the most thoroughly tested and the one that is often used in research studies.
Green tea has been shown to inhibit the growth of cancer cells, possibly because of a phytochemical it contains called “catechins.”
The top anti-cancer foods to help your body stay cancer-free!
- brussel sprouts
- green beans
- onions (red)
- sweet potatoes
- strawberries, organic
Dr. Sears, or Dr. Bill as his “little patients” call him, has been advising busy parents on how to raise healthier families for over 40 years. He received his medical training at Harvard Medical School’s Children’s Hospital in Boston and The Hospital for Sick Children in Toronto, the world’s largest children’s hospital, where he was associate ward chief of the newborn intensive care unit before serving as the chief of pediatrics at Toronto Western Hospital, a teaching hospital of the University of Toronto. He has served as a professor of pediatrics at the University of Toronto, University of South Carolina, University of Southern California School of Medicine, and University of California: Irvine. As a father of 8 children, he coached Little League sports for 20 years, and together with his wife Martha has written more than 40 best-selling books and countless articles on nutrition, parenting, and healthy aging. He serves as a health consultant for magazines, TV, radio and other media, and his AskDrSears.com website is one of the most popular health and parenting sites. Dr. Sears has appeared on over 100 television programs, including 20/20, Good Morning America, Oprah, Today, The View, and Dr. Phil, and was featured on the cover of TIME Magazine in May 2012. He is noted for his science-made-simple-and-fun approach to family health.