Foods That Fight Cancer™
The blueberry is one of the few fruits native to North America. Native Americans used the berries and parts of the plant for medicine. Today, blueberries have a rockstar reputation among fruits; one popular claim is that blueberries help reduce age-related memory loss. It's too early to know whether that's true, but we do know they contain powerful phytochemicals called anthocyanins, which give these berries their blue color.
What's in Blueberries?
Blueberries are an excellent source of vitamins C and K, manganese and a good source of dietary fiber. Blueberries are among the fruits highest in antioxidant power, largely due to their many phytochemicals:
- Anthocyanins, catechins, quercetin, kaempferol and other flavonoids
- Ellagitannins and ellagic acid
- Pterostilbene and resveratrol
Full Glossary for Foods That Fight Cancer
The Cancer Research
Blueberries contain numerous phytochemicals and nutrients, many of which are well studied in the laboratory. They also contain dietary fiber, which can act in several ways to lower cancer risk, including helping with weight control. Excess body fat increases the risk of seven different cancers, and dietary fiber can increase the feeling of fullness.
What Current Evidence Shows: AICR/WCRF Expert Report and its Updates (CUP)
Blueberries are fruits that contain dietary fiber. After a systematic review of the global scientific literature, AICR/WCRF weighed the strength of the evidence linking these factors to lower risk for several cancers.
|Diets high in:||CONVINCINGLY lower risk of the following cancers:|
|Foods containing dietary fiber||Colorectum|
|Diets high in:||PROBABLY lower risk of the following cancers:|
|Fruits||Mouth, Pharynx, Larynx
Source: Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective and the 2011 Continuous Update Project (CUP): Colorectal Cancer.
”…the more you look at these foods, the more you see what a complex mixture of protective compounds they have.”
- Karen Collins, MS, RD, CDN.
Open Areas of Investigation: Laboratory Research
Laboratory research is extensive on blueberry compounds such as flavonoids and ellagic acid.
- Vitamin C protects cells’ DNA by trapping free radicals and inhibiting formation of carcinogens.
- In cell studies, blueberry extract and anthocyanins, as well as ellagic acid and the urolithins that form from it, decrease free radical damage to DNA that can lead to cancer. They also decrease growth and stimulate self-destruction of mouth, breast, colon and prostate cancer cells.
- In animal studies, blueberries decrease inflammatory cytokines, esophageal cancer and pre-cancerous changes in the colon, although impact on colon cancer is less clear. In other animal studies, blueberries decrease estrogen-induced mammary cancer and DNA damage.
- Pterostilbene increases self-destruction of lung, stomach, pancreatic and breast cancer cells. In an animal study, it also decreased formation of pre-cancerous colon polyps and reduced markers of inflammation.
- Dietary fiber reduces cells’ exposure to cancer-causing substances, and healthful gut bacteria use it to produce short-chain fatty acids that protect colon cells.
Open Areas of Investigation: Human Studies
Most human studies look at overall fruit consumption. Comparing people with and without cancer, the studies show lower risk of several cancers in those who eat more fruits compared to those who eat relatively few.
Studies are not clear about how well we absorb anthocyanins and ellagic acid from the digestive tract. Several studies show that eating blueberries increases antioxidant activity in the blood, although results vary and the studies do not show consistent signs of preventing DNA damage.
Bacteria in our colon convert the ellagitannins and ellagic acid to urolithins, which can be absorbed and seem to offer antioxidant, anti-inflammatory and direct anti-cancer effects. In addition, unabsorbed compounds may exert protective effects inside the digestive tract. This research is ongoing.
In the Kitchen
- Choose firm, plump, dry blueberries with dusty blue color. Avoid berries that are soft, shriveled or with any sign of mold.
- Buy frozen blueberries too. These also are high in nutrients and antioxidant phytochemicals.
- Treat yourself to wild blueberries with even more antioxidant power than the more common cultivated blueberries.
- Refrigerate blueberries for up to 10 days.
- Wait to wash until ready to eat.
- Whirl blueberries alone or with other fruits into a smoothie or fruit freeze drink.
- Top cereal or yogurt with fresh or dried blueberries.
- Add blueberries to a green salad.
- Blueberries play well with other fruits! Alone or in combinations, enjoy them in muffins, pancakes, and fruit crumble or crisp desserts.
- Be creative with blueberries: try a blueberry quesadilla with wild blueberry sauce.
- U.S. Department of Agriculture, A.R.S., Oxygen Radical Absorbance Capacity (ORAC) of Selected Foods, Release 2. 2010.
- Wolfe, K.L., et al., Cellular antioxidant activity of common fruits. Journal of agricultural and food chemistry, 2008. 56(18): p. 8418-26.
- Borges, G., et al., Identification of flavonoid and phenolic antioxidants in black currants, blueberries, raspberries, red currants, and cranberries. Journal of agricultural and food chemistry, 2010. 58(7): p. 3901-9.
- World Cancer Research Fund / American Institute for Cancer Research, Food, Nutrition, Physical Activity and the Prevention of Cancer: a Global Perspective, 2007: Washington, DC. p. 82-113.
- Adams, L.S., et al., Blueberry phytochemicals inhibit growth and metastatic potential of MDA-MB-231 breast cancer cells through modulation of the phosphatidylinositol 3-kinase pathway. Cancer research, 2010. 70(9): p. 3594-605.
- Faria, A., et al., Blueberry anthocyanins and pyruvic acid adducts: anticancer properties in breast cancer cell lines.Phytotherapy research : PTR, 2010. 24(12): p. 1862-9.
- Seeram, N.P., et al., Blackberry, black raspberry, blueberry, cranberry, red raspberry, and strawberry extracts inhibit growth and stimulate apoptosis of human cancer cells in vitro. Journal of agricultural and food chemistry, 2006. 54(25): p. 9329-39.
- Boateng, J., et al., Selected fruits reduce azoxymethane (AOM)-induced aberrant crypt foci (ACF) in Fisher 344 male rats. Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 2007. 45(5): p. 725-32.
- Simmen, F.A., et al., Lack of efficacy of blueberry in nutritional prevention of azoxymethane-initiated cancers of rat small intestine and colon. BMC gastroenterology, 2009. 9: p. 67.
- Stoner, G.D., et al., Multiple berry types prevent N-nitrosomethylbenzylamine-induced esophageal cancer in rats. Pharmaceutical research, 2010. 27(6): p. 1138-45.
- Wang, L.S., et al., Berry ellagitannins may not be sufficient for prevention of tumors in the rodent esophagus. Journal of agricultural and food chemistry, 2010. 58(7): p. 3992-5.
- Aiyer, H.S. and R.C. Gupta, Berries and ellagic acid prevent estrogen-induced mammary tumorigenesis by modulating enzymes of estrogen metabolism. Cancer prevention research, 2010. 3(6): p. 727-37.
- Aiyer, H.S., S. Kichambare, and R.C. Gupta, Prevention of oxidative DNA damage by bioactive berry components. Nutrition and cancer, 2008. 60 Suppl 1: p. 36-42.
- Alosi, J.A., et al., Pterostilbene inhibits breast cancer in vitro through mitochondrial depolarization and induction of caspase-dependent apoptosis. The Journal of surgical research, 2010. 161(2): p. 195-201.
- Mannal, P.W., et al., Pterostilbene inhibits pancreatic cancer in vitro. Journal of gastrointestinal surgery : official journal of the Society for Surgery of the Alimentary Tract, 2010. 14(5): p. 873-9.
- Pan, M.H., et al., Pterostilbene induces apoptosis and cell cycle arrest in human gastric carcinoma cells. Journal of agricultural and food chemistry, 2007. 55(19): p. 7777-85.
- Schneider, J.G., et al., Pterostilbene inhibits lung cancer through induction of apoptosis. The Journal of surgical research, 2010. 161(1): p. 18-22.
- Mannal, P., D. McDonald, and D. McFadden, Pterostilbene and tamoxifen show an additive effect against breast cancer in vitro. American journal of surgery, 2010. 200(5): p. 577-80.
- Paul, S., et al., Dietary intake of pterostilbene, a constituent of blueberries, inhibits the beta-catenin/p65 downstream signaling pathway and colon carcinogenesis in rats. Carcinogenesis, 2010. 31(7): p. 1272-8.
- Stoner, G.D., L.S. Wang, and B.C. Casto, Laboratory and clinical studies of cancer chemoprevention by antioxidants in berries. Carcinogenesis, 2008. 29(9): p. 1665-74.
- Stoner, G.D., et al., Cancer prevention with freeze-dried berries and berry components. Seminars in cancer biology, 2007. 17(5): p. 403-10.
- Mazza, G., et al., Absorption of anthocyanins from blueberries and serum antioxidant status in human subjects. Journal of agricultural and food chemistry, 2002. 50(26): p. 7731-7.
- Kay, C.D. and B.J. Holub, The effect of wild blueberry (Vaccinium angustifolium) consumption on postprandial serum antioxidant status in human subjects. The British journal of nutrition, 2002. 88(4): p. 389-98.
- Prior, R.L., et al., Plasma antioxidant capacity changes following a meal as a measure of the ability of a food to alter in vivo antioxidant status. Journal of the American College of Nutrition, 2007. 26(2): p. 170-81.
- Wilms, L.C., et al., Impact of multiple genetic polymorphisms on effects of a 4-week blueberry juice intervention on ex vivo induced lymphocytic DNA damage in human volunteers. Carcinogenesis, 2007. 28(8): p. 1800-6.
- Serafini, M., et al., Antioxidant activity of blueberry fruit is impaired by association with milk. Free radical biology & medicine, 2009. 46(6): p. 769-74.
- González-Sarrías, A., et al., NF-kappaB-dependent anti-inflammatory activity of urolithins, gut microbiota ellagic acid-derived metabolites, in human colonic fibroblasts. The British journal of nutrition, 2010. 104(4): p. 503-12.
- Cerdá, B., F. Tomás-Barberán, and J. Espín, Metabolism of antioxidant and chemopreventive ellagitannins from strawberries, raspberries, walnuts, and oak-aged wine in humans: identification of biomarkers and individual variability. Journal of agricultural and food chemistry, 2005. 53(2): p. 227-35.
Blueberry Quesadilla with Wild Blueberry Sauce
- One bag (10 oz.) frozen blueberries, preferably wild
- 1/2 Fuji apple, peeled, cored and finely chopped
- 1/4 cup sugar
- 1/2 teaspoon ground cinnamon
- 4 Tbsp. blueberry fruit spread
- 4 (8-inch) whole-wheat tortillas
- 1 cup (2 oz.) shredded part-skim milk mozzarella cheese
- 1 cup (8 oz.) part-skim milk ricotta cheese
- Grated zest of 1 lemon
- 2 Tbsp. dried blueberries
In medium saucepan, combine frozen berries, apple, sugar and cinnamon. Cover, bring to boil over medium-high heat, reduce heat and simmer until fruit is soft, 10 minutes. Set Wild Blueberry Sauce aside. Makes 2 cups.
On work surface, spread 1 tablespoon of blueberry spread to cover each tortilla, leaving 1/2-inch border all around. In bowl, combine mozzarella and ricotta cheeses with zest. Spread 1/2 cup of cheese mixture over half of each tortilla. Sprinkle dried blueberries over mixture, then fold the tortilla over to enclose the filling.
Heat griddle or large, heavy skillet over medium-high heat. Add quesadillas and cook until crisp and lightly browned on bottom, 3 minutes. Turn and crisp on second side, 2-3 minutes.
To serve, place a quesadilla on each of 4 plates and top with 1/4 cup of warm sauce. The remaining sauce keeps, covered in the refrigerator, for five days.
Makes 4 servings.
Per serving: 400 calories, 9 g total fat (5 g saturated fat), 67 g carbohydrate, 15 g protein, 6 g dietary fiber, 420 mg sodium.
Below are answers to some of the most frequently asked questions we get asked.
Which fruits and vegetables should I be eating?
Eat as many different vegetables and fruits as you can. Variety is the key to obtaining the many protective phytochemicals. Each vegetable and fruit has its own profile of health-promoting substances.
The phytochemicals found in cantaloupe are different from those in broccoli or leeks or cherries. Try to include a lot of colors on your plate. Aim to eat some bright red, green, orange, blue, purple and yellow vegetables and fruits each day.
Should I buy organic foods whenever possible?
There are many reasons to eat organic foods, but currently, there is no convincing evidence that shows a difference between organic and conventionally grown foods related to cancer risk. Studies show pesticide residues on conventionally grown foods are almost always within safety tolerance limits.
If you are concerned about pesticide residues and can afford to spend more, organic produce may be a choice for you. Eating generous servings of a large variety of veggies and fruits - whether organic or not will benefit your health. The advantages of including more vegetables and fruits in your diet outweigh the potential risks from pesticides.
Can grilled meats really cause cancer?
Lab studies show that exposing meats to direct flame, smoke and intense heat (like when you grill or broil) can cause the formation of carcinogens (cancer-causing substances). Cooking methods that involve less heat, such as microwaving, baking, steaming and poaching, do not promote the formation of these substances.
Several strategies you can use to cut carcinogen formation on meat include marinating, flipping frequently, removing excess fat from meat before cooking, and microwaving for part of the cooking time. So for delicious and healthful options, try grilling vegetables, veggie burgers and fruit slices and cut down on meat, fish and poultry.