Introduction:
Colon cancer and cancer of the rectum usually begins as a small polyp. While most colon polyps are benign, some do become cancerous. Colon cancer symptoms may include a change in bowel habits or bleeding, but usually colon cancer strikes without symptoms. Some dietary supplements might reduce the risk of colon cancer. Limiting meat consumption and eating vegetables, legumes, fruit, whole gains, and fiber may reduce the risk of colon cancer. This and other research based prevention topics will be represented below.
Colorectal cancer screening:
Colorectal cancer screening ages 50-75: The U.S. Preventive Services Task Force recommends screening for colorectal cancer for all individuals 50-75 years old with either fecal occult blood testing every year, fecal occult blood testing every 3 years plus sigmoidoscopy every 5 years, or screening colonoscopy every 10 years (26).
Colorectal cancer screening ages 76-85: The routine screening for colorectal cancer among adults age 76-85 years is not recommended by the U.S. Preventive Services Task Force unless not previously screened and if benefit outweighs the risk. The rationale not to screen after age 75 is the fact that the benefit is not seen until 7 years later in clinical trials. (26)
Colorectal cancer screening ages 85 years and older: The U.S. Preventive Services Task Force recommends against screening for colorectal cancer since risk of mortality outweighs the benefits (26).
Since 2008, the American College of Radiology, the U.S. Multi-Society Task Force on Colorectal Cancer, and the American Cancer Society have also collectively favored testing with annual guaiac-based fecal occult blood test with 2 to 3 stool samples, annual fecal immunochemical test, or annual stool DNA test and if positive, perform flexible sigmoidoscopy (with insertion to 40 cm/splenic flexure every 5 years), colonoscopy every 10 years, double contrast barium enema every 5 years, and computed tomography colonography every 5 years (27).
According to the U.S. Preventive Services Task Force (USPSTF), the American College of Physicians, American Academy of Family Physicians, American College of Preventive Medicine, and Centers for Disease Control and Prevention have similar recommendations or have endorsed the USPSTF recommendation (26).
Calcium supplementation and colorectal polyps:
Calcium supplementation and recurrence of colorectal adenomas: Researchers reviewed 3 randomized controlled trials (1,485 patients) and found that calcium supplementation was associated with a significant 20% reduction in the risk of recurrence of colorectal adenomas, harmless tumors, compared with placebo. (1)
Calcium dose and recurrence of colon adenomas: In a meta-analysis by Carroll C., et al, 3 trials showed a reduction of recurrence of colon adenomas for subjects who took 1200 – 2000 mg per day of a calcium supplement, but no decrease in risk for those with advanced adenomas. Also as part of the meta-analysis, 2 trials were found by the author which showed no benefit of calcium in those without increased risk of colorectal cancer. (2)
Palacios C et al found that subjects with a median of 1180 mg per day of calcium whether from dietary calcium intake or calcium from supplements as opposed to a median of 1036 mg per day had less colorectal neoplasia. (29)
Household food may reduce colorectal adenomas:
Household food may reduce size and number of colorectal adenomas: Aged garlic extract (AGE) reduced the progression of colorectal adenomas, harmless growths in the colon. Participants (n=51) with colorectal adenomas received AGE either at a high dose (active group, 2.4 mL/d) or a low dose (control group, 0.16 mL/d). Findings show that adenoma size increased in the control group, but AGE significantly prevented development of adenomas (both size and number) after 12 months of high dose treatment. (3)
Household food associated with lower risk of colon cancer: In an investigation of 127 foods regularly used by the 41,387 Iowa women (aged 55-69 years) who were studied over a five-year period, only garlic was found to be associated with a statistically significant decrease in colon cancer. The beneficial effects of garlic proved better than fiber or other vegetables. (4)
Curcumin and colorectal cancer:
Curcumin and colorectal cancer prevention: A 15-week study conducted on mice found that curcumin supplementation may have chemopreventive properties against colorectal cancer. Curmurin at 0.1%, 0.2% or 0.5% in the diet of mice was examined. Compared with untreated mice, curcumin at a dietary amount of 0.2%-0.5%, reduced benign tumors by 39% and 40%, respectively. Dietary curcumin also partially restored suppressed hematocrit values (a measure of the percentage of red blood cells in whole blood). Traces of curcumin were detected in the plasma and tissues of the small intestine (between 39 and 240 nmol/g) for 2-8 hours after dosing. The researchers concluded, curcumin may have a benefical effect against cancer and recommend a daily dose of 1.6 grams of curcumin for possible benefits to be seen in humans. (5)
Curcumin and familial adenomatous polyposis: The combination of curcumin and quercetin appears to reduce the number and size of ileal and rectal adenomas in 5 patients with familial adenomatous polyposis without much toxicity. Patients received curcumin 480 mg and quercetin 20 mg orally 3 times a day. The number and size of polyps were assessed at baseline and after therapy. All 5 patients had a decreased polyp number and size from baseline after a mean of 6 months of treatment with curcumin and quercetin. The mean percent decrease in the number and size of polyps from baseline was 60.4% and 50.9%, respectively. Minimal adverse side effects and no laboratory abnormalities were noted. (6)
Diet and colon cancer:
Diet and colon cancer: The risk of colon cancer was found to be higher in individuals with a high meat consumption, a low legume consumption, and a high body mass compared to their low meat consumption, high legume consumption and low body mass counterparts in this 6 year prospective study examining 32,051 white participants. Compared to non-meat eaters, individuals eating meat at least 1 time per week had an 85% increased risk of colon cancer. Participants who ate red meat at least 1 time per week had a risk 1.9 times that of those who abstained from eating red meat. Those who ate white meat at least 1 time per week had a risk 3.2 times that of those who abstained from eating white meat. Legume consumption of >2 times/week compared to <1 time/week was associated with a 47% lower risk of colon cancer. Finally, a body mass index >25.6 kg/m2 was associated with a risk 2.63 times that of a body mass index less than 22.5 kg/m2. (7)
Red meat consumption and cancer:
Red meat has been found to be associated with various forms of cancer in this multisite case-control study of 11 cancer sites in Uruguay. High consumption of red meat was associated with an increased cancer risk of the oral cavity and pharynx (odds ratio [OR]= 3.65), esophagus (OR= 3.36), larynx (OR=2.91), stomach (OR= 2.19), colorectum (OR= 3.83), lung (OR= 2.17), breast (OR= 1.97), prostate (OR= 1.87), bladder (OR= 2.11) and kidney (OR= 2.72). Lamb was also associated with increased cancer risk. Eating a lot of processed meat was also linked to an increased risk of cancers of the esophagus (OR= 1.63), larynx (OR= 1.84), stomach (OR= 1.62), colorectum (OR= 2.15), lung (OR= 1.70) and breast (OR= 1.53). (8)
Frequency of red meat intake and risk of colon cancer and other cancers: It has long been suspected that red meat contributed to cancer risk in patients. According to a study conducted between 1983 and 1996 on patients with a red meat intake of at least 7 times per week, the incidence of cancers of the stomach, colon, rectum, pancreas, bladder, breast, endometrium, and ovaries was higher. Therefore, it suggested that the reduction of red meat in the diet might lower the risk factors for these types of cancers. Of note, cancer of the oral cavity, pharynx, esophagus, liver, gallbladder, larynx, kidney, thyroid, prostate, Hodgkin’s disease, non-Hodgkin’s lymphomas and multiple myeloma were not found to be associated with meat intake. Of note, the study found that there was no reduction in risk of any of the cancers mentioned above with meat intake. (9)
Dietary characteristics and colon cancer:
A prospective study of 35,215 Iowa women aged 55-59 years without a history of cancer examined the relationship between consumption of sucrose, meat, fat and reproductive factors to colon cancer incidence from 1986 to 1990. In this time, 212 incident or newly diagnosed cases were recorded. Factors found to be associated with increased risk of colon cancer were consumption of sucrose, height, and body mass index. Although other studies have indicated an increase in cancer with meat consumption, eating meat was not associated with colon cancer risk in this study. (10)
Milk protein and colon cancer:
The prevention of colon cancer by dietary consumption of 20g/100g whey protein or casein (protein found in cow’s milk) or Purina mouse food was studied in A/J mice. After 20 weeks of treatment, the whey protein-fed group had almost 3 times the number of plaque forming cells in the spleen (signalling an immune response) than did the casein-fed mice (although both values were substantially below normal). After 24 weeks, compared to either the casein or Purina diet mice, whey protein-fed mice had a lower number of new tumors. The tumor area was also less in the whey protein group in comparison to either the casein or Purina groups. There was no difference in body weight change among the dietary groups. In conclusion, whey protein diet appears to prevent the growth of colon tumors in mice. (11)
Vegetables, fruit, whole gains, fiber, and rectal cancer:
A study researching rectal cancer asked 952 people with rectal cancer and 1205 people without rectal cancer aged 30 to 79 years about their diet. Researchers used this information to examine which dietary factors and foods may be related to having a diagnosis of rectal cancer. Researchers found that 1) people who ate more than 5.5 servings of vegetables per day had 28% lower risk of rectal cancer when compared to people eating less than approximately two servings per day; 2) people who ate more than 3.5 servings of fruit per day had 27% lower risk of rectal cancer when compared to people eating less than approximately one serving per day; 3) people eating more than 3 servings of whole grains per day had 31% lower risk of rectal cancer when compared to people eating less than one-half of a serving of whole grains per day; 4) people who ate more than 34 grams of fiber per day had 46% lower risk of rectal cancer when compared to people eating less than 16 grams of fiber per day; and 5) people who ate more than 4.5 servings of refined grains (such as white bread, doughnuts, bakery goods, cookies and cakes) per day had 42% higher risk of rectal cancer when compared to people eating less than 1.5 servings of refined grains per day. In summary, having more vegetables, fruit, whole grains and fiber in the diet reduced the risk of rectal cancer in this study. Having more refined grains in the diet increased risk of rectal cancer in this study. (12)
Brassica vegetable consumption and cancer risk:
An extensive review of epidemiological studies published prior to 1996 reported that the majority (67%) of 87 case-control studies found an inverse association between some type of brassica vegetable intake (the broccoli family including cabbage, kale, broccoli, Brussels sprouts, and cauliflower) and cancer risk at various sites. For cabbage, broccoli, cauliflower, and Brussels sprouts, these percentages were 70, 56, 67, and 29%, respectively. The results of 7 cohort studies also showed an inverse relationship between brassica consumption and risk of cancer. The higher the consumption of brassica vegetables the lower the risk of cancer was noted. The inverse association appeared to be most consistent for cancers of the lung and digestive tract and least consistent for prostatic, endometrial, and ovarian cancer. In summary, a high consumption of brassica vegetables is associated with a decreased risk of cancer. (13)
Legume intake and colorectal cancer:
High consumption of legumes (beans, lentils) have been found to be associated with a decrease risk of various forms of cancer in a multisite case-control study of 11 cancer sites in Uruguay. Legume consumption and risk of various cancer were analyzed in 3,539 cancer cases and 2,032 cancer-free individuals. Comparing those who ate the most legumes (top 33%) against those who ate the least legumes (bottom 33%), high consumption of legumes was associated with a significant decrease in cancer risk of the oral cavity and pharynx (52% risk reduction), esophagus (46% risk reduction), larynx (45% risk reduction), upper aerodigestive tract (50% risk reduction, stomach (31% risk reduction), colorectum (57% risk reduction), kidney (59% risk reduction), and all sites combined (32% risk reduction). However, no significant association was found between legume consumption and risk of cancer of the lung, breast, prostate or bladder. (14)
Green tea and colorectal cancer:
Amount of green tea consumption and risk of colorectal cancer: Researchers conducted an extensive large population-based case-control study in Shanghai, China in order to see whether green tea consumption had any impact on cancers of the colons, rectum, and pancreas. The research team found that the greater the consumption of green tea, the lesser the risk of cancer. Odds ratios were used with 95% confidence intervals to determine odds of developing various cancers with consumption of green tea. Compared to non-regular tea drinker, men consuming at least 300 g/month experienced reductions in their odds of developing colon cancer, rectal cancer, and pancreatic cancer by 18%, 28%, and 37%, respectively. For women, the respective reductions in the odds of those consuming at least 200 g/month were 33%, 43%, and 47%. As a result, it appears that green tea may, in fact, lower the odds of developing both colorectal and pancreatic cancers. (15)
Women, green tea and colon cancer risk: Middle age and older women who drink 3 or more cups of mostly green tea each week have lower risk of colon, esophagus and other digestive system cancers, suggests this large study conducted among 70,000 Chinese women. Study researchers gathered data on tea drinking and other lifestyle habits when the women entered the study, at ages 40 to 70, and every two to three years thereafter. In the study about 28 percent of women were regular tea drinkers, defined as drinking at least 3 cups of tea a week for at least 6 months. After 11 years, researchers found that regular tea drinkers had a 14% reduced risk of all digestive system cancers combined, compared to non-tea drinkers. Drinking two to three cups daily – as opposed to three cups weekly – reduced their risk even more: 21%. This large prospective cohort study found that tea consumption was associated with reduced risk of colorectal and stomach/esophageal cancers in Chinese women. (16)
Coffee consumption and colorectal cancer:
Coffee consumption and colorectal cancer risk: In this meta-analysis, authors identified 25 case–control and 16 cohort studies related to coffee consumption and colorectal cancer risk. Results from case–control studies comparing the highest versus the lowest/non category of coffee consumption showed a significant reduction in colorectal cancer (15% risk reduction) and colon cancer (21% risk reduction), but not rectal cancer (5% risk reduction). For cohort studies, risk of colorectal cancer, colon cancer, and rectal cancer were reduced by 6%, 7%, and 2%, respectively. In subgroup analyses using case–control studies, significant inverse associations were found in females for colorectal cancer and in Europe for colorectal and colon cancer, while the subgroup analyses of cohort studies found that coffee drinks substantially decreased risk of colon cancer only in Asian women. (17)
Women, coffee consumption, and colon cancer risk: An analysis of 96,162 subjects (46,023 men and 50,139 women) found that the higher the amount of coffee consumption, the lower the risk of developing colon cancer. Specifically, women drinking 3 or more cups of coffee a day were found to have half the risk of developing colon cancer (but not rectal cancer) compared with those who drank no coffee at all. No benefit in terms of colon cancer risk reduction, however, was found in men. (18)
Resveratrol and colon cancer:
The relationship between resveratrol, a chemopreventive compound (found in the skin of red grapes, red wine, berries, peanuts, and other food products) and colon cancer was analyzed by Juan, ME et al. Studies conducted in vitro (in an artificial environment such as a petri dish) showed that protective activity takes place by prevention of proliferation and the initiation of cell death (apoptosis). In animal models of colon carcinogenesis, the process by which normal cells are transformed into cancer cells, resveratrol not only reduced the number of lesions before the formation of a tumor but also reduced the risk of developing new tumors and the multiplicity of tumors. Current findings suggest that oral administration of resveratrol may contribute to the prevention of colon cancer. (19)
Indian gooseberry and cancer:
Scientists tested the anti-cancer effects of Phyllanthus emblica (PE), Indian gooseberry known for its medicinal properties. In a series of experiments on mice and on human cancer cell lines, they found that an extract of PE may help slow tumor growth and promote apoptosis (a type of programmed cell death essential for stopping the proliferation of cancer cells). PE extract at 50-100 microg/mL significantly inhibited cell growth of six human cancer cell lines: lung, liver, cervical, breast, ovarian and colorectal. Additionally, researchers saw a 50% reduction of tumor numbers and volumes in mice treated with PE extract. PE extract at 25 and 50 micrograms/mL was also shown to inhibit invasiveness of breast cancer cells. These results suggest PE has anti-cancer properties against certain cancer cells. (20)
Folic acid and colorectal adenoma:
Folic acid (FA) supplementation (1 mg/d) in healthy individuals (aged 50 and older) may reduce the risk ratios of colorectal adenoma (CRA) or harmless growths in the colon. In this study, at the end of a 3-year follow-up period, 14.88% of participants taking FA had developed CRA, compared to 30.70% in the placebo group. Compared to placebo, the FA group had a 46% reduced risk ratio of left-side adenoma and 64% reduced risk ratio for advanced CRA. Additionally, participants with low levels of folate may be at higher risk of CRA. (21)
Vitamins A, C, and E decreased recurrence of colon cancers:
Antioxidant vitamins A, C, and E were found to lower the recurrence rate of cancers of the colon. Individuals (n=255) with a history of colonic adenoma were randomized to receive treatment with either (1) vitamin A (30,000 IU per day), vitamin C (1 gram per day), and vitamin E (70 mg per day); (2) lactulose; or (3) placebo for an average of 18 months. At the end of the treatment period, adenoma recurrence had occurred in 5.7% of the antioxidant vitamin group compared to 14.7% in the lactulose group and 35.9% in the placebo group. (22)
Vitamin D and colorectal cancer:
Bischoff-Ferrari, HA et al made several strong points favoring a role of optimal levels of vitamin D in prevention of colorectal cancer. After reviewing studies, the authors stated that colon cancer incidence increases with further distances from the equator and a lower risk of colon cancer or colon adenomas occurs with higher 25-hydroxyvitamin D levels. Bischoff-Ferrari, HA et al stated that most vitamin D supplementation trials have resulted in inverse relationship of vitamin D supplements to colorectal cancer, and optimal 25-hydroxyvitamin D levels correlated with reduced colon mucosa proliferation. The author’s review of research also concluded that colon cancer cells also became less aggressive after exposed to vitamin D3 or 25-hydroxyvitamin D in vitro. The authors found the optimal level of vitamin D for all the health factors examined to start at 75 nmol/L (30 ng/mL), and the best was between 90 and 100 nmol/L (36-40 ng/mL). Based on this literature review, the authors suggest that the current intake of vitamin D for adults (200 to 600 IU) is insufficient to achieve optimal health outcomes. Among adults an intake of 1000 IU daily or greater is needed to achieve the optimal level of vitamin D. (23)
Glucosamine, chondroitin and colorectal cancer:
The authors of a study examined associations of various herbal and specialty supplements with lung and colorectal cancer risk in men and women age 50 to 76 years old. They found that any use of glucosamine and chondroitin, which have anti-inflammatory properties, over the previous 10 years, the chance of lung cancer occurring was 26% less for glucosamine and 28% less for chondroitin. The chance of colorectal cancer occurring was 27% less for glucosamine and 35% less for chondroitin. Other supplements that reduced the odds of colorectal cancer included fish oil (35% less chance of occurrence), methylsulfonylmethane (54% less chance of occurrence), and St. John’s wort (65% less chance of occurrence). In contrast, garlic pills were associated with a statistically significant 35% higher chance of colorectal cancer occurrence. (24)
Aspirin and NSAIDs for prevention of colorectal cancer:
To prevent colorectal cancer in individuals at average risk for colorectal cancer the U.S. Preventive Services Task Force (USPSTF) recommends against the routing use of aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs). According to the USPSTF, aspirin is required in higher doses than cardiovascular and ischemic stroke prevention. The higher doses of aspirin and NSAIDs required to prevent polyps and colorectal cancer poses a risk of severe bleeding episodes. Therefore, the USPSTF has determined that the risk of hemorrhagic stroke with aspirin outweighs the benefit of colorectal cancer prevention. The risk of gastrointestinal bleeding and hemorrhage with NSAIDs outweigh the benefits of colorectal cancer prevention. (25)
Bardia A et al did however determine as part of a cohort study that cancer incidence and cancer mortality was reduced even in patients that used aspirin infrequently compared to those that never used it. In that study, women with the lowest all-cause mortality took aspirin 2-5 times per week. There was no statistically significant impact on cancer incidence or mortality among women who used non-aspirin NSAIDs, compared to those who did not. (28)
The safest approach is that aspirin should not be used specifically for cancer prevention, but if aspirin is used for cardiovascular disease prevention, there may be a small added benefit of cancer prevention.
Assessment and Plan: Colorectal Cancer, Adenocarcinoma of the Colon, Rectal Cancer, Colon Cancer, Colon Polyps
- Colorectal cancer screening:
- Ages 50-75: The U.S. Preventive Services Task Force recommends screening for colorectal cancer for all individuals 50-75 years old with either fecal occult blood testing every year, fecal occult blood testing every 3 years plus sigmoidoscopy every 5 years, or screening colonoscopy every 10 years (26).
- Ages 76-85: The routine screening for colorectal cancer among adults age 76-85 years is not recommended by the U.S. Preventive Services Task Force unless not previously screened and if benefit outweighs the risk. The rationale not to screen after age 75 is the fact that the benefit is not seen until 7 years later in clinical trials. (26)
- Ages 85 years and older: The U.S. Preventive Services Task Force recommends against screening for colorectal cancer since risk of mortality outweighs the benefits (26).
- Recommendations by other organizations for colorectal cancer screening:
- Since 2008, the American College of Radiology, the U.S. Multi-Society Task Force on Colorectal Cancer, and the American Cancer Society have collectively favored testing with annual guaiac-based fecal occult blood test with 2 to 3 stool samples, annual fecal immunochemical test, or annual stool DNA test and if positive, perform flexible sigmoidoscopy (with insertion to 40 cm/splenic flexure every 5 years), colonoscopy every 10 years, double contrast barium enema every 5 years, and computed tomography colonography every 5 years (27).
- According to the U.S. Preventive Services Task Force (USPSTF), the American College of Physicians, American Academy of Family Physicians, American College of Preventive Medicine, and Centers for Disease Control and Prevention have similar recommendations or have endorsed the USPSTF recommendation (26).
- There are especially strong genetic links seen between family members with colorectal cancer (30), and therefore enhanced efforts of prevention may be warranted in those with family history.
- Calcium and colon cancer:
- Preventive Health advisor supports adequate, but not excessive intakes of calcium from food sources rather than supplements since high calcium intakes from supplements, and sometimes food, were associated with a higher risk of coronary artery disease and a higher risk of prostate cancer in men (32-34). See calcium section for further information.
- Shaukat, A et al found that calcium supplementation was associated with a significant 20% reduction in the risk of recurrence of colorectal adenomas compared with placebo (1).
- Carroll, C. et al, described 3 trials showing a reduction of recurrence of colon adenomas at a calcium dose of 1200–2000 mg per day, but no decrease in risk for those with advanced adenomas was seen, and the same author also mentioned 2 trials which showed that no benefit of calcium was seen in those without increased risk of colorectal cancer (2).
- Palacios C et al found that subjects with a median of 1180 mg per day of calcium whether from dietary calcium intake or calcium from supplements was higher than patients with colorectal neoplasia who had a median calcium intake of 1036 mg per day (29).
- Therefore, calcium intakes higher than about 1180 mg per day whether from dietary calcium intake or calcium from supplements may reduce the risk of colorectal neoplasia and the recurrence of colorectal adenomas (1,2,29).
- Ensure good nutritional status with calcium and vitamin D. Lappe JM et al concluded that improvement of nutritional status with calcium and vitamin D significantly lowered cancer risk in post-menopausal women. (31)
- Obtain the recommended calcium intake from food sources and adequate vitamin D intake from foods, supplements or sun exposure. To see concentrations of calcium in foods, please see:: http://www.iom.edu/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D/DRI-Values.aspx
To research calcium contained in foods click here: https://www.ars.usda.gov/SP2UserFiles/Place/12354500/Data/SR25/nutrlist/sr25w301.pdf
- Vitamin D and colon cancer:
- Preventive Health advisor recommends periodic check of vitamin D level for patients suspected of vitamin D deficiency, insufficiency or suboptimal levels for colon cancer prevention which is assessed by physicians using a blood test for the concentration of the compound 25(OH)D.
- Moore et al found as of 2007 that neither children nor adults in the US were obtaining the RDA for vitamin D (39).
- Bischoff-Ferrari, HA et al made several strong points favoring a role of optimal levels of vitamin D in prevention of colorectal cancer (23):
- Colon cancer incidence increases with further distances from the equator and a lower risk of colon cancer or colon adenomas occurs with higher 25-hydroxyvitamin D levels.
- Most vitamin D supplementation trials have resulted in inverse relationship of vitamin D supplements to colorectal cancer, and optimal 25-hydroxyvitamin D levels correlated with reduced colon mucosa proliferation.
- Colon cancer cells became less aggressive after exposed to vitamin D3 or 25-hydroxyvitamin D in vitro.
- The authors found the optimal level of vitamin D for all the health factors examined to start at 75 nmol/L (30 ng/mL), and the best was between 90 and 100 nmol/L (36-40 ng/mL).
- Michaëlsson K et al found that a vitamin D level of 24 to 34 ng/ml (60 to 85 nmol/L) approximately translates to a vitamin D dose of 2000 IU/d and corresponded to the lowest cardiovascular-related, cancer-related, and all-cause mortality (37).
- Vieth reported that the ideal level of vitamin D intake for adults should be 50 mg (2000 IU) per day (35).
- Bosomworth NJ conducted a review of multiple studies, and determined that 500-1500 IU/d of vitamin D reduced cancer mortality and all-cause mortality (36).
- To see concentrations of vitamin D in foods, please see: Nutritive Value of Foods, United States Department of Agriculture, Agricultural Research Service, Home and Garden Bulletin Number 72. May be accessed at: https://www.ars.usda.gov/SP2UserFiles/Place/12354500/Data/SR25/nutrlist/sr25w324.pdf and http://www.nal.usda.gov/fnic/foodcomp/Data/HG72/hg72_2002.pdf
- See the section on vitamin D for further information.
- Garlic:
- Aged garlic extract reduced the size and number of colorectal adenomas at a dose of 2.4 mL daily compared to control group after 12 months (3).
- Researchers looked at 127 foods regularly used by 41,387 Iowa women age 55-69 years found that garlic was associated with a statistically significant decrease in colon cancer and proved better than fiber or other vegetables (4).
- Curcumin (active compound in turmeric):
- In mice, curcumin at a dietary amount of 0.2%-0.5%, reduced benign tumors by 39% and 40%, respectively, so researchers extrapolated an equivalent dose recommendation for humans and a daily dose of 1.6 grams of curcumin, believed by the authors to offer potential benefit (5).
- A small study on patients with familial adenomatous polyposis were given curcumin 480 mg and quercetin 20 mg orally 3 times daily, and all 5 patients in the study had a decreased polyp number and size from baseline after a mean of 6 months of treatment with a mean percent decrease in the number and size of polyps from baseline of 60.4% and 50.9%, respectively (6).
- Minimal adverse side effects from curcumin and no laboratory abnormalities were noted. (6).
- See section on turmeric/curcumin for further information.
- Diet and colon cancer:
- Risk of colon cancer according to Singh and Fraser (7):
- Risk of colon cancer was higher in individuals with a consumption high in meat low in legumes, and with high body mass compared to consumption low in meat, high in legumes and with low body mass.
- Eating meat at least 1 time per week had an 85% higher risk of colon cancer than non-meat eaters
- Eating red meat at least 1 time per week had a risk 1.9 times higher than those who abstained from eating red meat.
- Eating white meat at least 1 time per week had a risk 3.2 times that of those who abstained from eating white meat.
- Legume consumption of >2 times/week compared to less than once per week was associated with a 47% lower risk of colon cancer.
- Finally, a body mass index >25.6 kg/m2 was associated with a risk 2.63 times that of a body mass index less than 22.5 kg/m2.
- A case-control study of 11 cancer sites in Uruguay found that high consumption of red meat was associated with an increased cancer risk of colorectal cancer (OR= 3.83) (8).
- Red meat intake of at least 7 times per week resulted in higher incidence of cancers of the stomach, colon, rectum, pancreas, bladder, breast, endometrium, and ovaries (9).
- A study of 35,215 Iowa women aged 55-59 years without a history of cancer were followed until 212 of them developed colon cancer and factors found to be associated with increased risk of colon cancer were consumption of sucrose, height, and body mass index, but meat intake did not have an increased risk in this study (10).
- After mice were fed Purina, casein or whey protein for 24 weeks, and compared to either the casein or Purina diet mice, whey protein-fed mice had a lower number of new tumors (11).
- Slattery, ML et al found the following regarding colon cancer risk (12):
- Those that ate 5.5 servings of vegetables per day had 28% lower risk of rectal cancer when compared to people eating less than approximately two servings per day
- Those that ate more than 3.5 servings of fruit per day had 27% lower risk of rectal cancer when compared to people eating less than approximately one serving per day.
- Those that ate 3 servings of whole grains per day had 31% lower risk of rectal cancer when compared to people eating less than one-half of a serving of whole grains per day
- Those that ate more than 34 grams of fiber per day had 46% lower risk of rectal cancer when compared to people eating less than 16 grams of fiber per day
- Those that ate more than more than 4.5 servings of refined grains (such as white bread, doughnuts, bakery goods, cookies and cakes) daily had 42% higher risk of rectal cancer when compared to people eating less than 1.5 servings of refined grains per day.
- Verhoeven, DT et al found that most case-control studies found an inverse association between brassica vegetable intake (the broccoli family including cabbage, kale, broccoli, Brussels sprouts, and cauliflower) and a lower the risk of many cancers, but especially lung and digestive tract cancers (13).
- Comparing those who ate the most legumes (top 33%) against those who ate the least legumes (bottom 33%), high consumption of legumes was associated with a significant decrease in colorectal cancer risk (57% risk reduction) (14).
- Green tea and colon cancer:
- Men consuming at least 300 grams of green tea per month experienced reductions odds of developing colon cancer, rectal cancer, and pancreatic cancer in men by 18%, 28%, and 37%, respectively and women taking 200 grams of green tea per month had reduced odds of the same cancers by 33%, 43%, and 47% respectively compared to non-tea drinkers (15).
- Women age 40-70 who drank 3 or more cups of mostly green tea each week for 6 months were allowed in a study and after following for 11 years, they were noted to have 14% lower risk of colon, stomach and esophageal cancers, and 21% lower risk for 2-3 cups of green tea daily compared to non-tea drinkers (16).
- Coffee and colon cancer:
- The highest vs. the lowest category of coffee consumption showed a significant reduction in colon and colorectal cancer of 21% and 15% respectively (17).
- 96,162 subjects (46,023 men and 50,139 women) were evaluated for coffee consumption and it was found that women drinking 3 or more cups of coffee a day had half the risk of developing colon cancer (but not rectal cancer) compared with those who drank no coffee at all, but no benefit in colon cancer risk reduction was found in men (18).
- Resveratrol and colon cancer: Animal models of colon cancer found that resveratrol not only reduced the number of lesions before the formation of a tumor but also reduced the risk of developing new tumors and the multiplicity of tumors (19).
- Indian gooseberry, scientific name: Phyllanthus emblica, a.k.a. amla and colon cancer: Indian gooseberry extract at 50-100 microg/mL significantly inhibited cell growth of colorectal cancer cells in vitro (20). This is an agent likely safe in amounts used in Indian cooking, but requires further investigation in humans.
- Folic acid and colorectal adenomas: Over a 3 year study with healthy adults over age 50 who took folic acid at a dose of 1 mg daily for 3 years, 14.88% of participants taking folic acid developed colorectal adenomas vs. 30.70% in the placebo group and authors believed that those with low levels of folate may be at higher risk of colorectal adenomas (21).
- Vitamins A, C, and E and colonic adenoma: Subjects randomized to receive (1) vitamin A (30,000 IU per day), vitamin C (1 gram per day), and vitamin E (70 mg per day); (2) lactulose; or (3) placebo for 18 months were found to have a reduced adenoma recurrence of 5.7% of the vitamin group compared to 14.7% in the lactulose group and 35.9% in the placebo group (22).
- Glucosamine, chondroitin, fish oil, methylsulfonylmethane, St John’s wort, and colorectal cancer: Use of glucosamine and chondroitin over the previous 10 years appeared to reduce the risk of colorectal cancer occurring by 27% less for glucosamine, 35% less for chondroitin, 35% for fish oil, 54% less for methylsulfonylmethane, 65% less for St. John’s wort, but garlic pills appeared to have a 35% higher risk colorectal cancer occurrence (24).
- Aspirin, nonsteroidal anti-inflammatory drugs, (NSAIDs) and colon cancer:
- The Preventive Services Task Force (USPSTF) and most physicians do not recommend aspirin solely for colorectal cancer prevention because higher doses than those used for cardiovascular disease/stroke prevention are required to accomplish this goal. The risk of gastrointestinal bleeding with and aspirin outweigh the benefits of colorectal cancer prevention. (25)
- Bardia A et al however determined as part of a cohort study that cancer incidence and cancer mortality was reduced even in patients that used aspirin infrequently compared to those that never used it. In that study, women with the lowest all-cause mortality took aspirin 2-5 times per week. There was no statistically significant impact on cancer incidence or mortality among women who used non-aspirin NSAIDs, compared to those who did not. (28)
- The safest approach is that aspirin should not be used specifically for cancer prevention, but if aspirin is used for cardiovascular disease/stroke prevention, there may be a small added benefit of cancer prevention.
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