Preventing Adenomas / Colorectal Cancer: Folic Acid Wouldn’t Help to Patients with History of Polyps
Cancer of the colon or rectum is the third most common cancer. It causes thousands of deaths each year. If the disease is found early, it is much easier to cure. Screening tests are very important. Roughly 57,000 people die annually from colorectal cancer, the second leading cause of cancer death in America, but the American Cancer Society estimates that with colon screenings as many as half of those deaths could be eliminated.
Colorectal cancer develops in the digestive system, which processes food for energy and rids the body of solid waste. Together, the colon and rectum form a muscular tube about 5 feet long known as the large intestine. The colon (the first and largest part of the large intestine) absorbs water and nutrients from food and serves as a storage place for solid waste. The waste moves from the colon into the rectum (the final 6 inches of the large intestine) where it passes out of the body through the anus. Cancers affecting either of these organs are called colorectal cancer.
Many colorectal cancers are thought to arise from adenomatous polyps in the colon. These mushroom-like growths are usually benign, but some may develop into cancer over time.Routine medical care can help prevent disease and save lives.Screening guidelines for identification and control of risk factors and early detection of diseases and are working to promote these unified guidelines to physicians:
Men & Women:
- Blood pressure measurement:
- Starting at age 20, each regular healthcare visit, at least every two years
- Body Mass Index (BMI) measurement:
- Starting at age 20, each regular healthcare visit
- Blood cholesterol test:
- Starting at age 20, at least every five years
When colon cancers are detected and treated at an early state (and have not spread beyond the colon or rectum) they are cured in 90% of all cases! The American Cancer Society recommends that beginning at age 50 men and women should follow one of these five testing options:
Adult men should have their weight, cholesterol levels and blood pressure checked. Men older than 50 should be tested for colorectal cancer. If your doctor orders this test, it does not mean he or she thinks you have cancer. This is a routine test that everyone should have. Your doctor will also make sure you have all the shots you need.
Evidence suggests a link between colorectal cancer and dietary folate intake and folate status . One study reported that women who take multivitamin supplements containing folic acid for prolonged periods have a significantly reduced risk of colorectal cancer .Currently however, the scientific evidence is not sufficiently clear for recommending increased folate intake in populations at risk for colorectal cancer.
Population-based studies have found that colorectal cancer is less common among individuals with very high dietary intakes of folic acid. The reverse appears to be true as well: low folic acid intake increases risk of colorectal tumors. To have a significant effect on reducing the risk of colorectal cancer, it appears that at least 400 mcg of folic acid per day over the course of at least 15 years is required. Similarly, many clinicians recommend folic acid supplementation to people who are at high risk for colon cancer (for example, people with a strong family history of colon cancer).
Supplemental folic acid might increase seizures in people with seizure disorders, particularly in very high doses. Doses less than 1,000 micrograms have rarely been associated with increased seizure activity.
Research suggested that getting adequate amounts of the B vitamin folate or folic acid — the synthetic form of the vitamin — can help reduce your risk of colorectal cancer. Even people with a family history of the disease may be able to lower their risk by limiting alcohol consumption and taking 400 micrograms of folic acid daily.
But most recently researchers suggesting that not only won't folic acid prevent colorectal cancer in people with a history of colon polyps, new research suggests that the vitamin supplement may actually help those cancers grow.
Three years after taking one milligram of folic acid daily, those with a history of polyps had a 32 percent higher risk of having an advanced adenoma (polyp) compared to the group taking a placebo pill daily, researchers are reporting. An advanced adenoma indicates that a polyp has undergone pre-cancerous changes in its cells that may later develop into colon cancer.
"We found that folic acid supplements were not useful for preventing adenomas and that this population tended to do worse on folic acid, which was a surprise," said the study's lead author, Bernard Cole, an associate professor of community and family medicine at Dartmouth Medical School.The findings are published in the Journal of the American Medical Association.
Each year, about 145,000 Americans are diagnosed with colorectal cancer, according to the U.S. Centers for Disease Control and Prevention, and about 56,000 die annually from the disease.
Previous observational studies had indicated that folic acid might be effective at decreasing colon cancer, and the polyps that eventually develop into the disease, because people with low levels of folate -- the natural form of folic acid, a B vitamin -- were more likely to develop colon cancer and polyps, Cole explained.
To better assess folic acid's cancer-prevention ability, Cole and his colleagues designed a double-blind, placebo-controlled, randomized trial that included slightly more than 1,000 adults who had a history of recent adenomas. Their adenomas had been removed during a colonoscopy prior to the start of the study.
Half the participants were randomly selected to take 1 milligram of folic acid daily for the duration of the study, while the rest were given a placebo. The daily recommended amount of folic acid is 400 micrograms, less than half that given to the study participants, according to the National Institutes of Health. Pregnant women are advised to get 600 micrograms daily, because folic acid has been shown to reduce birth defects.
The study volunteers underwent two more colonoscopies, one after three years and then another after an additional three to five years.
After the first round of colonoscopies, the researchers found that the incidence of at least one adenoma was 44.1 percent for those on folic acid and 42.4 percent for those taking the placebo. Of more concern was that those taking folic acid had a 32 percent higher risk of having an advanced adenoma than the placebo group.
Only 60 percent of the study participants underwent the second follow-up colonoscopy. But in those who did, 41.9 percent of those taking folic acid had at least one adenoma, compared to 37.2 percent of those taking a placebo. The risk of an advanced adenoma was 67 percent higher for the folic acid group.
The researchers found no significant effect on the results when they factored in sex, age, smoking history, aspirin use, alcohol use, body mass index, and average folate levels.
Cole said that while the results were surprising, other studies may offer an explanation. "Some of these studies have shown that folate seems to have a dual effect on cancer development. High levels of folate tend to prevent cancer if there's no cancer in the system. On the other hand, other studies suggest that folate may feed undetectable microscopic lesions," he said.
Cole emphasized that this study's findings only apply to people with a history of polyps and not to the population in general.
Cornelia Ulrich, an associate member of the cancer prevention program at the Fred Hutchinson Cancer Research Center in Seattle, said, "This was an important trial that showed clearly there's no benefit from taking folic acid for patients with prior polyps, and possibly, there could be some harm."
Ulrich, who co-wrote an editorial in the same issue of the journal, said she's concerned that people who take supplements, eat fortified foods and eat or drink so-called health drinks or snack bars, may end up consuming as much folic acid as was used in this study.
"People who have had a polyp should carefully review how much additional folic acid they get from health bars and drinks," she said.
And, anyone getting treatment for colon and other cancer should discuss any use of supplements -- folic acid or others -- with their doctor, because they could interfere with their treatment.
Both Cole and Ulrich said the most important step anyone can take for colon cancer prevention is to follow whatever colonoscopy screening schedule their doctor recommends.
In relation to colorectal cancer and adenomas, the evidence over a study indicates that fiber works only if it is undigested in the upper gut and then fermented by anaerobic bacteria in the colon. This process produces short-chain fatty acids and alterations in the metabolism of nitrogen, bile acids, and bacteria. Other carbohydrates, such as resistant starch, the nondigestible oligosaccharides, some sugar alcohols, and in some populations, lactose, also have these properties. To understand the role of fiber in colorectal cancer we must account for these other dietary carbohydrates.
When it comes to attacking those last two points, you can reduce your overall cancer risk by consuming a plant-based diet of fruits, vegetables, vegetable oils, whole grains and legumes, and by maintaining your weight. In addition, current research has supported the relationship between folate, calcium and lutein and the prevention of colorectal cancers.
A number of delicious recipes featuring foods rich in nutrients and phytochemicals -- chemicals from foods found specifically in plants. These dietary substances have been shown to decrease the risk of colorectal cancer.In addition, women with high levels of vitamin B-6 in their diets are less likely to develop colorectal cancer than are women with lower B-6 levels.
These recipes contain antioxidants, including carotenoids. Antioxidants act as scavengers to inhibit "free radicals" within the body, which may damage cells. Carotenoids, beta-carotene being the most popular, are specific phytonutrients that give some fruits and vegetables their bright colors.
There is no evidence to suggest that it is possible to consume sufficient natural folate to pose a risk of toxicity. However, this clearly does not apply to folic acid given in supplements or fortified foods. The main concern with fortification of high levels of folic acid is the masking of the diagnosis of pernicious anaemia, because high levels of folic acid correct the anaemia, allowing the neuropathy to progress undiagnosed to a point where it may become irreversible,even upon treatment with vitamin B12.
Controlling your weight alone can reduce your risk of colorectal cancer. And staying physically active may significantly cut your colon cancer risk. Exercise stimulates movement through your bowel and reduces the time your colon is exposed to harmful substances that may cause cancer.