High-Fibre Diet May Lower Colon Cancer Risk

(life) Colorectal cancer is the seventh most common cancer diagnosed in both men and women in India.

The cause of colon cancer is multifactorial and complex. Risk factors include sedentary lifestyle, obesity, tobacco use, low fiber diet and alcohol consumption. Dr Niranjan Naik, Director, Surgical Oncology, Fortis Memorial Research Institute, Gurugram sheds some light on the need for a high fibre diet to lower the risks.

High-risk for colon cancer includes age above 60 years, a positive family history of colorectal cancer and having familial polyposis syndrome. For screening colonoscopy is recommended starting at age 50 and then every 10 years after that, if the results be normal.

Eating a diet which is high-fibre is associated with a reduced risk of colorectal cancer, according to new research that analyzed 25 different studies. Analysis compared groups with the highest intake of fibre daily with groups with the lowest intake.

High dietary fiber is thought to reduce the risk of colon cancer is by decreasing gastrointestinal transit time, dilution of fecal carcinogens, increasing stool bulk and causing bacterial fermentation of fiber to short-chain fatty acids with anti-carcinogenic properties.

Colonic adenomas are formed initially, which may progress to become cancer in some individuals. Individuals consuming the highest intake of dietary fiber have reduced risks of developing colorectal adenoma and distal colon cancer and that this effect of dietary fiber, particularly from cereals and fruit, may begin early in colorectal carcinogenesis. Dietary fiber may act early in the adenoma- carcinoma sequence and reduce both the risk of adenoma and cancer.

The European Prospective Investigation of Cancer and Nutrition (EPIC) Study evaluated diet and colon cancer in 519,978 people living in 10 countries with a broad range of dietary habits. The volunteers, who ranged in age from 25 to 70, were tracked for six years. Compared with the people who ate the least fiber, those who ate the most enjoyed a 42 per cent reduction in the risk of colon cancer. No source of fiber was more protective than others; the study did not evaluate fiber supplements. Another study of 2,157 residents of Utah and California linked high consumption of fiber to a 46% reduction in the risk of rectal cancer.

Dietary fiber is a non-starch complex carbohydrates which is found in plant foods. They are of 2 types: soluble and insoluble. There are not non-vegetarian (animal) sources for fiber.

Soluble fiber dissolves in water to form a gel, which promotes delayed emptying and early satiety. It is easily digested in the colon, which also can cause bloating and gas. Soluble fiber is often associated with cardiovascular and diabetes prevention and colon health, as it reduces blood cholesterol and glucose levels. It does this in 2 ways.

Firstly, the soluble fibre is fermented to the short-chain fatty acids, these are absorbed and metabolized by the liver for bile synthesis. Second, fiber passes through the body undigested.

Soluble-fiber sources include apples, barley, citrus fruits, peas, avocado, husks, legumes, oats, rye, and many vegetables, such as broccoli and carrots.

Insoluble fiber does not dissolve in water and is much less fermentable or gassy. It promotes bowel movements by adding bulk and water to stool, creating a stool softening action in the digestive system.

Insoluble-fiber sources include brown rice, fruits like apples, legumes, seeds, whole grains, vegetables such as Brussels sprouts and cabbage, and wheat bran.

Fiber supplements available include gums, inulins, lignins, pectins, and psyllium or isabgol husk.

Juice is not a good source of fiber. Even if juice is made from fresh fruits and vegetables, the fiber is often gets removed in the juicing process. Ideally, you should get fiber from whole food sources, not supplements or juices.

Researches showed that each 10-gram a day increase in total fiber and cereal fiber was linked with a 10% reduction in colorectal cancer risk. Aim for fiber intake amounts of 25 to 35 grams per day or a ratio of 14grams of fiber/1000kCal consumed. In regard with fiber, more is not necessarily better, so do not overdo it. Too much of high fiber can be disruptive, in turn affecting mineral absorption and GI distress.

Colon cancer does not happen overnight. Usually it can take many years to develop. So starting to eat whole grains at an early age is important.

Eat more whole grains. It not only reduces colorectal cancer risk, they and other sources of fiber have other health benefits like reduced cholesterol levels, better blood sugar levels and less constipation. Whole grains and total dietary fibre have already been identified as protective against cardiovascular disease. Fiber slows the absorption of carbohydrates, reducing insulin levels. It also binds bile acids, lowering blood levels of LDL cholesterol. When a high-fiber diet includes lots of fruit and vegetables, it helps to lower blood pressure.

Be sure to increase your fiber intake gradually. Adding large quantities of fibre into the diet too quickly can cause gas or discomfort. Instead, try to add a little more fibre to each of your meals by including a piece of fruit or by switching processed or refined grains with whole grains.

Fiber could reduce exposure of the colorectal passage to carcinogenic N-nitroso compounds produced on processed meat consumption. Drink plenty of water, staying hydrated will help ensure that the additional fiber doesn't cause stomach problems.

So, to reduce your cancer risk, change your lifestyle. Act now.

( With inputs from IANS )