Fiber Helps Battle the Bulge

Years of research has shown that fiber plays a role in a healthy weight. Here's how: ⁴

• Taking longer to chew - slowing down the rate at which we eat and giving our bodies a chance to let us know when we are full
• Absorbing fluid (as much as 15 times its own weight) to swell up in the stomach and upper intestines, helping us to feel full
• Containing fewer calories on a weight for weight basis, higher fiber foods tend to have fewer calories than lower fiber foods

Many studies have explored the role of fiber in weight management. Here's a taste:

• Two major US studies following the health of men and women over many years suggest that people who eat high fiber diets tend to be slimmer than those who don't ^5,6
• A review of the effects of fiber on calorie intake and body weight found that eating an additional 14g fiber each day resulted in a 10% fall in calorie intake and weight loss of about 4 pounds within 3 months. ⁷
• A recent analysis of the National Health and Nutrition Examination Survey (NHANES) 1999-2004 data showed that consumption of fiber is associated with lower body weight measures in US adults. ⁸

 

Fiber Keeps the Digestive System Working Well

When it comes to overall wellness, maintaining good digestive health is just as important as maintaining a healthy heart or strong bones. Good digestive health will not only help to avoid the discomfort of occasional constipation, but also has an impact on immunity and overall well-being.

Increasing your intake of fiber (particularly wheat bran) prevents food from lingering in the digestive system longer than it needs to (which can cause a bloated, uncomfortable feeling). Fibers help to absorb water and create bulk, which speeds up the passage of food through the digestive system, helping to prevent constipation.

Increasing fiber intake (particularly insoluble fibers such as wheat bran) provides more bulk, making it easier for the muscles of the digestive tract to move its contents along. This speeds up the passage of food, decreasing transit time and preventing constipation.

Fiber and Friendly Bacteria - Supporting Good Digestive Health

Few people think about what's inside their digestive tract, and if they did, most would squirm at the thought of it being full of bacteria.

Popular belief is that all bacteria are bad, but many bacteria play important roles in helping maintain health and vitality. For example, the bacteria in our lower digestive tract are vital to our health. Before we are born, our intestines are sterile and contain no bacteria. Through the birthing process, we obtain bacteria from our mother and these bacteria rapidly build up over the first few weeks of life. On average, our digestive 'bugs' number around 100,000 billion and weigh around 2 pounds.

Friendly gastrointestinal bacteria help: ⁹

• Keep "bad" bacteria out of our digestive tract tract.
• Manufacture vitamins from the undigested fiber that makes it through to the colon, which are then absorbed and used.
• Provide fuel to our colonic cells, which is thought to help reduce the risk of bowel cancer.
• Help support immune function in the digestive tract and throughout the body.

Certain fiber ingredients, such as inulin or fructo-oligosaccharides, are called 'prebiotic' fibers. ¹⁰ Prebiotic fibers selectively feed and stimulate the growth of friendly bacteria in the digestive tract. Many fiber-rich foods contain prebiotic fibers and help keep the bacteria in your digestive tract healthy. Functional prebiotic fibers may be added to other foods to give specific digestive health benefits as well. ¹¹

 

Fiber Looks After Your Heart

Since the late 1970s, we have known that people who eat higher-fiber diets tend to have fewer heart attacks than those who eat low-fiber diets.

Fiber helps to keep hearts fit and healthy by:

• Lowering LDL blood cholesterol ("bad cholesterol")
• Lowering blood pressure
• Helping keep weight under control
• Helping control blood sugar levels (see Fiber and Diabetes section)

In fact, according to research published by Pereira and colleagues in 2004, increasing fiber intake by 10g per day (equivalent to one bowl of high-fiber cereal, one large banana and one serving of carrots) could significantly reduce the risk of heart disease. ¹³

A Special Role for Soluble Fiber

Many people are aware that high cholesterol increases the risk of developing heart disease. When cholesterol levels are high, the arteries leading to and from the heart are more likely to become clogged with fatty cholesterol deposits (a bit like lime scale building up inside a pipe) that may reduce the amount of blood flow. Reduced blood flow causes angina and, if blood flow stops, a heart attack occurs.

Soluble fibers (such as fiber from legumes, psyllium, and the beta glucans from oats) are very effective in helping to lower LDL cholesterol. Once in the body, these soluble fibers act like a sponge, soaking up cholesterol and helping to remove it from the body.

Including three servings of soluble fiber each day may help combat high cholesterol:

• 1 bowl of Kellogg's® Smart Start®
• 2-3 tablespoons of beans, chick peas or lentils.
• 2-3 tablespoons of peas.
• 1 medium apple or pear or 6 dried plums.
• 1 citrus fruit, such as a grapefruit or orange or 2 clementines.
• 1 serving of carrots or sweet potatoes. (For even more fiber, leave the skin on the sweet potato.)
• 1 bowl of oat-based cereal or oatmeal.

The evidence that a diet high in soluble fiber reduces the risk of heart disease is so strong that the Food and Drug Administration (FDA) has approved two health claims related to fiber and heart disease:

• "Diets low in saturated fat and cholesterol and rich in fruits, vegetables and grains products that contain some types of dietary fiber, particularly soluble fiber, may reduce the risk of heart disease, a disease associated with many factors."
• "Soluble fiber from foods such as oat bran, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease."

 

Fiber Keeps You Feeling Great

Research has shown that boosting fiber intake improves mood and feelings of well-being. Given that so many people fight a daily battle with fatigue, it is good to know that something as simple as eating more fiber could help to replenish energy.

A study at the University of Cardiff in the United Kingdom found that people who had higher intakes of fiber intakes had less emotional distress, fewer cognitive difficulties and less fatigue. ¹⁴ Or put more simply, they felt happier, more energetic and had better mental function than those eating foods with less fiber.

This particular study looked at dietary fiber from wheat bran cereals. The researchers think the decrease in fatigue seen in their study may be due to an improvement in digestion (better removal of "waste products" from the body) or possibly an increase in the numbers of friendly bacteria in the lower digestive tract. ¹⁵

Additional research has also shown high-fiber breakfasts to reduce fatigue and increase satiety¹⁶.

 

Fiber May Help to Reduce the Risk of Diabetes

According to a number of studies, eating foods rich in fiber has been associated with a reduced risk of Type 2 diabetes. ^{17, 18}

The role of fiber in preventing diabetes is unclear. The action is likely to be a combination of the effects from fiber, including helping the body to manage blood sugar, insulin and healthy body weight. The impact of other fiber- related dietary components such as magnesium, folate, vitamin B6 and vitamin E may also play a role.

While emerging research is showing a link between fiber and diabetes, it is important to understand is that the recommended intake of fiber for people with diabetes is the same as for the general population, 25g per day for women and 38g per day for men. So while every food in a diabetes meal plan doesn't have to be high in fiber, it is important to strive to meet the recommended intake through a combination of foods by the end of the day. Increased activity levels are also recommended for diabetes management.

 

Fiber and Cancer

In the 1970s, renowned physician Denis Burkitt observed that people who ate diets full of fiber-rich foods tended to have much lower rates of bowel cancer than people eating diets with low levels of fiber. Over the years, this observation has been supported by some of the world's leading experts, who suggest that eating a diet rich in fiber could substantially reduce the risk of developing not only cancer of the bowel but other cancers, too - such as cancer of the esophagus. ¹⁹

New research suggests that by changing their diet to one rich in high-fiber foods, women could help protect themselves against developing breast cancer. ^{20, 21} While the research is early and the number of studies looking at fiber and breast cancer is small, these initial results are just one more reason to increase the fiber content of our diets.

It appears that there are several ways that fiber may be helping to reduce the risk of cancer. It is likely that these act in combination to provide protective effects:

• Fiber is fermented in the bowel by friendly bacteria, producing substances called short-chain fatty acids. These provide energy for the cells lining the walls of the bowel (which is the lower part of the digestive tract), helping them to renew and repair themselves to stay healthy.
• Fiber speeds up the passage of food and waste through the bowel, reducing the amount of time any toxic substances stay in the body.
• Foods rich in fiber also tend to be rich in antioxidants, vitamins and minerals, which have all been linked to cancer protection.
• Fiber is thought to alter hormone levels in the body, particularly lowering estrogens that have been linked to breast cancer risk.

The evidence in relation to cancer is so strong that in 1993 the Food and Drug Administration approved a health claim to support the consumption of fiber for cancer prevention:

• "Diets low in fat and rich in fiber-containing grain products, fruits and vegetables may reduce the risk of some types of cancer."

References:

4. Slavin et al (2007) Dietary fiber and satiety. Nutrition Bulletin 32: S32-S42
5. Liu et al (2003) Relation between changes in intakes of dietary fiber and grain products and changes in weight and development of obesity among middle-aged women. AJCN 78: 920-927
6. Koh-Banerjee et al (2004) Changes in whole-grain, bran and cereal fiber consumption in relation to 8-y weight gain among men. AJCN 80: 1237-1245
7. Howarth NC et al (2001) Dietary fiber and weight regulation Nutr Rev 59:129-139
8. Consumption of Fiber is Associated with Lower Body Weight Measures in US Adults: The National Health and Nutrition Examination Survey (NHANESS) 1999-2004, S.S. Cho, T.A. Nicklas, C.E. O'Neil.
9. Guamer et al (2003) Gut flora in health and disease. The Lancet 360: 512-519
10. Gibson et al (1995) Dietary modulation of the human colonic microbiota: introducing the concept of prebiotics. J Nutr 125, 1401-1412.
11. International Food Information Council Fiber Fact Sheet 2008
12. Jefferson A (2005) Diet and Digestive Health Primary Healthcare 15: 27-31
13. Pereira et al (2004) Dietary Fiber and Risk of Coronary Heart Disease. Arch Int Med 164: 370-376
14. Smith A et al (2001) High fiber cereals reduce fatigue. Appetite 37: 1-3
15. Smith, AP. 2005. The concept of wellbeing: relevance to nutritional research. British Journal of Nutrition, 93, Suppl. 1, S1-S5.
16. Pasman WJ et al (2003) Effects of two breakfasts, different in carbohydrate composition, on hunger satiety and mood in healthy men. Int J Obes Relat Metab Disord 27: 663-8
17. Cochrane Database of Systematic Reviews 2008 Issue 2. Priebe MG, van Binsbergen JJ, de Vos R, Vonk RJ. Whole grain foods for the prevention of type 2 diabetes mellitus. http://www.cochrane.org/reviews/en/ab006061.html
18. Scientific Advisory Committee on Nutrition (2008) Statement On dietary Fiber see http://www.sacn.gov.uk/pdfs/final_sacn_position_statement_for_website_dietary_fibre.pdf
19. World Cancer Research Fund (2007) Food, nutrition, physical activity and the prevention of cancer: a global perspective.
20. Cade et al (2007) Dietary Fiber and risk of breast cancer in the UK Women's Cohort Study. Int J Epid 36: 231-238
21. Mattisson et al (2004) Intakes of plant foods, fiber and fat and risk of breast cancer - a prospective study in the Malmo Diet and Cancer Cohort Br J Cancer 90: 122-127
22. Bingham et al (2003) Dietary fiber in food and protection against colorectal cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC): an observational study. The Lancet 361: 1496-1501