The Case for Eating Fiber

I want to help you prepare for this situation because you might be expected to answer it soon. What are the benefits of eating fiber?

Let’s go over a hypothetical situation. Your patient walks in to your office and says “Dr. I don’t know what to believe about fiber, is there really a benefit to eating brown rice instead of white rice? They have about the same number of calories and white rice tastes better, does fiber really make a significant difference?”

And now, since you’ve read Why Should I Eat Fiber? An Overview, you’re prepared and have been waiting for this question for a while now. You light up with joy because you’ve had lectures for the past 8 years of your life and now it’s time for you to relay knowledge to someone else.

So, you let them have it, and I mean really let them have it, like you’ve had this planned before they even came into the office.

It went like this:

Fiber is a carbohydrate that is unable to be digested by the body and is essential for maintaining proper health. Fiber helps regulate the use of sugar in the body, and keeps blood sugar and hunger in check [1].

There has been debate on how much fiber one should eat and the recommended is 20 to 30 grams daily, however I propose to reap the full benefits of fiber, more is needed. Diets filled with high fiber foods have demonstrated extreme benefits for the individual. Fiber has been shown to ward off many diseases and helps with weight loss by reducing the amount we eat at meals and keeping us full for longer.

So, first things first, there are two types of fiber: soluble fiber and insoluble fiber. Soluble fiber dissolves in water and insoluble fiber does not.

Soluble Fiber: According to Dr. Raymond, MD, of Gastrointestinal Consultants Ltd. in Virginia Beach, Va., “Soluble fiber attracts water to form a big, globby gel that will slowly creep down the digestive tract.” Therefore, soluble fiber will help to slow material down in the digestive track which can help with diarrhea [2]. Foods that are high in soluble fiber include oatmeal, beans, lentils, carrots, apples, blueberries and others. In addition, soluble fiber can help lower glucose levels and lower blood cholesterol.

Insoluble Fiber: On the other hand, insoluble fiber can speed things up through the digestive system and help alleviate or prevent constipation. Insoluble fiber works like that of a laxative and is mainly found in wheat bran, legumes, and seeds [3].

The differences between the ways that soluble and insoluble fibers interact with water give them both distinct properties. However, it is important to consume a high fiber diet in which one consumes both fibers. There has been much research on the benefits of a diet filled with high fiber foods including a lower risk of constipation, obesity, diverticulitis, heart disease, type 2 diabetes, colon cancer, and breast cancer [1].

Dietary fiber can be beneficial in the following ways:

Helps with constipation: Dietary fiber has been shown to make stool softer by binding to water as it passes through the digestive tract which makes the stool heavier allowing for less risk of constipation [1].

Weight Loss: A diet filed with high fibrous foods is a fantastic way to lose weight. In fact, Joel Fuhrman, MD, author of Eat to Live, says, “a high fiber food diet may be the best way to lose weight” [4]. This is a benefit of insoluble fiber because it cannot be digested and helps keep people full for longer. Your brain sends signals to your body that you need to eat, but fibrous foods remain in the digestive tract for longer periods of time will decrease the frequency of the signals, preventing overeating, and allowing you to eat less often [3].

Diverticulitis: Diverticulitis is an inflamed intestine and is a common disorder that affects many people in the western world and experts believe this results from a low-fiber diet [5]. Typically, people that eat a high fiber diet, have a lesser chance to develop this disorder, which may be the reason why people in Asia and Africa, where their diets are higher in fiber, have a lower incidence of diverticulitis.

Heart Disease: Cardiovascular disease is the leading cause of death in the world, accounting for 17.3 million deaths per year [6]. In recent years, nearly one in every three deaths in the U.S. was because of heart disease.

One way to reduce the chances of heart disease is to change one’s diet. A pooled analysis published by Mark Pereira, PhD, showed that consumption of dietary fiber from cereals and fruits is inversely associated with risk of coronary artery disease. The author believes dietary fiber may help decrease the risk of coronary artery disease by lowering blood pressure, improving insulin sensitivity, and improving blood lipid profiles [7]. Furthermore, researchers at Harvard conducted a study that found a high dietary fiber intake was linked to a 40%less chance of developing coronary artery disease and a lower risk for developing metabolic syndrome [8].

Type 2 diabetes: Type 2 diabetes has increased dramatically in recent years and studies are linking the prevalence of diabetes to not only lifestyle characteristics, but to the individual’s diet.

A study published by Matthias Schulze that used female nurses, found a positive association between high-glycemic-index diets and risk of type 2 diabetes [9]. The study proposes two major mechanisms that may be the cause for this increased risk from high-glycemic-index diets and agrees with the findings from the Nurses’ Health Study [10] and the Health Professionals Follow-Up Study [11]. In the publication by Schulze, he discovered the nurses who ate a high fiber diet had less of a risk to develop type 2 diabetes, specifically, those who ate cereal fiber.

Colon Cancer: Cancer has leeched into most of our lives indirectly or directly by affecting family, friends, or us.

A study published that dealt with fiber and colon cancer risk in women found that there was no evidence fiber reduces the risk of colorectal cancer [12]. However, their experiment was flawed as Dr. Joel Fuhrman stated in his book Eat to Live, “the participants were not eating a diet high in fiber by my standards.” Also, Dr. Fuhrman doesn’t say fiber can be associated with a lower risk of colon cancer, but foods that are already high in fiber like fruits and vegetables can be [4]. Some studies that have been published simply added a high fiber supplement to the individual’s diet and would you expect a 12-gram fiber supplement to do anything against the terrible American Diet?

Moreover, a high fiber diet encourages a healthy colon and bacteria in the gut may protect against colon cancer [13]. A recent study showed that dietary fiber is associated with a reduced risk of distal colon cancer and a modest inverse association was found between total fiber and colorectal cancer risk. The study found evidence that high fiber intakes from grains and fruits are associated with a reduced risk of cancer and incident colorectal adenoma. The researchers also discovered a risk reduction for advanced adenoma, which may be even more likely to progress to colorectal cancer [14].

Breast Cancer: There are links between high fiber food diets and decreased risk of breast cancer. Breast cancer is the most common cause of cancer in women and 14% of all cancer related deaths in women.

A meta-analysis of sixteen prospective studies showed that there was an inverse association between high dietary fiber intake and breast cancer risk [15]. The study specifically highlighted that intake of soluble fiber in levels over 25 g/day was inversely associated with breast cancer risk. Furthermore, the author notes the need for future studies that clarify the biological mechanism(s) behind this finding. This is a tremendous discovery that demonstrates a plausible way, through diet, a women’s risk of breast cancer can be reduced.

Fiber is essential for our health for many reasons. You can get soluble fiber from oatmeal, nuts, berries, beans, and apples, and insoluble fiber from the skins of fruit, whole wheat bread and brown rice [16].

Following a diet that incorporates high fiber foods can be extremely beneficial to your health and prevent or decrease your risk for multiple diseases and cancers.

References

[1] “Fiber”, The Nutrition Source, 2017. [Online]. Available: https://www.hsph.harvard.edu/nutritionsource/carbohydrates/fiber/. [Accessed: 06- Aug- 2017].

[2] K. McCoy, “Soluble vs. Insoluble Fiber for IBS”, EverydayHealth.com, 2017. [Online]. Available: https://www.everydayhealth.com/ibs/soluble-vs-insoluble-fiber-for-ibs.aspx. [Accessed: 03- Aug- 2017].[3] R. Howard, “What Are the Benefits of Insoluble Fiber?”, Healthyeating.sfgate.com. [Online]. Available: http://healthyeating.sfgate.com/benefits-insoluble-fiber-5526.html. [Accessed: 08- Aug- 2017].

[4] J. Fuhrman, Eat to live. New York: Little, Brown and Co., 2012.

[5] “Diverticulitis Diet”, WebMD, 2017. [Online]. Available: http://Diverticulitis Diet. [Accessed: 06- Aug- 2017].

[6] D. Mozaffarian, Heart Disease and Stroke Statistics – At-a-Glance. American Heart Association, 2015.

[7] M. Pereira, E. O’Reilly, K. Augustsson, G. Fraser, U. Goldbourt, B. Heitmann, G. Hallmans, P. Knekt, S. Liu, P. Pietinen, D. Spiegelman, J. Stevens, J. Virtamo, W. Willett and A. Ascherio, “Dietary Fiber and Risk of Coronary Heart Disease”, Archives of Internal Medicine, vol. 164, no. 4, p. 370, 2004.

[8] E. Rimm, “Vegetable, Fruit, and Cereal Fiber Intake and Risk of Coronary Heart Disease Among Men”, JAMA: The Journal of the American Medical Association, vol. 275, no. 6, p. 447, 1996.

[9] M. Schulze, S. Liu, E. Rimm, J. Manson, W. Willett and F. Hu, “Glycemic index, glycemic load, and dietary fiber intake and incidence of type 2 diabetes in younger and middle-aged women”, American Society for Clinical Nutrition, 2004.

[10] J. Salmerón, “Dietary Fiber, Glycemic Load, and Risk of Non—insulin-dependent Diabetes Mellitus in Women”, JAMA: The Journal of the American Medical Association, vol. 277, no. 6, p. 472, 1997.

[11] J. Salmeron, A. Ascherio, E. Rimm, G. Colditz, D. Spiegelman, D. Jenkins, M. Stampfer, A. Wing and W. Willett, “Dietary Fiber, Glycemic Load, and Risk of NIDDM in Men”, Diabetes Care, vol. 20, no. 4, pp. 545-550, 1997.

[12] C. Fuchs, E. Giovannucci, G. Colditz, D. Hunter, M. Stampfer, B. Rosner, F. Speizer and W. Willett, “Dietary Fiber and the Risk of Colorectal Cancer and Adenoma in Women”, New England Journal of Medicine, vol. 340, no. 3, pp. 169-176, 1999. [13] L. Ferrarelli, “Why a High-Fiber Diet Prevents Cancer”, Science Signaling, vol. 8, no. 359, pp. ec8-ec8, 2015.

[14] A. Kunzmann, H. Coleman, W. Huang, C. Kitahara, M. Cantwell and S. Berndt, “Dietary fiber intake and risk of colorectal cancer and incident and recurrent adenoma in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial”, American Journal of Clinical Nutrition, vol. 102, no. 4, pp. 881-890, 2015.

[15] D. Aune, D. Chan, D. Greenwood, A. Vieira, D. Rosenblatt, R. Vieira and T. Norat, “Dietary fiber and breast cancer risk: a systematic review and meta-analysis of prospective studies”, Annals of Oncology, vol. 23, no. 6, pp. 1394-1402, 2012.

[16] “Guide to Soluble and Insoluble Fiber”, WebMD. [Online]. Available: http://www.webmd.com/diet/features/insoluble-soluble-fiber. [Accessed: 06- Aug- 2017].

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Matt DiCerbo

Is a contributor to The Almost Doctor’s Channel.