How Much Fiber Do You Need per Day?

How much of a good thing is a good thing? For all of the talk about how great fiber appears to be, no one seems to be able to agree on how much we really need. You can’t measure the amount of fiber in your blood or colon because you don’t absorb fiber – so, determining adequacy levels gets a little tricky.

What We Need

US Dietary Guidelines

The 2005 US Dietary Guidelines for Carbohydrates recommend that adults eat 14 grams of dietary fiber for every 1,000 calories. Since a good ballpark for most adults is 2,000 calories per day to maintain a healthy body weight, this works out to no less than 28 grams of dietary fiber per day.

Institutes of Medicine

The Dietary Reference Intake (DRI) committee is a group of nutrition experts who set recommendation levels for healthy Americans and Canadians. The DRI committee does not have enough data to set an Estimated Average Requirement (EAR) level for dietary fiber, which means it can’t confidently develop a Recommended Dietary Allowance (RDA) level either. As such, we have to settle for the less scientifically derived upon Adequate Intake (AI) level. The AI for fiber is based on median fiber intake levels that help achieve low risk for developing heart disease and the IOM recommendations are gender-specific:

Female Daily Fiber Recommendations:

• Age 50 & younger: 25 grams per day
• Age 51 & older: 21 grams per day

Male Daily Fiber Recommendations:

• Age 50 & younger: 38 grams per day
• Age 51 & older: 30 grams per day

What We Get

Regardless of whose recommendations you follow, one thing is certain: Americans are not getting enough fiber. Usual intakes in the US average about 15 grams per day¹. Essentially, we are getting only half of the amount of dietary fiber that most scientific groups recommend!

References:

1.) Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: Energy, Carbohydrates, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids. Washington, DC: National Academies Press; 2002

Health Benefits of Fiber

Why is fiber the favored component of dietitian-recommended meal plans? Because increasing dietary fiber provides a number of healthful benefits for the body. The American Dietetic Association’s position on the Health Implications of Dietary Fiber outlines the benefits of fiber in four key areas:

• Cardiovascular disease prevention
• Gastrointestinal health
• Weight management
• Diabetes

Heart Health

Increasing dietary fiber helps lower total cholesterol levels and LDL (“bad cholesterol”). Blood cholesterol levels are reduced when bile acids are excreted from the body. Soluble fiber binds bile acids. This may help explain why increasing dietary fiber – particularly the soluble type - increases excretion of cholesterol, which in turn lowers levels of cholesterol circulating in the blood.

Gut Check

Insoluble fiber binds water, making your stools softer, bulkier and heavier. This helps move things along in the gut, reducing the likelihood of constipation, hemorrhoids and diverticulosis.

Weight Loss

High fiber foods like fruits, vegetables, whole grains and legumes such as kidney beans and lentils increase satiety. Satiety is the feeling of fullness. High fiber fruits and vegetables tend to be low in calories, which help satisfy and counteract hunger with relatively few calories. Foods that are high in fiber make you feel fuller for longer and decrease consumption of excessive calories that lead to weight gain.

Blood Sugar Regulation

Fiber containing foods take longer to digest than their lower-fiber counterparts. Certain types of fiber slow gastric emptying and glucose absorption. For people with diabetes, including high fiber foods is beneficial for normalizing blood sugar levels¹.

What About Cancer?

Contrary to popular belief, there is not a clearly established link between dietary fiber intake and the development of colon cancer. Increasing dietary fiber intake may be associated with lower rates of colon cancer, but the exact mechanism of the relationship is not entirely known. Diets high in animal fats and protein – which tend to be low in fiber – have been linked to higher rates of colon cancer².

One thing to keep in mind is that you don’t increase your risk of any chronic disease by increasing dietary fiber. Even though we may not know exactly why fiber is beneficial in every disease state, it seems safe to say that increasing dietary fiber is almost always helpful and rarely harmful.

References
1. Jenkins DJ, Kendall CW, Augustin LS,Vuksan V. High-complex carbohydrate or lente carbohydrate foods? Am J Med. 2002;113(suppl 9B):30S-37S
2. Lanza E, Yu B, Murphy G, Albert PS, Caan B, Marshall JR, Lance P, Paskett ED, Weissfeld J, Slattery M, Burt R, Iber F, Shike M, Kikendall JW, Brewer BK, Schatzkin A. Polyp Prevention Trial Study Group. The polyp prevention trial continued follow-up study: No effect of a low-fat, high-fiber, high-fruit, and vegetable diet on adenoma recurrence eight years after randomization. Cancer Epidemiol Biomarkers Prev. 2007;16:1745-1752

What is a Whole Grain?

A whole grain food will generally contain more fiber per serving than a refined or processed grain. According to the Whole Grain Council, a whole grain product is a food that contains the essential parts and nutrients that occur naturally in grains (excluding the husk).

After the husk of a whole grain has been discarded, the three remaining parts of a whole grain are:

1. The bran - outer layer that contains fiber, B vitamins, iron, zinc & other micronutrients
   
2. The endosperm - middle layer and starchy carbohydrate component with a bit of other nutrients
   
3. The germ - innermost compartment with unsaturated fat, B vitamins and other vitamins & minerals
   

If you keep all three parts together - the bran, endosperm and germ - the ensuing product is a whole grain ingredient. Refined grain processing - which results in lower fiber products - discards the bran and the germ, keeping only the endosperm, and leading to a lower-fiber grain product.

Welcome to the Future

Most nutrition professionals and Americans of average intelligence have no problem rattling off litanies of what you shouldn't eat; but is there anything out there that's good for you which you can actually eat more of?

Not withstanding people with unique GI disorders, almost everyone can benefit from more dietary fiber. This intent of this blog is to highlight the health benefits of fiber and track the food industry's attempts to capitalize on what science has been proving for years: fiber is good for you...and Fiber is the Future.