the Difference Between Dietary Fiber and Rough Fiber

Cellulose

Dear Nutritionist: The calorie inquiry from the Food and Drug Administration distinguishes between crude fiber and dietary fiber.
What are the differences between the two? Do they have different physiological functions in the human body? Additionally, which type of fiber is indicated in the fiber content on commercially sold food products?

Xiao Pingguo, 20~29 year old female. Ask Date: 2003/10/27

Dr. Shi Guimei reply Nutrition

Hello! Dietary fiber refers to the type of fiber that cannot be digested or absorbed by human digestive enzymes.
It includes cellulose, hemicellulose, plant gums, pectin, mucilage, and other polysaccharides, as well as lignin.
Crude fiber refers to the portion that remains after chemical treatment with acids and bases, which includes cellulose and lignin.
The fiber content indicated on food labels typically refers to dietary fiber.
The functions of various types of fiber are as follows:
1.
Cellulose: Composed of polymerized glucose, it has the ability to absorb water and is insoluble in water and common solvents.
It is abundant in unprocessed bran, whole wheat flour, legumes, root vegetables, cabbage, cucumbers, broccoli, and Brussels sprouts.
It helps increase stool bulk, enhance satiety, prevent constipation, and reduce cancer risk.
2.
Hemicellulose: A complex polysaccharide containing polysaccharide aldehydes.
It is most abundant in seaweeds, whole grains, gluten-containing grains, and vegetables such as mustard greens and Brussels sprouts.
It can stimulate intestinal peristalsis, prevent constipation, lower cancer risk, reduce serum cholesterol, and slow the rise of postprandial blood sugar levels.
3.
Plant Gums: These are water-soluble substances that form a gel-like consistency, found abundantly in oats, barley, legumes, psyllium, and chia seeds.
They can stimulate intestinal peristalsis, prevent constipation, lower cancer risk, reduce serum cholesterol, and slow the rise of postprandial blood sugar levels.
4.
Pectin: Found in high amounts in apples, citrus fruits, persimmons, pears, bananas, strawberries, legumes, cauliflower, carrots, cabbage, pumpkins, and potatoes, pectin is a gel-forming polysaccharide with strong water-retaining properties.
It can stimulate intestinal peristalsis, prevent constipation, lower cancer risk, reduce serum cholesterol, and slow the rise of postprandial blood sugar levels.
5.
Mucilage: A polysaccharide that is highly viscous and water-retaining, found in seaweeds and seeds, such as alginic acid in kelp, which easily forms a gel when in contact with water.
It can encapsulate various substances and facilitate their excretion, including cholesterol and bile, thus helping to lower blood cholesterol levels and prevent atherosclerosis.
6.
Lignin: Found primarily in wood, bamboo, straw, and older vegetable stems, lignin is difficult to swallow.
It helps increase stool bulk, enhance satiety, prevent constipation, and reduce cancer risk.
Sincerely,
Nutritionist Shih Kuei-Mei, Director of the Nutrition Department, Taoyuan Hospital, Ministry of Health and Welfare.

Reply Date: 2003/10/27

More Info

The distinction between dietary fiber and rough fiber is an important topic in nutrition, as both types of fiber play different roles in human health. Dietary fiber, also known as non-digestible carbohydrates, is a broad category that includes various types of fibers that cannot be digested by human enzymes. This includes cellulose, hemicellulose, pectin, gums, and lignin. On the other hand, rough fiber specifically refers to the remnants of plant material that remain after chemical treatment with acids or bases, primarily consisting of cellulose and lignin.

Differences Between Dietary Fiber and Rough Fiber
1. Composition:
- Dietary Fiber: This includes soluble and insoluble fibers. Soluble fibers dissolve in water and can help lower blood cholesterol and glucose levels. Examples include pectin (found in fruits) and beta-glucans (found in oats). Insoluble fibers do not dissolve in water and are beneficial for digestive health, helping to prevent constipation by adding bulk to the stool. Sources include whole grains, nuts, seeds, and vegetables.

- Rough Fiber: This term is often used in the context of animal feed and refers to the fibrous parts of plants that are not easily digestible. It primarily includes cellulose and lignin, which contribute to the structural integrity of plant cell walls.

2. Physiological Effects:
- Dietary Fiber: It has numerous health benefits, including promoting regular bowel movements, preventing constipation, and reducing the risk of chronic diseases such as heart disease, diabetes, and certain types of cancer. Soluble fiber can also help regulate blood sugar levels and lower cholesterol.

- Rough Fiber: While it can contribute to digestive health by adding bulk to the diet, its benefits are less pronounced compared to the diverse effects of dietary fiber. It is primarily important in the context of animal nutrition rather than human health.

Food Labeling and Fiber Content
When it comes to food labeling, the fiber content listed on nutrition labels typically refers to dietary fiber. This is the fiber that has been shown to have beneficial effects on health. The term "fiber" on food packages generally encompasses both soluble and insoluble fibers, and manufacturers are required to report the total dietary fiber content.

Conclusion
In summary, while both dietary fiber and rough fiber are important components of our diet, they serve different purposes and have different health implications. Dietary fiber is crucial for maintaining digestive health and preventing chronic diseases, while rough fiber is more relevant in the context of animal nutrition. When looking at food labels, consumers should focus on the total dietary fiber content, as this is what contributes to health benefits.
Incorporating a variety of fiber sources into your diet—such as fruits, vegetables, whole grains, and legumes—can help ensure you receive the full spectrum of health benefits associated with dietary fiber. Aim for a daily intake of at least 25 grams for women and 38 grams for men, as recommended by health authorities, to support overall health and well-being.

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