The cellulose in the skin of the apple is primarily ______ fiber.

Pectin is a type of water-soluble fiber found in a variety of fruits and vegetables. Commercially, it’s used to make jams and jellies because it turns into a sticky gel-like compound when combined with water. Pectin’s sticky properties also contribute to your health by attaching to cholesterol-rich bile within your intestines and carrying it out of your body. Citrus fruits and apples are particularly rich sources of pectin.

Pectin is a type of carbohydrate -- specifically a polysaccharide -- that’s found in the cell walls of plants, especially the leaves, roots and fruits. It acts mainly to bind plant cells together. Pectin content varies widely among plants and even within the same plant over time. In general, pectin is broken down by enzymes as fruit ripens and becomes softer. Pectin and other dietary fibers do not contribute significantly to nutrition -- primarily because your intestines can’t digest them very well -- but they do contribute to health. Pectin consumption impacts blood cholesterol levels and it help regulates blood glucose levels. It also helps remove toxins such as lead and mercury from your body.

The fruits containing the most pectin are citrus fruits, especially grapefruits, lemons and oranges. The majority of the pectin resides in the citrus peel, but the pulp also contains some. You'd need to eat a equivalent of 6 grapefruits to get a significant amount of pectin — however, you can easily get more from each grapefruit by using the peel via zest. Use citrus zest to add flavor to homemade salad dressings and marinades, or add it to plain yogurt of cottage cheese.

Apples are also an excellent source of pectin. In practical terms, apples are often a better source than citrus fruit because most people eat the apple skins, which is where a significant proportion of the pectin resides. In contrast, the vast majority of people remove and discard the pectin-rich peel from citrus fruit. The amount of pectin in apple pulp ranges widely, from 0.14 to 1.15 percent of weight. Variety, growing conditions and ripeness affect pectin content.

A number of other fruits are very good sources of pectin -- assuming you eat them with their skin -- and these include all berries, peaches, apricots, cherries and grapes. Berries particularly notable for their pectin content include strawberries, blackberries, raspberries and dewberries. Bananas are also a good source, especially if you don’t let them get too ripe or soft before eating them.

Health experts have long recommended consuming roughage, commonly called fiber, to improve digestive health (1).

Roughage is the portion of plant foods, such as whole grains, nuts, seeds, legumes, fruits, and vegetables, that your body can’t digest.

However, it’s an important food source for the beneficial bacteria in your gut. It may also aid weight management and decrease certain risk factors for heart disease.

This article explains what roughage is, reviews its benefits, and provides a list of roughage-rich foods.

The cellulose in the skin of the apple is primarily ______ fiber.
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Roughage, or fiber, refers to the carbs in plants that your body cannot digest. This article uses the terms roughage and fiber interchangeably.

Once roughage reaches your large intestine, it’s either broken down by your gut bacteria or exits your body in your stools (2).

There are two main types of fiber — soluble and insoluble. Most foods high in roughage contain a combination of these but are usually richer in one type (3, 4).

In the gut, soluble fiber absorbs water to become gel-like. This allows your gut bacteria to break it down easily. Chia seeds and oats are both high in soluble fiber (2, 5, 6).

In contrast, insoluble fiber has a more rigid microscopic structure and does not absorb water. Instead, it adds bulk to stools. Fruits and vegetables contain high amounts of insoluble fiber (1, 4).

You should try to eat 14 grams of fiber for every 1,000 calories you consume per day. That’s about 25 grams for women and 38 grams for men. Unfortunately, only about 5% of people reach this recommendation (7).

Not eating enough fiber can negatively affect your health. For example, eating a diet low in fiber has been linked to digestive issues like constipation and dysbiosis, which is the abnormal growth of harmful bacteria in the gut (8, 9, 10).

Diets low in fiber are also associated with an increased risk of obesity, colon cancer, and breast cancer (11, 12, 13).

Summary

Roughage, also known as fiber, refers to carbs that your body cannot digest. Most people don’t eat enough fiber. Recommendations suggest that women consume about 25 grams of fiber per day, while men should consume 38 grams.

You may have heard that adding roughage to your diet can improve your digestion.

Indeed, roughage has numerous healthy effects on your gut, such as increasing the bulk of stools, decreasing constipation, and feeding beneficial gut bacteria.

Foods high in roughage are also naturally richer in vitamins, minerals, and antioxidants than low-fiber foods like refined grains. Plus, they may even help you lose weight (14).

Improves digestion and gut health

Dietary fiber plays many different roles in gut health.

Insoluble fiber helps alleviate constipation by adding bulk to stools, while the gel-like consistency of soluble fiber helps move stools more easily through your digestive tract (15).

One study in over 62,000 women found that those who ate at least 20 grams of fiber daily were much less likely to experience constipation than those who ate only 7 grams or less per day (16).

Another study in 51 people looked into the effects of eating fiber on constipation. Every day for 3 weeks, participants ate 240 grams of bread — either rye or white. The rye bread contained 30 grams of fiber, while the white bread contained 10 grams.

Compared to the white-bread group, the rye-bread group experienced a 23% faster transit time of bowel movements, 1.4 more bowel movements per week, and softer stools that passed more easily (17).

Dietary fiber also act as a prebiotic, which feeds the beneficial probiotic bacteria in your gut, enabling them to thrive and limit the growth of harmful bacteria.

The prebiotics in fiber may also reduce your risk of colon cancer by promoting healthy bowel movements and strengthening the layer of tissue lining your intestines (18).

Helps you manage your weight

Consuming fiber may also help you reach and maintain a healthy weight.

In one study, 28 adults increased their fiber intake from 16 to 28 grams per day. They followed one of two high-fiber diets daily for four weeks — either 1.5 cups (318 grams) of beans or a combination of fruits, vegetables, and whole grains.

On both high-fiber diets, participants ate about 300 fewer calories per day and lost about 3 pounds (1.4 kg), on average. At the same time, they reported higher levels of fullness and less hunger than before they started the high-fiber diet (19).

Eating more fiber may also increase your resting metabolic rate (RMR), which is the number of calories you burn at rest.

A 6-week study in 81 adults found that those who ate a diet containing about 40 grams of fiber daily had a higher RMR and burned 92 more calories per day, compared to those who ate a diet with only about 21 grams of fiber per day (20).

In addition, many high-fiber foods, such as whole fruits and vegetables, are low in calories. Try eating more of these foods to feel full and satisfied. They will help keep your calorie intake low, which may promote weight loss.

May benefit blood sugar control

High-fiber foods help slow digestion, which may help stabilize your blood sugar levels by slowing the absorption of sugar into your bloodstream (21, 22).

In fact, some studies have shown that fiber may help regulate blood sugar and insulin levels. Insulin is a hormone that helps transport blood sugar into your cells and directs your body to burn it for energy or store it as fat (23).

Keeping blood sugar levels moderate is important, as spikes in blood sugar can damage your body over time and may lead to diseases like diabetes (24).

One study in 19 people with type 2 diabetes looked into the effects of eating a fiber-rich breakfast on blood sugar levels.

Those who ate a high-fiber breakfast that included 9–10 grams of fiber had significantly lower post-meal blood sugar than those who consumed a low-fiber breakfast containing only 2–3 grams of fiber (25).

What’s more, a study in 20 overweight adults found that those who consumed at least 8 grams of fiber at breakfast had lower post-meal insulin levels (24).

Maintaining low insulin levels may also help you lose weight by decreasing the number of calories your body stores as fat (26).

May decrease cholesterol and blood pressure levels

Dietary fiber may help lower high cholesterol and blood pressure levels, both of which are risk factors for heart disease.

One 28-day study examined the heart-healthy effects of eating fiber in 80 people with high cholesterol.

Researchers observed that people who ate 3 grams of soluble fiber daily from oats experienced a 62% reduction in total cholesterol and a 65% reduction in LDL (bad) cholesterol, compared to a control group (6).

In another 4-week study, 345 people ate 3–4 grams of beta-glucan, a soluble fiber found in oats, daily. This group experienced significant reductions in LDL (bad) cholesterol, compared to a control group (27).

Furthermore, eating fiber may reduce your blood pressure.

A review of 28 studies noted that people who ate diets higher in beta-glucan, a type of fiber found in oats, had lower blood pressure than those who consumed diets lower in this fiber (28).

To date, most of the research on fiber and blood pressure has focused on the effects of fiber supplements — not the fiber in food. Thus, more research is needed (28, 29, 30).

Summary

Roughage has numerous health benefits. It helps improve digestion and promotes gut health. It may also improve certain risk factors for heart disease and help you manage your weight and blood sugar.

Fiber, or roughage, is found in virtually all plant foods, including whole grains, fruits, vegetables, beans, nuts, and seeds.

However, some of these foods are naturally higher in roughage than others. Here are some of the best sources of roughage:

  • Chia seeds: 10 grams per 2-tablespoon (28-gram) serving (31)
  • Lentils: 8 grams per 1/2-cup (96-gram) serving (32)
  • Black beans: 8 grams per 1/2-cup (86-gram) serving (33)
  • Lima beans: 7 grams per 1/2-cup (92-gram) serving (34)
  • Chickpeas: 7 grams per 1/2-cup (82-gram) serving (35)
  • Wheat bran: 6 grams per 1/4-cup (15-gram) serving (36)
  • Kidney beans: 6 grams per 1/2-cup (125-gram) serving (37)
  • Flax seeds: 6 grams per 2-tablespoon (22-gram) serving (38)
  • Pears: 6 grams per medium (178-gram) pear (39)
  • Avocado: 5 grams per 1/2 avocado (68 grams) (40)
  • Oats: 4 grams per 1/2-cup (40-gram) uncooked serving (41)
  • Apples: 4 grams per medium (182-gram) apple (42)
  • Raspberries: 4 grams per 1/2-cup (62-gram) serving (43)
  • Quinoa: 3 grams per 1/2-cup (93-gram) cooked serving (44)
  • Almonds: 3 grams per 1-ounce (28-gram) serving (45)
  • Green beans: 3 grams per 1-cup (100-gram) serving (46)
  • Corn: 3 grams per 1 large ear (143 grams) (47)

These foods are particularly high in roughage, but many other whole foods can help you increase your fiber intake too.

Simply making an effort to include more vegetables, fruits, nuts, seeds, beans, and whole grains in your diet is an excellent way to increase your fiber intake and improve your overall health.

Summary

Almost all plant foods contain roughage. Beans, lentils, wheat bran, pears, and chia and flax seeds are a few of the best sources.

Roughage, or fiber, has long been recommended to help with digestive issues like constipation, but it also plays many other important roles in your body.

For example, the roughage in plant foods can promote optimal gut health, help you manage your weight, and even reduce your risk of heart disease.

Unfortunately, most people do not eat enough of this important nutrient.

Luckily, foods high in roughage are easy to add to your diet. Eating more healthy whole grains, legumes, fruits, vegetables, nuts, and seeds is a simple and delicious way to boost your fiber intake and improve your health.