High-fiber foods - a diet guide

Getting enough fiber in your diet is essential to maintaining a healthy digestive system and bowel function. Fiber is commonly associated with the digestive system and ‘keeping regular’, however, including fiber-rich foods in your diet can also lower your risk of heart disease, stroke, and diabetes, and help you lose weight.

Fiber is found in the edible part of plant-based foods such as fruits, vegetables, grains, nuts, and legumes. Fiber is a complex carbohydrate, a type of sugar that the small intestine does not digest or absorb. This effectively ‘cleans’ out your digestive system as the fiber moves through to the large intestine or colon. This helps ease bowel movements and flush out any toxins in your intestines.

The 2 different types of dietary fiber

Dietary fiber contains starch, simple sugars and non-polysaccharides which bulk up fecal matter and increase its viscosity or thickness, the time it takes to travel through the gut and also the production of short chain fatty acids (SCFA).

There are two different types of fiber that work together to maintain a healthy digestive system.

1. Insoluble fiber does not dissolve in water and acts as a ‘bulking agent’, increasing the volume or weight of stools. This helps food pass more easily through the stomach and intestines and may help reduce constipation, diverticular disease, and hemorrhoids.

2. Soluble fiber dissolves in water and acts like a sponge, absorbing water from food and converting it to a gel-like substance during digestion. Soluble fiber makes the bowel contents softer and able to move more quickly. It also slows down the absorption of glucose (blood sugar) and helps control blood sugar levels and reduce cholesterol.

Foods can contain both soluble and insoluble fiber. Some foods such as meat, dairy, and sugar contain none.

Fiber has many health benefits

A high fiber diet is commonly associated with digestive and bowel health, however, there are many other health benefits to consuming fiber-rich foods. Some of these benefits are:

• Weight control: Fiber slows down the digestion of foods - the rate at which food passes from the stomach and the rest of the digestive system. Foods high in fiber add bulk to your diet, which makes you feel fuller for longer and reduces your appetite. This can help with weight loss and weight management. High-fiber foods tend to be lower in calories as well.
• Heart health: Fiber, particularly soluble fiber, can help lower the risk of coronary heart disease and stroke by reducing risk factors. Bad LDL (low-density lipoprotein) cholesterol, diabetes, and excess weight (obesity) can have a negative impact on heart health. Including high-fiber foods in your diet can increase good HDL (high-density lipoprotein) cholesterol, lower LDL cholesterol, lower blood pressure, and help reduce weight.
• Reducing and controlling blood sugar levels: Dietary fiber plays an important role in reducing and controlling blood sugar levels in people with diabetes. Fiber, specifically insoluble fiber, slows the absorption of glucose and improves blood sugar levels after a meal.
• Improved digestion: Fiber, or roughage, is most commonly known for helping people to 'keep regular’ and reduce constipation. Fiber bulks up stools in the intestinal tract and helps improve bowel movements and make them easier to pass. This can help alleviate and prevent both constipation and diarrhea and may also reduce your risk for diverticulitis (inflammation of the intestine), hemorrhoids, gallstones, kidney stones, and provide some relief for irritable bowel syndrome (IBS).
• Reduced cancer risk. Diets rich in high-fiber foods have been linked to a reduced risk of some cancers, particularly colorectal cancer. Fiber helps bowel movements move more quickly and may decrease the chance of contact with carcinogens or toxins.
• Skin health. Eating fiber, especially psyllium husk (a type of plant seed), can clean toxins out of your body, enhancing the health and condition of your skin.

How much fiber do I need?

Most people do not eat the amount of fiber they need. The recommended amount is 14 grams for every 1000 calories. Your exact fiber needs will vary depending on your age, sex, and energy needs. Below are recommended daily fiber intakes.

Young children should have some fiber as part of a well-balanced diet. However, too much fiber is overly filling and can prevent them from absorbing the minerals and vitamins they need to develop.

^{*Also known as Dietary Reference Intake (DRI)}

How much fiber is in my food?

It is best to start by gradually adding fiber to your diet and increasing your water intake. Fiber requires water to work efficiently, so the more fiber you add to your diet, the more fluids you need to drink. Good sources of food that are high in fiber include:

Supplements are another source of fiber

Supplements are another source of fiber that are useful if there is a problem increasing how much fiber you get from your diet or you need to quickly top-up your daily fiber intake.

Fiber supplements come in a few different forms - powders you dissolve in water or add to food, chewable tablets, and wafers.

It is best to get your recommended fiber intake from foods which are naturally high in fiber. Supplements are not a long-term solution or a replacement for eating a healthy diet. If you do need to take supplements, make sure you take them with plenty of water.

Relying solely on supplements for your fiber intake is associated with a number of disadvantages including:

• You miss out on essential vitamins, minerals, and other nutrients supplied by high-fiber foods.
• Supplements will not fill you up or help you maintain your weight.
• Fiber supplements can interact with some antidepressants, cholesterol-lowering medications, and the anticoagulant drug warfarin. If you are taking any medications consult your healthcare professional before taking a supplement to check for any potential interactions.

Risk of eating too much fiber

Excessive amounts of fiber may hinder the uptake of minerals, vitamins, energy, and protein that your body needs. This is especially true for young children including preschoolers, which is why a high fiber diet is not generally recommended for this age group.

Too much fiber or a sudden increase in fiber can also cause side effects such as wind, bloating, abdominal pain, and constipation.

Tips for boosting the fiber in your diet

• Gradually increase the amount of fiber in your diet to avoid bloating and gas, which can occur if you increase the amount of fiber you eat too quickly.
• Make sure to drink plenty of water, especially when transitioning to a high-fiber diet or taking a supplement because the fiber absorbs water in the body.
• Start your day with a high-fiber cereal that has oats, bran, or wheat in it, or add a tablespoon or two of unprocessed wheat bran to your preferred cereal. Try alternative breakfast meals such as baked beans on wholewheat toast.
• Include simple snacks to your day such as a handful of nuts, unpeeled fruit, or raw vegetables.
• Eat the peel on fruits and vegetables as it’s a good source of fiber.
• Eat whole fruit and vegetables rather than juicing them as you lose fiber content.
• Add lentils, chickpeas, peas, and vegetables to soups, stews, sauces, or meals with mince. For example, add grated carrot or zucchini to a spaghetti sauce.
• Switch out white rice, bread, and pasta for wholemeal products.
• Consult your healthcare professional if you are experiencing any problems or have concerns regarding the amount of fiber in your diet.