Dietary fiber is a critical component of a healthy diet, yet isn’t talked about very much. Despite its well-documented benefits, many people do not consume adequate amounts of fiber. The recommended dietary requirements for fiber vary by age and gender. According to the Dietary Guidelines for Americans and the Institute of Medicine, the following are the daily fiber intake recommendations:

Adult Women: 25 grams per day

Adult Men: 38 grams per day

Soluble vs Insoluble Fiber

There are 2 types of dietary fiber: soluble and insoluble. Soluble fiber dissolves in water to form a gel-like substance. It is found in various plant-based foods such as oats, beans, lentils, apples, citrus fruits, carrots, barley, and psyllium husks. This type of fiber helps regulate the digestive process by slowing down the movement of food through the stomach and intestines. By forming a gel-like substance, soluble fiber can increase feelings of fullness and help with weight management. It can help prevent diarrhea by absorbing water and forming a gel that slows down digestion. It slows the absorption of sugar, which helps control blood sugar levels and can be beneficial for people with diabetes. Soluble fiber can also help lower blood cholesterol levels by binding to cholesterol particles and bile acids in the digestive system and facilitating their excretion. This binding can also help move toxic products out of the body, especially mycotoxins from mold.

The other type of fiber, insoluble fiber, does not dissolve in water. It adds bulk to the stool and passes through the digestive system largely intact. It is found in whole grains, nuts, beans, vegetables like cauliflower and potatoes, and the skins of some fruits, such as apples and pears. It helps to keep the colon clean and may reduce the risk of colon cancer by speeding up the passage of food and waste through the digestive tract, reducing the time harmful substances are in contact with the intestinal walls.

Current Trends in Dietary Fiber Intake

Recent surveys and studies indicate that most people do not consume enough dietary fiber. The average daily intake of fiber is significantly below the recommended levels. For instance, the National Health and Nutrition Examination Survey (NHANES) conducted in the United States found that the average fiber intake for adults is about 15 grams per day, well below the recommended amounts. By some estimates, only 7% of Americans eat enough fiber!

One reason for this shortfall is the prevalence of highly processed foods in modern diets. These foods often lack sufficient fiber and are high in refined sugars and unhealthy fats. Additionally, many people are not consuming enough fruits, vegetables, whole grains, and legumes—whole, unprocessed foods that are naturally high in fiber. An increase in dietary fiber is associated with a whole host of good health outcomes, including lowering inflammation, improving the gut microbiome, and relieving chronic pain.

Dietary Fiber in Chronic Fatigue & Fibromyalgia

The challenge of increasing dietary fiber in the diet of those with MECFS, fibromyalgia, and the like is twofold:

1. How can one increase fiber intake without worsening a gut condition like irritable bowel syndrome?

2. How can one increase dietary intake without loading up on carbohydrates, which are a no-go for those with mitochondrial dysfunction?

You may remember from a previous post that foods high in FODMAPs can worsen digestive symptoms, which are so common to those with post-viral conditions. FODMAP-rich foods are difficult to digest. The fiber in these foods is left undigested or partially digested in the intestine, where it can ferment, causing bloating, gas, and other discomfort. It is important then to choose foods that are high in dietary fiber but also low in FODMAPs. Vegetables that are high in fiber and low in FODMAPs include eggplant, carrots, green beans, and all types of potatoes. Fruits low in FODMAPs include green bananas, oranges, kiwis, raspberries, and strawberries.

The other issue regarding dietary fiber is the carbohydrate content. The mitochondrial dysfunction seen in fibromyalgia, long-haul COVID, and ME/CFS does not take kindly to a high carbohydrate diet. Such diets tend to lead to excess fatigue and can promote inflammation. Unfortunately, many good sources of dietary fiber, like whole grains, are also high-carbohydrate foods. However, it is still possible to increase your dietary fiber intake by choosing low-carbohydrate fiber sources. Let’s look at some examples:

Best Low-Carbohydrate Fiber Sources

Leafy Greens: Vegetables like spinach, kale, and Swiss chard are low in carbohydrates but high in fiber. They are also rich in vitamins and minerals that support overall health.

1 cup (220 g) of cooked kale: 2.6g of fiber

1 cup (220 g) of cooked spinach: 4.3g of fiber

Cruciferous Vegetables: Broccoli, cauliflower, and Brussels sprouts are great fiber-rich, low-carb options that can be used in a variety of dishes.

1 cup (220 g) of cooked Brussels sprouts: 3.9g of fiber

1 cup (220 g) of cooked cauliflower: 1.7g of fiber

Avocados: Avocados are not only high in fiber but also provide healthy fats that can help with satiety and inflammation.

½ avocado: 6.75g of fiber

Nuts and Seeds: Almonds, chia seeds, flaxseeds, and pumpkin seeds are excellent sources of fiber with low carbohydrate content.

½ cup of almonds (71g): 8.4g of fiber

½ cup of pumpkin seeds (56g): 6g of fiber

Berries: While fruits generally contain carbohydrates, berries such as raspberries, blackberries, and strawberries are relatively low in carbs and high in fiber.

1 cup (170g) of blueberries: 4g of fiber

1 cup (170g) of blackberries: 8g of fiber

Coconut: Both fresh coconut meat and unsweetened coconut flakes provide fiber without a significant amount of carbohydrates.

1 cup (80g) of coconut: 7g of fiber

Legumes in Moderation: While legumes like lentils and chickpeas contain starchy, complex carbohydrates, they are also very high in fiber. Some legumes are low in net carbs (the fiber content minus the fiber), making them good choices for an anti-inflammatory diet. Consuming the least starchy legumes in moderation can provide fiber benefits without excessive carbs on a low-carb diet.

1 cup (210g) of cooked lentils: 15.6g of fiber

1 cup (177g) of cooked kidney beans: 13.1g of fiber

Stay Hydrated: Drinking plenty of water helps fiber do its job better, aiding in digestion and preventing constipation.

Bottom Line

Aim for 25g of dietary fiber each day. Men, and those with higher body mass, should consume closer to 38g per day. Increasing dietary fiber intake offers a multifaceted approach to managing chronic pain and fatigue. From reducing inflammation and enhancing gut microbiota diversity to potentially alleviating chronic pain, the benefits of a high-fiber diet are substantial. As always, by making simple dietary changes, those with chronic pain and fatigue can take proactive steps toward improving their symptoms and overall quality of life. Dietary fiber is a nutrition topic that isn’t talked about enough, yet most people don’t consume enough. Are you?