Fiber plays an essential role in maintaining a healthy digestive system, supporting blood sugar regulation, reducing bad cholesterol, controlling weight, and preventing many chronic diseases. The World Health Organization (WHO) recommends adults consume at least 400 g of fruits and vegetables daily, with a fiber intake of 25 g or more daily, depending on age and gender.

Doctor Tran Thi Tra Phuong, from the Department of Nutrition at Tam Anh General Hospital Hanoi, highlights the adverse effects of fiber deficiency.

Constipation

Fiber retains water in the intestines and supports effective bowel movements. With insufficient fiber, stool can become dry and hard, leading to prolonged transit time in the colon and an increased risk of constipation. This persistent condition causes discomfort and raises the risk of hemorrhoids or colorectal issues.

Doctor Tra Phuong advises on a diet that meets daily fiber needs for adults. *Photo: Tam Anh General Hospital*.

Frequent hunger

Soluble fiber absorbs water, forming a gel in the digestive tract. This slows gastric emptying and prolongs the feeling of fullness after meals. When fiber is lacking, food is digested quickly, leading to earlier hunger, increased snacking, and difficulty controlling daily calorie intake.

This partly explains why low-fiber diets are often linked to an increased risk of weight gain and obesity. Fiber-rich foods, such as green vegetables, fruits, legumes, and whole grains, typically have a low energy density but promote satiety. Conversely, refined and processed foods often contain less fiber but are high in calories, fat, and sugar.

Increased risk of diabetes

When consuming carbohydrate-containing foods, fiber helps slow the absorption of sugar into the bloodstream. If the body lacks fiber, blood sugar levels tend to rise quickly after meals and then drop suddenly. This can lead to feelings of fatigue, drowsiness, or hunger shortly after eating. A low-fiber diet is associated with a higher risk of type 2 diabetes.

Cholesterol imbalance

Soluble fiber helps reduce bad cholesterol by limiting its absorption in the intestines. When dietary fiber is insufficient, the body loses one of its natural mechanisms for cholesterol control.

Declining gut health

Trillions of bacteria residing in the digestive tract use fiber as a nutrient source to produce short-chain fatty acids, which are compounds that nourish intestinal cells. With prolonged fiber deficiency, the diversity of the gut microbiome declines, impacting digestive and metabolic health.

Everyone should increase their daily intake of green vegetables, whole fruits, legumes, nuts, and whole grains to ensure adequate fiber. This increase should be gradual and accompanied by sufficient water intake to allow the digestive system to adapt well.

Thuy Hanh