Even though eating the recommended amount of fibre helps prevent diabetes, if you have long-standing diabetes (usually over 10 years), your stomach can become less effective at emptying due to a condition known as ‘gastroparesis’. This occurs because of damage to the vagus nerve. Symptoms include heartburn, reflux, bloating, abdominal pain, nausea or vomiting. In this instance, adding too much soluble fibre (especially in the form of supplements) can worsen these symptoms so please go especially slowly and pay attention to how you feel during and after meals. In a worst-case scenario, undigested food and fibre can coalesce to form a hardened lump called a ‘bezoar’ that blocks food from leaving the stomach and causes an exacerbation of the symptoms listed above. It is similar to a hairball in cats but is a ‘fibre ball’ in humans. There are various ways to treat a bezoar but prevention is always better than cure.
Similarly, if you have IBS (irritable bowel syndrome), diverticular disease, Crohn’s disease, ulcerative collitis or colon cancer, fibre may irritate your condition at certain stages of the illness so please follow your doctor’s advice if you have been told to decrease your fibre intake.
Regardless of your state of health, if you eat more than 60 grams of fibre a day, there is a risk that you will reduce absorption of minerals such as iron, zinc, and calcium. This occurs because the fibre can bind to the minerals to form insoluble salts that are excreted in your stools.
Goldilocks got it right again.