Slag-free diet

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Robert Maurer

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The following indications are for informational purposes EXCLUSIVELY and are not intended to replace the opinion of professionals such as a doctor, nutritionist or dietician, whose intervention is necessary for the prescription and composition of PERSONALIZED food therapies.


What is the slag-free diet?

Slag-free diet is a misnomer used to refer to the low-residue or low-fiber diet.

Slag: dietary fiber

Dietary fiber is a set of purely vegetable molecules, partly also contained in mushrooms, which cannot be digested by humans.

The fibers can also have very different chemical-physical characteristics; for example, some are soluble in water, while others remain as they are. A fraction of the solubles is also called viscous, due to the typically mucilaginous form it takes when dissolving in water. Insoluble fibers, on the other hand, tend to ferment, significantly increasing fecal volumes.
Fibers are very important nutritional factors, as they perform tasks that are very useful for the body:

  • Increased satiety and reduced energy intake with food;
  • Regulation of intestinal peristalsis: the insoluble ones tend to increase, due to the distension reflex, the contraction (of segmentation and advancement) of the smooth muscles of the colon;
  • Slowing of the absorption of sugars, with consequent reduction of the glycemic index and the surge in insulin;
  • Modulation and reduction of the absorption of lipids and bile acids; the most evident effect is visible on cholesterol, which tends to decrease;
  • In general, caloric reduction and positive action on metabolism, with a reduction in the risks associated with diabetes, metabolic pathologies and cardio-vascular diseases;
  • Cleaning of the intestinal lumen from toxic compounds (for example, the residues of food carbonization) and prevention of some types of cancer;
  • Prebiotic action: some fibers are the "favorite food" of the good bacteria that colonize the intestine. It is known that the physiological flora is responsible not only for intestinal homeostasis but also for the production of certain vitamins and immune support.

Note: carbohydrates NOT available (nutritional factors with a marked prebiotic function) can support the beneficial bacterial colonies of the intestine without, however, excessively and mechanically stimulate peristalsis (similar to viscous soluble fibers).


Main features of the slag-free diet

The slag-free diet is a very low-fiber diet; consequently, it is poor in foods of plant origin that are part of:

  • III fundamental group of foods: cereals, tubers and derivatives
  • IV fundamental group of foods: starchy legumes and derivatives
  • VI and VII fundamental group of foods: fruits and vegetables rich in vitamins A and C
  • Oil seeds: walnuts, hazelnuts, almonds, pine nuts, pistachios, pecans, Brazil nuts, macadamia, peanuts etc.
  • Bran and dietary fiber supplements.

Ancillary features of the slag-free diet

In addition to the very low concentration of fiber, the slag-free diet can benefit from additional measures such as:

  • Low concentration of lactose and lactulose (resulting from heating the milk)
  • Total absence of non-tolerated molecules (food intolerances and allergies, drugs, supplements, etc.)
  • Lowest possible concentration of toxic or irritating molecules (polycyclic aromatic hydrocarbons, acrolein, acrylamide etc.)
  • Absence of aggressive spices for the intestinal mucosa (black pepper, chilli, coriander, cumin, turmeric, curry, ginger, wasabi, etc.)
  • Use of delicate cooking methods, total but not excessively prolonged and intense
  • Prevalence of highly digestible foods
  • Prevalence of foods that are well chewable and free of wood waste, such as seeds.


Practical interventions

First of all, you need to reduce the portions and the frequency of consumption of the foods rich in fiber described in the previous chapters. Furthermore, the parts without insoluble fibers and seeds should be preferred. They are vegetables poorer in fiber than the average of the SAME group:

  • Refined cereals, flours and white derivatives
  • PASTE legumes with the vegetable pass (NOT smoothies) - however not recommended
  • Peeled and deprived fruits and vegetables; better squeezed, extracted or centrifuged
  • Raw leafy vegetables instead of cooked ones (to reduce portions); even if cooking offers the advantage of pre-digesting the fibers, reducing the effects of abdominal distension, bloating, bloating, flatulence and diarrhea.

Other precautions necessary for the proper functioning of the slag-free diet are:

  • Avoid milk, especially hot milk, which can be substituted for yogurt
  • Drink a lot of water, to compensate for the liquids not taken with fruit, vegetables and first courses
  • Progressive reintroduction of fiber in the diet
  • Do not eat foods that contain ≥ 1g of fiber per serving
  • Always consult the nutrition labels of processed foods, making sure they contain less than 1g of fiber per serving
  • If considered useful, make use of probiotic supplements; it is advisable to pay close attention as in some cases they can make the situation worse.


When is the slag-free diet necessary?

Although dietary fibers are very useful for the correct functioning of the organism, sometimes, for exceptional reasons and health, it is necessary to reduce them as much as possible or select them ensuring only the viscous soluble fraction. This need may vary according to the specific case and it would not be correct to generalize too much the specific nutritional interventions of the slag-free diet; however, hoping not to be excessively approximate, we can define that the slag-free diet finds application above all in the following cases:

Acute diarrhea

Chronic diarrhea

Unleashed by

  • bacterial, viral, protozoal or other parasitic infections,
  • microbiological or chemical poisoning,
  • food intolerance and allergy (such as lactose, gluten, nickel, etc.),
  • anxious emotional states,
  • certain drugs (antibiotics but not only),
  • laxatives,
  • intestinal radioactive therapy,
  • preparations for endoscopic diagnostic investigations of the intestinal tract (e.g. colonoscopy)

Provoked by

  • intestinal diseases, often of an inflammatory and autoimmune nature, such as Crohn's disease and ulcerative rectal colitis, or irritable bowel syndrome with a tendency to diarrhea,
  • drugs (antibiotics),
  • celiac disease (untreated celiac disease with intestinal complications),
  • intestinal resection (for cancer, Crohn's disease, ulcerative colitis, heart attack, parasitosis, etc.)


Useful supplements in the slag-free diet

The supplements potentially useful in the slag-free diet are those that compensate for diarrheal discharges and provide the typical nutrients of vegetables; particularly:

  • Vitamins: vitamin C, carotenoids (especially beta-carotene, lycopene, etc.), vitamin K, folic acid
  • Minerals: in particular magnesium, but also potassium.

Probiotic sources may also be useful, possibly fortified with specific NON-fibrous prebiotics (such as certain resistant polysaccharides), which help restore homeostasis of physiological bacterial flora.

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