A liquid diet is a diet that mostly consists of liquids, or soft foods that melt at room temperature (such as gelatin and ice cream). A liquid diet usually helps provide sufficient hydration, helps maintain electrolyte balance, and is often prescribed for people when solid food diets are not recommended, such as for people who suffer with gastrointestinal illness or damage, or before or after certain types of medical tests or surgeries involving the mouth or the digestive tract.
A more substantial alternative to liquid diets is the mechanical soft diet, which accepts all types of liquids plus puréed or softened solid foods, such as overcooked pasta, scrambled eggs, bananas and cheesecake. For people who cannot swallow at all, a liquid diet may be delivered to the stomach or intestines through a feeding tube instead. When food cannot be delivered to the digestive tract, e.g., if the digestive tract needs to be empty in preparation for gastrointestinal surgery, then parenteral nutrition (nutrients by intravenous infusion) is the primary choice.
Types
Clear
A clear liquid diet, sometimes called a surgical liquid diet because of its perioperative uses, consists of a diet containing exclusively transparent liquid foods that do not contain any solid particulates. This includes vegetable broth, bouillon (excepting any particulate dregs), clear fruit juices such as filtered apple juice, clear fruit ices or popsicles, clear gelatin desserts, and certain carbonated drinks such as ginger-ale and seltzer water. It excludes all drinks containing milk, but may accept tea or coffee.
Typically, this diet contains about 500 calories per day, which is too little food energy for long-term use.
If a clear liquid diet is undertaken for the purpose of an endoscopy or colonoscopy, then fruit juices or other liquids that are colored red or purple are strongly discouraged, as they can easily be mistaken for blood in the digestive tract.
Full
A full or strained liquid diet consists of both clear and opaque liquid foods with a smooth consistency.
It includes milk, milkshakes, cocoa, coffee, teas, plain ice cream (ice cream that does not contain pieces of fruit, chocolate, or candy), smooth plain milk or dark chocolate (allowed to melt in the mouth), certain custard desserts, gelatins and puddings absent of coconut or other inclusions or toppings, strained cream soups, fruit nectar with or without pulp, coconut water or coconut milk without pulp or bits of coconut flesh, smooth cooked cereal such as cream of wheat (oatmeal is best avoided due to it having a larger fiber content), butter, and honey.
Water should mostly be consumed as thirst suggests, although it contains no nutrients. Patients who follow this diet may also take liquid vitamin supplements.
Some individuals who are told to follow a full-liquid diet are additionally permitted certain components of a mechanical soft diet, such as strained meats, sour cream, cottage cheese, ricotta, yogurt, mashed vegetables or fruits, etc.
Lactose-free
A lactose-free diet is a liquid diet that is specialized in not having foods that may have milk or cheese in it. It is usually only prescribed to people who may be lactose intolerant. It only differs from a full liquid diet in that it usually omits ice cream (including sherbet, but not milk-free sorbet), yogurt, cheese, certain creams, and any pre-made/pre-packaged foods that may contain milk or cheese.
Low-fiber
A low-fiber liquid diet is a diet that requires avoiding or lowering foods that may contain large amounts of fiber. This diet is usually used for people suffering from certain digestive problems such as Inflammatory bowel disease. Common foods omitted from this diet are cooked cereals (such as cream of wheat), oatmeal, and certain fruit or vegetable mushes.
Controversies
There are a few controversies associated with these types of diets, one being that they may contain too little important food sources to provide adequate nutrient or caloric intake, and cannot be used for a prolonged period of time. This is mostly associated with the lactose-free liquid diet, as it omits milk, a liquid high in calories, protein, and calcium. Another is that they may contain too little fiber, and could cause certain bowel disorders such as constipation. Liquid diets could also, in certain circumstances, provide electrolyte imbalances that could affect heart rhythm.
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