Liquid food is an important part of nutritional therapy. In medicine, it is mostly used to prevent or treat malnutrition because it usually contains a lot of calories. Liquid food is also used in the treatment of inflammatory bowel diseases (IBD) by providing additional calories to one’s diet.
When is liquid food used?
Liquid food is used when patients have an increased need for nutrients. If the patient is malnourished or has a chewing or swallowing disorder, they can resort to liquid food. There is also low-calorie liquid food that is used as a meal replacement for losing weight, although such low-calorie liquid food is rather insignificant in the medical context.
Therapy with liquid food may be necessary in the following situations or with the following clinical diagnoses:
- Serious infections and injuries
- Chewing and swallowing disorders
- After surgery
- Inflammatory bowel disease
- Short bowel syndrome
- Metabolic diseases
- Multiple food allergies
- Chronic liver disease
- Renal insufficiency
Chronic inflammatory bowel diseases such as Crohn's disease often lead to patients being underweight and lacking nutrients. Nutritional therapy with liquid food can even be recommended with severe ulcerative colitis.
Did you know? The first liquid food was developed for space travel, which is why it’s colloquially known as “astronaut food.” Since then, liquid food has undergone major changes and been adapted to various medical requirements.
Why is liquid food used for IBD?
Acute IBD flare-ups are often accompanied by loss of appetite, pain, and severe diarrhea. As a result, many sufferers consume less food, and the absorption of nutrients in the intestine is reduced. At the same time, the acute metabolic rate increases the basal metabolic rate, and more energy is used.
Being underweight and malnutrition are therefore major problems with inflammatory bowel diseases, especially Crohn's disease. As a result, some IBD patients consume liquid food.
Depending on the course of the disease, deficiency symptoms can also occur. Vitamin B12, folic acid, and zinc in particular are often lacking. With severe diarrhea, there may also be a lack of potassium, magnesium, calcium and phosphate. Vitamin D deficiency is also common. Growth delays can occur as a result of malnutrition, especially in children. The risk of developing osteoporosis is increased in older patients.
How does liquid food affect the course of the disease?
Studies have shown that nutritional therapy can support the healing process with Crohn's disease and can extend symptom-free phases (so-called remission phases). No effects on the healing process and maintenance of remission were found for patients with ulcerative colitis. In both cases, nutritional therapy should be given if being underweight or malnutrition lead to complications.
When is liquid food prescribed?
The normal diet is first adjusted before liquid food is prescribed. It should meet the special nutritional requirements of the respective disease. If a corresponding adjustment of the diet is not possible or does not achieve the desired effect, liquid food is then used as the next measure.
Before liquid food is prescribed, the patient's personal nutritional needs have to be determined. If the needs are slightly higher, so-called normocaloric liquid food is used. This contains about as many calories as normal food. If the need for energy is greatly increased, high-calorie liquid food is prescribed.
With some clinical pictures, the nutrients are tailored specifically to the disease. Depending on the condition, liquid food is prescribed in addition to the normal diet or the diet is completely switched to liquid food.
How many calories are in liquid food?
Depending on the number of calories per milliliter, a distinction is made between low-calorie, normocaloric and high-calorie liquid food. They contain the following energy density:
- Low-calorie: up to 0.9 kcal/ml
- Normocaloric: 1 kcal/ml
- High-calorie: more than 1.1 kcal/ml
There is also very high-calorie liquid food with up to 5 kcal/ml, which is offered in 120 ml bottles. That means a total of 600 calories is already consumed with one bottle. For comparison: The same amount of orange juice has an energy content of 48 calories. Even vanilla ice cream only has around 165 calories per 120 ml. In order to gain weight, an additional 1,000 calories are often planned in per day. This allows an average patient to gain one kilogram of weight per week.
Most of the energy is consumed in the form of fat. Many products contain medium-chain fatty acids (MCT) so that the large amounts of fat do not burden the gut. The body can absorb these relatively easily.
What are alternatives to liquid food?
With liquid food, patients continue to receive nutrition naturally, namely through the mouth, throat, and gastrointestinal tract. If this is not possible, the patient often receives their calorie intake via a gastric tube (enteral nutrition). In most cases, a tube is placed into the stomach via the nose (transnasal). The natural route of food via the gastrointestinal tract (enteral route) is largely preserved. Only the mouth and throat are left out.
Enteral nutrition brings food into the body that has already been broken down into its components. The nutrients can be completely absorbed in the upper part of the intestine and the rest of the digestive system is relieved, making it particularly easy for patients to consume this food.
When is liquid food recommended and when is a gastric tube recommended?
Nutritional therapy helps to maintain a normal body weight and to provide the body with sufficient nutrients. If solid food cannot adequately meet one’s energy requirements with inflammatory bowel diseases, liquid food or feeding via a gastric tube are options.
When additional energy intake of less than 600 calories per day is required, liquid food is used. With additional energy of more than 600 calories per day is needed, feeding via a gastric tube is usually best.
Which liquid food is recommended for IBD?
Currently, high-molecular liquid food is usually recommended so as not to suppress the digestive work of the intestine. “High molecular” means that the food components have not yet been broken down. Many suppliers of special liquid foods for inflammatory bowel diseases also offer low-molecular preparations. In these products, the nutrients are already broken down into their components.
There are also other preparations with a high proportion of medium-chain fatty acids that the body can easily absorb. In addition, some preparations contain anti-inflammatory additives such as glutamine or TGF-beta. However, studies have so far been unable to find any noteworthy benefits of such a composition.
Being underweight can have many causes. The liquid food that should be used in this case depends on the cause. However, if liquid food is used exclusively to gain weight, all high-calorie medical liquid food products are generally suitable.
Does low-calorie liquid food help you lose weight?
In obese patients, the use of low-calorie liquid food for weight loss is being tested. However, implementation often fails because chewing is part of enjoying a meal. Many affected people do not want to do without chewing in the long term. Chewing also promotes satiety and controls eating behavior. If you only consume liquid food and don’t measure it exactly, you can end up consuming more food and still feel hungry.
What types of liquid food are there?
As the name suggests, liquid food has a liquid or slightly mushy form or is mixed as a powder with some liquid. Proteins, carbohydrates, fats, and micronutrients are contained according to the nutritional requirements. Typical ingredients include water or milk, cooking oil, modified starch, hydrolyzed protein, artificial vitamins, minerals, trace elements, colorings, and preservatives.
What liquid food flavors are there?
Savory liquid food tastes a bit like soup. These usually contain ingredients such as pureed vegetables, which are often used in soups. However, the taste experience cannot be compared to a fresh soup.
Many people prefer sweet liquid food. It is easier to create a normal taste experience with this kind of liquid food because many sweet foods such as ice cream, pudding, and fruit yoghurt already have a slightly liquid consistency. Sugar is also a good source of energy. The taste of sweet liquid food is usually fruity or milky, and popular varieties include chocolate, vanilla, and strawberry.
Where can you buy liquid food?
Liquid food is available in various drugstores and supermarkets. When buying, you should make sure that it is a medical product that is tailored to your personal needs.
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