Cancer patients are among the most vulnerable to malnutrition. It is estimated that it may affect up to 30-85% of patients. In 5-20%, cachexia may be the direct cause of death in the terminal stage of the disease. Proper nutritional management is therefore closely related to the effectiveness and success of treatment . How to support the patient in nutritional treatment? Are there any preparations that can reduce the risk of malnutrition?
Table of content:
- What is ONS?
- Classification of oral food supplements
- Overview of ONS preparations available on the Polish market
- Advantages of using ONS in the diet
- Usage of ONS in nutrition
- Gastrointestinal complaints that may occur when using ONS
What is ONS?
Oral food supplements, abbreviated as ONS, are food for special medical purposes. They are used in oncological nutrition. The main indication for their use is malnutrition and the risk of its development . They can contain all nutrients or selected elements. They are available in the form of finished products in the form of liquid solutions, powders, or tablets.
ONS easily provide the right amount of energy, macronutrients, vitamins, and minerals, the deficiencies of which are observed in over 70% of oncological patients. Unfortunately, in Poland, unlike Western European countries and some Central European countries, these preparations are not reimbursed .
Classification of oral food supplements
There are many classifications of oral nutritional supplements:
Depending on the composition:
- Complete preparations, containing all macro- and micro-ingredients
- Incomplete preparations containing one or more ingredients
Depending on the calorific value:
- Hypocaloric < 1 kcal/ml
- Isocaloric approx. 1 kcal/ml
- Hypercaloric > 1 kcal/ml
Depending on the energy and protein values:
- High energy, with increased fat content > 30%
- High protein, containing 20-25% and approx. 7-8g/100ml of diet
Depending on the degree of protein hydrolysis:
- Polymeric-whole protein molecules
- Oligomeric (peptide)-peptide chains up to 50 amino acids
- Monomeric (elementary)-single amino acids
Depending on the application:
- Intended for use in specific diseases (kidney, liver, diabetes, etc.)
- Intended for use in specific clinical situations (dysphagia, malabsorption syndrome, etc.) 
Overview of ONS preparations available on the Polish market
- Nutridrink – complete, hypercaloric, polymeric, residue-free, available in four flavors: neutral, vanilla, strawberry, forest fruit.
- Nutridrink protein – complete, hypercaloric, polymeric, residue-free, available in four flavors: neutral, vanilla, mocha, peach-mango, strawberry, forest fruit, red fruit, tropical fruit and ginger.
- Nutridrink Protein Omega 3 – complete, hypercaloric, polymeric, low-residue, available in strawberry and apple flavor.
- Nutridrink Yoghurt Style – complete, hypercaloric, polymeric, low-residue, available in raspberry and vanilla flavors.
- Nutridrink Multi Fiber – complete, hypercaloric, polymeric, high-residue, available in strawberry and vanilla flavor.
- Nutridrink Juice Style – fat-free, hypercaloric, polymeric, residue-free, available in strawberry and apple flavor [4,5].
Nestlé Health Science
- Resource 2.0 – complete, high energy, high protein, flavor: pineapple-mango, mint-chocolate, apricot, vanilla.
- Resource 2.0+ Fiber – complete, high-energy, high-protein, high-residue, taste: coffee, forest fruits.
- Resource Protein – complete, high-energy, high-protein, no residue, flavor: chocolate, apricot, strawberry, vanilla, forest fruits.
- Resource Refresh – incomplete, high-energy, normal protein, flavor: peach-mint tea.
- Resource Diabet Plus – complete, high energy, high protein, low glycemic index, flavor: strawberry, vanilla.
- Resource Junior – complete, high-energy, adapted to the needs of children over 1 year old, flavor: vanilla, strawberry, chocolate.
- Isosource Standard – complete, normocaloric, 20% MCT, neutral taste.
- Isosource Standard Fiber – complete, normocaloric, 20% MCT, 3% fiber, neutral taste.
- Isosource Protein – complete, high-calorie, high-protein, 20% MCT, neutral taste [4,6].
- Fresubin Energy Drink – complete, high-energy, high-protein, available in six flavors: strawberry, vanilla, blackcurrant, chocolate, lemon and neutral.
- Fresubin Energy Fiber Drink – complete, high-energy, high-protein, high-residue, available in three flavors: banana, caramel, cherry.
- Fresubin Protein Energy Drink – incomplete, high-energy, high-protein, available in the flavor of chocolate, vanilla, wild strawberry, nut, tropical fruit.
- Supportan Drink – complete, high-energy, high-protein, available in two flavors: cappuccino and tropical fruit .
Advantages of using ONS in the diet
Basic advantages of ONS:
- They are a concentrated source of energy and nutrients in a small volume
- They are convenient to use, they can be eaten alone or as an addition to a meal
- They do not contain potentially harmful substances, i.e., gluten, lactose, purines, cholesterol
- Possibility to choose a preparation adapted to a specific disease, such as low-protein preparations addressed to patients with renal failure
- Packed in a sterile atmosphere, so they are free from any bacteria 
Usage of ONS in nutrition
Oral nutritional supplements do not have to be consumed only as ready-to-drink preparations. Many manufacturers encourage patients to use them when preparing traditional meals. On the Internet, you can find many recipes using ONS, both sweet and savory. Liquid preparations can be used, e.g., for preparing various cocktails, whitening soups or diversifying curd pastes, and ONS in powder when baking. Loss of appetite and changes in taste and smell are very common in cancer patients. As a consequence, the taste of the above preparations will not be acceptable to all of them. By smuggling ONS into classic dishes, there is a chance not only for the patient to consume them, but also to increase the nutritional value of a given meal .
Gastrointestinal complaints that may occur when using ONS
In the case of an improperly selected supplement, patients may experience various side effects such as diarrhea, constipation, nausea, vomiting, heartburn, or flatulence. What’s more, the wrong ONS can increase the patient’s weight loss, worsen his nutritional status and discourage him from eating similar products. So, how do you deal with side effects?
Diarrhea is the most common problem, affecting as many as 60% of patients using ONS preparations. A common mistake contributing to their formation is improper consumption of the product, e.g., too fast or too much. If, despite taking the preparation according to the recommendations, diarrhea still occurs, it is worth trying to mix it with constipating products and administering it at room temperature, not directly from the refrigerator. The final option is to choose a lower osmolarity, isocaloric or low-fat formula.
Things are a bit different when nausea or vomiting occurs. In such a situation, you should try to take chilled products. It is also worth betting on preparations with a neutral taste, based on whey proteins, and low in casein. As in the case of diarrhea, you can try preparations with lower osmolarity or mix it with food products.
When constipation occurs, it is recommended to select ONS with fiber and proper hydration.
Smell and taste disorders as well as anorexia are common problems in cancer patients. In such cases, it is recommended to pick products with a neutral flavor. It is also worth putting the preparation in the form of a powder and trying to mix them with other food products .
Oral food supplements are of great benefit to cancer patients struggling with appetite disorders and nutritional deficiencies. However, it should be remembered that ONS must be selected carefully, considering the patient’s condition, type of cancer, and the presence of comorbidities. It is also critical that the products are consumed according to the manufacturer’s instructions. This will help to avoid the appearance of unwanted side effects.
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