In case of acute and chronic illness nutritional problems are widespread, and a reduced dietary intake in combination with effects of catabolic disease rapidly lead to malnutrition. A high prevalence of protein energy malnutrition in patients has been reported. A close relation between malnutrition and re-admission rate, cost of hospital care in terms of length of stay in hospital as well as mortality has been documented. A Cochrane review of the use of oral nutritional supplementation suggested that oral nutrition not only provided nutrients, but also has significant improvements on psychological and social functions, possibly through enhancing sensation of taste and flavor which is an important mediator of pleasure and well-being. Therefore, an oral option of nutrition is always considered as the first choice of nutritional intervention, in particular in situations where nutritional interventions, such as assisted feeding, are difficult, time-consuming and demanding due to advanced morbidity and slow responses. In this randomized controlled trial, the investigators will explore the gaps of nutritional needs and the potential use of nutrition supplementation in the management of malnutrition among patients in Hong Kong. The investigators aim to improve the nutrient intakes and the nutritional status of participants through a specially formulated oral nutrition supplement titled "Fresubin® Powder Fibre" to reverse malnutrition status due to acute and chronic illness. Fresubin® Powder Fibre is a nutritionally complete powder product to be reconstituted in different caloric densities (1.0 to 1.5 kcal/ml) and containing high quality protein and vitamin D for the dietary management of participants with or at the risk of malnutrition.

Inclusion Criteria:

• Chinese origin aged 18 or above
• Normally reside in Hong Kong
• Could speak and understand Chinese
• Being screened as malnourished or at risk of malnutrition using the Mini Nutritional Assessment-Short Form (MNA-SF) with a score at 11 or below
• Willing to follow the study procedures
• Written informed consent form

Exclusion Criteria:

• Recent (i.e. past 3 months) or concurrent participation in any clinical trial or dietary intervention program
• Self-reported allergy or intolerance to the ingredients of the nutrition supplement
• Consumption of additional ONS, tube feeding or parenteral nutrition
• Use of medications (Amphetamine and its derivatives, Levothyroxine, Biguanides) that could affect study outcomes
• With cancer conditions that are currently undergoing treatment
• Poorly controlled or unstable chronic obstructive pulmonary disease
• Poorly controlled or unstable cardiovascular disease or diabetes or hypertension
• Recent unhealed bone fracture (within the past 12 months)
• Existing gastrointestinal (GI) diseases or pathological findings, which do not allow enteral feeding, e.g. intestinal atony, ileus, acute upper GI bleeding, shock, or malabsorption, e.g. inflammatory bowel disease, pancreatic disease, or previous surgical GI resection
• Severely impaired gastrointestinal function, i.e. severe constipation or acute diarrhea (≥ 3 loose or watery stools per day)
• Dysphagia or high aspiration risk
• Long-term bedridden
• Liver failure or severe renal insufficiency (i.e. significant renal impairment at eGFR of <30 ml/min, or significant liver impairment as indicated by ALT>100 or history of liver cirrhosis) in the past 3 months before enrollment
• Relevant central nervous system and/or psychiatric disorders, i.e. Stroke, Alzheimer's disease, Parkinson's disease, traumatic brain injury, depression or other mood disorders
• Planned surgery or hospitalization during study period
• With any other indication of a major medical or psychological illness, as judged by the investigators as ineligible to participate the study