Oral Nutritional Supplements (ONS)

What Are Oral Nutritional Supplements?

Oral Nutritional Supplements (ONS) are specially formulated, nutrientdense products designed to provide additional calories, protein, vitamins, and minerals to individuals who are unable to meet their nutritional requirements through regular food alone. They are typically presented as readytodrink liquids, powders that can be mixed with water or milk, and softserve bars or puddings.

Why They Are Needed

Malnutrition remains a common, often underdiagnosed problem in hospitals, longterm care facilities, and community settings. Factors that can impair adequate intake include:

• Reduced appetite due to disease or medication.
• Difficulty chewing or swallowing (dysphagia).
• Physical limitations that make food preparation challenging.
• Increased metabolic demands from infection, surgery, or trauma.

When these factors lead to a negative energy or protein balance, patients are at higher risk for infection, delayed wound healing, loss of muscle mass, and longer hospital stays. ONS can bridge the gap between dietary intake and nutritional needs.

Types & Common Formulations

ONS products differ in caloric density, protein source, and added nutrients. The most common categories include:

• Standard highcalorie drinks ~1.5kcal/mL, 1015g protein.
• Highprotein drinks 2030g protein per serving, often wheybased.
• Fiberenriched formulas contain soluble or insoluble fiber to aid gastrointestinal health.
• Immunemodulating formulas enriched with arginine, omega3 fatty acids, and nucleotides.
• Diseasesspecific formulas e.g., diabeticfriendly (lowglycemic), renal (restricted potassium/phosphorus), or COPD (higher calorietoprotein ratio).

Choosing the appropriate formulation requires an assessment of the individual's medical condition, taste preferences, and specific nutrient gaps.

Clinical Indications

Guidelines from ESPEN, the American Society for Parenteral and Enteral Nutrition (ASPEN), and local health authorities recommend ONS for:

• Patients identified as atrisk of malnutrition (e.g., MUST score 1).
• Individuals with documented weight loss >5% over 36months.
• Postoperative patients needing extra calories and protein.
• Older adults with frailty, sarcopenia, or chronic disease.
• Patients with conditions that increase metabolic demand (cancer, severe burns, sepsis).

Benefits & Expected Outcomes

When prescribed and adhered to, ONS can deliver measurable improvements:

• Weight stabilization or gain especially important in cachectic states.
• Enhanced muscle mass and strength reducing functional decline.
• Shorter length of stay in acute care settings.
• Reduced infection rates and better wound healing.
• Improved quality of life through better energy levels and reduced fatigue.

Metaanalyses indicate that each additional 400kcal/day of ONS can increase the odds of a positive nutritional outcome by up to 30%.

How to Use & Best Practices

1. Assessment Perform a comprehensive nutrition screening (e.g., MUST, NRS2002).
2. Prescription Tailor the product, dose, and timing to the patients needs.
3. Timing Offer ONS between meals to avoid satiety interference, or between snacks for patients who tolerate frequent small volumes.
4. Monitoring Record intake, weight, and relevant labs weekly for the first month.
5. Adjustment If target intake is not met, consider flavor changes, higherdensity products, or combining oral with enteral feeding.

Education of patients, families, and caregivers is essential. Demonstrating how to mix powders, storing opened containers, and addressing taste preferences can improve adherence.

Contraindications & Precautions

While ONS are generally safe, they are unsuitable in certain situations:

• Severe dysphagia with high aspiration risk consider thickened liquids or enteral feeding.
• Allergy to protein source (e.g., whey, soy, milk).
• Uncontrolled diabetes when using highsugar formulas opt for diabeticfriendly versions.
• Renal failure with strict potassium/phosphorus limits use renalspecific formulas.

Always review medication interactions (e.g., thiaminerich formulas with certain diuretics) and monitor electrolytes when highvolume ONS are used.

Cost, Reimbursement & Access

ONS are considered medical nutrition therapy in many health systems. Reimbursement policies differ:

• In the United States, Medicare Part B covers ONS for patients with a documented medical need and a physicians order.
• European countries often fund ONS through national health services when indicated by a dietitian.
• For private payers, bulk purchasing programs and manufacturer assistance programs can reduce outofpocket expenses.

Costeffectiveness analyses have demonstrated savings from reduced hospital readmissions and shorter acutecare stays that offset the price of the supplements.

Frequently Asked Questions

How many servings per day are typical?

Most protocols start with 12 servings (200400mL each) per day, providing 300800kcal and 1030g protein. The exact number is individualized.

Can ONS replace regular meals?

No. ONS are meant to supplement, not substitute, a varied diet. They are most effective when used in addition to regular meals.

What if a patient dislikes the taste?

Many brands offer multiple flavors. Mixing powder with flavored beverages (e.g., lowfat milk, fruit juice) can improve acceptability. Switching to a different texture (e.g., puddingstyle) may also help.

Is there a risk of overfeeding?

Yes, especially in patients with reduced mobility or renal impairment. Regular monitoring of weight, fluid balance, and lab values helps prevent excess caloric or fluid intake.

Can ONS be used in children?

Specific pediatric formulas exist, but adulttype ONS are not appropriate for children without specialist guidance.

References

1. ESPEN guideline on clinical nutrition in the adult hospital setting. Clin Nutr. 2022.

2. Avenell A, et al. Oral nutritional supplements for older people. Cochrane Database Syst Rev. 2021.

3. ASPEN Clinical Guidelines for Nutrition Support Therapy. 2023.

4. Stratton RJ, et al. Nutritional status and outcomes in patients undergoing surgery. JAMA Surg. 2020.

5. Milkman J, et al. Costeffectiveness of oral nutrition supplements. Health Econ. 2021.