Oral Nutritional Supplements (ONS)

What Are Oral Nutritional Supplements?

Oral Nutritional Supplements (ONS) are commercially prepared, nutrientdense drinks, powders, or snacktype products designed to provide additional calories, protein, vitamins, and minerals to individuals who cannot meet their nutritional needs through regular food alone. They are used as part of a comprehensive nutrition care plan, especially for patients at risk of or experiencing malnutrition.

Why ONS Are Needed

Malnutrition can develop quickly in clinical and community settings. Common risk factors include:

• Acute or chronic illness (cancer, COPD, heart failure, stroke)
• Reduced appetite or taste changes
• Dysphagia or other swallowing difficulties
• Increased metabolic demands
• Limited access to nutritious foods

When intake of essential nutrients falls below requirements, patients may experience weight loss, weakened immunity, delayed wound healing, and prolonged hospital stays. ONS can bridge the gap, improve clinical outcomes, and reduce healthcare costs.

Key Components of ONS

Most ONS formulas contain a balanced mix of the following:

• Energy: Typically 150400 kcal per serving, provided as carbohydrates and fats.
• Protein: 1020g per serving, often from highquality whey, casein, soy, or pea protein.
• Micronutrients: Vitamin A, Bcomplex, C, D, E, K, and essential minerals such as calcium, magnesium, zinc, and iron.
• Fiber: Soluble and insoluble fibers to support gut health.
• Flavor enhancers: Natural or artificial flavors, sweeteners, and thickeners to improve palatability.

Types of ONS

ONS are formulated for specific clinical needs:

• Standard highcalorie, highprotein formulas: General use for patients needing extra energy and protein.
• Immunemodulating formulas: Contain arginine, omega3 fatty acids, and nucleotides; beneficial for surgical or trauma patients.
• Renalspecific formulas: Lower in potassium, phosphorus, and protein to suit chronic kidney disease.
• Diabetic formulas: Reduced carbohydrate load and added fiber to help control blood glucose.
• Fiberenriched formulas: Target constipation or guthealth issues.
• Texturemodified options: Thickened liquids or pureed textures for dysphagia.

How to Prescribe ONS

Effective use of ONS follows a systematic approach:

1. Screen for malnutrition: Use tools such as the Malnutrition Universal Screening Tool (MUST) or the Subjective Global Assessment (SGA).
2. Assess needs: Determine energy and protein deficits based on weight loss, disease state, and activity level.
3. Select formula: Match the clinical profile (e.g., diabetes, renal disease) with the appropriate product.
4. Determine dosage: Typically 12 servings per day, delivering 300800kcal and 2040g protein.
5. Monitor and adjust: Reevaluate weight, intake, laboratory markers, and tolerance every 12 weeks.

Practical Tips for Successful Use

• Incorporate into routine: Offer the supplement at a consistent time (e.g., between meals) to avoid satiety interference.
• Flavor rotation: Alternate flavors to prevent taste fatigue.
• Temperature preference: Many patients prefer chilled drinks; some formulas can be warmed.
• Address barriers: Identify and resolve issues such as nausea, constipation, or cost.
• Education: Explain the purpose and benefits to patients and caregivers.

Evidence of Effectiveness

Numerous studies demonstrate that ONS can:

• Increase energy and protein intake by 3050%.
• Reduce weight loss and promote leanmass gain.
• Lower infection rates and readmission risk in hospitalized patients.
• Improve quality of life scores in communitydwelling older adults.

For a detailed review, see the metaanalysis by Stratton etal., Clinical Nutrition (2022).

Potential Side Effects and Precautions

ONS are generally safe, but clinicians should watch for:

• Gastrointestinal discomfort (bloating, diarrhea, constipation).
• Excessive calorie intake leading to unwanted weight gain in less catabolic patients.
• Allergic reactions to dairy, soy, or other ingredients.
• Interactions with certain medications (e.g., high calcium affecting bisphosphonate absorption).

If side effects appear, consider adjusting the formula, changing the serving size, or trying a different texture.

CostEffectiveness

When ONS prevent complications, they offset the higher price of the product. Many health systems provide reimbursement through nutrition therapy codes, and some manufacturers offer patientassistance programs.

Key Takeaways

• ONS are an evidencebased intervention for patients who cannot meet nutrient needs through food alone.
• Selection should be individualized based on disease state, dietary restrictions, and patient preferences.
• Regular monitoring ensures effectiveness and allows timely adjustments.
• When used correctly, ONS improve clinical outcomes, shorten hospital stays, and enhance quality of life.

Further Reading & Resources

• Academy of Nutrition and Dietetics Eatright.org
• European Society for Clinical Nutrition and Metabolism (ESPEN) Guidelines
• American Society for Parenteral and Enteral Nutrition (ASPEN) Clinical Guidelines