Statistics and studies: dietary supplements accelerate healing and reduce hospital costs

IN BRIEF

• Hospital nutritional supplementation interventions (particularly oral nutritional supplements, ONS) are associated with average reductions in length of stay and readmissions in several observational studies and meta-analyses.
• Systematic reviews and economic analyses indicate that the appropriate use of ONS can be cost-effective and reduce expenditure per episode of care. [1]
• The most robust evidence comes from studies on malnourished or at-risk patients: benefits are less clear in unselected populations. [2][3]
• For specific nutrients (e.g., vitamin D), results are mixed: RCTs in critically ill patients have not shown a consistent effect on hospital length of stay, although some sub-analyses are interesting and suggest further research. [5]
• Interpreting the data requires caution: there are differences between observational association and causal proof; clinical context, timing, and nutritional formula modulate the effects.

Abstract: what does science say?

Nutritional supplementation in a hospital setting includes the use of complete oral products (ONS), vitamin and mineral supplementation, and, more generally, nutritional support strategies. The aggregated literature shows that, when the intervention targets malnourished or nutritionally at-risk patients, the use of ONS is associated with reductions in length of stay, a lower probability of complications, and a decrease in readmissions, with potential economic savings. These findings come from meta-analyses and large observational databases that document consistent associations but not always definitive causal proof. For single nutrients (e.g., vitamin D), high-quality RCTs have yielded conflicting results: there is no consensus on a general effect on hospital length of stay, although signals may emerge in well-defined subgroups. In summary, supplementation appears useful if rationally applied in selected subjects; however, it remains essential to distinguish between observational evidence, biological plausibility, and causal proof, and to promote controlled studies that evaluate clinical outcomes and costs.

Main section

Definition and scope

"Dietary supplements" in a hospital setting refer to nutritional products formulated to supplement ordinary nutrition: from high-energy and protein drinks (ONS) to vitamin or single micronutrient supplements. Their use can be temporary (during hospitalization) or extended to the post-discharge period. The primary clinical objective is to correct or prevent malnutrition, improve treatment response, and accelerate functional recovery. The context includes surgical patients, frail elderly individuals, people with chronic or acute illnesses that reduce oral intake. The expected effect depends on the nutritional profile of the product (energy, protein, micronutrients), compliance, and the timing of the intervention.

What the available evidence shows

Meta-analyses and reviews indicate that ONS administered to malnourished or at-risk patients can reduce the length of stay by several days, reduce complications, and decrease readmissions, with associated economic benefits. [1][2][3] Results emerge from both RCTs (for selected groups) and analyses of large observational databases using bias control techniques. However, when the population is not selected for nutritional risk, the impact is less consistent. Furthermore, the literature documents differences between products (e.g., standard ONS vs. formulations enriched with HMB/protein) and between clinical settings (surgery, internal medicine, rehabilitation). [6]

Dependence on dose, frequency, and context

The observed benefits depend on multiple factors: the severity of malnutrition or risk, the timing of supplementation initiation (pre-, peri-, or post-operative), the duration of treatment, and the composition of the formula. Meta-analyses on high-protein ONS show better effects if supplementation is appropriate for protein content and duration. [2] Furthermore, interventions that include nutritional counseling and monitoring show more robust results than the product alone administered without clinical support. The estimated economic savings in analyses are often correlated with a combination of reduced length of stay and fewer readmissions. [1]

PRACTICAL SECTION

What it means in practice

For patients and healthcare providers, the practical points derivable from the evidence are clear but measured: nutritional supplementation is most effective when it targets those at risk (malnutrition, involuntary weight loss, poor food intake) and when it is part of an organized care pathway. Studies on large databases and systematic reviews indicate associations with an average reduction in length of stay and costs per episode in selected contexts; these results have also been observed in economic analyses that estimate average savings per patient. [1][2] From an operational perspective, this means: implementing early nutritional screening in hospitals, offering ONS when indicated, accompanying supplementation with counseling and monitoring, and planning post-discharge continuity when necessary. It is important to remember that simply taking a product does not guarantee benefits if it is not part of a comprehensive clinical evaluation. [3][6]

KEY POINTS TO REMEMBER

• Hospital nutritional supplementation is supported by evidence showing benefits in malnourished or at-risk patients: shorter length of stay and fewer readmissions in various analyses. [2][3]
• The quality of evidence varies: meta-analyses and RCTs on selected groups are more robust than uncontrolled observational studies. [4]
• Reported economic benefits depend on the healthcare context and the correct clinical application of the intervention. [1]
• For isolated nutrients (e.g., vitamin D), clinical results are heterogeneous: some RCTs have not confirmed reductions in length of stay in the critical population. [5]
• Clinical decisions must be individualized, based on nutritional assessment, and integrated into a multidisciplinary therapeutic pathway.

LIMITATIONS OF EVIDENCE

Difference between observational studies and causal proof

Much of the work showing savings and reductions in length of stay comes from observational analyses of large databases or from heterogeneous studies; such studies detect associations but cannot always demonstrate causality. Even when advanced statistical techniques are used (propensity score, instrumental variables), the possibility of residual confounding remains: for example, patients receiving ONS may have different access to care or socioeconomic differences that influence the outcome. [1][2]

Methodological limitations and context variability

Differences between studies (populations, formulations, duration, measured outcomes) make it difficult to generalize results. Some RCTs on critical populations have not shown significant benefits for outcomes such as length of stay, highlighting the importance of correctly selecting patients and clearly defining the intervention. Furthermore, conflicts of interest and funding from industry companies have been present in some studies: this requires a critical and transparent reading of the works. [5][6]

Need for cautious interpretation

The evidence indicates strong biological plausibility: adequate energy and protein intake supports tissue repair, immune function, and rehabilitation. However, the translation into a uniform reduction in length of stay is not automatic and requires integrated care programs. Well-sized and independent randomized studies are needed that measure both clinical and economic outcomes and clearly define patient selection criteria and supplementation composition. [4][6][7]

Editorial conclusion

The overall assessment of contemporary literature leads to a balanced message: hospital nutritional supplementation, when rationally applied to selected patients and integrated into structured care pathways, is associated with measurable benefits for clinical recovery and healthcare costs. It is not a panacea or a substitute for medical therapy, but a clinical tool that can improve the overall effectiveness of care. Hospital policies should promote early nutritional screening, multidisciplinary nutritional support pathways, and post-discharge continuity when indicated. In terms of research, independent clinical trials are needed to establish optimal thresholds, timings, and compositions of supplementation, as well as transparent economic evaluations. Communication to the public and professionals must remain cautious, clear, and based on the best available evidence.

Editorial note

This article was originally published in a previous version and updated to reflect current scientific literature and guidelines. The update followed editorial and methodological criteria aimed at clarity, transparency, and source verification. The content is for informational and educational purposes; it does not replace clinical judgment or consultation with a healthcare professional. For individual therapeutic decisions, it is necessary to consult your doctor or healthcare team.

SCIENTIFIC RESEARCH

1. Elia M, Normand C, Norman K, Laviano A. A systematic review of the cost and cost effectiveness of using standard oral nutritional supplements in the hospital setting. Clin Nutr. 2016;35(2):370-380. https://doi.org/10.1016/j.clnu.2015.05.010
2. Cawood AL, Elia M, Freeman R, Stratton RJ. Systematic review and meta-analysis of the effects of high-protein oral nutritional supplements on healthcare use. Proc Nutr Soc. 2008;67(Suppl):E118. https://doi.org/10.1017/S0029665100591034
3. Milne AC, Avenell A, Potter J. Meta-analysis: protein and energy supplementation in older people. Ann Intern Med. 2006;144(1):37-48. https://doi.org/10.7326/0003-4819-144-1-200601030-00008
4. Beck AM, et al. A systematic review and meta-analysis of the impact of oral nutritional supplements on hospital readmissions. Ageing Res Rev. 2013;12(4):884-897. https://doi.org/10.1016/j.arr.2013.07.002
5. Amrein K, Schnedl C, Holl A, et al. Effect of high‑dose vitamin D3 on hospital length of stay in critically ill patients with vitamin D deficiency: the VITdAL‑ICU randomized clinical trial. JAMA. 2014;312(15):1520–1530. https://doi.org/10.1001/jama.2014.13204
6. Loman BR, Luo M, Baggs GE, et al. Specialized high‑protein oral nutrition supplement improves home nutrient intake of malnourished older adults without decreasing usual food intake. JPEN J Parenter Enteral Nutr. 2019;43(6):794-802. https://doi.org/10.1002/jpen.1467
7. Jhee JH, et al. The effects of oral nutritional supplements in patients with maintenance dialysis therapy: a systematic review and meta-analysis of randomized clinical trials. PLoS One. 2018;13(9):e0203706. https://doi.org/10.1371/journal.pone.0203706
8. Study on specialized ONS and handgrip strength (randomized clinical trial). Clin Nutr. 2020; (see DOI). https://doi.org/10.1016/j.clnu.2020.08.035
9. Philipson TJ, Thornton Snider J, Lakdawalla D, Stryckman B, Goldman D. Impact of oral nutritional supplementation on hospital outcomes. American Journal of Managed Care. 2013;19(2):121-128. [DOI not available/publication on AJMC; cited for historical reference and context of data presented in literature].