need to either refine study protocols or confirm the effectiveness of nutritional approaches in lessening the health outcomes of TBI. Because of the paucity of data about the efficacy of most of the nutrition approaches reviewed, the committee thought it premature to direct DoD to adopt any of them at this time. For some approaches for which enough preclinical and, in some cases, clinical data exist the committee sees the potential benefits and reached consensus about research needed in some promising areas. The research recommended will serve to confirm published results and to refine the protocols (i.e., optimal route of administration, timing, and dose). There is even less data being generated about the effectiveness of nutritional interventions in combination, either with one another or with other forms of treatment. Investigating the synergistic or antagonistic effects of nutrients is an important area of research for the future. However, there are more pressing areas to investigate that are highlighted below.
It is important to note that, as requested in the statement of task, this report has reviewed nutritional interventions only for primary (i.e., acute) and secondary (i.e., subacute) effects. The effects of TBI are conceptually categorized as primary, secondary, and long-term effects, based on the amount of time elapsed since the injury; but in reality, the boundaries of these definitions are ambiguous. For example, the impact of some of the early pathogenic events related to cell death may linger in the more chronically injured brain, into the time when there is upregulation of growth factors linked to plasticity and ongoing angiogenesis. Moreover, events such as angiogenesis, typically associated with wound healing, are initiated within the more acutely injured brain. Because of these challenges, this report includes, in addition to acute effects, some studies that also evaluate outcomes that are seemingly long-term but that might be initiated in the acute phase of the disease. This report does not address other outcomes such as neurodegenerative (e.g., Alzheimer’s disease, Parkinson’s disease), neuroendocrine, psychiatric, and other nonneurological disorders that appear later in life and for which a causal relationship with the original injury has not been clearly established.
The report is limited in that it did not evaluate the role of nutritional therapies in the rehabilitation phase and did not address the long-term effects of TBI, despite evidence indicating that nutritional therapies may be beneficial. Based on the literature searches the committee concluded that conducting a review of the nutrition approaches to improve long-term effects of TBI, which was part of the initial task and later excluded because of financial constraints, would also be important. Specifically, it would be important to review the alterations in metabolism associated with TBI, together with the nutritional interventions that could enhance or impair recovery from those long-term health disorders in the areas of motor dysfunction and cognitive, neuropsychiatric, and neurodegenerative states, should be reviewed (see also workshop papers by Metzger, Gomez-Pinilla, and Sands in Appendix C).
The committee concluded that there is already sufficient evidence to indicate that nutrition should be added to the toolbox of interventions for TBI treatment and recovery. A summary of the committee’s recommendations follows. Only one recommendation calls for updating evidence-based guidelines for severe TBI, to provide patients with energy and protein (Box 17-1). The remaining recommendations identify additional research needs in study methodologies (Box 17-2), nutritional assessments (Box 17-3), and specific recommendations for research on nutritional interventions that have been prioritized into the most promising (Box 17-4) and other research (Box 17-5). Finally, the committee includes a general recommendation to develop evidence-based clinical nutritional guidelines, and to continue to update them as more evidence becomes available (Box 17-6).