Nutritional therapy and infectious diseases: a two-edged sword

"Feed a Cold, Starve a Fever?" A Review of Nutritional Strategies in the Setting of Bacterial Versus Viral Infections

PURPOSE OF REVIEW

Some data, mostly originally derived from animal studies, suggest that low glucose intake is protective in bacterial sepsis but detrimental in overwhelming viral infections. This has been interpreted into a broad belief that different forms of sepsis may potentially require different nutritional management strategies. There are a few mechanistic differences between the host interactions with virus and bacteria which can explain why there may be opposing responses to macronutrient and micronutrient during the infected state. Here, we aim to review relevant evidence on the mechanisms and pathophysiology of nutritional management strategies in various infectious syndromes and summarize their clinical implications.

RECENT FINDINGS

Newer literature - in the context of the SARS-CoV-19 pandemic - offers some insight to viral infections. There is still limited clinically applicable data during infection that clearly delineate the role of nutrition during an active viral vs bacterial infections. Based on contrasting findings in different models of viruses and bacteria, the macronutrient and micronutrient needs may depend more on specific infectious organisms that may not be generalizable as bacterial versus viral. Overall, the metabolic effects of sepsis are context dependent, and various host-specific (e.g., age, baseline nutritional status, immune status, comorbidities) and illness variables (phase, duration, and severity of illness) play a significant role in determining the outcome besides pathogen-specific (virus or bacterial or fungi and combined infections) factors. Microbe therapy (probiotics and prebiotics) seems to have therapeutic potential in both viral and bacterial infected states, and this seems like a promising area for further practical research.

Immunomodulatory role and potential utility of various nutrients and dietary components in SARS-CoV-2 infection

Recently, the outbreak of severe acute respiratory syndrome cornoavirus-2 (SARS-CoV-2), causing coronavirus disease 2019 (COVID-19), has become a great perturbation all around the globe and has many devastating effects on every aspect of life. Apart from the oxygen therapy and extracorporeal membrane oxygenation, Remdesivir and Dexamethasone have been proven to be efficacious against COVID-19, along with various vaccine candidates and monoclonal antibody cocktail therapy for Regeneron. All of these are currently at different stages of clinical trials. People with weak immunity are more prone to a severe infection of SARS-CoV-2. Therefore, early and judicious nutritional supplementation along with pharmacological treatment and clinician collaborations are critical in restituting the current situation. Nutritional supplements help in acquiring strong immunity to prevent the progression of disease any further. Vitamin C, vitamin D, selenium, zinc and many other nutritional and dietary supplements inhibit the production of inflammatory cytokines during a viral infection and prevents several unwanted symptoms of infection. Many dietary components like citrus fruits, black elderberry, ginger, and probiotics have the ability to attack viral replication. These supplements can also tame the overriding immune system during coronavirus infection. Keeping in view these facts, nutritional and dietary supplements can be used along with other management modalities. These nutritional and dietary supplements are potential candidates to curb the convulsive unfolding of novel COVID-19, in combination with other standard treatment protocols. In this review, various search engines were used to exploit available literature in order to provide a comprehensive review on nutritional and dietary supplements with respect to the viral infections. It will also provide a brief overview on some of the clinical trials that are in progress to assess the role of nutritional supplements, either alone or in combination with other pharmacological drugs, in fight against COVID-19.

Immunomodulating Effects of Fungal Beta-Glucans: From Traditional Use to Medicine

The importance of a well-functioning and balanced immune system has become more apparent in recent decades. Various elements have however not yet been uncovered as shown, for example, in the uncertainty on immune system responses to COVID-19. Fungal beta-glucans are bioactive molecules with immunomodulating properties. Insights into the effects and function of beta-glucans, which have been used in traditional Chinese medicine for centuries, advances with the help of modern immunological and biotechnological methods. However, it is still unclear into which area beta-glucans fit best: supplements or medicine? This review has highlighted the potential application of fungal beta-glucans in nutrition and medicine, reviewing their formulation, efficacy, safety profile, and immunomodulating effects. The current status of dietary fungal glucans with respect to the European scientific requirements for health claims related to the immune system and defense against pathogens has been reviewed. Comparing the evidence base of the putative health effects of fungal beta-glucan supplements with the published guidance documents by EFSA on substantiating immune stimulation and pathogen defense by food products shows that fungal beta-glucans could play a role in supporting and maintaining health and, thus, can be seen as a good health-promoting substance from food, which could mean that this effect may also be claimed if approved. In addition to these developments related to food uses of beta-glucan-containing supplements, beta-glucans could also hold a novel position in Western medicine as the concept of trained immunity is relatively new and has not been investigated to a large extent. These innovative concepts, together with the emerging success of modern immunological and biotechnological methods, suggest that fungal glucans may play a promising role in both perspectives, and that there are possibilities for traditional medicine to provide an immunological application in both medicine and nutrition.

Beta Glucan: Supplement or Drug? From Laboratory to Clinical Trials

Glucans are part of a group of biologically active natural molecules and are steadily gaining strong attention not only as an important food supplement, but also as an immunostimulant and potential drug. This paper represents an up-to-date review of glucans (β-1,3-glucans) and their role in various immune reactions and the treatment of cancer. With more than 80 clinical trials evaluating their biological effects, the question is not if glucans will move from food supplement to widely accepted drug, but how soon.

Immune response from a resource allocation perspective

The immune system is a life history trait that can be expected to trade off against other life history traits. Whether or not a trait is considered to be a life history trait has consequences for the expectation on how it responds to natural selection and evolution; in addition, it may have consequences for the outcome of artificial selection when it is included in the breeding objective. The immune system involved in pathogen resistance comprises multiple mechanisms that define a host's defensive capacity. Immune resistance involves employing mechanisms that either prevent pathogens from invading or eliminate the pathogens when they do invade. On the other hand, tolerance involves limiting the damage that is caused by the infection. Both tolerance and resistance traits require (re)allocation of resources and carry physiological costs. Examples of trade-offs between immune function and growth, reproduction and stress response are provided in this review, in addition to consequences of selection for increased production on immune function and vice versa. Reaction norms are used to deal with questions of immune resistance vs. tolerance to pathogens that relate host health to infection intensity. In essence, selection for immune tolerance in livestock is a particular case of selection for animal robustness. Since breeding goals that include robustness traits are required in the implementation of more sustainable agricultural production systems, it is of interest to investigate whether immune tolerance is a robustness trait that is positively correlated with overall animal robustness. Considerably more research is needed to estimate the shapes of the cost functions of different immune strategies, and investigate trade-offs and cross-over benefits of selection for disease resistance and/or disease tolerance in livestock production.

Cranberry components for the therapy of infectious disease

Summary of the in vitro data support a beneficial effect of cranberry or its proanthocyanin constituents by blocking adhesion to and biofilm formation on target tissues of pathogens. In vivo data partially support these beneficial effects. Consumption of various cranberry products benefited young and elderly females in preventing urinary tract infections, and in conjunction with antibiotic treatment in eradicating Helicobacter pylori infections in women. Mouthwash supplemented with an isolated cranberry derivative reduced significantly the caryogenic mutans streptococci. None of the mice infected intranasal with lethal dose of influenza virus and treated with cranberry fraction died after two weeks. Further studies should focus on the active cranberry component as supplement for food and other products especially where whole juice or powder cannot be used.

Nutrition therapy cost analysis in the US: pre-mixed multi-chamber bag vs compounded parenteral nutrition

BACKGROUND

Bloodstream infections (BSI) occur in up to 350 000 inpatient admissions each year in the US, with BSI rates among patients receiving parenteral nutrition (PN) varying from 1.3% to 39%. BSI-attributable costs were estimated to approximate $US12 000 per episode in 2000. While previous studies have compared the cost of different PN preparation methods, this analysis evaluates both the direct costs of PN and the treatment costs for BSI associated with different PN delivery methods to determine whether compounded or manufactured pre-mixed PN has lower overall costs.

OBJECTIVE

The purpose of this study was to compare costs in the US associated with compounded PN versus pre-mixed multi-chamber bag (MCB) PN based on underlying infection risk.

METHODS

Using claims information from the Premier Perspective™ database, multivariate logistic regression was used to estimate the risk of infection. A total of 44 358 hospitalized patients aged ≥18 years who received PN between 1 January 2005 and 31 December 2007 were included in the analyses. A total of 3256 patients received MCB PN and 41 102 received compounded PN. The PN-associated costs and length of stay were analysed using multivariate ordinary least squares regression models constructed to measure the impact of infectious events on total hospital costs after controlling for baseline and clinical patient characteristics.

RESULTS

There were 7.3 additional hospital days attributable to BSI. After adjustment for baseline variables, the probability of developing a BSI was 30% higher in patients receiving compounded PN than in those receiving MCB PN (16.1% vs 11.3%; odds ratio = 1.56; 95% CI 1.37, 1.79; p < 0.0001), demonstrating 2172 potentially avoidable infections. The observed daily mean PN acquisition cost for patients receiving MCB PN was $US164 (including all additives and fees) compared with $US239 for patients receiving compounded PN (all differences p < 0.001). With a mean cost attributable to BSI of $US16 141, the total per-patient savings (including avoided BSI and PN costs) was $US1545.

CONCLUSION

In this analysis of real-world PN use, MCB PN is associated with lower costs than compounded PN with regards to both PN acquisition and potential avoidance of BSI. Our base case indicates that $US1545 per PN patient may be saved; even if as few as 50% of PN patients are candidates for standardized pre-mix formulations, a potential savings of $US773 per patient may be realized.

Methods to identify and compare parenteral nutrition administered from hospital-compounded and premixed multichamber bags in a retrospective hospital claims database

PURPOSE

Use of parenteral nutrition (PN) is indicated for patients who are unable to meet their needs enterally. PN may be administered via custom-compounded mix or commercially available ready-to-use multichamber bags (MCB), but little is known about potential differences in clinical outcomes between these delivery systems. This study was undertaken to assess the feasibility of comparing custom-compounded and MCB PN in a large hospital claims database.

METHODS

Hospital claims data from the Premier Perspective Comparative Hospital Database (PCD) reported from 2005 through 2007 were analyzed. The authors searched the data for patients who received any PN products, including compounded PN and MCB PN. Coding algorithms for identifying patient characteristics, risk factors, and outcomes of interest were explored.

RESULTS

Using hospital billing claims, the authors identified patients in the database treated with premixed PN from multichamber bags ("MCB only," n = 4699) and patients treated with custom-compounded PN solution ("compounded PN," n = 64,315). Methods of identifying PN administration groups, patient characteristics and risk factors, outcomes of interest, and data limitations are described.

CONCLUSIONS

Exploratory analysis suggests that comparisons of PN administered via compounding and MCB are possible using the Premier data. The ability to control for many identifiable risk factors allows data to be presented for the use of PN and related outcomes in both a clinically sensible and relevant manner, albeit with some limitations.

Macro and micro minerals: are frozen fruits a good source?

Fruits are rich in minerals, which are essential for a wide variety of metabolic and physiologic processes in the human body. The use of frozen fruits has greatly spread in the last years not only in the preparation of juices, but also as raw material for yogurts, candies, cookies, cakes, ice creams, and children's food. However, up to now there is no data about the mineral profile of frozen fruits. This is the first database to quantify the levels of minerals in 23 samples of frozen fruits, including the most used around the world and some native fruits from the Amazon rainforest in Brazil. Considering the Dietary Reference Intakes, 100g of frozen fruits can provide 0.2 to 2.8% of macro and 2.5 to 100% of microminerals for adults (31-50 years old). Although geographical differences should be considered, these data can help to plan diets and to develop population interventions aiming to prevent chronic diseases.

Phytochemicals of cranberries and cranberry products: characterization, potential health effects, and processing stability

Emerging evidence is elucidating how non-nutrient phytochemicals underlie the health promotion afforded by fruits and vegetables. This review focuses on Vaccinium macrocarpon, the American cranberry, compiling a comprehensive list of its known phytochemical components, and detailing their prevalence in cranberry fruit and its products. Flavonoids, especially colored anthocyanins, abundant flavonols, and unique proanthocyanidins, have attracted major research attention. Other notable active components include phenolic acids, benzoates, hydroxycinnamic acids, terpenes and organic acids. Health effects of cranberries, cranberry products, and isolated cranberry components in humans and animals, as well as in vitro, are debated. Evidence for protection from several bacterial pathogens, cancer, cardiovascular disease, and inflammation is compelling, while neuroprotection and anti-viral activity also have begun to draw new consideration. Emerging bioavailability data is considered and potential molecular mechanisms are evaluated, linking phytochemicals to health effects through their biochemical properties and reactions. Finally, the effects of processing and storage on cranberry phytochemicals is discussed, with a focus on identifying research gaps and novel means to preserve their natural, health-promoting components.

Relationship between energy balance and complications after subarachnoid hemorrhage

BACKGROUND

Subarachnoid hemorrhage patients are hypermetabolic and at risk for developing medical complications. A relationship was hypothesized between energy balance and complications following subarachnoid hemorrhage.

METHODS

Fifty-eight consecutive poor-grade subarachnoid hemorrhage patients (mean age, 58; range, 26-86; 66% women) were studied between 2005 and 2007. Caloric intake and energy expenditure were assessed. In-hospital complications over the first 14 days posthemorrhage were defined as renal failure, fever (>38.3 degrees C), any infection, anemia, hyperglycemia (>11 mmol/L), and myocardial infarction. Energy balance was calculated by subtracting energy expenditure from caloric intake.

RESULTS

Enteral nutrition was begun 1 day posthemorrhage (range, 0-5 days). Recommended (mean +/- SD) caloric intake was 28 +/- 3 kcal/kg/d, and the actual was 14 +/- 5 kcal/kg/d. Enteral nutrition accounted for 67% of caloric intake; propofol and dextrose infusions accounted for 33% of caloric intake. Cumulative energy balance over the first 7 days was -117 +/- 53 kcal/kg. The average energy balance during the first 7 days after subarachnoid hemorrhage significantly correlated with the total number of infectious complications (r = -0.5, P < .001) but not medical complications (r = -0.2, P = .1). After adjustment for Hunt-Hess grade, fever, hyperglycemia, and anemia, negative energy balance during the first 7 days after subarachnoid hemorrhage correlated with the number of infectious complications (P = .01).

CONCLUSIONS

Infectious complications after subarachnoid hemorrhage are associated with negative energy balance. Studies are needed to better understand the impact of negative energy balance on outcome after subarachnoid hemorrhage.

Early nutrition support in the intensive care unit: a US perspective

PURPOSE OF REVIEW

Early nutrition support, defined as within the first 24-48 h of ICU care, is recommended by clinical practice guidelines. The purpose of this paper is to provide an evidence-based US perspective on early nutrition support in critical illness, explain its mechanism of action, and describe its implementation using combined enteral and parenteral nutrition support.

RECENT FINDINGS

Recent American and Canadian guidelines recommend starting enteral nutrition within the first 24-48 h of ICU care. This is mainly due to accrued 'energy debt' from underfeeding in certain patients. This energy debt leads to increased risks of complications and longer lengths of stay. Strong clinical evidence, however, in the form of prospective, randomized, controlled intervention studies of early nutrition support in the setting of routine intensive insulin therapy, is lacking.

SUMMARY

Early enteral nutrition should be first-line therapy in the ICU. If a caloric goal of 20-25 kcal/kg/day is not possible, then combined enteral and parenteral nutrition should be started. In the new age of intensive insulin therapy, parenteral nutrition has not been shown to confer significant additional infective risk. There are many unanswered questions, but a proactive posture for metabolic support in the ICU is advocated.