Early Signs of Impaired Gut Function Affect Daily Functioning in Patients With Advanced Cancer Undergoing Chemotherapy

The importance of protein sources to support muscle anabolism in cancer: An expert group opinion

This opinion paper presents a short review of the potential impact of protein on muscle anabolism in cancer, which is associated with better patient outcomes. Protein source is a topic of interest for patients and clinicians, partly due to recent emphasis on the supposed non-beneficial effect of proteins; therefore, misconceptions involving animal-based (e.g., meat, fish, dairy) and plant-based (e.g., legumes) proteins in cancer are acknowledged and addressed. Although the optimal dietary amino acid composition to support muscle health in cancer is yet to be established, animal-based proteins have a composition that offers superior anabolic potential, compared to plant-derived proteins. Thus, animal-based foods should represent the majority (i.e., ≥65%) of protein intake during active cancer treatment. A diet rich in plant-derived proteins may support muscle anabolism in cancer, albeit requiring a larger quantity of protein to fulfill the optimal amino acid intake. We caution that translating dietary recommendations for cancer prevention to cancer treatment may be inadequate to support the pro-inflammatory and catabolic nature of the disease. We further caution against initiating an exclusively plant-based (i.e., vegan) diet upon a diagnosis of cancer, given the presence of elevated protein requirements and risk of inadequate protein intake to support muscle anabolism. Amino acid combination and the long-term sustainability of a dietary pattern void of animal-based foods requires careful and laborious management of protein intake for patients with cancer. Ultimately, a dietary amino acid composition that promotes muscle anabolism is optimally obtained through combination of animal- and plant-based protein sources.

Intestinal dysfunction in chronic disease

PURPOSE OF REVIEW

This review will discuss recent studies showing that patients with chronic wasting diseases suffer from a variety of small intestinal impairments which might negatively impact the colonic microbiota and overall well-being. New insights will be addressed as well as novel approaches to assess intestinal function.

RECENT FINDINGS

Small intestinal dysfunction can enhance the amount and alter the composition of undigested food reaching the colon. As a result of reduced protein digestion and absorption, a large amount of undigested protein might reach the colon promoting the presence of pathogenic colonic bacteria and a switch from bacterial fiber fermentation to protein fermentation. While microbial metabolites of fiber fermentation, such as short-chain fatty acids (SCFA), are mainly considered beneficial for overall health, metabolites of protein fermentation, i.e. ammonia, branched SCFAs, hydrogen sulfide, polyamines, phenols, and indoles, can exert beneficial or deleterious effects on overall health. Substantial advances have been made in the assessment of small intestinal dysfunction in chronic diseases, but studies investigating the connection to colonic microbial metabolism are needed. A promising new stable isotope approach can enable the measurement of metabolite production by the colonic microbiota.

SUMMARY

Several studies have been conducted to assess intestinal function in chronic diseases. Impairments in intestinal barrier function, sugar absorption, protein digestion, and absorption, as well as small intestinal bacterial overgrowth were observed and possibly might negatively impact colonic bacterial metabolism. We suggest that improving these perturbations will improve overall patient health.

State of the art: the role of citrulline as biomarker in patients with chemotherapy- or graft-versus-host-disease-induced mucositis

PURPOSE OF REVIEW

Serum or plasma citrulline levels are used as biomarker for a broad spectrum of intestinal functions. During high-dose chemotherapy, citrulline levels are decreased due to mucositis, a common side effect of chemotherapy. This may decrease intestinal function and result in diarrhea. In this review, most recent studies investigating citrulline as biomarker for intestinal function are discussed, with focus on patients with oncological diseases, specifically hematological malignancies with chemotherapy- or Graft-versus-Host-disease (GVHD)-induced mucositis.

RECENT FINDINGS

Citrulline has recently been widely studied in relation to intestinal function and various clinical conditions. It seems therefore a promising noninvasive biomarker in clinical practice for more than intestinal function alone. The association between citrulline levels and intestinal function in patients with hematological malignancies, with or without mucositis remains unclear, as no other parameters of intestinal function for this purpose were assessed.

SUMMARY

In conclusion, citrulline seems to be a promising noninvasive biomarker for various intestinal conditions in general, and potentially for intestinal function in patients with chemotherapy- or GVHD-induced mucositis. It is unclear from recent literature whether high fecal volume or diarrhea as side effect, results in impaired intestinal function and severe malabsorption and if citrulline biomarkers can be useful to detect this.

Impaired intestinal function is associated with lower muscle and cognitive health and well-being in patients with congestive heart failure

BACKGROUND

Small- and large-intestinal perturbations have been described as prevalent extracardiac systemic manifestations in congestive heart failure (CHF), but alterations in protein digestion and absorption and plasma short-chain fatty acid (SCFA) concentrations and the potential link with other systemic effects (muscle and cognitive health) have not been investigated in CHF.

METHODS

We analyzed protein digestion and absorption with dual stable tracer method in 14 clinically stable, noncachectic CHF outpatients (mean left ventricular ejection fraction: 35.5% [95% CI, 30.9%-40.1%]) and 15 controls. Small-intestinal non-carrier-mediated permeability and active carrier-mediated glucose transport were quantified by sugar permeability test. Plasma SCFA (acetate, propionate, butyrate, isovalerate, valerate) concentrations were measured as intestinal microbial metabolites. Muscle function was assessed by isokinetic dynamometry, cognition by a battery of tests, and well-being by questionnaire.

RESULTS

Protein digestion and absorption were impaired by 29.2% (P = .001) and active glucose transport by 38.4% (P = .010) in CHF. Non-carrier-mediated permeability was not altered. Whereas plasma propionate, butyrate, and isovalerate concentrations were lower in CHF (P < .05), acetate and valerate concentrations did not differ. Overall, intestinal dysfunction was associated with impaired leg muscle quality, emotional distress, and cognitive dysfunction (P < .05).

CONCLUSIONS

We identified impaired protein digestion and absorption and altered SCFA concentrations as additional intestinal dysfunctions in CHF that are linked to reduced muscle and cognitive health and well-being. More research is needed to implement strategies to improve intestinal function in CHF and to investigate the mechanisms underlying its link with other systemic manifestations.

The Effects of Pro-, Pre-, and Synbiotics on Muscle Wasting, a Systematic Review-Gut Permeability as Potential Treatment Target

Muscle wasting is a frequently observed, inflammation-driven condition in aging and disease, known as sarcopenia and cachexia. Current treatment strategies target the muscle directly and are often not able to reverse the process. Because a reduced gut function is related to systemic inflammation, this might be an indirect target to ameliorate muscle wasting, by administering pro-, pre-, and synbiotics. Therefore, this review aimed to study the potential of pro-, pre-, and synbiotics to treat muscle wasting and to elucidate which metabolites and mechanisms affect the organ crosstalk in cachexia. Overall, the literature shows that Lactobacillus species pluralis (spp.) and possibly other genera, such as Bifidobacterium, can ameliorate muscle wasting in mouse models. The beneficial effects of Lactobacillus spp. supplementation may be attributed to its potential to improve microbiome balance and to its reported capacity to reduce gut permeability. A subsequent literature search revealed that the reduction of a high gut permeability coincided with improved muscle mass or strength, which shows an association between gut permeability and muscle mass. A possible working mechanism is proposed, involving lactate, butyrate, and reduced inflammation in gut–brain–muscle crosstalk. Thus, reducing gut permeability via Lactobacillus spp. supplementation could be a potential treatment strategy for muscle wasting.

Intestinal function is impaired in patients with Chronic Obstructive Pulmonary Disease

BACKGROUND & AIMS

Gastrointestinal symptoms are prevalent extrapulmonary systemic manifestations of Chronic Obstructive Pulmonary Disease (COPD), but have been rarely studied. We dissected the perturbations in intestinal function in human patients with COPD using comprehensive metabolic and physiological approaches.

METHODS

In this observational study, small intestinal membrane integrity and active carrier-mediated glucose transport were quantified by sugar permeability test in 21 clinically stable patients with moderate to severe COPD (mean FEV₁, 41.2 (3.2) % of predicted) and 16 healthy control subjects. Protein digestion and absorption was analyzed using stable tracer kinetic methods. Plasma acetate, propionate, and butyrate concentrations were measured as markers of intestinal microbial metabolism.

RESULTS

Compared with healthy controls, non carrier-mediated permeability was higher (0.062 (95% CI [0.046, 0.078]) vs. 0.037 (95% CI [0.029, 0.045]), P = 0.009) and active glucose transport lower in COPD (31.4 (95% CI [23.4, 39.4])% vs. 48.0 (95% CI [37.8, 58.3])%, P = 0.010). Protein digestion and absorption was lower in COPD (0.647 (95% CI [0.588, 0.705]) vs. 0.823 (95% CI [0.737, 0.909]), P = 0007), and impairment greater in patients with dyspnea (P = 0.038), exacerbations in preceding year (P = 0.052), and reduced transcutaneous oxygen saturation (P = 0.051), and was associated with reduced physical activity score (P = 0.016) and lower quality of life (P = 0.0007). Plasma acetate concentration was reduced in COPD (41.54 (95% CI [35.17, 47.91]) vs. 80.44 (95% CI [54.59, 106.30]) μmol/L, P = 0.001) suggesting perturbed intestinal microbial metabolism.

CONCLUSIONS

We conclude that intestinal dysfunction is present in COPD, worsens with increasing disease severity, and is associated with reduced quality of life.