Background/rationale

Gastrointestinal (GI) resection refers to the surgical removal of damaged or diseased portions of the GI system [1]. This type of surgery is a major stressor to the body. One of the organs most affected by surgery is striated skeletal muscle, which has important locomotor and metabolic functions. Muscle is central to protein metabolism, which relies on protein turnover. This includes protein synthesis from free amino acids, as well as protein degradation to generate free amino acids. Muscle integrity is based on the principle of homeostasis between protein anabolism and catabolism. This homeostasis is disrupted during major surgery, and protein imbalance can result [2,3].

Surgery induces a generalized inflammatory state in patients. This is the result of the activation of various signaling pathways such as the NF-kB pathway [4]. This inflammation leads to a breakdown in muscle homeostasis due to an increase in catabolic activity and anabolic resistance, and consequently muscle atrophy [5]. The immune response following surgery increases energy requirements, which requires an increase in caloric intake. However, during hospitalization, patient caloric intake is reduced and rarely exceeds 1,200 to 1,500 kcal, whereas the Food and Agriculture Organization recommends a minimum daily intake of 1,800 kcal for a healthy Indian adult [6,7]. This deficit can be explained by the inability of some patients to eat normally due to GI surgery. Hospitalization can also contribute to a reduction in appetite. Moreover, many patients suffer from malabsorption of nutrients, partly due to vomiting or loose bowel movements [8]. Patients᾽ inability to supplement their dietary requirements exogenously forces the body to find another source of energy to ensure proper recovery. As a result, the body is forced to dip into the stores of amino acids found in muscles. This leads to muscle wasting and poor muscular health [9].

Finally, another reason why GI surgery promotes muscle loss is prolonged immobilization [7]. In the case of hospitalization, physical activity is greatly reduced, which limits the activation of protein synthesis pathways. Immobilization thus leads to an imbalance in protein homeostasis, reducing protein synthesis while increasing protein degradation [10-12].

To preserve muscular integrity and maintain the patient’s general condition, it is essential to address the various mechanisms that lead to a decline in muscular health. In this context, perioperative management of the patient can reduce mortality, morbidity, length, and cost of hospitalization [13]. The Enhanced Recovery After Surgery Society has established guidelines to standardize perioperative management specific to surgery, including nutritional management and early mobilization, which are known to be crucial for good recovery [14,15].

In this context, several studies have investigated “immunonutrients” that can potentially speed up recovery by enhancing the immune response and preventing skeletal muscle loss [16]. Immunonutrients identified to date include certain essential amino acids, such as branched-chain amino acids (arginine, leucine, glutamine), omega-3 fatty acids (EPA, DHA), and vitamin D [9]. These nutrients act on the immune system as immunomodulators and stimulate an anti-inflammatory response. They also impact muscle protein metabolism by reducing the activation of proteolysis mechanisms and stimulating protein synthesis pathways [17]. Combining these nutrients with physiotherapy could potentially be highly effective at preserving muscle health, but this has yet to be demonstrated, particularly in the case of hospitalization following GI surgery.

Objectives

We conducted a pilot randomized-controlled study involving GI surgery patients at Amrita Institute of Medical Sciences (AIMS), Kochi to investigate the impact of immunonutrition combined with physiotherapy on patients’ muscle health and inflammatory status.

Ethics statement

This study was approved by the Ethics Committee of Amrita School of Medicine, India (ECASM-AIMS-2023-244) and included 20 patients. Informed consent was obtained from all patients.

Study design

It is a randomized controlled study. It was described according to the CONSORT (Consolidated Standards of Reporting Trials) statement (available at: https://www.consort-statement.org/).

Setting

Patients were enrolled 3 days after undergoing major GI resection surgery at Amrita School of Medicine, Kochi from June to August 2023.

Interventions/Participants

Surgeries included in this study were anterior resections of the colon, rectum, small intestine, stomach and liver. Patients selected were aged between 30 and 75 years. Patients with central nervous system failure and multiple organ failure were excluded.

Among patients meeting these criteria, two groups of 10 patients were initially formed. One patient in the test group (n=9) and four patients in the control group (n=6) dropped out of the study before its completion. The test group (IMM) received a protein- and immuno-nutrient-enriched formula in the form of 25 g of powder to be diluted in a glass of water. This product was enriched in whey protein, arginine, omega-3 fatty acids, and vitamins (Table 1). The control group (CTL) received an isocaloric and protein-enriched formulation. These supplements were consumed by the subjects over a period of 3 weeks following the operation, 3 times a day after each meal (Fig. 1).

Table 1

Micro and macro-nutrient composition of the protein and immune-enriched supplement powders

Nutritional fact	Per 100 g	Per 25 g (1 portion)
Energy (kcal)	410.00	102.50
Nutrient
Carbohydrate (g)	53.93	13.48
Total sugars (fructose)	6.00	1.50
Dietary fibers	4.51	1.13
Protein (g)	22.95	5.74
L-Arginine	5.10	1.27
Ribonucleic acid sodium salt	0.62	0.16
Fat (g)	11.62	2.90
Polyunsaturated fatty acids	2.40	0.60
Linoleic acid: Omega-6	2.36	0.06
Linolenic acid: Omega-3 (mg)	5.00	1.25
Vitamin
A (µg)	523.50	130.90
D (µg)	2.72	0.68
E (mg)	10.00	2.50
C (mg)	32.78	8.20
Mineral
Iron (mg)	4.92	1.23
Zinc (mg)	4.92	1.23
Selenium (µg)	40.98	20.49

This table shows the major macro- and micro-nutrient components of the protein and immune-enriched commercial formula given to the IMM group. After each meal (3 times a day), a 25-g powder portion of this supplement dissolved in water was taken by the patients assigned to the IMM group.

IMM group = immuno supplementation+physiotherapy.

Fig. 1. Experimental design of the conducted study. Twenty patients that have undergone gastrointestinal (GI) surgery resection were unrolled in the study. Patients were assigned randomly to either IMM group (immuno supplementation+physiotherapy) or CTL group (isocaloric supplementation+ physiotherapy). Various data were collected during the study at 3 different time points including M1: 3 days post-surgery; M2: day of discharge (1 week post-surgery); and M3: follow-up day (3 weeks post-surgery). BMI = body mass index; BMR = basal metabolic rate; CRP = C-reactive protein.

Coupled with this nutritional management, limb and respiratory physiotherapy were set up for both groups of patients. Daily physiotherapy sessions began 3 days after the operation, at the same time as the supplementation. Limb physiotherapy was performed for 15 minutes and consisted of stretching or walking exercises of light to moderate intensity. Respiratory physiotherapy consisted of incentive spirometry exercises to encourage the patient to take slow, maximal inspirations and exhalations motivated by visual feedback. The first sessions were supervised by a physiotherapist. Thereafter, the patients performed these exercises independently, using the necessary equipment and following the guidelines laid down by the physiotherapist.

Outcomes

In this study, following outcomes were investigated: demographic findings of the patients and the following measured outcomes, including weight, height, body mass index (BMI), basal metabolic rate (BMR), fat mass, lean body mass, dietary caloric intake, muscle strength, breath holding time, and C-reactive protein (CRP) as an inflammation marker.

Data sources/measurement

Various parameters were assessed at 3 different time points: 3 days post-surgery (M1); on the day of discharge from hospital, which was 1-week post-surgery (M2); and 3 weeks post-surgery (M3).

Anthropometric measurements

Each patient᾽s weight was determined using a Healthgenie impedance scale. After measuring the height of the patient, BMI was determined according to the formula:

BMI=weight (kg)/height (m)²

The Asian BMI classification was used for body type interpretation as follows:

<18.5 – Underweight

18.5–22.9 – Normal

23.0–24.9 – Overweight at risk

25.0–29.9 – Obese grade one

≥30.0 – Obese grade two

Body fat was measured using an impedance scale and an OMRON HBF-306 body fat monitor. The average of these measurements is presented.

Lean body mass was assessed in two different ways, and values reported correspond to the average of these. First, lean mass was measured using an impedance balance. Second, it was determined using a formula that included measurement of the tricipital skin fold (TSF) and brachial circumference (BC). The tricipital crease was measured using a skinfold tool behind the left arm of each patient. The BC was measured on the left arm using a tape measure. These values were used to calculate lean body mass using the following formulae:

CMB=BC (cm)–[π×TSF (cm)]

M=CMB²/4π

Male=height (cm)×[0.0264+0.0029×(M–10)]

Female=height (cm)×[0.0264+0.0029×(M–6.5)]

Basal metabolic values presented are the averages of 3 assessment methods, including the values given by the impedance-metered scale and the body fat monitor, as well as a calculation method. The formulas used to determine BMR were those of Harris and Benedict:

Male=66.47+13.75×weight (kg)+5.0×height (cm)

–6.75×age

Female=655+9.56×weight (kg)+1.84×height (cm)

–4.67×age

Physical performance

Muscular strength was assessed using the hand grip test performed with the SQUEGG “smart squeeze ball” device. This tool was connected via Bluetooth to an MSAT application to collect the recorded data. In this test, the patient in a sitting position holds a tool in the palm of his/her hand and squeezes his/her fist with as much force as possible. Measurements were taken 3 times for each hand and the duration of the contraction was 3 seconds. There was a 10-second rest between each repetition and a 30-second rest between measurements of the left and right hand. Average force recorded for both hands was taken as the patient’s muscular strength.

Respiratory capacity was assessed using the breath holding test. This test measures the maximum apnea time after exhalation following a normal respiratory cycle.

24-hour recall

Patients’ dietary caloric intake was calculated using the 24-hour recall method. Patients were asked about the composition and quantity of their meals and snacks during the days preceding M1, M2, and M3.

Inflammatory markers

Blood levels of CRP were determined by serum analysis using a Cobas c 701/702 clinical analyzer (Roche) per the manufacturer’s instructions.

Bias

None.

Study size

Sample size estimation was not done since small target patients were included as a pilot study.

Randomization

Participants were recruited on the day of surgery and assigned to either the control or experimental group in the order of odd and even numbers.

Blinding (masking)

No blinding was done.

Statistical methods

Values were analyzed using the Statistics Kingdom website (https://www.statskingdom.com/). Graphs were produced with Excel (Microsoft) and values are shown as mean±standard deviation. The Mann–Whitney U-test was used to compare values of the CTL group with those of the IMM group. Results with P<0.05, P<0.05, or P<0.01 were considered significant. Paired Wilcoxon signed rank test was used to compare values between the different time points within each group. Comparisons with P<0.05 were considered statistically significant.

Participants

This pilot study included 20 patients admitted to AIMS for GI resection. Most of these patients had GI cancer (n=20) and other comorbidities (type 2 diabetes, cardiovascular disease, hypertension). Participants were randomly assigned to the CTL (n=10) or IMM (n=10) groups. Participants assigned to the CTL group were 55±9 years old on average and had a mean BMI of 26.7±4.6 kg/m². Patients assigned to IMM group were 55±6 years old on average and had an average BMI of 25.6±4.7 kg/m². Participants’ baseline characteristics were similar between the groups (Table 2). No significant difference in the length of hospitalization after surgery was observed between the two groups (Table 3).

Table 2

Three-day post-operative baseline anthropometric and clinical characteristics of the study subjects

	CTL (n=10)	IMM (n=10)
Female	4	6
Age (yr)	55±9	55±6
Weight (kg)	66.2±11.7	65.9±13.3
Body mass index (kg/m2)	26.7±4.6	25.6±4.7
Body type interpretation	Obese grade I	Obese grade I
Comorbidities
Type 2 diabetes	1	4
Cardiovascular disease	-	1
Hypertension	2	-
Cancer	4	6

Values are presented as number only or mean±standard deviation.

CTL = isocaloric supplementation+physiotherapy; IMM = immuno supplementation+physiotherapy.

Table 3

Length of hospitalization of patients who completed a randomized trial of 3 weeks of supplementation after gastrointestinal resection surgery

	Post-surgery hospitalization days number
CTL	8±2
IMM	7±1

Values are presented as mean±standard deviation.

CTL = isocaloric supplementation+physiotherapy; IMM = immuno supplementation+physiotherapy.

Body composition

Participants’ weight decreased significantly in the CTL and IMM groups during the time of the study. No significant differences were observed between the CTL and IMM groups. However, over time, differences within groups were observed. In the CTL group, weight at M3 was significantly lower than at M1. In the IMM group, mean patient weight was significantly lower at M2 and M3 than at M1. Both groups experienced significant weight loss over the course of the study, starting earlier for the IMM group (Fig. 2A). No significant differences in BMI or fat mass values were found between the two groups (Fig. 2B, C). There was also no significant difference in lean fat mass between the IMM and CTL groups. Nevertheless, a significant increase in the lean mass of the IMM group was observed at the end of the study compared to the M1 value; this increase was not observed in the control group (Fig. 2D).

Fig. 2. Body composition values analyses of patients in the CTL and IMM groups at different time points. (A) Weight analysis. (B) Body mass index (BMI) analysis. (C) Fat mass analysis. (D) Lean mass analysis. M1 = 3 days post-surgery; M2 = day of discharge (1 week post-surgery); M3 = follow-up day (3 weeks post-surgery); CTL = isocaloric supplementation+physiotherapy; IMM = immuno supplementation+physiotherapy. The Mann–Whitney U-test was used to compare CTL vs. IMM patients. Paired Wilcoxon signed rank test was used to compare M2 and M3 to M1. Significant results are presented as ^#P<0.05, ^##P<0.01.

Physical performance

Muscle strength in the IMM group was not significantly different from that in the CTL group throughout the study. However, the IMM group showed significantly greater muscle strength at M3 than at M1. This increase was not observed in the CTL group (Fig. 3A). Breath hold test results were not significantly different between the two groups or within groups at the 3 different time points (Fig. 3B).

Fig. 3. Physical performance of patients in the CTL and IMM group at different timepoints. (A) Muscle strength analyses. (B) Breath holdanalyses. M1 = 3 days post-surgery; M2 = day of discharge (1 week post-surgery); M3 = follow-up day (3 weeks post-surgery); CTL = isocaloric supplementation+physiotherapy; IMM = immuno supplementation+physiotherapy. Mann–Whitney U-test was used to compare CTL and IMM patients. Paired Wilcoxon signed rank test was used to compare M2 and M3 to M1. Significant results are presented as ^#P<0.05.

Inflammation status

CRP values in the CTL and IMM groups did not differ significantly. For both groups, CRP values at M2 and M3 were significantly lower than at M1. The decrease over time was significantly greater in the IMM group than in the CTL group (Fig. 4).

Fig. 4. C-reactive protein (CRP) levels in the CTL and IMM groups at different time points. M1 = 3 days post-surgery; M2 = day of discharge (1 week post-surgery); M3 = follow-up day (3 weeks post-surgery); CTL = isocaloric supplementation+physiotherapy; IMM = immuno supplementation+physiotherapy. Mann–Whitney U-test was used to compare CTL and IMM patients. Paired Wilcoxon signed rank rest was used to compare M2 and M3 to M1. Significant results are presented as ^#P<0.05, ^##P<0.01.

BMR and caloric intake

BMR values of participants in the IMM and CTL groups were not significantly different and BMR values of patients in the CTL and IMM groups did not vary significantly over the course of the study. Intake at M2 for patients in both groups was significantly lower than the BMR value (CTL: 757 vs. 1,350 calories; IMM: 767 vs. 1,360 calories). Calorie intake increased significantly for both groups between M2 and M3 (CTL: 1,302 vs. 1,300, respectively; IMM: 1,344 vs. 1,317, respectively). At the end of the study, no significant differences between BMR and intake were noted between groups (Table 4).

Table 4

BMR and intake of the 15 patients who completed a randomized trial of 3-week supplementation after gastrointestinal surgery at different time points

		M1	M2	M3
CTL	BMR (kcal)	1,389±194	1,350±202	1,300±203
	Intake (kcal)	Liquid diet	757±125**	1,302±243#
IMM	BMR (kcal)	1,379±236	1,360±241	1,317±240
	Intake (kcal)	Liquid diet	767±214***	1,344±177##

Values are presented as mean±standard deviation.

BMR = basal metabolic rate; M1 = 3 days post-surgery; M2 = day of discharge (1 week post-surgery); M3 = follow-up day (3 weeks post-surgery); CTL = isocaloric supplementation+physiotherapy; IMM = immuno supplementation + physiotherapy.

Mann–Whitney U-test was performed to compare BMR vs. intake, significant results are indicated by **P<0.01 and ***P<0.001.

Paired Wilcoxon sign rank test was used to compare M2 and M3 to M1.

Paired Wilcoxon sign rank test was used to compare M2 vs. M3.Significant results are presented as ^#P<0.05 and ^##P<0.01.

Interpretation/Comparison with previous studies

In this pilot study, we set out to assess the impact of immunonutrient supplementation coupled with physiotherapy on the muscular health of patients who had undergone GI surgery. During the study, the test (IMM) and control (CTL) groups received immunonutrients or protein-enriched supplements and isocaloric protein supplementation coupled with physiotherapy.

Significant weight loss was observed in all patients following surgery. Fettes et al. [18] reported that over 75% of patients who underwent major or moderate GI surgery lost significant weight over one and a half years. This confirms that major GI surgery has a significant negative impact on body weight. Neither of the two supplements given to the CTL and IMM groups was able to counteract this weight loss. This can be explained, on the one hand, by significant acute inflammation characterized by a high CRP level immediately after surgery. On the other hand, it was found that during hospitalization, daily nutritional intake following surgery was well below the essential needs of the patients’ bodies. In fact, during this period, patients had an average caloric deficit of 44% compared with the BMR.

However, patient body composition, i.e., the percentage of muscle and fat mass, did not appear to be negatively impacted by this weight loss. This may be due to the supplements the patients received. Moreover, patients who received immuno-supplementation had an increased percentage of lean body mass at the end of the study. Given that patient weight had decreased, this suggests that immuno-supplementation preserved or limited the loss of muscle mass and did so more effectively than simple protein supplementation. de Luis et al. [19] observed that immuno-supplementation with arginine and omega-3 fatty acids increased the lean mass of patients who had undergone major surgery. In that study, an increase in lean mass was observed following a 12-week period of supplementation. Percentages of fat and lean mass did not change despite weight loss, implying a proportional decrease in their masses.

In the current study, muscle strength increased after 3 weeks of immuno-supplementation. This phenomenon, which was not observed in patients in the control group, can be explained by better recovery. We attribute this to a greater reduction in inflammation in the test patients than in the control patients due to the anti-inflammatory support provided by the immuno-nutrients. Previous studies have reported a reduction in CRP following supplementation with immuno-nutrients such as zinc [20] and DHA [21]. Finally, this earlier recovery enabled members of the test group to return to normal physical activity more quickly than the control group, which may also explain the increase in muscle strength and the preservation of lean mass in this group.

Respiratory complications following major GI surgery are among the most frequent major complications. These involve the acute or chronic loss of respiratory capacity in a patient. Breath holding time reflects respiratory capacity. We found no difference in patient respiratory capacity either during the study or between groups. This may be explained either by the absence of respiratory complications following surgery, or by compensation for the impact by respiratory physiotherapy or nutritional supplementation. Nevertheless, in this study, immunonutrient supplementation did not affect respiratory capacity.

As shown by the percentages of lean mass and muscle strength of IMM patients, immuno-supplementation has a beneficial impact on the muscular health of GI surgery patients.

Arginine was one of the components of the supplement the IMM group received. This amino acid is known for its ability to stimulate rapid cell growth and renewal [22]. Omega-3 fatty acids, which were also a component of the immunesupplement, have recognized anti-inflammatory effects, partly linked to inhibition of IkB phosphorylation in the NF-kB signaling pathway. A reduction in cytokines, chemokines, and acute-phase proteins such as IL-6 and CRP has also been observed with omega-3 enrichment. These fatty acids increase Akt phosphorylation, activating the Akt/mTOR signaling pathway, leading to protein synthesis [23]. Vitamins A, D, E and C, which have immunomodulating and antioxidant properties, were also included in the immuno-supplement. Among these, vitamin D is known to stimulate protein synthesis. Other micronutrients included in the formulation, namely iron, zinc and selenium, also have immunomodulating properties. Indeed, iron supplementation is known to limit the pro-inflammatory response of type 1 macrophages induced by low levels of iron. Zinc contributes to the maturation of T lymphocytes, while selenium’s antioxidant properties protect immune cells from oxidative stress [24].

Both groups received a protein supplement consisting of rapidly digestible proteins, so muscle protein synthesis was stimulated throughout the study period. Both groups also performed daily physiotherapy exercises. This also helped to maintain the patients’ muscular health. These factors may explain why there were no significant differences in any of the variables of interest between the two groups.

Limitations

As this was a pilot study, the small number of patients recruited and the short intervention period were limitations of this study. A more significant number of study participants recruited and a more extended intervention period could provide the effect of the oral nutritional immuno-supplement on muscle health and inflammation status after gastrointestinal resection.

We demonstrated the benefits of immuno-supplementation combined with physiotherapy following GI surgery on patients’ muscular health and inflammatory status, two intrinsically linked phenomena. Inflammatory status as well as muscular health, which is characterized by muscle strength and lean body mass, were found to improve following a 3-week course of immuno-supplementation. Although no statistically significant differences were found between the control and immune-supplementation groups, there was a clear clinical difference between groups observed based on the ability of the patients on the intervention group to get back to its daily habits quicker than the other group and this was observed during the different interviews that we did with the patients. As this was a pilot study, the small number of patients recruited and the short intervention period may explain the lack of significant differences between groups.

Conceptualization: CB, AA. Data curation: CB, AA. Formal analysis: CB, AA. Investigation: CB, AA. Methodology: CB, AA. Project administration: NP, SOV. Resources: NP, SOV. Software: CB, AA. Supervision: NP, SOV. Validation: NP, SOV. Visualization: CB, AA. Writing – original draft: CB, AA. Writing – review & editing: all authors.

The authors of this manuscript have no conflicts of interest to disclose.

None.

Contact the corrresponding author for data availability.

Dietitians in the Department of Clinical Nutrition, Amrita Hospital, Kochi.