Per Kilogram Versus Nitrogen Balance Methods for Daily Protein Requirement in Cancer Patients

The goal of this study is to compare the effects of two dietary protein supplementation methods (per kg \[PK\] vs nitrogen balance equation \[NBE\]) on nutritional status, muscle strength, lean body mass, physical performance, and dietary compliance in cancer patients.

The main questions it aims to answer are:

Does the PK method improve muscle strength and lean body mass more effectively than the NBE method?

Which method better supports nutritional status and physical performance in cancer patients?

Are there differences in dietary compliance between the two methods?

Researchers will compare the PK method (1.2-1.5 g/kg/day protein) to the NBE method (protein requirements based on nitrogen balance) to evaluate their impact on these outcomes.

Participants will:

Follow a personalized diet plan based on either the PK or NBE method

Attend follow-up visits at weeks 4 and 8 for assessments of BMI, muscle mass, muscle strength, gait speed, serum albumin, and CRP

Engage in moderate aerobic exercise (brisk walking) for at least 30 minutes a day, 5 days a week

Materials and Methods

Study Population: Cancer patients over 18 years of age, who were admitted to the outpatient clinics of Istanbul University, Institute of Oncology, between September 2019 and January 2020, were included. Informed written consent was obtained from all participants prior to the study. Exclusion criteria were: age below 18, inability to feed orally (due to dementia, impaired consciousness, dysphagia, etc.), dialysis dependence, psychiatric and/or eating disorders, and those on home parenteral nutrition.

Malnutrition Risk ScreeningMalnutrition (MN) risk was screened using the Nutritional Risk Screening 2002 (NRS-2002) tool. Patients with an NRS-2002 score ≥3 were considered at risk of malnutrition.

Assessment of Daily Energy and Protein RequirementsDaily energy requirements (DER) were estimated by adding activity and stress factors to the basal energy requirement calculated using the Harris-Benedict equation. The daily protein requirement was determined using the PK method in one group and the NBE method in the other, with a 1:1 allocation ratio. The PK group received 1.2-1.5 g/kg/day of protein. The NBE group recorded their food intake and collected 24-hour urine samples for nitrogen balance calculation. Nitrogen balance was calculated by subtracting daily nitrogen excretion (urinary urea/2.14 + 3 g from feces) from nitrogen intake (24-hour protein consumption \[g\]/6.25). The predicted daily protein requirement in the NBE group was calculated as daily nitrogen loss x 6.25 (g protein).

Personalized Diet Plan and Follow-UpA personalized diet plan was prepared for all patients according to their calculated requirements by two expert dietitians from Istanbul University, Istanbul Faculty of Medicine, Clinical Nutrition Team. Oral enteral nutrition products were added if dietary intake was insufficient to meet daily calorie and/or protein needs. Follow-up visits were conducted at the 4th and 8th weeks post-admission. Each visit included assessments of nutritional status, food consumption, BMI, muscle mass, muscle strength, gait speed, serum albumin, and C-reactive protein (CRP).

Measurements of Anthropometrics, Muscle Strength, and Physical PerformanceAnthropometric measurements were performed using bioelectrical impedance analysis (BIA) (Tanita MC 780 MA, Japan) to assess body weight, fat-free mass (FFM), fat ratio, total body water (TBW), bone weight, and visceral adiposity index. BMI was calculated as weight in kilograms divided by height in meters squared. Muscle strength (kg) was measured using a handheld dynamometer (Jamar, USA), with three repetitions per hand, and the highest measurement from the dominant hand was used. Gait speed (m/s) was assessed using a 4-meter walk test. All measurements were conducted by two nurses from Istanbul University, Istanbul Faculty of Medicine, Clinical Nutrition Team.

Physical Exercise PlanModerate-intensity aerobic exercise (brisk walking) for at least 30 minutes per day, 5 days a week, was planned for each patient by a physiotherapist from the Physical Therapy and Rehabilitation Department.

Eligibility Criteria:
Inclusion Criteria:

Cancer patients aged over 18 years

Patients admitted to the outpatient clinics of Istanbul University, Institute of Oncology, between September 2019 and January 2020

Exclusion Criteria:

Patients aged below 18 years

Patients unable to feed orally (such as those with dementia, impaired consciousness, dysphagia, etc.)

Dialysis patients

Patients with psychiatric and/or eating disorders

Patients receiving home parenteral nutrition