Research brief
Body composition of patients on a very low-protein diet: a two-year survey with DEXA

https://doi.org/10.1016/S1051-2276(03)00117-1Get rights and content

Abstract

Background: It has been reported that patients on a very-low-protein diet (VLPD) maintain a satisfactory nutritional status because of a conserved adaptive metabolic response. However, only few studies have examined the course of nutritional status and body composition in the long term (2 years).

Methods: Thirteen stable patients (8 men; age, 55 ± 12 years; glomerular filtration rate (GFR), 15 ± 5 mL/min) receiving a VLPD (0.3 g/kg/day protein) supplemented with amino acids and ketoanalogues (SVLPD) were studied for 2 years. A joint visit with a physician and a dietitian and routine blood and urine analyses were performed every month. Dual-energy x-ray absorptiometry (DEXA), which was used to assess modification of body composition, and GFR (urinary 51Cr-EDTA) and urinary urea and creatinine excretion, which were used to assess nutritional status and compliance to the diet, were assessed every 3 months.

Results: GFR, albumin, and prealbumin levels remained stable. Urea urinary excretion decreased at 3 months and then slightly increased at 2 years, but the calculated protein intake remained low at 0.38 ± 0.1 g/kg/day. Energy intake remained close to 30 kcal/kg/day. No significant change was observed for total fat mass or percent fat mass. After an initial decrease, lean body mass stabilized at 6 months and then increased significantly from 6 to 24 months (P = .02, paired t-test); the mean increase during this period was of 2 kg, that is, 4.6%. Urinary creatinine excretion showed the same profile. Total bone mass, lumbar or hip site bone mass, and Z-score significantly decreased from T0 to 1 and 2 years (P < .05).

Conclusion: This study confirms that a supplemented VLPD is nutritionally safe for a long period, but attention must be paid to bone mass.

Section snippets

Patients and methods

Thirteen ambulatory patients (8 men, 5 women; age range, 39–70 years; average age, 55 ± 12 years) with advanced chronic renal failure (CRF) (mean glomerular filtration rate [GFR] measured using urinary clearance of 51Cr EDTA, 15 ± 4.7 mL/min/1.73 m2) were enrolled in the study. SVLPD was proposed to all adult patients with advanced CRF, excluding those with severe comorbid conditions that might superimpose a hypercatabolic state. Patients who obviously could not adapt to the dietary

Body composition

To determine body composition, a whole-body scan was performed using a fan-beam model QDR-4500A dual-energy x-ray absorptiometry (DEXA) densitometer (Hologic Inc, Waltham, MA).

The scan time was 3 minutes, and the radiation dose was approximately 2 μSv per scan. Total and regional analyses were performed using the standard manufacturer’s protocol. A segmentation of the whole-body image was obtained in 6 subregions: left arm, right arm, trunk, left leg, right leg, and head. In each, the results

Statistics

Data are expressed as mean ± 1 SD. ANOVA for repeated measures (alpha level, 5%) was first used to compare body composition data at different times, then a paired t-test was used to compare 2 time points for LBM and biologic values at T0, T12, and T24 months. Analyses were performed using Stat View 5.0 (Abacus Concept, Berkeley, CA).

Results

The average baseline and 24-month clinical and blood chemistry values are reported in Table 1. Blood urea values significantly decreased from T0 to T24 in accordance with low protein intake. The compliance was good and assessed by the urea urinary excretion as shown in Figure 1. Protein intake was 0.81 ± 0.29 before VLPD, 0.31 ± 0.08 at 3 months, 0.39 ± 0.15 at 12 months, and 0.38 ± 0.12 g/kg/day at 24 months. No significant variation existed from month 3 to month 24 at quarterly evaluation.

DEXA results

Body mass index remained stable during the 24-month follow-up. No significant change occurred in total fat mass or percentage of fat mass between T0 and T24.

After an initial decrease in LBM in the first 3 months, from 44.9 ± 11.8 Kg to 43.7 ± 11 (mean difference, 1.387 kg; paired t test P = .034), a progressive increase occurred resulting in a significant increase of 2 kg (P = .027), whereas there was no significant change per the overall follow-up (P = .2). These evolutions in LBM are shown in

Discussion

In this 2-year prospective study, we have followed up for 2 years the course of nutritional status and body composition of 13 patients with advanced CRF put on a SVLPD. Body weight and body composition evolved into 2 distinct phases after the initiation of the dietary prescription.

During the first 3 months, LBM decreased, particularly in men, whereas fat mass did not change. After the third month, even with a slight but not significant progression of renal failure, body weight increased

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