Design.
Randomised, crossover, double-blind, controlled, 1:1 allocation clinical trial. Participants were randomly assigned to first receive one bottle of an oligomeric or polymeric oral nutritional supplement. This was followed by a 7-day washout period without receiving another oral nutritional supplement. At the end of this period, participants ingested a container of the type of supplement they had not initially received.
Eligibility criteria.
Inclusion criteria: persons of either sex aged ≥ 12 and ≤ 50 years, diagnosed with AN according to DSM-5 criteria(19), with adequate cultural level and understanding of the clinical study, and who signed the informed consent form.
Exclusion criteria: women who were pregnant, breastfeeding or had given birth in the 6 weeks prior to the screening visit; people with an allergy or intolerance to any component of the products under study, or who were participating in a concomitant trial that conflicted with this study.
Participants were recruited from the Unidad de Trastornos de la Conducta Alimentaria (UTCA) of the Hospital Regional Universitario de Málaga, Spain. All users seen at the clinic who met the inclusion criteria and had no exclusion criteria were offered to participate in the study.
Informed consent was obtained from all subjects involved in the study. The study was conducted in accordance with the Declaration of Helsinki, and approved by the Malaga Provincial Research Ethics Committee on 30 September 2021, code 1735-N-21.
Location.
The study was carried out at the UTCA of the Hospital Regional Universitario de Málaga, Spain.
Intervention.
Participants were summoned for breakfast in the dining room of the UTCA day hospital. They had been previously instructed to come fasting. On arrival, they filled in the "Digestive Symptom Questionnaire", had their weight and height measured, and underwent bioimpedance and dynamometry. They were then offered a container of the intervention nutritional supplement (oligomeric or polymeric, according to randomisation) to be consumed, under the supervision of healthcare staff, within a maximum period of one hour. After this hour, they remained in the day hospital for a further hour and then completed the "Product sensory evaluation questionnaire" and, again, the "Digestive symptoms questionnaire". Participants were recalled one week later to receive a pack of the type of intervention supplement they had not received initially (oligomeric or polymeric) and the same procedure as at the previous visit was repeated, except that weight and height measurement, bioimpedance measurement and Jamar dynamometry were not performed again.
Intervention products.
Product A (oligomeric nutritional formula): "Bi1 peptidic". Hypercaloric and hyperproteic formula, formulated with 100% hydrolysed whey protein, additional glutamine, fat content of 70% medium chain triglycerides and 23% extra virgin olive oil, with eicosapentaenoic and docosahexaenoic acid, no fibre. (Table 1).
Table 1
Composition of the oligomeric supplement "Bi1peptidic" and polymeric "Bi1 control hp/hc" per 100 ml.
|
Oligomeric
|
Polymeric
|
Energy (kcal)
|
150
|
150
|
Fat (g)
-Saturated fatty acids (g)
Monounsaturated fatty acids (g)
-Polyunsaturated fatty acids (g)
--EPA (mg)
--DHA (mg)
|
4.8
3.6
0.87
0.33
46
29
|
5.67
0.95
1.89
2.83
|
Carbohydrates (g)
-Sugars (g)
|
19
0.88
|
17.3
6.8
|
Fibre (g)
|
0
|
0
|
Protein (g)
|
7.9
|
7.5
|
Salt (g)
|
0.33
|
0.23
|
Osmolality (mOsm/l)
|
580
|
410
|
EPA: eicosapentaenoic acid. DHA: docosahexaenoic acid. |
Product B (standard-polymeric nutritional formula): "Bi1 control hp/hc". Hypercaloric and hyperproteic formula, isocaloric and isoproteic compared to product A. Calcium caseinate as protein source, with sunflower oil, without fibre. (Table 1).
The study products were stored in a place with appropriate conditions for food preservation, with controlled access and at room temperature.
Outcome measures of primary and secondary objectives.
-
Digestive tolerance: was assessed using the "Digestive Symptom Questionnaire", a questionnaire designed for this study. It consists of 6 items, which assess the presence, and if applicable, the intensity of the following symptoms: nausea, vomiting, diarrhoea, constipation, reflux or heartburn, and pain. Each item has a score from 0 (none) to 10 (maximum) with whole numbers.
-
Sensory perception of the supplements: was assessed using the "Product sensory evaluation questionnaire", a questionnaire designed for this study. It consists of 11 items, which assess how the patient perceives the organoleptic characteristics of the product and their satisfaction after taking it. The items evaluated are: degree of satisfaction with the taste, degree of sweetness, degree of saltiness, degree of bitterness, degree of acidity, degree of aftertaste, degree of satiety, satisfaction with the smell, satisfaction with the appearance/colour, sensation after taking it, overall score. Each item has a score from 0 (none) to 10 (maximum) with whole numbers.
Additional measurements.
-
Weight: was measured using a digital scale for clinical use (SECA 665), with the person's back to the indicator, barefoot, wearing a minimum of warm clothing (trousers and T-shirt), heels together, looking straight ahead and with an upright posture.
-
Height: a measuring rod (Holtain limited, Crymuch) was used, with the person standing with his back to it, barefoot, in an upright position, with the heels, buttocks, upper mid-back and head in contact with the vertical axis of the stadiometer; the arms extended parallel to the body, the feet joined by the heels forming a 45º angle and the head positioned following the horizontal Frankfort plane. At the time of reading, the individual had to look straight ahead and take a deep breath in order to compensate for the shortening of the intervertebral discs.
-
Bioimpedancemetry: was performed with an Akern BIA-101/Nutrilab analyser (Akern SRL, Pontassieve, Florence, Italy). The measurements were performed in the supine position, with abducted upper (30º) and lower (45º) limbs. Dedicated software (Bodygram Dashboard from AKERN, Pontassieve, Florence, Italy) was used to perform analyses of the results. Fat mass and lean mass were determined.
-
Hand dynamometry: it was measured in dominant hand with a Jamar dynamometer (Asimow Engineering Co., Los Angeles, CA, USA). For this test, the person was sitting comfortably with shoulder adducted and forearm neutrally rotated, elbow flexed to 90°, and forearm and wrist in a neutral position. They were told to perform three consecutive contractions one minute apart from each other. The mean of the three measurements was recorded.
Sample size.
With a confidence level of 95%, a statistical power of 80%, an estimated difference of 2 points on the nausea scale between groups (standard deviation of 1.5), 20 subjects should be recruited (10 per group); taking into account an expected loss ratio of 10%, the required sample size was 22 participants (11 per group).
Randomization.
A simple 1:1 randomisation was performed. Using a computer programme, a table was obtained with a randomisation sequence for each new participant recruited to start taking either the oligomeric or the polymeric supplement. The initial assigned treatment was named with the code with which the intervention supplements were labelled (one code for the oligomeric and one for the standard formulation).
Blinding.
Double-blinding was performed. Neither the study participants nor their caregivers or data collectors were aware of the formula that had been assigned to each participant. Blinding was achieved by identical presentation of the intervention products, which were packaged and labelled in the same way. They differed only by the identification number. Only the person responsible for the statistical analysis knew the numerical designation corresponding to the oligomeric and standard formula.
Statistical analysis
The analysis conducted was per protocol. Participants who completed the study were analysed. To determine whether the variables followed a normal distribution, the Shapiro-Wilk test was applied. As it was found that the variables did not follow a normal distribution, non-parametric tests were applied. Paired sample tests were used, as each subject received both supplements. Baseline characteristics were described by absolute number and percentage, or median and interquartile range, depending on the variable. To study whether there was a difference in the score on the "Digestive Symptom Questionnaire" between before and after taking each supplement, the Wilcoxon signed-rank test was used. To analyse whether there was a difference in the worsening cateogry (yes/no) on the "Digestive Symptom Questionnaire" between the two supplements, McNemar's test was used. To study whether there was a difference in the score on the "Product sensory evaluation questionnaire" between the two supplements, the Wilcoxon signed-rank test was used. A significance level of p < 0.05 was applied for all tests. The data were computerised and analysed using the statistical package SPSS version 25.