TRABAJO ORIGINAL / Otros

Effects of oat bran and nutrition counseling on the lipid and glucose profile and anthropometric parameters of hypercholesterolemia patients

Efectos del salvado de avena y del asesoramiento nutricional en el perfil de lípidos y glucosa y en los parámetros antropométricos de los pacientes con hipercolesterolemia

Simone Raimondi de Souza¹, Gláucia Maria Moraes de Oliveira¹, Ronir Raggio Luiz² and Glorimar Rosa^1,3

¹Postgraduate Program of Medicine/Cardiology. Federal University of Rio de Janeiro.
²Institute of Collective Health. Rio de Janeiro Federal University. ]]> ³Josué de Castro Institute of Nutrition. Federal University of Rio de Janeiro. Brazil

Correspondence

ABSTRACT

Background: In order to prevent chronic, non communicable disease, it is essential that lifestyle is modified to include a diet high in fiber.
Aim: To assess the effect oat bran (OB) in conjunction with nutrition counseling (NC) have on lipid and glucose profile, anthropometric parameters, quality of diet, and ingestion of ultraprocessed foods (UPF) and additives in hypercholesterolemia sufferers.
Method: This was a 90-day, double-blind, placebo-controlled, block-randomized trial undertaken on 132 men and women with LDL-c ≥ 130 mg/dL. The participants were sorted into two groups: OB Group (OBG) and Placebo Group (PLG), and were given NC and 40g of either OB or rice flour, respectively. Lipid and glucose profile were assessed, as were the anthropometric data, quality of diet (Diet Quality Index revised for the Brazilian population - DQI-R) and whether or not UPF or additives were consumed.
Results: Both groups showed a significant decrease in anthropometric parameters and blood pressure, as well as a significant reduction in total and LDL cholesterol. There was also an improvement in DQI-R in both groups and a decrease in consumption of UPF. Blood sugar, HOMA-IR and QUICKI values were found to be significantly lower only in the OBG.
Conclusion: Our findings in lipid profile and anthropometric parameters signify that NC has a beneficial effect, which is attributable to the improved quality of diet and reduced consumption of UPF. Daily consumption of 40 g of OB was found to be of additional benefit, in decreasing insulin-resistance parameters.

RESUMEN

Antecedentes: con el fin de prevenir la enfermedad crónica, no transmisible, es esencial que el estilo de vida se modifique para incluir una dieta alta en fibra.
Objetivo: evaluar el efecto de la harina de avena (DE) en conjunto con consejos de nutrición (NC) sobre el perfil lipídico y glucémico, los parámetros antropométricos, la calidad de la dieta, y la ingestión de alimentos ultraprocesadas (UPF) y aditivos en los enfermos de hipercolesterolemia.
Método: se realizó un ensayo de 90 días, doble ciego, controlado con placebo, aleatorizado realizado en 132 hombres y mujeres con c-LDL ≥ 130 mg/dl. Los participantes fueron clasificados en dos grupos: DE Group (OBG) y el grupo placebo (PLG), y se les dio NC y 40 g de DE o de harina de arroz, respectivamente. Se evaluó el perfil lipídico y la glucemia, así como los datos antropométricos, la calidad de la dieta (Índice de Calidad de la dieta revisada para la población brasileña ICD-R) y si se consumieron UPF o aditivos.
Resultados: ambos grupos mostraron una disminución significativa en los parámetros antropométricos y la presión arterial, así como una reducción significativa en el colesterol total y LDL. También hubo una mejora en la ICD-R en ambos grupos y una disminución en el consumo de la UPF. La glucemia, HOMA-IR, y QUICKI fueron significativas en inferiores sólo en el grupo que consumió salvado de avena.
Conclusión: nuestros hallazgos sobre las modificaciones en el perfil lipídico y en los parámetros antropométricos significan que los consejos nutricionales tienen un efecto beneficioso, que es atribuible a la mejoría en la calidad de la dieta y al menor consumo de alimentos ultraprocesados. El consumo diario de 40 g de salvado de avena proporciona un beneficio adicional, al disminuir los parámetros de resistencia insulínica.

Palabras clave: Harina de avena. Beta-glucano. Asesoramiento nutricional. Hipercolesterolemia. Dislipidemia. Enfermedades crónicas no transmisibles.

Introduction

In the prevention of chronic, non communicable disease, it is vital to create an environment conducive to health and healthful choices (2). Research in primary and secondary prevention shows that in dyslipidemia sufferers nutrition counseling inhibits the modulation of mechanisms that regulate lipid and glucose metabolism (7,8).

Oat (Avena sativa L.) contains beta-glucans, soluble fibers that may act to inhibit the absorption of fats and carbohydrates. Although the Food and Drug Administration (FDA) and ANVISA (Brazil's health watchdog) consider a daily intake of 3 g of beta-glucans to be sufficient to curtail cholesterol absorption, clinical trials have provided controversial results (11-13), which compels further investigation.

The main objective of our study is to assess the effect oat flour consumption coupled with nutrition counseling have on the lipid and glucose profile, anthropometric parameters, quality of diet and the ingestion of processed foods and additives in hypercholesterolemia sufferers.

Material and methods

This study was approved by the Research Ethics Committee monitoring studies involving human beings at the Aloysio de Castro State Cardiology Institute (IECAC) -ruling no. 47305. All the participants that agreed to take part in the research signed a free and informed consent form (FICF).

The sample calculation was based on a pilot study involving 44 individuals (14 men, 30 women), using Openepi software version 3.0 (Open Source Epidemiological Statistics for Public Health, available at www.openepi.com), with a 95% (α) confidence interval, the power of 80%, and a 1:1 size ratio between the sample groups. We took into account differences between mean (intervention vs. placebo) decrease in LDL-c, of 30 mg/dl x 15 mg/dL (absolute values), with variability (SD) of 30. The resulting number was 63 individuals for each group.

We performed a 90-day, double-blind, placebo-controlled block-randomized trial on men and women over 20 years of age whom we found at the Aloysio de Castro State Cardiology Institute. Criteria for inclusion: LDL-c ≥ 130 mg/dL, either taking or not taking lipid-lowering medication. Criteria for exclusion: water restrictions, use of dietary-fiber supplements, or pregnancy or lactation. We selected 227 individuals of whom 134 met the inclusion criteria. The screening and inclusion phase took place between October 2012 and January 2014.

The included individuals were sorted into two groups: Oat Bran Group (OBG) and Placebo Group (PLG). The nutrition counseling they were given was based on Dez Passos para uma Alimentação Saudável do Ministério da Saúde (14) (Ten Steps to a Healthy Diet published by the Ministry of Health). During each appointment individuals were given a box containing 30 daily portions of a morning mixture, comprising either fat-free powdered milk, sucralose-based artificial coloring and 40 g of oat bran (OBG) containing the equivalent of 3 g of beta-glucans, or 40 g of corn starch and rice flour (PLG), with instructions to consume the preparation as porridge in the morning. Each participant was monitored for 90 days through monthly visits.

Quality of diet was assessed through the 24HR throughout the entire intervention by using the Food Processor^® software version 7.2 (25), the Nutritional Composition Table for Foods Consumed in Brazil (26), the Table for Assessing Dietary Intake in Home Food Proportions (27), and Dietary Reference Intakes (28). We applied the Diet Quality Index revised for the Brazilian population (DQI-R) (29), with a cutoff point of 75 percentile (75 p), taking as the baseline the points the DQI-R attributed to all the 24HRs at basal time (t0). DQI-R values greater than or equal to 75 p were deemed "adequate standard diet", while under 75 p was an "inadequate standard diet".

The assessment of ultraprocessed foods and additives was performed by way of 24HR, with the consumption of such foods as chocolate, margarine, cookies, whole milk, foods with fillings, soft drinks, candies, added sugar, instant noodles, vegetable oil, sodium and processed juices quantified before and after the nutritional intervention.

Exploratory analysis of the data was done by calculating the measures of central tendency and amplitude (median and interquartile range). We assessed the normality of the variables using the Komolgorov Smirnoff method. As most of the variables were not of normal distribution, we adopted the non-parametric Mann-Whitney and Wilcoxon tests. We used the SPSS software package (Statistical Package for the Social Sciences) version 20.0. The level of statistical significance we adopted was 5% (p < 0.05).

Results

One hundred and thirty-two participants completed the study, 66 in each group. Their overall characteristics are presented in table I. We found that there was no difference between the groups, testament to the effectiveness of the randomization. Around half the patients had at least one risk factor and around a fifth had suffered some sort of cardiovascular event. Around 40% used medication to treat high blood pressure, and 15% of the OBG and 17% of the PLG were taking hypolipidemic medication, without properly controlling LDL-c.

Table III presents the variation between laboratory parameters over the course of the study. Both groups showed a significant decrease in total cholesterol and LDL-c. The HOMA-IR and QUICKI glucose values showed a significant decrease only in the group that was given the oat flour intervention.

Table IV presents the nutritional data over the course of the study and it shows that both groups reduced their carbohydrate consumption and achieved a normal distribution of macronutrients. However, only the OBG saw a significant increase in dietary fiber consumption.

In our diet-quality analysis, classified by DQI-R, we found the value 80.57 in 75 p. At t0 27% of the OBG participants were found to have adequate eating habits, with a score ≥ 80.57. In the PLG, 23% practiced an adequate diet. By the end of the study, the percentages increased significantly to 88% and 89% in the OBG and PLG, respectively.

Table V presents anthropometric, biochemical and blood pressure data from the pre- and post-intervention periods, as related to quality of diet. The OBG and PLG were subdivided into DQI-R < p75 versus DQI-R ≥ p75 categories. We found that even the individuals who began the study with adequate eating habits improved their score. By the end of the study both subgroups achieved practically the same DQI-R. OBG and PLG participants were found to eat a low quantity of processed food at t0, which lowered even more once both the OBG and PLG had undergone 90 days of nutritional intervention.

Discussion

Our findings from the lipid profile and anthropometric parameters show that nutrition counseling has a beneficial effect that can be attributed to the improvement in diet quality and the decreased consumption of ultraprocessed foods in our study. Nutrition intervention at a population level is shown to be beneficial over time, especially when the lifestyle changes proposed are followed, both in primary and secondary prevention (30). These measures seem to have a greater effect in developing nations where large segments of the population are low-income. However, it is necessary to involve society and health care professionals in order to see that the strategies being proposed are carried out step by step (31).

Karmally et al. (32) compared the effects of oat flour consumption (3 g of beta-glucans) with corn-based cereal lacking in soluble fiber in 152 individuals with hypercholesterolemia for six weeks. They noted a drop in TC and LDL-c of 4.5% and 5.3%, with no decrease in BM. Chen et al. (33) assessed 102 individuals with hypercholesterolemia taking 8g of beta-glucans over 90 days, with no significant results in BM, WC, TC or LDL-C. Maki et al. (11) conducted a study on 144 overweight or obese adults with LDL-c ≥ 130 mg/dL and taking 3 g beta-glucans and undergoing a BM-loss program over a period of 12 weeks. They found a significant decrease in TC, LDL-c and not in HDL-c in the intervention group, with minor decreases in BM.

A recent systematic revision of the use of beta-glucans for lowering blood sugar and lipids in diabetic patients showed benefits stemming both from low and high doses over prolonged periods of use. The authors stress that there is a dearth of longitudinal studies where the beneficial effects can be better evaluated (36). A possible mechanism to explain this effect could be that the gelatinous layer created by the beta-glucans prevents the enterocytes from absorbing glucose (37). There are also reports of a decrease in insulin resistance in obese women who ingest high doses of beta-glucans (38). These results are similar to the results of this study, which present a significant drop in serum glucose, HOMA-IR and QUICKI, suggesting a decrease in insulin resistance in dyslipidemia sufferers. However, these findings were obtained through much higher doses than the ones previously described (38).

The inclusion of patients both in primary and secondary prevention may have masked the effect OF had on lipid profile due to 20% of the sample using of hypolipidemic medication. However, all the patients involved had LDL-c ≥ 130 mg/dL, suggesting a lack of control, even while employing pharmacological measures. The same reasoning applies to 10% of the diabetic patients taking oral hypoglycemic agents. When patients taking hypolipidemic and hypoglycemic drugs were excluded from the sample group, results were not affected.

Conclusion

The findings pertaining to lipid profile and anthropometric parameters show that NC has a beneficial effect attributable to the improved quality of diet and decreased consumption of UPF. Daily consumption of 40 g of OF was shown to be of added benefit in lowering the parameters relating to insulin resistance.

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Correspondence:
Glorimar Rosa.
Departamento de Nutrição e Dietética.
Instituto de Nutrição Josué de Castro ]]> da Universidade Federal do Rio de Janeiro.
Av. Carlos Chagas Filho, 373.
Edifício do Centro de Ciências da Saúde,
Bloco J/2^o andar. Cidade Universitária.
CEP: 21941-902. Rio de Janeiro, Brasil
e-mail: glorimar@nutricao.ufrj.br

Received: 27/10/15
Accepted: 12/11/15