The Effect Of Low-Fat And Low-Cholesterol Dietary Intervention On LDL Sub-Groups In Turkısh Dyslipidemic Patients

The aim of this study is to compare LDL sub-group concentration before and after a diet with low-fat and low-cholesterol prescribed to dyslipidemic patients for 12 weeks.

The study was conducted between January 2018-July 2019 in Erciyes University Health Application and Research Center. This study was planned as a clinical trial for treatment and 47 patients were included. All participants were given written consent. The study was evaluated to be ethically appropriate by Erciyes University Faculty of Medicine Clinical Research Ethics Committee.

A low-fat (\<30% of total energy), and low-cholesterol (\<200 mg/day) diet was planned for the participants at the baseline, according to the gender, lifestyle, working conditions, nutritional habits, BMI, concomitant diseases and risk conditions. The patients were called for monthly controls and followed up for a total of 12 weeks. When the patients admitted at the first and second months, Body Impedance Analyzer (BIA) measurements were performed and dietary adherence was controlled. If necessary, the energy requirements of the patients were re-calculated and their diets were re-newed and if the patients had any questions on the diet, they were answered. Blood samples were taken from the patients at the baseline and after 12 weeks and the effects of a low-fat, low-cholesterol diet on biochemical and anthropometric measurements were evaluated. Energy restricted diet were planed for overweight and obese patients (\~ 500-1000 kcal/day). In addition, patients were recommended to walk at a moderate speed for at least 30-40 min per day.

Data Collection A questionnaire including socio-demographic characteristics, nutritional habits, physical activity status, and comorbid diseases was filled by the researcher. The food consumption frequency of the participants was evaluated by dividing the frequencies into four groups as consuming 5-6 times daily, consuming every other day, consuming 1-2 times a week and consuming 1-2 times a month or never at all. Food consumption records were also taken from each patient. Physical activity was questioned by the 'International Physical Activity Questionnaire (short form).

Statistical analysis The suitability of the data for normal distribution was evaluated by histogram, q-q graphs and Shapiro-Wilk test. Variance homogeneity was tested with Levene test. Two groups independent samples t-test and Mann-Whitney U-tests were used for quantitative variables. In the qualitative data, two repeated measurement comparisons were used with McNemar-Bowker test. The paired t-test and Wilcoxon tests were used in the quantitative data for two repeated measurements. Spearman analysis was used to evaluate the relationship between quantitative variables. Data analysis was performed by Turcosa Cloud (Turcosa Ltd Co) statistical software. Significance level was accepted as p\<0.05.

Anthropometric measurements After the completing the questionnaire, anthropometric measurements were taken. Body weight: When the patient was in fasting state in the morning measured with thin clothes. While measuring body weight, the individual was asked to remove his heavy clothes (coats, jackets, etc.), belongings in the pockets (wallet, key ring, phone, address book etc.) and shoes. Attention is given to place the feet on the balance and to ensure a balanced distribution of body weight to the two feet. The individual was asked to stand upright and without moving. The measurement was made with a sensitivity of 0.1 kg (100 g). Height: The height was measured with a stadiometer while the feet were side-by-side and the head was in the Frankfort plane. Body mass index (BMI): BMI was calculated by dividing subjects body weight by square of his/her height. \[BMI = Body weight (kg)/height (m)²\]. Waist circumference: The waist circumference was measured with a non-elastic tape measuring the mid-point between the lower rib and the crista iliac crest. Waist-to height ratio: It was calculated by the division of waist circumference (cm) into height (cm). Neck circumference: Neck circumference was measured with a non-elastic plastic band from the middle of the neck height between the middle cervical spine and the middle anterior neck with a sensitivity of 0.1 cm. In men with Adam's apple, it was measured just below the protrusion. BIA measurements: Body composition of the participants was determined with Tanita BC-418 MA (Tanita Corporation of America, Inc., Arlington Heights, IL) device. In order to make accurate measurements; metal jewelery on individuals, socks, clothes that will affect the measurement excessively were removed and information about the person's age, height, gender and whether they are dealing with regular sports activities were entered into the device. Then, individuals were removed from the instrument with their heels on the electrodes and the measurement was made. It was taken into consideration that participants did not perform intensive physical activity 24-48 hours before the measurement. It was observed that individuals did not have heavy physical activity 24-48 hours before the measurement, they were fasted for at least 4 hours, no alcohol was used 24 hours before, and they did not consume too much beverages (tea, coffee) before the measurement (at least 4 hours).

Biochemical parameters In the Endocrinology polyclinic; the patients were diagnosed with dyslipidemia by an endocrinologist and their fasting blood glucose (mg/dL), triglycerides (mg/dL), total cholesterol (mg/dL), HDL-cholesterol (mg/dL), LDL-cholesterol (mg/dL) levels were evaluated. Patients were selected according to the inclusion criteria and blood was drawn after fasting for at least 10-12 hours. Very low density lipoprotein (VLDL (mg/dL)), large-LDL (mg/dL), small-LDL (mg/dL) medium density lipoprotein (IDL (mg/dL)) (Mid A, B, C) values. After centrifugation, blood samples were kept in the freezer at -80°C in Erciyes University Endocrinology Service until analysis period. For patients who were not initially evaluated for insulin (mg/dL), some blood was collected and delivered to Erciyes University Blood Collection Department and studied at the Central Biochemistry Laboratory of Erciyes University. Fasting blood glucose, triglyceride, total cholesterol, HDL-cholesterol and LDL-cholesterol levels were measured by spectrophotometric method using Roche Diagnostics (Basel, Switzerland). Insulin was measured by the ECLIA study method using the Roche Diagnostics (Mannheim, Germany). LDL subgroups were measured in serum samples using a Lipoprint System (Quantimetrix Inc., Redondo Beach, CA, USA). This system separates lipoproteins in a non-denaturing gel gradient of polyacrylamide based on net surface charge and size. The dye binds proportionally to the relative amount of cholesterol in each lipoprotein. After the electrophoresis, densitometric analyzes and proportional concentrations of lipoprotein classes and subclasses were calculated on the Lipoware software. In this system, VLDL, IDL corresponding to 3 midbands (Mid A, B, C) and 7 LDL subgroups: LDL-1 to -2 (large, bouyant, pattern A); LDL-3 to -7 (small, dense; pattern B). The system also gives the average LDL particle size. Type A if particle size was ≥268Â, medium level if particle size was 265-268Â, type B if particle size was ≤265Â.

Eligibility Criteria:
Inclusion Criteria

* Being diagnosed with dyslipidemia by an endocrinologist
* Those who do not have a history of diabetes, hyperthyroidism, hypothyroidism (including those who have hypothyroidism but receive replacement therapy)
* 25-65 years
* Body Mass Index (BMI) = 25-40 kg/m²
* Smoking three or less than three cigarettes a day
* Not using herbal supplements.
* Not being in pregnancy or lactation period
* Volunteering to participate in the study

Exclusion Criteria:

* Not being diagnosed with dyslipidemia
* Using a drug that affects the lipid profile
* Not being in the age range of 25-65
* BMI = 25-40 kg/m² not
* Smoking more than three cigarettes a day
* Using herbal supplements
* Being in the pregnancy or lactation period
* Not willing to participate in the study