The aim of this study was to investigate the effect of daily walnut consumption on dyslipidemia in dietary. Within a year, the patients who have been suggested taking walnut or not in their individual dietary were scanned retrospectively and randomized into 2 groups. The first group consists of 72 cases (only those taken on the diet program) and the second group consists of 73 cases (walnut consumption in regulated diet). Baseline blood lipid parameters and anthropometric measurements were assessed in both groups and compared with values at 3rd month.
Cardiovascular diseases are important cause of mortality and morbidity especially in developing countries, and dyslipidemia, a common health problem, is one of the most important cardiovascular risk factors [
Among the nuts, it has been found that the effects of walnuts on health are promising. Walnut has been suggested due to being rich in antioxidant-active polyphenols and unsaturated fatty acids in its composition and nutritionally recommended for healthy nutrition and protective effects against cardiovascular diseases [
Walnut has a higher content of PUFAs, including linolenic acid (omega-3), which has antiatherogenic effects and some epidemiological studies suggest that linolenic acid may provide certain cardiovascular benefits [
Polyphenols, one of the important compounds of walnut, provide a protective effect on the cardiovascular system by preventing oxidation. Walnut contains ellagintannin polyphenols (glansrine A), which haveantioxidant effects [
In these limited studies, although the effect of walnut consumption on the lipid profile has been investigated, more clinical trials are needed in this area. In our study, it is aimed to evaluate whether the possible effect of daily walnut consumption on lipid profile in patients with dyslipidemia is not required or lipid parameters not controlled by lifestyle modification is considered medication according to the guidelines of the American Heart Association/American College of Cardiology (AHA/ACC) of 2013 [
In the study, between June 2015 and June 2016, 145 of 450 cases were examined at the age of 18 and above who applied to the Family Physician Diet Policlinic of Mersin University (305 cases were excluded due to exclusion criteria). It was structured as a subgroup analysis of the prospective study which was approved by Local Ethic Committee dated May 28, 2015, and number 2015/166.
The inclusion criteria for the examination were the following: 18 years and over, fasting blood sugar ≤110 mg/dl, and according to the 2013 AHA/AAC Guidelines for the treatment of dyslipidemia, patients who do not need medication or if lipid parameters not controlled by lifestyle modification is considered medication.
The exclusion criteria for the examination were the following: obesity (Body Mass Index (BMI) ≥35 kg/m2), with known coronary artery disease, acute or chronic inflammation, a known walnut allergy, smoking, with a known systemic or metabolic disease, having antidiabetic, hypolipidemic, antihypertensive or anti-inflammatory drug, vitamin E or hormone replacement therapy in the last 3 months.
2 groups were randomized. Only individualized diet, recommended by AHA Dietary Guidelines [
In addition, Maras 18, one of the walnut cultivar produced in our region, was analyzed to determine fatty acid profiles using chromatographic technique [
SPSS (version 21.0) statistic software package was used for data analysis. For continuous data, the results are presented as mean value ± SDs. The Kolmogorov–Smirnov test was applied to verify whether the continuous variables showed a normal distribution. Independent samples
Oil extraction was performed using 5 g of homogenized kernels using hexane as a solvent by automatic Soxhlet equipment (Gerhardt Soxtherm), and triplicate analysis were done. The residue was dried under vacuum concentrator. Methyl esterification was done using Boron trifluoride/methanol (FAMEs) Bligh and Dyer (1959) (AOAC, 1990).
After the methyl esterification, fatty acids were analysed by Gas chromatography with an auto sampler (Perkin Elmer, Shelton, CT, USA) equipped with a flame ionization detector and a fused-silica capillary SGE column (100 m × 0.32 mm, ID 0.25
The baseline demographic characteristics, anthropometric measurements, and blood lipid parameters (including total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), very low-density lipoprotein cholesterol (VLDL), and triglycerides (TG) of participants with control group (only regulated diet) and subjects group (walnut consumption in regulated diet)) are given in Table
Baseline values of demographic characteristics, anthropometric measurements, and blood lipid parameters between control and subject groups.
Variable | Control group ( |
Subject group ( |
MVU-t value |
|
---|---|---|---|---|
Gender (male/female) | 24 (33.3%)/48 (66.7%) | 25 (34.2%)/48 (65.8%) | ||
Age (years) | 40.7 ± 9.59 | 41.0 ± 10.84 | −0.16 |
0.87 |
Height | 167.4 ± 9.10 | 166.8 ± 8.20 | 2.56 | 0.79 |
Weight (kg) | 85.0 ± 13.18 | 86.3 ± 11.17 | 2.80 | 0.48 |
BMI (kg/m2) | 30.1 ± 2.91 | 30.9 ± 2.55 | 2.97 | 0.16 |
WC (cm) | 103.5 ± 9.36 | 104.4 ± 9.84 | 2.75 | 0.61 |
TC (mg/dl) | 251.5 ± 27.54 | 249.2 ± 39.16 | 2.30 | 0.20 |
HDL (mg/dl) | 48.5 ± 9.57 | 47.0 ± 10.16 | 0.97 |
0.33 |
LDL (mg/dl) | 152.2 ± 16.31 | 152.2 ± 15.92 | 2.64 | 0.95 |
VLDL (mg/dl) | 49.5 ± 13.63 | 49.9 ± 14.55 | 2.63 | 0.97 |
TG (mg/dl) | 247.5 ± 68.16 | 249.6 ± 72.61 | 2.63 | 0.98 |
MVU-t, Mann–Whitney
Triglycerides (TG) at the baseline and at 3rd month measurements of the study population are compared in Table
The comparison of baseline and at 3rd month values for both groups.
Variable | Regulated diet baseline | Regulated diet at 3rd month | ± (%) | WSR-t |
|
---|---|---|---|---|---|
Weight (kg) | 85.0 ± 13.18 | 82.0 ± 12.15 | −3.50 | −7.37 | <0.001 |
TC (mg/dl) | 251.5 ± 27.54 | 236.5 ± 22.03 | −5.96 | −7.39 | <0.001 |
HDL (mg/dl) | 48.5 ± 9.57 | 48.6 ± 9.30 | +2.08 | 0.374 | 0.708 |
LDL (mg/dl) | 152.2 ± 16.31 | 145.1 ± 15.21 | −4.66 | −7.40 | <0.001 |
VLDL (mg/dl) | 49.5 ± 13.63 | 42.6 ± 11.68 | −13.93 | −7.40 | <0.001 |
TG (mg/dl) | 247.5 ± 68.16 | 213.0 ± 58.43 | −13.93 | −7.37 | <0.001 |
|
|||||
Variable | Walnut consumption in regulated diet baseline | Walnut consumption in regulated diet at 3rd month | ± (%) | WSR-t |
|
|
|||||
Weight (kg) | 86.4 ± 11.17 | 83.4 ± 10.368 | −3.47 | −7.42 | <0.001 |
TC (mg/dl) | 249.2 ± 39.16 | 218.5 ± 32.98 | −12.31 | −7.42 | <0.001 |
HDL (mg/dl) | 47.0 ± 10.16 | 51.6 ± 10.27 | +9.78 | 7.50 | <0.001 |
LDL (mg/dl) | 152.2 ± 15.92 | 129.9 ± 13.27 | −14.65 | −7.43 | <0.001 |
VLDL (mg/dl) | 49.9 ± 14.55 | 37.0 ± 10.68 | −25.5 | −7.43 | <0.001 |
TG (mg/dl) | 249.6 ± 72.61 | 185.1 ± 53.46 | −25.84 | −7.42 | <0.001 |
WSR-t, Wilcoxon signed rank test; TC, total cholesterol; HDL, high-density lipoprotein cholesterol; LDL, low-density lipoprotein cholesterol; VDLC, very low-density lipoprotein cholesterol; TG, triglycerides.
Comparison of the groups at the end of 3 months is presented in Table
Comparison of the groups at 3rd month.
Variable | Regulated diet ( |
Walnut consumption in regulated diet ( |
(%) | MVU-t |
|
---|---|---|---|---|---|
Weight (kg) | 82.0 ± 12.15 | 83.4 ± 10.36 | −1.67 | 2.82 | 0.427 |
TC (mg/dl) | 236.5 ± 22.03 | 218.5 ± 32.98 | −7.61 | 1.5 | <0.001 |
HDL (mg/dl) | 48.6 ± 9.30 | 51.6 ± 10.27 | +6.17 | 3.01 | 0.125 |
LDL (mg/dl) | 145.1 ± 15.21 | 129.9 ± 13.27 | −10.47 | 1.56 | <0.001 |
VLDL (mg/dl) | 42.6 ± 11.68 | 37.0 ± 10.68 | −13.14 | 1.78 | <0.001 |
TG (mg/dl) | 213.0 ± 58.43 | 185.1 ± 53.46 | −13.09 | 1.79 | <0.001 |
MVU-t, Mann–Whitney
The fatty acid analysis of kernel of Maras 18 variety is shown in Table
Fatty acids analysis of kernel of Maras 18 (%).
Myristic acid | Palmitic acid | Stearic acid | Arachidic acid | Margaric acid | SFA | Palmitoleic acid | Oleic acid | MUFA | Linoleic acid | Linolenic acid | PUFA | |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Mean | 0.02 ± 0.00 | 5.98 ± 0.12 | 2.39 ± 0.17 | 0.03 ± 0.00 | 0.07 ± 0.00 |
|
0.19 ± 0.03 | 21.98 ± 2.85 |
|
54.37 ± 2.60 | 14.69 ± 0.61 |
|
In this study, it was intended to examine whether the effect of daily walnut consumption on lipid profile in patients with dyslipidemia medication is not required or if lipid parameters not controlled by lifestyle modification is considered medication according to the guidelines of the AHA/ACC of 2013 [
Many studies have shown that consumption of walnuts decreases the TC, LDL, and TG and increases the HDL and apolipoprotein levels [
In a study conducted on 49 volunteers with a high LDL level (from 130 mg/dl), walnut diet was recommended for one group instead of olive oil and other fatty foods. The reduction in TC level in the walnut diet group was about 9% (about 25 mg/dl), while in the control group was 5% (14 mg/dl). LDL was reduced 11% (22 mg/dl) in the walnut diet, while in the control group, this ratio was 6%, and the HDL was similar in both diet groups [
Also, our findings of lower cholesterol in response to walnut consumption are in agreement with the recently presented metaanalysis that examined the effects of nuts on blood lipids and cardiovascular risk factors [
Although walnuts have very high energy, in our study, weight was significantly decreased (there were no significant difference between the groups) and BMI and WC not changed. This result was also supported by others [
The results of our study have shown that the mean rate of the SFA was 8.51 ± 0.30%, MUFA was 22.18 ± 2.89%, and PUFA was 69.07 ± 3.22% in Maras 18. Also, Kafkas et al. [
In conclusion, these results confirm the findings of other studies showing that walnut consumption lowers cardiovascular risk and the walnut support in dietary interventions improve blood lipid levels. In the management of hyperlipidemia, that is an important part of family medicine practices, more studies are needed to ensure definitely walnut consumption into the diet for the ambulatory patients, who do not need medication but suggested lifestyle changes only.
Also, this study has limitations. It could not be made sure whether all the volunteers consumed the same type (Maras 18) and amount of walnut. In addition, dietary compatibility was assessed on the basis of the notifications of individuals.
The data used to support the findings of this study are available from the corresponding author upon request.
The authors declare that there are no conflicts of interest regarding the publication of this paper.