Dierential Association of Dietary Linoleic Acid

and Alpha-linolenic Acid with Adipose Tissue in a

Sample of Iranian Adults; A Cohort-based Cross-

sectional Study

Esmail Karami1, Saeid Hadi2, Mohsen Mohit3, Seyed Jalil Masoumi4

1 Lifestyle Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran

2 Department of Nutrition, School of Medicine, AJA University of Medical Sciences, Tehran, Iran

3 Student Research Committee, Department of Clinical Nutrition, School of Nutrition and Food Sciences, Shiraz University of Medi-

cal Sciences, Shiraz, Iran

4 Department of Clinical Nutrition, School of Nutrition and Food Sciences, Shiraz University of Medical Sciences, Shiraz, Iran

GMJ.2023;12:e3023

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 Correspondence to:

Seyed Jalil Masoumi, Department of Clinical Nutrition,

School of Nutrition and Food Sciences, Shiraz Universi-

ty of Medical Sciences, Shiraz, Iran.

Telephone Number: +989173150269

Email Address: masoumi7415@gmail.com

Received 2023-04-09

Revised 2023-04-30

Accepted 2023-05-03

Abstract

Background: Overweight and obesity are the most critical risk factors for chronic diseases.

The quality of dietary fatty acids as one of the factors aecting fat accumulation has received

little attention. This study investigates the association between dietary linoleic acid (LA)

and alpha-linolenic acid (ALA) with body fat indices in a sample of healthy Iranian adults.

Materials and Methods: In this cohort-based cross-sectional study, 3,195 individuals aged 20 to 60

who participated in the Shiraz University of Medical Science Employees Health Cohort study were

included. Dietary intake was assessed using a validated 118-item Food Frequency Questionnaire

(FFQ), and body composition was assessed by the bioelectrical impedance analysis method. Mul-

tiple linear regression adjusted for relevant confounders was used to determine the associations.

Results: Mean dietary intake of LA was 14.20 ± 7.01 mg/day for men and 13.90 ± 6.71 mg/day

for women. Additionally, the daily intake of ALA was 0.18 ± 0.18 mg/day in men and 0.17 ± 0.19

mg/day in women. Dietary intake of ALA for men had an inversely signicant association with

body fat mass (BFM) (β: -0.585, 95% CI: -1.137, -0.032, P=0.038), percentage of body fat (PBF)

(β: -0.537, 95% CI: -0.945, -0.129, P=0.010), Visceral Fat Area (VFA) (β: -2.998, 95% CI: -5.695,

-0.302, P=0.029), and Waist to Hip Ratio (WHR) (β: -0.689, 95% CI: -1.339, -0.040, P=0.038).

Conclusion: Higher dietary ALA intake was associated with lower BFM, BFP, VAF, and WHR

in men. The present study conrms that ALA intake should be considered a preventive treat-

ment to improve body composition. However, further research is recommended in this regard.

[GMJ.2023;12:e3023] DOI:10.31661/gmj.v12i0.3023

Keywords: Fatty acids; Linoleic Acids; Alpha-linolenic Acid; Body Fat; Overweight

Introduction

Overweight and obesity have doubled

during the last 40 years. About 30% of

the world’s population faces abnormal body

fat accumulation [1]. The overweight preva-

lence among Iranian adults reported 35.8%

(37% men, 35% women), 22.3% (16% men,

26.3% women) for obesity prevalence, and

31.1% (15.6% men, 41.2% women) for cen-

tral obesity prevalence [2]. Body fat is a mix-

ture of essential and storage fat. Essential fats

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Karami E, et al. Linoleic Acid and Alpha-linolenic Acid Correlation with Adipose Tissue

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are found in small amounts in bone marrow,

heart, lung, liver, kidney, and nervous sys-

tem; in men, about 3% of body fat is essential,

and in women, this amount is 12% of body

fat. Storage fat in adipose tissue is mainly

in the form of triglycerides, which are under

the skin and internal organs to protect them

against damage. The amount of total body fat

that is related to health is 18-24% in men and

31-25% in women [3]. Excess body fat and

visceral fat area (VFA) is strongly associated

with adverse metabolic outcomes, including a

disturbed lipid prole, blood glucose imbal-

ance, and insulin resistance [4, 5]. This con-

dition will increase the chances of cardiovas-

cular diseases, cancers, and diabetes [6, 7].

Several approaches including surgery, phar-

macological therapy, and diet therapy have

been proposed for obesity treatment [8].

Dietary factors play a key role in obesity man-

agement [9]. Although the intercellular path-

ways that inuence the distribution of body

fat mass are not well dened, dietary com-

ponents and macronutrient composition can

lead to dierent body fat distribution patterns

[10, 11]. Among the macronutrients, fats are

more accused of adipose tissue accumulation

because they produce more energy than car-

bohydrates and proteins by providing nine

kcal/g [12].

The percentage of dietary fat in the total di-

etary energy is estimated to be 20-35% to

prevent chronic diseases [13]. A direct as-

sociation was found between excess dietary

fat and body fat mass [14]. Fatty acids have

dierent eects on body composition and

fat distribution, but there is no consensus on

the exact impact of each [15, 16]. Also, it has

been conrmed that dietary fatty acid com-

position aects obesity-related genes and is

correlated with some mutations [17]. Poly-

unsaturated Fatty Acids (PUFA) have at least

two double bonds in their chemical structure

[18]. PUFAs with more than 20 carbons are

called long-chain polyunsaturated fatty acids

(LC-PUFA) [18]. Based on therapeutic life-

style change (TLC) recommendations, a max-

imum of 10% of total energy intake should be

allocated to PUFAs [19]. Linoleic acid (LA)

and alpha-linolenic acid (ALA) are essential

LC-PUFAs with double bonds in the sixth

(Omega-6) and third bonds (Omega-3) from

the methyl side, respectively. LA and ALA are

used to produce some other essential fatty ac-

ids in the body [20, 21]. Insucient intake of

LA and ALA, causes deciency symptoms. It

is recommended to provide 1-2% of an indi-

vidual’s energy intake by LA and ALA, sep-

arately [22]. The main dietary sources of LA

include soybean oil, corn oil, sunower oil,

and almond oil [23]. Also, the main dietary

sources of ALA include canola oil, axseed

oil, sh oil, and chia seeds [20].

To date, there was no denitive consensus on

the relation between specic PUFAs, includ-

ing ALA and LA, and adipose tissue [24-27].

This study aimed to investigate the association

between dietary LA and ALA with body fat

mass (BFM), percentage of body fat (PBF),

VFA, body mass index (BMI), waist circum-

ference (WC), hip circumference (HC), and

waist-to-hip ratio (WHR) in a sample of Ira-

nian adults.

Materials and Methods

Ethics

This study was approved by the Ethics Com-

mittee of Shiraz University of Medical Sci-

ences (No: IR.SUMS.REC.1399.744). Also,

all the methods of the current research were

performed according to the Helsinki guide-

lines [28]. Informed consent was obtained

from all the participants.

Study Population

The current study is a cohort-based cross-sec-

tional study conducted on the baseline data

obtained from August 2017 to February 2020

that was obtained from the Employees Health

Cohort registry system of the Shiraz Univer-

sity of Medical Science. The subjects were

employees of Shiraz University of Medical

Sciences and aged between 20-60 years old.

Individuals with chronic diseases including

high blood pressure, diabetes, and cardiovas-

cular disease unable to communicate to an-

swer (blind, deaf, dumb, and paralyzed people

unable to travel to the cohort center or patients

with mental and psychological disorders)

were also excluded from the study.

Data Collection

Participants’ demographic data including gen-

Linoleic Acid and Alpha-linolenic Acid Correlation with Adipose Tissue Karami E, et al.

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der (male, female), age (years), marital status

(single, married, widow, and divorced), recent

educational degree (less than bachelor’s de-

gree, bachelor’s degree or higher), number of

children (under three, three and higher) were

collected via a standard social-demographic

questionnaire. Also, the mobility and physi-

cal activity of subjects was assessed using the

international physical activity questionnaire

(IPAQ) [29]. Physical activity scores were

calculated for walking (3/3 MET- min/week),

moderate (4 MET- min/week), and vigorous

activity (8 MET- min/week).

Dietary Assessment

The dietary intake was assessed using a re-

liable and validated 118-item food frequen-

cy questionnaire (FFQ) through face-to-face

interviews with the participants. The validity

of energy and nutrient estimates using FFQ

has been conrmed among Iranian adults

[30]. FFQ consists of standard serving sizes

of foods. Data was collected on daily, week-

ly, monthly, and annual consumption of each

food. FFQs were completed by an experi-

enced nutritionist. The amount of consumed

food was converted to grams of food per day,

and then intake of energy and nutrient were

obtained using the Nutritionist IV software

(version 4.0, supplied by First Databank, San

Francisco, United States).

Anthropometric Assessment

Participants’ height was measured with an

accuracy of 0.5 cm using a wall stadiometer

after standing without shoes (Seca, Germa-

ny). Also, the weight was recorded by a scale

with an accuracy of 100 g (Seca808; Seca,

Germany) with at least clothes. WC was mea-

sured in the middle of the distance between

the lowest rib margin and the iliac crest with

a tape measure while exhaling and standing.

HC was measured with tape around the wid-

est part of the hip over light clothes. All of

the measurements were evaluated by trained

experts. WHR was obtained by dividing WC

(cm) by HC (cm). BMI was also calculated

by dividing weight (Kg) by the square of the

height (m2) [31].

The bioelectric impedance analysis (BIA)

method and body composition measurement

device (InBody 770, InBody BSM170; made

in South Korea) was used to evaluate body

fat. After the calibration of the device, par-

ticipants stood on the device in their normal

attire, without shoes. They held the pads at a

45-degree angle so that the device could per-

form body analysis.

Statistical Analysis

Quantitative and qualitative data are present-

ed as mean ± standard deviation (SD) and fre-

quency (percent), respectively. Because the

total energy intake plays a determining role in

micronutrient intake, we adjusted the dietary

intake of LA, and ALA for total energy intake

and then categorized them into tertiles. The

residual method was employed for adjusting

the dietary LA and ALA from total energy in-

take. One-way analysis of variance (ANOVA)

and the chi-squared test were used to com-

pare the means of quantitative and categori-

cal variables across tertiles of adjusted dietary

LA and ALA in both genders. The association

between dietary LA and ALA and body fat

parameters was investigated using multiple

linear regression with a 95% condence in-

terval. SPSS version 26 (developed by IBM,

Chicago, United States) software was used to

perform the analyses. The P<0.05 is consid-

ered a signicant level.

Results

In the current cross-sectional study, out of 3195

subjects, men contained 43.91% (n=1403)

participants with a mean age of 40.89 ± 7.23

years, and women included 56.09 % (n=1792)

participants with a mean age of 40.99 ± 6.76

years. Total energy intake (2440.89 ± 772.84,

P:<0.001), dietary LA intake (14.58 ± 7.36,

P=0.007), and dietary ALA intake (0.20 ±

0.18, P<0.001) signicantly higher in men

than in women.

Other demographic characteristics of study

subjects, categorized by gender, and the ter-

tiles of energy-adjusted intake of LA and ALA

are presented in Tables-1 and -2.

The crude and multifactorial adjusted coe-

cients (β) with 95 percent condence intervals

of body fat indicators across tertiles of dietary

intake of LA and ALA in women and men

are shown in Tables-3 and -4, respectively.

Additionally, no signicant association was

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Karami E, et al. Linoleic Acid and Alpha-linolenic Acid Correlation with Adipose Tissue

observed between tertiles of dietary intake

of LA and body fat parameters in both males

and females. There was a signicant inverse

association in the second adjusted model for

BFM, PBF, VFA, and WHR in men, in which

a higher dietary ALA intake was associated

with a lower BFM (β: -0.585, 95% CI: -1.137,

-0.032, P=0.038), PBF (β: -0.537, 95% CI:

-0.945, -0.129, P=0.010), VFA (β: -2.998,

95% CI: -5.695, -0.302, P=0.029), and WHR

(β: -0.689, 95% CI: -1.339, -0.040, P=0.038).

Also, unlike men, in women, no signicant

association was found between dietary ALA

intake and body fat in dierent models (Ta-

ble-3).

Discussion

To the best of our knowledge, this was the

rst cohort-based cross-sectional study inves-

tigating the association of specic PUFAs,

including dietary LA and ALA intake, with

adipose tissue. Our nding showed that di-

etary intake of ALA in men had an inversely

signicant association with BFM, PBF, VFA,

WC, and WHR.

Table 1. Demographic Characteristics of Study Subjects by Gender

Variables Total

(n=3195)

Women

(n=1792)

Men

(n=1403) P-value

Age (years) 40.95 ± 6.97 40.99 ± 6.76 40.89 ± 7.23 0.695

Marital status, n (%)

Single

Married

Other (divorced, widow)

457 (14.30%)

2580 (80.75%)

158 (4.94%)

344 (19.2%)

1309 (73.04%)

139 (7.75%)

113 (8.05%)

1271 (90.6%)

19 (1.35%)

<0.001

Last educaon degree, n (%)

Under BSc

BSc and higher

1176 (36.8%)

2019 (63.2%)

503 (28.34%)

1289 (71.93%)

673 (47.96%)

730 (52.03%)

<0.001

Number of children, n (%)

Under 3

3 and higher

2868 (89.76%)

327 (10.23%)

1658 (92.52%)

135 (7.53%)

1210 (86.24%)

192 (13.68%)

<0.001

Physical acvity (Met-min/

week)

Low and Moderate

High

1892 (59.21%)

1303 (40.79%)

1160 (64.73%)

632 (35.26%)

732 (52.17%)

671 (47.82%)

<0.001

Energy intake (Kcal/d)

2172.47 ±

728.89

1962.46 ±

615.97

2440.89 ±

772.84 <0.001

Dietary LA intake (g/d) 14.2 ± 7.01 13.90 ± 6.71 14.58 ± 7.36 0.007

Dietary ALA intake (g/d) 0.18 ± 0.18 0.17 ± 0.19 0.2 ± 0.18 <0.001

Quantitative data are presented as mean ± standard deviation, qualitative data are presented as number

(%).

The P-value was obtained from a one-way analysis of variance test (ANOVA) and chi-square test for quan-

titative and qualitative data, respectively.

A signicant P-value is considered at P<0.05.

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Linoleic Acid and Alpha-linolenic Acid Correlation with Adipose Tissue Karami E, et al.

Table 2. Demographic Characteristics of Study Subjects by Energy-adjusted Tertiles of LA and ALA Intake

Variables

LA ALA

(n=1065)

-value

(n=1065)

-value

Age (years) 41.78 ±

7.17

40.99 ±

6.83

40.08 ±

6.82

<0.001 41.47 ±

6.91

41.25 ±

6.94

40.12 ±

7.01

<0.001

Gender, n (%)

Male

Female

585

(54.92%)

480

(45.08%)

425

(39.9%)

640

(60.10%)

393

(36.9%)

672

(63.10%)

<0.001

600

(56.33%)

465

(43.66%)

391

(36.71%)

674

(63.29%)

412

(38.66%)

653

(61.33%)

<0.001

Marital

Status, n (%)

Single

Married

Other

(divorced,

widow)

134

(12.58%)

890

(83.56%)

(3.86%)

154

(14.5%)

857

(80.5%)

(5%)

169

(15.87%)

833

(78.22%)

(5.91%)

0.031

146

(13.70%)

880

(82.63%)

(3.67%)

170

(15.96%)

830

(77.93%)

(6.10%)

141

(13.3%)

870

(81.7%)

(5%)

0.024

Last

educaon

degree, n (%)

Under BSc

BSc and

higher

393

(36.9%)

672

(63.1%)

382

(35.86%)

683

(64.13%)

401

(37.65%)

664

(62.35)

0.693

461

(43.28%)

604

(56.72%)

354

(33.23%)

711

(66.77%)

361

(33.88%)

704

(66.11%)

<0.001

Number of

children, n (%)

Under 3

3 and higher

923

(86.66%)

142

(13.33%)

877

(82.35%)

188

(17.65%)

971

(91.17%)

(8.83%)

<0.001

921

(86.47%)

144

(13.52%)

965

(90.61%)

100

(9.39%)

974

(91.45%)

(8.55%)

<0.001

Physical

acvity (Met-

min/week)

Low and

Moderate

High

659

(61.87%)

406

(38.12%)

633

(59.43%)

432

(40.57%)

600

(56.33%)

465

(43.66%)

0.33

623

(58.5%)

442

(41.50%)

675

(63.38%)

390

(36.62%)

594

(55.77%)

471

(44.22%)

0.001

Energy intake

(Kcal/d)

2194.8 ±

824.19

2060.88

± 638.09

2261 ±

698.19 <0.001 2386.1 ±

844.18

1938.51

± 562.16

2192 ±

682.13 <0.001

Total LA

intake (g/d)

8.73 ±

2.85

12.72 ±

3.32

21.15 ±

6.93 <0.001 14.09 ±

6.88

12.5 ±

5.73

16.00 ±

7.83 <0.001

Quantitative data are reported as mean ± standard deviation, qualitative data are presented as number

(%). The P-value was obtained from a one-way analysis of variance test (ANOVA) and chi-square test for

quantitative and qualitative data, respectively. The signicant P-value is considered at P<0.05.

LA; linoleic acid, ALA; alpha-linolenic acid

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Karami E, et al. Linoleic Acid and Alpha-linolenic Acid Correlation with Adipose Tissue

Table 3. Association of Dietary LA and ALA Intake with Body Fat and Anthropometric Indices in Iranian

Women.

Variables

LA ALA

β ± SE R295 % CI P

-value β ± SE R295 % CI P

-value

Men

BFM

Crude 0.068 ± 0.23 <0.001 -0.383,

0.520 0.767 0.126 ±

0.234 <0.001 -0.333,

0.584 0.591

Model 1 0.130 ±

0.226 0.067 -0.312,

0.572 0.565 0.284 ±

0.229 0.06 -0.164,

0.733 0.214

Model 2 0.099 ±

0.225 0.076 -0.342,

0.541 0.659 0.326 ±

0.229 0.077 -0.123,

0.775 0.155

PBF

Crude 0.096 ±

0.172 <0.001 -0.242,

0.434 0.577 -0.176 ±

0.175 0.001 -0.52,

0.167 0.313

Model 1 0.150 ±

0.168 0.07 -0.181,

0.480 0.375 -0.037 ±

0.171 0.069 -0.372,

0.298 0.828

Model 2 0.145 ±

0.169 0.072 -0.186,

0.476 0.39 -0.032 ±

0.172 0.071 -0.369,

0.305 0.851

VFA

Crude 0.651 ±

1.234 <0.001 -1.769,

3.071 0.598 -0.077 ±

1.253 <0.001 -2.533,

2.380 0.951

Model 1 1.118 ±

1.199 0.081 -1.233,

3.468 0.351 0.932 ±

1.215 0.08 -1.152,

3.315 0.443

Model 2 1.008 ±

1.199 0.086 -1.344,

3.361 0.401 1.081 ±

1.22 0.086 -1.311,

3.472 0.376

BMI

Crude -0.028 ±

0.125 <0.001 -0.272,

0.217 0.825 0.035 ±

0.126 <0.001 -0.213,

0.283 0.782

Model 1 0.009 ± 0.12 0.092 -0.227,

0.245 0.942 0.123 ±

0.122 0.092 -0.116,

0.362 0.313

Model 2 -0.006 ±

0.12 0.104 -0.241,

0.229 0.96 0.141 ±

0.122 0.105 -0.098,

0.381 0.246

Crude -0.282 ±

0.295 0.001 -0.862,

0.297 0.339 -0.07 ±

0.3 <0.001 -0.658,

0.518 0.815

Model 1 -0.129 ±

0.283 0.103 -0.685,

0.427 0.649 0.196 ±

0.287 0.103 -0.367,

0.76 0.494

Model 2 -0.187 ±

0.283 0.111 -0.742,

0.368 0.509 0.273 ±

0.288 0.111 -0.292,

0.837 0.343

Crude -0.002 ±

0.229 <0.001 -0.451,

0.447 0.992 0.227 ±

0.232 0.001 -0.228,

0.683 0.328

Model 1 0.045 ±

0.227 0.036 -0.401,

0.491 0.843 0.312 ±

0.230 0.037 -0.14,

0.764 0.176

Model 2 -0.005 ±

0.227 0.047 -0.450,

0.440 0.981 0.381 ±

0.231 0.048 -0.071,

0.833 0.098

WHR

Crude -0.003 ±

0.002 0.001

-0.007,

0.001 0.157 -0.003 ±

0.002 0.001 -0.007,

0.001 0.131

Model 1 -0.002 ±

0.002 0.087 -0.005,

0.002 0.384 -0.001 ±

0.002 0.087 -0.005,

0.003 0.56

Model 2 -0.002 ±

0.002 0.088 -0.006,

0.002 0.348 -0.001 ±

0.002 0.087 -0.005,

0.003 0.615

Results obtained from multiple linear regression analysis. Data presented as β coe󰀩cients (95%) ±

standard error. Model 1: adjusted for age, Marital Status, Last education degree, number of children, and

physical activity. Model 2: additionally, adjusted for energy intake, and dietary ber.

The signicant P-value is considered at P<0.05.

LA; linoleic acid, ALA; alpha-linolenic acid, SE; standard error, BFM; body fat mass, PBF; percentage of

body fat, VFA; visceral fat area, BMI; body mass index, WC; waist circumference, HC; hip circumference,

WHR; waist to hip ratio

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Linoleic Acid and Alpha-linolenic Acid Correlation with Adipose Tissue Karami E, et al.

Table 4. Association of Dietary LA and ALA Intake with Body Fat and Anthropometric Indices in Iranian Men.

Variables LA ALA

β ± SE R295 %

-value β ± SE R295 % CI P

-value

Men

BFM

Crude 0.112 ±

0.286 <0.001 -0.449,

0.673 0.696 -0.502 ±

0.281 0.002 -1.052,

0.049 0.074

Model 1 0.140 ±

0.288 0.014 -0.425,

0.704 0.628 -0.569 ±

0.282 0.017 -1.123,

-0.016 0.044

Model 2 0.020 ±

0.287 0.032 -0.543,

0.582 0.945 -0.585 ±

0.282 0.035 -1.137,

-0.032 0.038

PBF

Crude -0.233 ±

0.211 0.001 -0.648,

0.181 0.269 -0.559 ±

0.207 0.005 -0.964,

-0.153 0.007

Model 1 -0.114 ±

0.212 0.021 -0.53,

0.301 0.59 -0.504 ±

0.207 0.025 -0.911,

-0.097 0.015

Model 2 -0.162 ±

0.212 0.029 -0.578,

0.254 0.444 -0.537 ±

0.208 0.033 -0.945,

-0.129 0.01

VFA

Crude 0.566 ±

1.395 <0.001 -2.171,

3.304 0.685 -2.744 ±

1.368 0.003 -5.428,

-0.059 0.045

Model 1 0.835 ±

1.406 0.012 -1.922,

3.593 0.552 -2.897 ±

1.378 0.015 -5.599,

-0.195 0.036

Model 2 0.258 ±

1.400 0.029 -2.488,

3.004 0.854 -2.998 ±

1.374 0.033 -5.695,

-0.302 0.029

BMI

Crude 0.033 ±

0.134 <0.001 -0.230,

0.295 0.808 - 0.182 ±

0.131 0.001 -0.440,

0.075 0.165

Model 1 0.027 ±

0.135 0.011 -0.237,

0.292 0.839 -0.225 ±

0.132 0.013 -0.485,

0.034 0.088

Model 2 -0.038 ±

0.134 0.033 -0.301,

0.224 0.774 -0.225 ±

0.132 0.035 -0.482,

0.033 0.088

Crude 0.397 ±

0.337 0.001 -0.263,

1.058 0.238 -0.582 ±

0.330 0.002 -1.230,

0.066 0.078

Model 1 0.431 ±

0.339 0.014 -0.233,

1.096 0.203 -0.670 ±

0.332 0.016 -1.322,

-0.018 0.044

Model 2 0.283 ±

0.337 0.034 -0.378,

0.945 0.401 -0.689 ±

0.331 0.036 -1.339,

-0.040 0.038

Crude 0.400 ±

0.249 0.002 -0.088,

0.888 0.108 -0.203 ±

0.244 <0.001 -0.683,

0.276 0.406

Model 1 0.321 ±

0.249 0.024 -0.168,

0.810 0.198 -0.378 ±

0.245 0.024 -0.858,

0.102 0.123

Model 2 0.209 ±

0.248 0.041 -0.278,

0.696 0.4 -0.364 ±

0.244 0.042 -0.843,

0.114 0.136

WHR

Crude 0.000 ±

0.002 <0.001 -0.003,

0.003 0.883 -0.004 ±

0.002 0.004 -0.007,

-0.001 0.016

Model 1 0.001 ±

0.002 0.03 -0.002,

0.005 0.424 -0.003 ±

0.002 0.033 -0.006,

0.000 0.052

Model 2 0.001 ±

0.002 0.039 -0.002,

0.004 0.573 -0.003 ±

0.002 0.042 -0.007,

0.000 0.034

Results obtained from multiple linear regression analysis. Data presented as β coe󰀩cients (95%) ±

standard error. Model 1: adjusted for age, Marital Status, Last education degree, number of children,

and physical activity. Model 2: additionally, adjusted for energy intake, and dietary ber.The signicant

P-value is considered at P<0.05. LA; linoleic acid, ALA; alpha-linolenic acid, SE; standard error, BFM;

body fat mass, PBF; percentage of body fat, VFA; visceral fat area, BMI; body mass index, WC; waist

circumference, HC; hip circumference, WHR; waist to hip ratio

8GMJ.2023;12:e3023

www.gmj.ir

Karami E, et al. Linoleic Acid and Alpha-linolenic Acid Correlation with Adipose Tissue

Obesity has been an ongoing trend in many

societies for decades[32]. The most eective

approach to treat obesity is lifestyle chang-

es including a restrictive diet and increasing

physical activity.

However, weight loss diets recommend re-

ducing the percentage of fats, and all fatty

acid types were reduced with this approach.

Dietary fatty acid quality has received little at-

tention in weight loss diets. Our study indicat-

ed that dietary AL and ALA can have dierent

eects on adipose tissue, so it is recommend-

ed to reduce the dietary sources of LA and

increase the dietary sources of ALA instead

of reducing the dietary sources of both fatty

acids in weight loss diets.

Consistent with these results, a clinical trial

reported that consuming ALA for 12 weeks

signicantly reduced visceral fat area, body

weight, and WC compared to a placebo

group [24]. A cohort-based cross-sectional

study showed that serum levels of ALA had

a protective eect on body weight and were

inversely associated with weight gain in chil-

dren aged 5 to 12 years [25].

An experimental study by Adrina et al. showed

that in the group fed with chia seeds as a rich

source of ALA for three weeks, visceral fat

tissue was signicantly reduced compared to

the control group.

Additionally, benecial eects on blood lip-

ids and glucose tolerance have been report-

ed in the intervention group [33]. In contrast

to the above studies, Australian and Spanish

cross-sectional studies reported that plasma

ALA concentration had a positive correlation

with body fat and obesity [26, 27]. To address

the challenge of inconsistent study results, a

study with a larger sample size and consider-

ing gender was needed.

Therefore, this study was designed with a

larger sample size and separate analyzes for

each gender. Also, in the case of the men-

tioned studies, supplementation [24] and plas-

ma level [25-27] are considered the criteria

for evaluating AL and ALA intake, but we

assessed the dietary intake of ALA and LA.

The following cellular mechanisms have been

proposed to explain the relationship between

higher intake of ALA and adiposity: a) ALA

decreases body fat by stimulating the expres-

sion of hepatic fat oxidation and intestinal be-

ta-oxidation genes [34, 35]; b) ALA can inhib-

it the conversion of LA to arachidonic acid,

which is a stimulator for adipogenesis through

prostaglandin synthesis and CAMP activation

[36]; c) by increasing the intake of dietary fat-

ty acids, their tendency to accumulate increas-

es. Among fatty acids, ALA has the highest

tendency to oxidation and the lowest tendency

to accumulate in humans [37].

In our study, a dierence was observed be-

tween the males and females in the relation-

ship between ALA dietary intake and adipose

tissue. Dierent responses of body composi-

tion to intake of fatty acids in the gender have

been observed in previous studies [38, 39].

Men have been reported to have higher rates

of fatty acid oxidation and lower resting ener-

gy expenditure than women [39]. In addition,

the dierence in sex hormones and adipose

tissue percentage can aect the fats’ oxidation

and storage [40].

The strength of the current study was the large

sample size (3195 subjects) and using of an

accurate method, and bioelectrical Impedance

analysis, to evaluate body fat. Also, all re-

quired information was collected with validat-

ed questionnaires by trained experts to reduce

any possible errors.

Additionally, because of a physiological dif-

ference between men and women in body fat

percentage, the analysis was performed sepa-

rately for both genders. Furthermore, to pre-

vent the eect of energy intake, the dietary

intake of ALA and AL was adjusted for total

energy intake. However, there were some lim-

itations in our study.

Firstly, the intake of ALA acid and LA includ-

ed in our study was completely based on the

consumption of meals, and the intake of pos-

sible supplements was not considered, which

in some people could aect the daily intake of

ALA and LA.

Secondly, factors including food preparation

and cooking steps aecting the content of

ALA and LA in foods have not been consid-

ered. Also, in this study, FFQ was used for as-

sessing food intake.

FFQ is usually a tool for long-term evaluation

of food intake, and estimating the amount of

food consumed from an FFQ is not complete-

ly accurate, so measurement errors are always

probable.

Conclusion

Our ndings show that a higher intake of

ALA is associated with lower body fat in men.

These results are important because, until

now, all types of fatty acids have been equal-

ly accused of fat accumulation. Future studies

on the quality of dietary fatty acids in weight

management programs are suggested.

Acknowledgments

The authors would like to thank all those who

participated in this study. This study was sup-

ported by the Vice Chancellor of Research

and Technology of Shiraz University of Med-

ical Sciences, Shiraz, Iran. (grant No # 1399-

01-84-22892)

Conict of Interest

We have declared that there is no conict of

interest.

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10 GMJ.2023;12:e3023