Hajipour et al.
Journal of Physiological Anthropology(2023) 42:17
https://doi.org/10.1186/s40101-023-00333-4

ORIGINAL ARTICLE

Journal of
Physiological Anthropology

Open Access

The effect of FTO gene rs9939609
polymorphism on the association
between colorectal cancer and different typesof dietary fat intake: a case‑control study
Azadeh Hajipour1, Naeemeh Hassanpour Ardekanizadeh2, Zahra Roumi3, Soheila Shekari3,
Bahareh Aminnezhad Kavkani3, Seyedeh Hayedeh Mousavi Shalmani4, Bojlul Bahar5, Shirin Tajadod6,
Marjan Ajami7, Ghasem Azizi Tabesh8, Maryam Gholamalizadeh9* and Saeid Doaei10*

Abstract
Background Colorectal cancer (CRC) is one of the most common cancers in the world. Some dietary factors suchas fat intake have been identified as the risk factors for CRC. This study aimed to investigate the effect of fat massand obesity-associated (FTO) gene rs9939609 polymorphism on the association between CRC and different typesof dietary fats.
Methods This case-control study was performed on 135 CRC cases and 294 healthy controls in Tehran, Iran. Dataon demographic factors, anthropometric measurements, physical activity, the intake of different types of dietary fats,
and FTO gene rs9939609 polymorphism was collected from all participants. The association between cancer and dietary fat intake in individuals with different FTO genotypes was assessed using different models of logistic regression.
Results Oleic acid intake was higher in the case group compared to the control group in both people with TT(7.2±3.46 vs. 5.83±3.06 g/d, P=0.02) and AA/AT genotypes (8.7±6.23 vs. 5.57 ±3.2 g/d, P<0.001). Among carriers of AA/
AT genotypes of FTO rs9939609 polymorphism, a positive association was found between CRC and higher intakesof oleic acid (OR=1.12, CI95% 1.03–1.21, P=0.01) and cholesterol (OR=1.01, CI95% 1.00–1.02; P=0.01) after adjusting
for age, sex, physical activity, alcohol use, smoking, calorie intake, and body mass index.
Conclusion Higher intakes of cholesterol and oleic acid were associated with a higher risk of CRC in FTO-risk allele
carriers. The association of CRC and dietary fat may be influenced by the FTO genotype. Further longitudinal studies
are warranted to confirm these findings.
Keywords Colorectal cancer, Fat mass and obesity-associated (FTO) gene, Dietary fats, Polymorphism, Genotype,
Oleic acid

*Correspondence:
Maryam Gholamalizadeh
Gholamalizadeh@sbmu.ac.ir
Saeid Doaei
Doaei@gums.ac.ir
Full list of author information is available at the end of the article© The Author(s) 2023. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which
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Hajipour et al. Journal of Physiological Anthropology(2023) 42:17

Introduction
Colorectal cancer (CRC) is the third most common
cancer worldwide [1]. The incidence of CRC is continuously increasing in developing countries [2, 3]. In Iran,
CRC is the third most prevalent cancer in women andthe fourth most prevalent in men [4].
Genetics and environmental factors have been identified as the most important risk factors for CRC [5].
Among several environmental factors, a diet rich in fat
may have a key role in the increased incidence of CRC[6]. In some studies, ω-6 polyunsaturated fatty acids(PUFAs) such as linoleic acid (LA, 18:2ω-6) and arachidonic acid (ARA, 20:4 ω-6) have been reported as
an enhancer of tumorigenesis, inflammation, and CRC
development [7]. Also, a recent study reported dietarytrans fatty acids (TFA), particularly elaidic acid, arepositively related to rectal cancer mainly because they
may lead to a higher inflammation and oxidative stressby irritation of the colon and rectal mucosa [8]. Someother studies indicated a positive relationship between
dietary intake of saturated fatty acids (SFA) andincreased risk of CRC [9]. However, some types of ω-3
polyunsaturated fatty acids, such as C20:5 ω-3 eicosapentaenoic acid (EPA) and C22:6 ω-3 docosahexaenoic
acid (DHA), may have anti-CRC effects [10, 11]. Furthermore, oleic acid may have some beneficial effects
against CRC [12].
On the other hand, obesity not only increases the riskof chronic diseases such as cardiovascular disease, stroke,and nonalcoholic fatty liver but also increases the riskof cancer [13]. Recent studies examined the interactions
between obesity, CRC, and obesity-related genetic factors
such as fat mass and obesity-associated protein (FTO)
genes [3, 14]. The FTO gene is noticeably expressed in
the hypothalamus and is associated with the regulation offood intake and energy balance [15]. FTO inhibitors suchas Meclofenamic acid (MA), FB23-2, and R2 hydroxyglutarate (R2HG) have been recently investigated as anticancer drugs in many types of cancer [16]. The mechanismof the effect of the FTO gene on CRC is not well understood. A previous study has reported the role of adenosine monophosphate-activated protein kinasealpha2(AMPKα2) in suppressing FTO and inducing apoptosis[17]. Another recent study indicated that FTO and cmyc
protooncogene (MYC) genes might also be responsible
for enhancing the proliferative and migratory functionsof CRC cells [18].
Due to the high prevalence of CRC and the lack of adequate research on the possible association of CRC with
the FTO gene and dietary fat intake, this case-control
study aimed to assess the effect of FTO gene rs9939609
polymorphism on the association between CRC and different types of dietary fat intake in the Iranian adults.

Page 2 of 8

Methods
This study was a case-control carried out on 135 CRC
cases and 294 healthy controls referred to Firoozgar
Hospital, Tehran, Iran. The inclusion criteria for the casegroup included age between 35 and 70 years, not morethan 6 months after the CRC diagnosis, and willingness
to participate in this study. The inclusion criteria for thecontrol group included people with age between 35 and70 years, no history of malignancy, lack of diseases affecting dietary intake, do not take drugs that affect bodyweight, and willingness to participate in this study. Innitially, 540 people (180 patients with CRC and 360 healthypeople matched in terms of age and sex) were included.
Some participants were excluded due to lack of access torequired data (n=62), consumption of fatty acid supplements and nutritional supplements containing fat in thelast year (n=38), and diagnosis of malignancy during thestudy in the control group (n=11). All participants wereexplained the details of the present study, and writtenconsent was obtained prior to the data collection.
Socio-demographic information of participants including age, gender, level of education, income level, medical
history, and marital and employment status was collected
through a face-to-face interview. Height and weight were
measured by trained people using SECA stadiometer andSeca scales with an accuracy of 0.5 cm and 100 g, respectively. The patients’ BMI was then calculated by the participants’ weight in kilograms divided by the square ofheight in meters. A validated International Questionnaire(IPAQ) was used to measure physical activity.
Dietary assessments

The required dietary information was collected throughface-to-face interviews by trained dietitians using a validated semi-quantitative Food Frequency Questionnaire(FFQ) consisting of 168 food items with standard portion sizes commonly consumed by Iranian people [19].
In order to validate of FFQ, twelve repeated 24 h dietary
recalls, two FFQ, biochemical markers in serum, andurine samples were used to assess the validity and theresults indicated that the FFQ has reasonable relative
validity and reliability for nutrient intakes in Tehranian
adults and appears to be an acceptable tool for assessing
nutrient intakes in this population [20]. The amount of
intake of different dietary fats, including saturated fatty
acids, trans and unsaturated fatty acids, ω-3 fatty acids,and ω-6 fatty acids was estimated using Nutritionist IV
software. Daily intakes of dietary fats were calculated foreach participant by using the US Department of Agriculture food consumption database, which was modified for
Iranian foods. The USDA provide the basic foundation
for food and nutrition investigations and monitoring,
policy, and dietary practice.

Hajipour et al. Journal of Physiological Anthropology(2023) 42:17

Genotyping

Five milliliters of the participants’ blood samples wascollected at the beginning of the study into ethylenediaminetetraacetic acid (EDTA) tubes. The samples weretransferred to the cellular and molecular laboratory of
Shahid Beheshti University of Medical Sciences, Tehran, Iran. The PCR products were examined to identify rs9939609 polymorphism of the FTO gene by the
Tetraprimer amplification refractory mutation system(ARMS) PCR method.
Blood samples were washed with (Tris-HCl 10
mmol/L, MgCl2 5 mmol/L, lysis buffer Triton X% 1 pH
7.6), and phosphate buffer saline (PBS) and red blood
cell (RBCs) were removed from the method. The DNA
extraction kit manufactured by GeneAll (GeneAll Biotechnology Co. Ltd, Korea) was used to extract andpurify DNA samples. After determining the DNA concentration, it was kept at a suitable temperature for the
next steps. To design the primers required to performthe PCR reaction, the sequence of adjacent single nucleotide polymorphism (SNP) target regions was extracted,
and the appropriate primers were designed by referringto the dbSNP database located at http://​www.​ncbi.​nlm.​
nih.​gov/​SNP (Table 1). Primers designed by the Basic
Local Alignment Search Tool (BLAST) Basic Local
Alignment Search Tool service on the National Center
for Biotechnology Information (NCBI) site were also
evaluated to find homologous regions in the humangenome. The desired SNPs were genotyped by allele-specific primers according to the last nucleotide at the endof ’3 primers and complementation of the SNP site, using
Tetraprimer the Amplification Refractory Mutation System polymerase chain reaction (Tetra -ARMS PCR).
This technique required four primers to genetically
amplify a large fragment of the template DNA containing the SNP (control fragment) and two smaller fragments representing each of the two allele products. The
primers were designed to produce allelic amplified fragments of different sizes and distinguished by agarose gelelectrophoresis. To increase the specificity of the reaction, in addition to the first nonpairing at the end of the’3 specific internal primers, an additional pairing was
intentionally created at the third position of the ’3’ endof each of the two internal specific primers. For specificPage 3 of 8

amplification of fragments around the desired polymorphism, 25 μl PCR including 200 ng DNA, 3 μl 10X PCR
buffer, 1.5 μl d10TP 10 mM, 1 μl 250 MgCl250 mM, 1.5
pH Internal go (OR and IF), 1 picomole of internal
return primer (IR), 0.5 picomoles of external go primer(OF), and 0.4 μl (2 units) of Taq DNA polymerase (synagen) by PCR (model thermocycler) Eppendorf, Germany). The optimum temperature schedule for PCR was
as follows: initial melting step 3 min, 30 temperature
repetitions with denaturation for 30 s, 45 s for binding
the primers, propagation temperature for 55 s, and eventually, and 10 min at room temperature were selected forfinal propagation. PCR products were then electrophoresed on٪ 1 agarose gel for 40 min at 80 volts, andfinally, the separated bands were observed and analyzed
by UV Gel Documentation. The sequences for the primers are presented in (Table 1).
Statistical analysis

The normal distribution of data was confirmed using
Kolmogorov–Smirnov normal distribution Test. General characteristics and dietary intake of the case andcontrol groups were compared by chi-square (for qualitative variables) and independent t test (for quantitative variables) methods. Independent tests were usedbecause people with different FTO genotypes (whichwere unmatched) were compared in the matchedcase and control groups. A simple dominant model
was used because it can cover a wide range of plausible genotype-phenotype relationships [21, 22]. The
association between CRC and the intake of dietaryfats in individuals with different FTO gene genotypes
was assessed using different models of logistic regression after adjusting the covariates as follows: Model
1: crude; Model 2: adjusted for age and sex (the malegroup was the reference group); Model 3: adjusted forage, sex, physical activity, alcohol use (no drink group
was the reference group), and smoking (no smoking
group was the reference group); and Model 4: adjusted
for age, sex, physical activity, alcohol use, smoking, calorie intake, and BMI. All statistical analyses were performed using SPSS software version 23, and P˂0.05 wasconsidered statistically significant.

Table 1 The sequences of the primers used for tetraprimer amplification refractory mutation system polymerase chain reaction(T-ARMS-PCR)
Gene

Primer sequence

Product size

Annealing temp. °C

FTO

Forward outer primer: AGT​TCC​AGT​CAT​T TT​TGA​CAGC​
Reverse outer primer: AGC​C TC​TCT​ACC​ATC​T TA​TGTC​
Forward inner primer: CCT​TGC​GAC​TGC​TGT​GAA​TATA​
Reverse inner primer: GAG​ACT​ATC​CAA​GTG​CAT​C TCA​

Control fragment: 429bp
T allele: 278bp
A allele: 194bp

59.50

Hajipour et al. Journal of Physiological Anthropology(2023) 42:17

Results
The general characteristics of the patients and healthy
participants included in this study are presented inTable 2. In TT FTO rs9939609 genotype carriers, themean BMI of the case group was significantly higher thanthe control group 29±3.9 vs. 27±3.31 kg/m2, P= 0.02). In
the AA/AT dominant genetic model, the cases had higher
age, smoking rate, weight, and BMI compared with thecontrol group (All P˂0.05). However, the controls had
higher heights than the cases. According to the results in
the TT genotype, the only significant factor is the BMI, in
which the cases had a higher amount of BMI comparedto the controls (P<0.02). The two groups also did not differ significantly in terms of gender, alcohol consumption,and physical activity in both types of genetic models.
The results of measuring the fat consumption in thecase and control groups based on the FTO rs9939609
genetic model are presented in Table 3. Significant differences were found in polyunsaturated fat and oleic acidintake in the TT genotype. Polyunsaturated fat intake
was higher in the control group, while oleic acid intake

Page 4 of 8

was higher in the case group. In addition, the AA/AT
genotype carriers of the case group had more consumption of oleic acid and DHA than the controls.
The association between CRC and dietary intake
among people with TT FTO rs9939609 genotype wasinvestigated by logistic regression, and the results arepresented in Table 4. No association was found between
the risk of CRC with the intake of different types of
dietary fats (Model 1). The results did not change after
adjustment for age and sex (Model 2), further adjustment
for physical activity, alcohol use, and smoking (Model3), and additional adjustment for calorie intake and BMI(Model 4).
The results of logistic regression on the interactions
between CRC and dietary intake among people with AA/
AT FTO rs9939609 genotype are reported in Table 5. The
risk of CRC was significantly associated with the dietary intake of cholesterol and oleic acid (Model 1). The
results did not change after adjustment for age and sex(Model 2), further adjustment for physical activity, alcohol use, and smoking (Model 3). However, no significant

Table 2 General characteristics of the case and control groups based on FTO rs9939609 genotype
TT genotype (n=154)

AA/AT genotype (n=275)

Cases (n= 46)

Controls (n= 108)

P

Cases (n= 89)

Controls (n= 186)

P

51.22±16.08

47.37±10.70

0.141

52.50±17.19

48.07±11.19<0.012

Males (n)25 (54.7%)

41 (47.6%)

0.082

58 (64.6%)

106 (57.3%)

0.201

Females (n)21 (45.3%)

57 (52.4%)

31 (35.4%)

80 (42.7%)

Alcohol use (n)15 (33%)

5 (5%)

0.061

9 (10.5%)

14 (7.6%)

0.462

Smoking (n)3 (6%)

9 (8.6%)0.594

37 (42%)24 (13%)<0.013Weight (kg)70.85±10.26

68.82±7.86

0.18370.03±10.89

69.62±9.08

0.031

Height (cm)155.83± 4.72

157.83 ± 6.87

0.082

156.2 ± 5.71

158.65 ± 7.81

0.022

BMI (kg/m2)

29.18 ± 3.90

27.67 ± 3.31

0.022

28.68 ± 4.06

27.58 ± 3.25

0.043

Physical activity(hours/week)

7.37 ± 1.84

7.30 ± 1.64

0.831

7.61 ± 2.02

7.33 ± 1.54

0.114

Age (years)
GenderBMI Body mass index

Table 3 Fat intake of the case and control groups based on FTO rs9939609 genotype
TT genotype

AA/AT genotype

Cases

Controls

P

Cases

Controls

Cholesterol (mg/d)

267.99 ± 46.32

265.09 ± 47.07

0.721

274.79 ± 56.80

251.8 ± 65.90

0.743

SFA (g/d)31.20 ± 4.87

32.03 ± 6.67

0.391

31.75 ± 6.39

31.03 ± 11.85

0.582

PUFas (g/d)

15.38 ± 3.72

16.88 ± 4.93

0.402

15.49 ± 4.80

16.39 ± 3.75

0.512

Oleic acid (g/d)

7.20 ± 3.46

5.83 ± 3.06

0.023

8.70 ± 6.23

5.57 ± 3.20

<0.011

Linoleic (g/d)

6.69 ± 2.63

6.33 ± 3.85

0.504

7.19 ± 4.68

5.82 ± 3.19

0.242

α-Linolenic acid(g/d)

0.88 ± 0.84

0.95 ± 0.77

0.614

0.82 ± 0.78

1.01 ± 0.72

0.124

DHA (g/d)0.07 ± 0.06

0.06 ± 0.05

0.645

0.07 ± 0.06

0.06 ± 0.05

0.313

SFA Saturated fatty acids, DHA Docosahexaenoic acid, PUFAs Polyunsaturated fatty acids

PHajipour et al. Journal of Physiological Anthropology(2023) 42:17

Page 5 of 8

Table 4 Logistic regression of the association between colorectal cancer and dietary intake among people with TT FTO rs9939609
genotype
Model 1Model 2Model 3Model 4

OR (CI95%)

P

OR (CI95%)

P

OR (CI95%)

P

OR (CI95%)

P

Total fat0.94 (0.89–1.01)

0.051

0.94 (0.88–1.00)

0.071

0.94 (0.88–1.00)

0.07

0.94 (0.88–1.01)

0.122

Cholesterol

0.94 (0.99–1.01)

0.552

0.99 (0.098–1.01)

0.872

0.99 (0.098–1.01)

0.87

0.99 (0.98–1.01)

0.651

SFA

1.01 (0.92–1.09)

0.862

1.01 (0.91–1.11)

0.873

1.01 (0.91–1.11)

0.87

1.01 (0.92–1.12)

0.751

MUFAs

1.00 (0.88–1.09)

0.771

0.96 (0.84–1.09)

0.584

0.96 (0.84–1.09)

0.57

0.97 (0.85–1.31)

0.652

PUFAs

0.98 (0.87–1.18)

0.831

0.99 (0.83–1.17)

0.911

0.99 (0.83–1.17)

0.91

0.98 (0.82–1.17)

0.843

Oleic acid1.01 (0.98–1.27)

0.811

1.09 (0.94–1.27)

0.242

1.09 (0.94–1.27)

0.24

1.06 (0.90–1.25)

0.431

Linoleic

1.10 (0.96–1.28)

0.163

1.07 (0.90–1.27)

0.401

1.07 (0.90–1.27)

0.40

1.10 (0.92–1.31)

0.262

Linolenic acid

0.99 (0.60–1.63)

0.982

1.10 (0.61–1.01

0.744

1.10 (0.61–1.01

0.74

1.07 (0.58–1.99)

0.80

EPA

1.28 (0.01–2.76)

0.512

8.87 (0.01–3.16)

0.313

8.87 (0.01–3.16)

0.01

4.59 (0.01–24.71)

0.353

DHA

2.88 (.04–18.2)

0.313

1.43 (0.01–29.27)

0.934

1.43 (0.01–29.27)

0.93

3.67 (0.01–10.10)

0.751

Model 1: crude. Model 2: adjusted for age and sex. Model 3: adjusted for age, sex, physical activity, alcohol use, and smoking. Model 4: adjusted for age, sex, physicalactivity, alcohol use, smoking, calorie intake, and BMISFA Saturated fatty acids, EPA, Eicosapentaenoic acid, DHA, Docosahexaenoic acid, MUFAs, monounsaturated fatty acids, PUFAs, Polyunsaturated fatty acids

Table 5 Logistic regression of the association between colorectal cancer and dietary intake among people with AA/AT FTO rs9939609
genotype
Model 1Model 2Model 3Model 4

OR (CI95%)

P

OR (CI95%)

P

OR (CI95%)

P

OR (CI95%)

P

Total fat0.99 (0.95–1.02)

0.552

0.98 (0.95–1.02)

0.551

0.98 (0.95–1.02)

0.552

1.01 (0.96–1.06)

0.522

Cholesterol

1.01 (1.00–1.02)

0.014

1.01 (1.00–1.02)

0.041

1.01 (1.00–1.02

0.043

1.01 (1.00–1.02)

0.037

SFA

0.95 (0.90–1.01)

0.131

0.96 (0.91–1.03)

0.304

0.96 (0.91–1.03)

0.303

0.99 (0.92–1.07)

0.938

MUFAs

1.00 (0.93–1.07)

0.957

1.01 (0.93–1.09)

0.752

1.01 (0.93–1.09)

0.751

1.04 (0.96–1.14)

0.282

PUFAs

0.90 (0.82–1.00)

0.051

0.90 (0.82–1.00)

0.052

0.90 (0.82–1.00)

0.054

0.92 (0.83–1.02)

0.112

Oleic acid

1.12 (1.03–1.21)

0.008

1.11 (1.02–1.25)

0.012

1.11 (1.02–1.25)

0.011

1.08 (0.98–1.19)

0.091

Linoleic acid

1.11 (0.98–1.21)

0.049

1.13 (0.98–1.25)

0.048

1.13 2(0.98–1.25)

0.06

1.11 (0.99–1.23)

0.052

α-Linolenic acid

1.11 (0.74–1.65)

0.612

1.12 (0.71–1.77)

0.601

1.12 (0.71–1.77)

0.603

1.22 (0.76–1.94)

0.411

EPA

1.01 (0.01–5.43)

0.087

1.01 (0.01–5.54)

0.091

1.01 (0.01–5.63)

0.092

1.01 (0.01–5.78)

0.153

DHA

6.97 (0.6–13.27)

0.424

2.02 (0.12–6.62)

0.221

2.02 (0.12–6.62)

0.218

3.10 (13–4.61)

0.211

Model 1: crude. Model 2: adjusted for age and sex. Model 3: adjusted for age, sex, physical activity, alcohol use, and smoking. Model 4: adjusted for age, sex, physicalactivity, alcohol use, smoking, calorie intake, and BMISFA Saturated fatty acids, EPA, Eicosapentaenoic acid, DHA Docosahexaenoic acid, MUFAs Monounsaturated fatty acids, PUFAs Polyunsaturated fatty acids

association between CRC risk and oleic acid was foundafter further adjustment for calorie intake and BMI.

Discussion
The obtained results from this study showed CRC
patients in the AA/AT genetic model had higher age,smoking rate, and weight compared with the control
group. Our results were in line with the results of several studies that have shown a weight gain, smoking, andadvanced age were positively associated with CRC risk
[23–26]. Moreover, in both genetic model groups, BMI
was greater in the cases. Previous studies consistently
reported that overweight and/or obesity was positively

associated with CRC [27, 28]. In the present study, controls of the AA/AT genotype group significantly weretaller than the cases. However, studies have shown that
greater height positively affects the chance of CRC [29–32]. Explaining this association, researchers suggested
reasons such as the higher length of the intestines andthe greater number of cells; therefore, taller people might
have a higher risk of cell mutations [32]. This contradiction in the findings can be the result of the differences in
the number, ethnicity/race, and nutritional status of thestudy subjects.
According to studies, the FTO gene was related to obesity and certain types of malignancies, including CRC, by

Hajipour et al. Journal of Physiological Anthropology(2023) 42:17

altering the impacts of leptin and adiponectin on colorectal carcinogenesis or participating in adipogenesis
and tumorigenesis through the mammalian target protein rapamycin (mTOR). FTO inhibitors have also beenreported as antiobesity and anticancer factors in vivo [33,34]. Furthermore, our previous study identified a significant positive association of the A allele with the risk ofdeveloping CRC in Iranians [35].
In our study, the cases in both genotype groups significantly consumed higher oleic acid. Also, dietary intakeof oleic acid was positively associated with CRC in the
AA/AT genotype group. Although dietary fat intake has
been related to increasing CRC risk, finding out specific
FA associations and their mechanistic basis was challenging [36, 37]. Several studies have shown a relationship between serum levels of specific fatty acids with
CRC [38, 39]. In line with our findings, a recent study
has reported that oleic acid can promote CRC metastasis. NADPH oxidase 4 (NOX4) expressions and reactive oxygen species (ROS) production can be affectedby increased angiopoietin-like 4 (ANGPTL4) secretion induced by oleic acid. Also, oleic acid provokes theexpression of the lipoprotein lipase inhibitor ANGPTL4
and prevents lipid overload in cells resulting in the
induction of NOX4 expression. These findings proposed that the tumor cell response to the high level oflipids such as oleic acid via triggering off the ANGPTL4/
NOX4/ROS axis could be one of the underlying causesof CRC metastasis [40]. Numerous studies reported that
DHA has antineoplastic properties, particularly in CRC,
by altering the morphology of cells to apoptotic forms,
disrupting cell connections, and reactivating caspase-3[41–43].
DHA is a potent agent in decreasing cell number andcell proliferation rate with induction of apoptosis in
KRAS mutants. KRAS mutations were found in about
40% of human CRCs that are able to activate chemotherapy-resistant CRC stem cells (CCSCs) [44]. Our findings
failed to confirm the result of these studies since DHA
consumption was related to CRC in the TT genotype andwas higher in the AA/AT cases. This may be due to the
FTO gene’s effect on this fatty acid’s role, so more studies need to be done on the relationship of this gene with
DHA fatty acid.
The results of this study also demonstrated that in the
AA/AT genotype, intake of cholesterol and linoleic waspositively associated with CRC. Okuno et al. suggested
that linoleic acid enhanced colon carcinogenesis [45].
Also, the results of a metaanalysis showed that there
was a positive association between linoleic intake and
CRC risk [46]. The linoleic acid metabolic pathway is
one of the most influential metabolic pathways in CRC
patients and plays an important role in the development

Page 6 of 8

of inflammation [47]. Studies have demonstrated thatlinoleic acid metabolism might be related to Enterobacteriaceae. These bacteria have a role in promoting
cancer and are significantly abundant in CRC patients[48]. 12,13-DHOME (isoleucotoxin diol) is one of themetabolites of cytochrome P450 monooxygenase oxidation of linoleic acid, which inhibits the immune systemand cell proliferation [49].
Inconsistent with the results, a positive association
between cholesterol and CRC risk has previously beenreported [50, 51]. The mechanism of the effect of cholesterol on cancer is stated in several studies. Squalene
epoxidase (SQLE) was a rate-limiting enzyme in cholesterol biosynthesis. Cholesterol can downregulate SQLE
gene expression. Thus, critical cellular checkpoints are
eliminated, increasing aberrant cell proliferation [52].
Furthermore, dietary cholesterol induces inflammatory
responses by increasing IL-1β, a potent cancer-promoting cytokine [53].
Our results showed that the intake of polyunsaturated fat was higher among controls in the TT genotype. Studies have reported the role of PUFAs, a small
group of dietary unsaturated fatty acids, in decreasing
tumor development and cancer complaints, especially
CRC [54, 55]. According to research, anticarcinogenic
effects of PUFAs against CRC were related to different mechanisms such as inducing oxidative stress;
altering fluidity, compressibility, fusion, and proteinfunction of cancer cell membranes; reducing inflammation by inhibition of cyclooxygenase (COX) activity; and also modulation of DNA methylation [55, 56].
A review of recent data showed that high amountsof fat induce tumor-promoting activities by alteringbile acid metabolism and gut microbiota composition[37]. It is similar to our finding that total fat positively
affects CRC.
As a strength, this study was the first study (according
to the authors’ information) to investigate the association
between different dietary fats and CRC in people withdifferent FTO genotypes. Different types of dietary fats
and fatty acids were considered in this study. However,this study had some limitations. First, the sample size wasrelatively small in the case group. Second, the FFQ wasused to collect information about food intake, which is aself-report tool and its accuracy may be questioned.

Conclusion
Results of the present study showed that the CRC patientswith the AA/AT allele of rs9939609 polymorphism areconsuming higher oleic acid and DHA. Also, in this group,
oleic acid, linoleic, and cholesterol had a positive association with CRC. While the TT genotype cases had a higher
intake of oleic acid, the controls consume more PUFA.

Hajipour et al. Journal of Physiological Anthropology(2023) 42:17

Furthermore, the total fat and DHA from the diet wererelated to a higher risk of CRC in the TT genotype. Futurecomprehensive studies are needed to verify these findings
and to address the underlying mechanisms of the difference in the relationship between various types of FTO genotypes and CRC.
Abbreviations
CRC​	Colorectal cancer
FTO	Fat mass and obesity-associated
BMI	Body mass index
DHA	Docosahexaenoic acid
Acknowledgements
We thank all the participants in this study for their good cooperation. This
paper was taken from the approved research project of Shahid Beheshti
University of Medical Sciences, Tehran, Iran.
Authors’ contributions
SD, AH, NHA, ZR, SSH, BA, HM, and GHAT designed the study and wereinvolved in the data collection, analysis, and drafting of the manuscript. SMP,
MGH, and SD were involved in the design of the study, analysis of the data,and critically reviewed the manuscript. The authors read and approved thefinal manuscript.
Funding
Funding for this study was provided by Cancer research center of Shahid
Beheshti University of Medical Sciences, Tehran, Iran (43004922).
Availability of data and materials
Not applicable

Declarations
Ethics approval and consent to participate
This study was approved by the Ethical Review Board at Cancer research
center of Shahid-Beheshti University of Medical Sciences, Tehran, Iran (Code:
IR.SBMU.PHNS.REC. 1402.002 (. A wrriten consent form was obtained from allparticipants at baseline.
Consent for publication
Institutional consent forms were used in this study.
Competing interests
The authors declare that they have no competing interests.
Author details
1
School of Health, Qazvin University of Medical Sciences, Qazvin, Iran. 2 Torbat
Jam Faculty of Medical Sciences, Torbat Jam, Iran. 3 Department of Nutrition,
Science and Research Branch, Islamic Azad University, Tehran, Iran. 4 Guilan
University of Medical Sciences, Rasht, Iran. 5 Nutrition Sciences and Applied
Food Safety Studies, Research Centre for Global Development, School of Sport& Health Sciences, University of Central Lancashire, Preston, UK. 6 Departmentof Nutrition, School of Public Health, International Campus, Iran Universityof Medical Sciences, Tehran, Iran. 7 Department of Food and Nutrition Policy
and Planning National Nutrition and Food Technology Research Institute
School of Nutrition Sciences and Food Technology, Shahid Beheshti Universityof Medical Sciences, Tehran, Iran. 8 Genomic Research Center, Shahid Beheshti
University of Medical Sciences, Tehran, Iran. 9 Cancer Research Center, Shahid
Beheshti University of Medical Sciences, Tehran, Iran. 10 Department of Community Nutrition, Faculty of Nutrition and Food Technology, National Nutrition
and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Received: 28 December 2022 Accepted: 17 July 2023

Page 7 of 8

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