The Effect of CoQ₁₀ Supplementation on Quality of Life in Women with Breast Cancer Undergoing Tamoxifen Therapy: A Double-Blind, Placebo-Controlled, Randomized Clinical Trial

Abstract

Background

Survival rates among breast cancer patients and the number of patients living with treatment side effects have improved, leading to increased focus on quality of life (QOL). The objective of this study was to determine the efficacy of CoQ₁₀ on QOL scores among breast cancer patients in Iranian undergoing tamoxifen therapy.

Methods

Thirty breast cancer patients were randomized into two groups. The first group received 100 mg CoQ₁₀, and the second group took fplacebo once a day for 8 weeks. QOL was evaluated by a standard QOL questionnaire and a specific questionnaire on QOL of breast cancer patients at baseline and the end of the study. Also, physical activity of patients was assessed with the IPAQ questionnaire and dietary intake determined by a 3-day dietary record.

Results

The data of 30 subjects were analyzed. According to QOL C30 data, CoQ₁₀ led to a significant increase in physical functioning (P=0.029), emotional functioning (P=0.031), and cognitive functioning (P=0.023) compared to placebo. Symptom scales revealed a notable reduction in appetite loss in the first group (P=0.01). Global health status showed no significant changes in either study arm. On the QOL BR23, progress in functions and decline in symptoms were not statistically significant. Arm symptoms showed significant reduction (P=0.022) in patients that received placebo.

Conclusion

This trial indicates that CoQ₁₀ supplementation has effects in ameliorating some dimensions of QOL in breast cancer patients. To generalize the results, larger and longer intervention studies are needed.

Clinical Trial Registration

IRCT2015042021874N1.

Keywords:

• breast cancer
• CoQ₁₀
• quality of life
• tamoxifen

Background

Breast cancer is the most common cancer in women in both developed and less developed countries. It is estimated that worldwide, over 627,000 women died in 2018 due to breast cancer.¹ More than 14% of mortality causes in women in Iran are related to breast cancer.² Although the incidence rate of breast cancer in Asian countries (such as Iran) is lower than in Western countries, the trend in Iran is rising.³ Breast cancer–survival rates differ considerably worldwide, ranging from 80% or over in North America, Sweden, and Japan to around 60% in middle-income countries and <40% in low-income countries.⁴

With regard to cancer, survival rate is considered one of the main prognostic indicators of the disease. In addition to various demographic factors, this index is influenced by the stage of cancer when diagnosed and the type of treatment, or in other words, diagnostic and therapeutic measures.^5,6 Studies conducted in Iran’s provinces over the past decade have estimated the 5-year survival rate in breast cancer patients to be 48%–87%.⁷ These differences may be due to patients’ biological, racial/genetic, geographical, socioeconomic, and cultural differences, and also different treatment options and patients’ access to these facilities.

The World Health Organization defines health as “a state of complete physical, mental, and social well-being, not merely the absence of disease or infirmity”. Therefore, this is necessary to comprise an estimation of well-being, evaluated by quantifying advances in quality of life (QOL) related to health care, in addition to changes in the frequency and severity of diseases by measuring health and health-care consequences.⁸ Researchers have proposed that at least 80% of cancer patients, particularly those undergoing multiple treatments, experience notable levels of fatigue that may negatively affect their QOL, emotional well-being, and treatment tolerance.⁹ Some practical techniques for breast cancer patients’ treatment are mastectomy, radiotherapy, and chemotherapy plus hormonal therapy. Although these effective treatment methods lead to increased survival rates in breast cancer patients, the QOL of such patients is fluctuating and often poor.^10,11 For example, long-term radiotherapy or chemotherapy often results in loss of self-confidence, substantial disruption in physical functioning, mental health, and well-being, and impaired QOL. In addition, total or partial mastectomy could be one of the reasons of psychological and emotional problems such as depression and anxiety, all affect QOL of breast cancer patients.^12,13

CoQ₁₀ is a lipophilic inner mitochondrial membrane cofactor with ten isoprenoid units that shuttle electrons in the formation of ATP, with wide distribution in the human body.¹⁴ Decreased critical levels of CoQ₁₀ result in the reduction of energy production and antioxidant-protection capacity in cancer patients, due to two factors: cancer is more prevalent in older persons and CoQ₁₀ synthesis declines with aging; and older cancer patients have multiple complications, such as oxidative stress, chemo/radiotherapy, and anticancer-drug usage, which lead to reductions in CoQ₁₀ levels.¹⁵

Studies on the effectiveness of CoQ₁₀ on QOL in different diseases have indicated that this supplement can have a beneficial effect on QOL.^16–18 However, there have been few studies on breast cancer,⁹ and to our knowledge, a trial evaluating the effect of CoQ₁₀ alone in breast cancer patients has not been done yet. Considering the high prevalence of breast cancer, in addition to its importance and effects on all life dimensions of patients, focusing on QOL as it relates to health and finding solutions to ameliorate QOL of these patients seems necessary. Therefore, we aimed to determine the efficacy of CoQ₁₀ on QOL scores that had been collected in a double-blind randomized clinical trial for Iranian women with breast cancer.

Methods

Patients

The target population of this randomized double-blind placebo-controlled clinical trial was women diagnosed as breast cancer patients with positive estrogen receptor by their physicians. Patients entered the study from the Medical Oncology Department of the Governmental Shaffa Hospital, Ahvaz, Iran after meeting the inclusion criteria: age 19–49 years, at least 6 months since chemotherapy and radiation therapy, a history of taking 20 mg/day tamoxifen for at least 1 year, not taking CoQ₁₀ supplements or other antioxidants, such as vitamin E, willingness to comply with all interventions and follow-up procedures, not pregnant or lactating, having no uncontrolled diseases, such as diabetes and thyroid disorders, and not taking nonprescription drugs, corticosteroids, or statins. Exclusion criteria comprised metastasis and total or partial mastectomy. There was no menstrual cycle in the patient/placebo group (14, 93.3%) or the patient/CoQ₁₀ group (14, 93.3%) with the exception of one person in each group with regular menstrual cycles. All patients were at stage 1 or 2 breast cancer. Informed consent was received from all subjects after explanation of the study.

A total of 143 women diagnosed as breast cancer patients with positive estrogen receptor were assessed for eligibility, and 30 patients met the inclusion criteria. Subjects were divided into two groups using simple random sampling: 15 breast cancer patients received 100 mg/day CoQ₁₀ orally (group A), and 15 breast cancer patients took 100 mg/day placebo (wheat flour encapsulated similarly in shape and color to the desired supplement, group B) for 2 months. For better absorption of supplements, subjects were advised to take them within meals, and compliance was calculated by counting the number of tablets given to each subject and recollected at the end of the trial. All procedures were performed at the Medical Oncology Department of Shaffa Hospital by the researchers, and patients were followed up by phone call weekly.

Assessment of Dietary Intake

A validated questionnaire and 3-day dietary record, including two weekdays and one weekend day, under supervision of a dietitian were completed by all subjects before and after the end of the study period. Dietary energy and nutrient intake were analyzed by Nutritionist IV software. Soy and soy products use were forbidden, because of estrogen-agonistic/antagonistic effects.¹⁹

Assessment of Quality of Life

The QOL of patients was evaluated using a standard QOL questionnaire (C30) and a specific questionnaire on QOL of breast cancer patients (BR23). The European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 encompasses 30 items, including five functional scales (physical, role, emotional, cognitive, and social) and nine symptom scales (fatigue, nausea and vomiting, pain, dyspnoea, insomnia, appetite loss, constipation, diarrhea, financial difficulties) plus one global health scale. The BR23 questionnaire consists of 23 questions designed to quantify QOL in breast cancer, including five functional scales (body image, sexual functioning, sexual enjoyment, future perspectives), and four symptom scales (systematic therapy side effects, breast symptom, arm symptoms, upset about hair loss).²⁰

The EORTC QLQ was translated into Persian and validated by Safaee et al²¹ and Montazeri et al.²² In general, the findings of these studies indicated that the Iranian version of the EORTC QLQ-C30 and QLQ-BR23 were reliable and valid measures of QOL in breast cancer patients and can be used in clinical trials and studies of outcome research in oncology. After information collection from patients by QOL questionnaires, raw scores for each subscale were calculated and then changed to 0–100 scales according to the guidelines of the EORTC scoring manual. Higher scores on functioning scales and global health status indicate better QOL or a high level of functioning. In the case of symptom scales, higher scores indicate the higher levels of symptoms, a critical indicator of QOL.⁹ Physical activity was assessed by the International Physical Activity Questionnaire,²³ which asks subjects about their physical activity in five sections: job-related, transportation, housework, recreation, and time spent sitting). In order to analyze this questionnaire, the relevant guidelines were used.²⁴

Sample Size

According to Premkumar et al, using Minitab software with 95% CI and test power of 90%, the sample size in each group was set at ten. To increase the accuracy of the study and to prevent a 50% drop, the sample size was increased to 15 individuals.

Statistical Analysis

Data were analyzed with SPSS version 22. The Shapiro–Wilk test was used to specify the normality of the variables’ distribution. The multi-item scales of EORTC QLQ-C30 and all subscales of BR23 were analyzed for relationships. ANCOVA and least significant–difference tests were applied to determine associations between study groups and independent/dependent variables measured before and after the trial. Dietary energy and nutrient intake were analyzed with Nutritionist IV. Values are presented as means ± SD, with significance set at P<0.05.

Results

Thirty patients (15 CoQ₁₀ and 15 Placebo) completed the study. Some subject characteristics at the beginning of the study (Table 1) were not significantly different between placebo and CoQ₁₀ groups. Dietary intake of energy and macronutrients was assessed and showed no differences between groups at baseline and had not changed at the end of 2 months (Table 2). Research has revealed that physical activity may affect CoQ₁₀ plasma levels,²⁵ and thus this was determined using the International Physical Activity Questionnaire (Table 3). No significant difference was observed between groups.

Table 1 Anthropometric and Demographic Characteristics in Breast Cancer Patients in the Study

Variables	Placebo	CoQ10	P-value
	n=15	n=15
Age (years)	36.33±7.73	40.66±5.19	0.108
Height (cm)	158.26±2.40	158.53±6.02	0.969
Weight (kg)	64.33±8.46	65.26±8.43	0.901
Body-mass index (kg.m-2)	25.66±3.15	25.96±3.01	0.250*
Educational			0.689
Illiterate	2 (13.3%)	6 (40%)
Primary	11 (73.3%)	7 (46.7%)
Secondary	1 (6.7%)	1 (6.7%)
College/university	1 (6.7%)	1 (6.7%)
Marital status			0.857
Married	14 (93.3%)	13 (86.7%)
Unmarried	1 (6.7%)	2 (13.3%)
Cigarette/alcohol			1
No	14 (93.3%)	14 (93.3%)
Yes	1 (6.7%)	1 (6.7%)
Physical activity			1
Light	15 (100%)	14 (93.3%)
Moderate	0	1 (6.7%)
Vigorous	0	0

Notes: Anthropometric data given as mean ± SD and demographic data as n (%). Kruskal–Wallis test used for age, height, and weight, and χ² used for other variables. *Difference between treatment and placebo groups at follow-up and baseline visits using ANCOVA.

Table 2 Dietary Intake of Energy and Macronutrients in Breast Cancer Patients in the Study

Variables	Before	After	P-value*
	Mean ± SD	Mean ± SD
Energy (kcal)			0.946
Patient/placebo	2,044.46±355.90	2,058.46±341.95
Patient/CoQ10	2,026.93±351.12	2,034.33±354.05
Protein (g)			0.192
Patient/placebo	60.65±10±66	61.65±10.85
Patient/CoQ10	45.74±8.58	49.04±10.16
Carbohydrates (g)			0.121
Patient/placebo	279.70±46.52	282.24±48.86
Patient/CoQ10	296.77±54.23	296.60±51.60
Fat (g)			0.111
Patient/placebo	74.69±14.39	74.47±13.19
Patient/CoQ10	73.01±14.45	75.16±15.57

Notes: *Difference between treatment and placebo groups at follow-up and baseline visits using ANCOVA.

Table 3 Physical Activity Levels of Breast Cancer Patients at Baseline and End Point of Study

Variables		Before	After	P-value
		(Mean ± SD)	(Mean ± SD)
Work domain	Walking, MET-minutes/week at work			0.234
	Patient/placebo	92.40±243.84	215.60±450.55
	Patient/CoQ10	195.80±458.36	46.20±178.93
	Moderate MET-minutes/week at work			0.288
	Patient/placebo	192±506.68	856±2268.17
	Patient/CoQ10	474.66±1541.04	250.66±863.14
	Vigorous MET-minutes/week at work			0.958
	Patient/placebo	896±2364.53	1,133.33±4,334.20
	Patient/CoQ10	56±216.88	37.33±144.59
	Total work, MET-minutes/week			0.541
	Patient/placebo	1,180.40±3115.06	2,204.93±679.48
	Patient/CoQ10	726.46±1927.19	334.20±912.93
Active transportation domain*	Walking, MET-minutes/week for transport			0.305
	Patient/placebo	272.80±211.47	595.10±1204.16
	Patient/CoQ10	600.60±758.22	262.90±240.44
	Total transport, MET-minutes/week			0.305
	Patient/placebo	272.80±211.47	595.10±1204.16
	Patient/CoQ10	600.60±758.22	262.90±240.44
Domestic and garden (yard work) domain	Vigorous MET-minutes/week yard chores			0.758
	Patient/placebo	641.66±1616.08	170.50±257.80
	Patient/CoQ10	34.83±55.45	60.50±149.97
	Moderate MET-minutes/week yard chores			0.846
	Patient/placebo	600±1125.39	380±277.23
	Patient/CoQ10	209.33±187.13	220±168.69
	Moderate MET-minutes/week inside chores			0.060
	Patient/placebo	793±774.72	552±450.54
	Patient/CoQ10	658±664.77	744±437.13
	Total domestic and garden moderate MET-minutes/week			0.160
	Patient/placebo	2,034.66±3461.93	1,102.50±884.95
	Patient/CoQ10	902.16±807.45	1,024.50±604.86
Leisure-time domain	Walking MET-minutes/week leisure			0.190
	Patient/placebo	376.20±427.69	311.30±194.51
	Patient/CoQ10	227.70±234.52	267.30±269.62
	Moderate MET-minutes/week leisure			0.159
	Patient/placebo	93.3±170.82	37.33±83.44
	Patient/CoQ10	10.66±28.14	140±300.57
	Vigorous MET-minutes/week leisure			0.549
	Patient/placebo	56±149.51	85.33±155.55
	Patient/CoQ10	352±967.96	320±877.91
	Total leisure-time MET-minutes/week			0.249
	Patient/placebo	525.53±593.27	433.96±255.81
	Patient/CoQ10	590.36±1038.92	727.30±1068.82
Sitting domain	Sitting, total minutes/week			0.060
	Patient/placebo	1,457.33±1,180.59	1,541.53±1,127.93
	Patient/CoQ10	1,988±1,005.74	1,776±826.66
	Average sitting total minutes/day			0.060
	Patient/placebo	208.19±168.65	220.21±161.13
	Patient/CoQ10	284±143.67	253.71±118.09

Notes: P-values for difference between treatment and placebo groups at follow-up and baseline visits using ANCOVA. Metabolic equivalent: 1 MET = 1 kcal/kg/hour). *This section includes two areas of walking and cycling. Due to the negative response to participation in cycling, this area was removed in the data analysis.

Tables 4 and 5 shows the effect of CoQ₁₀ on QOL components during the two phases of measurement and their changes during the study. According to QOL C30 data, analysis of the questionnaires showed that supplementation with CoQ₁₀ significantly increased physical functioning (P=0.029) compared to placebo. Also, emotional functioning and cognitive functioning of patients after supplementation significantly increased (P=0.031 and P=0.023, respectively). An insignificant increasing trend was observed on other functional scales, indicating better QOL than at the beginning of the study. Symptom scales revealed a notable reduction in appetite loss in the CoQ₁₀ group (P=0.01). Global health status showed no significant changes in the CoQ₁₀ or placebo arm. In the case of symptom scales, insignificant decreases were found in fatigue, nausea and vomiting, pain, insomnia, and constipation. However, financial problems increased significantly in the intervention group (P<0.0001). On the QOL BR23, progress on functional scales (body image, sexual functioning, sexual enjoyment, and future perspectives) and decline on symptom scales (systemic therapy side effects, breast symptoms, and upset with hair loss) were not statistically significant. Arm symptoms (BRAS) showed significant reduction (P=0.022) in subjects receiving placebo.

Table 4 Effect of Coenzyme Q₁₀ Supplementation on QOL C30 in Breast Cancer Patients

Variables			Before	After	P-value*
			Mean ± SD	Mean ± SD
Domains	Global health status/QOL	Question 29			0.970
		Patient/placebo	5.66±0.89	5.86±0.99
		Patient/CoQ10	5.20±1.01	5.46±0.91
		Question 30			0.770
		Patient/placebo	5.93±0.70	6.13±1.12
		Patient/CoQ10	5.40±1.05	5.73±0.96
	Functional scales	Physical functioning (PF2)			0.029
		Patient/placebo	83.11±14.22	84±12.54
		Patient/CoQ10	78.66±15.97	72.88±14.13
		Role functioning (RF2)			0.309
		Patient/placebo	94.44±8.13	92.22±12.38
		Patient/CoQ10	80±19.10	86.66±18.03
		Emotional functioning (EF)			0.031
		Patient/placebo	83.88±13.53	90±13.80
		Patient/CoQ10	65.55±17.49	80±12.51
		Cognitive functioning (CF)			0.023
		Patient/placebo	87.77±14.72	94±12.06
		Patient/CoQ10	75.55±15.25	83.33±15.43
		Social functioning (SF)			0.796
		Patient/placebo	95.55±13.31	93.33±13.80
		Patient/CoQ10	91.11±20.76	94±10.28
	Symptom scales/items	Fatigue (FA)			0.149
		Patient/placebo	14.07±18.52	18.51±17.65
		Patient/CoQ10	28.88±19.15	28.14±20.08
		Nausea and vomiting (NV)			0.153
		Patient/placebo	16.66±43.18	0
		Patient/CoQ10	10±16.42	3.33±9.34
		Pain (PA)			0.787
		Patient/placebo	14.44±17.66	18.88±27.36
		Patient/CoQ10	34.44±23.95	21.11±18.32
		Dyspnea (DY)			0.065
		Patient/placebo	0	4.44±11.72
		Patient/CoQ10	8.88±15.25	20±30.34
		Insomnia (SL)			0.811
		Patient/placebo	13.33±27.60	17.77±30.51
		Patient/CoQ10	26.66±33.80	15.55±21.33
		Appetite loss (AP)			0. 010
		Patient/placebo	6.66±18.68	20±21.08
		Patient/CoQ10	15.55±17.21	4.44±11.72
		Constipation (CO)			>0.999
		Patient/placebo	22.22±24.12	2.22±8.60
		Patient/CoQ10	15.55±21.33	2.22±8.60
		Diarrhea (DI)			0.540
		Patient/placebo	4.44±11.72	4.44±11.72
		Patient/CoQ10	2.22±8.60	2.22±8.60
		Financial difficulties (FI)			<0.0001
		Patient/placebo	42.22±38.76	37.77±24.77
		Patient/CoQ10	66.66±35.63	80±27.60

Notes: *Difference between treatment and placebo groups at follow-up and baseline visits using ANCOVA. P<0.05 significant.

Table 5 Effect of Coenzyme Q₁₀ Supplementation on QOL Br23 in Breast Cancer Patients

Variables			Before	After	P-value*
			Mean ± SD	Mean ± SD
Domains	Functional scales	Body image (BRBI)			0.948
		Patient/placebo	76.66±22.31	71.11±27.43
		Patient/CoQ10	65±20.70	70.55±20.86
		Sexual functioning (BRSEF)			0.951
		Patient/placebo	32.22±7.62	72.22±13.60
		Patient/CoQ10	27.38±19.17	71.79±23.94
		Sexual enjoyment (BRSEE)			0.347
		Patient/placebo	44.44±20.57	22.22±24.12
		Patient/CoQ10	23.80±24.20	30.95±27.62
		Future perspective (BRFU)			0.183
		Patient/placebo	57.77±38.76	55.55±34.88
		Patient/CoQ10	62.22±27.79	68.88±19.78
	Symptom scales/items	Systemic therapy side effects (BRST)			0.320
		Patient/placebo	20.31±21.85	18.73±17.76
		Patient/CoQ10	27.61±10.21	24.12±12.53
		Breast symptoms (BRBS)			0.651
		Patient/placebo	13.33±17.19	13.33±21.77
		Patient/CoQ10	8.33±7.71	10.55±11.55
		Arm symptoms (BRAS)			0.022
		Patient/placebo	20±18.87	14.81±20.85
		Patient/CoQ10	18.874±18.24	34.07±26.38
		Upset by hair loss (BRHL)			0.232
		Patient/placebo	11.11±27.21	15.55±35.33
		Patient/CoQ10	8.88±15.25	4.44±11.72

Notes: *Difference between treatment and placebo groups at follow-up and baseline visits using ANCOVA. P<0.05 is significant.

Discussion

Cancer treatments, such as chemotherapy, in breast cancer patients can cause several side effects and symptoms, including physical, functional, psychological and social difficulties (anxiety, depression, pain, fatigue, and arm morbidity), that affect QOL. Clinical trials have demonstrated that evaluation of QOL and making changes leads to treatment improvement, increasing survival in cancer patients.²⁶ It has been shown that numerous disease processes associated with CoQ₁₀ deficiency can benefit from CoQ₁₀ supplementation, including cancer. In this study, we evaluated the efficacy of CoQ₁₀ on QOL in breast cancer patients.²⁷

The results of this study demonstrated that oral CoQ₁₀ supplementation (100 mg/day) for 8 weeks had beneficial effects on physical, emotional, and cognitive functioning, as well as appetite. However, global health status remained unchanged after CoQ₁₀ supplementation. Furthermore, there was a not-inconsiderable improvement in other dimensions of EORTC questionnaire scores in the supplemented group that showed nonstatistically significant but clinical importance of CoQ₁₀ in ameliorating QOL. These outcomes were obtained despite the low sample size and short study duration, and for better understanding of CoQ₁₀ effects on QOL of breast cancer patients, more clinical trials are needed.

Although the effects of CoQ₁₀ on QOL among patients with other chronic diseases have been studied in several clinical trials with conflicting results, to our knowledge this is the first study indicating the effect of CoQ₁₀ supplementation alone on QOL in patients with breast cancer. There have been some clinical trials done to assess the effect of CoQ₁₀supplementation alone on QOL in breast cancer patients, and the their results were in line with our study.

Guilbot et al suggested that 12 weeks of a combination of feverfew, magnesium, and CoQ₁₀ at a dosage of 100 mg/day for migraine prophylaxis significantly reduced the number of days with migraine headache and improved QOL.¹⁶ In another study, Sharifi et al showed that both a therapeutic lifestyle–change diet and supplementation with CoQ₁₀ (150 mg/day) and L-carnitine had a positive effect on the physical and emotional subscales of the MacNew questionnaire in patients with myocardial infarction.¹⁷ In addition, Morris et al illustrated the CoQ₁₀'s potential role in improving QOL in patients with Parkinson’s disease and fibromyalgia. Also, it showed antidepressive effects and significantly reduced fatigue and improved ergonomic performance during exercise.²⁸ Other studies assessing the effect of CoQ₁₀ in combination with other nutrients, such as NADH, in chronic fatigue syndrome²⁹ and high-dose micronutrients in patients with chronic heart failure¹⁸ have indicated significant improvement in QOL and other dimensions of health care.

In contrast to our study, clinical trials have revealed conflicting results, eg, 300 mg/day CoQ₁₀ or placebo, each combined with 300 IU vitamin E, divided into three daily doses for 24 weeks led to increase in plasma CoQ₁₀ levels, but did not result in improved self-reported fatigue or QOL in breast cancer patients.⁹ Also, a study on amino-acid jelly containing CoQ₁₀ and L-carnitine in controlling fatigue in breast cancer patients receiving chemotherapy showed that EORTC QLQ-C30, and EORTC QLQ-BR23 scores were not significantly different between the two groups.³⁰ Muscle strength, muscle endurance, and QOL increased statistically significantly in all postpolio-syndrome patients in both groups of CoQ₁₀ supplementation and placebo, which revealed CoQ₁₀ had no beneficial effect.³¹

Multiple roles as an antioxidant, a membrane stabilizer, and specifically mitochondria regulation, which optimize cell-energy generation, are some aspects of cellular CoQ₁₀ functioning. Lowered CoQ₁₀ levels are connected with high inflammation, oxidative/nitrosative stress, and dysfunction of mitochondria, which are activated by intracellular signaling pathways, including NFκB, MAPK, and JAK–STAT. As such, proteins and fatty acids in cell membranes can be attacked by ROS, which reduces membrane fluidity and diminishes the performance of cell-membrane receptors and ion channels, thus disrupting intercellular and intracellular signaling processes and leading to such disorders as fatigue, hyperalgesia, depression, and neurodegenerative processes.^27,32,33 Also, in depleted levels of CoQ₁₀, uncoupling proteins do not function correctly, which causes inability in regulating cellular fuel metabolism and other ATP-dependent processes.^27,34 Some genes involved in mitochondrial biogenesis and replication due to increasing energy demands are under CoQ₁₀ control. As a consequence, stimulating oxidative metabolism in response to increased demands for energy could be affected in CoQ₁₀ deficiencys.³⁵ CoQ₁₀ treatment decreases fatigue, depression, and hyperalgesia through its anti-inflammatory, antioxidant, and neuroprotective effects. Also, it decreases muscle weakness, increases walking distance, and improves exercise tolerance and oxygen consumption by modification of the performance of complex I of the electron-transfer chain.²⁸ Given that, sex and dietary intake are considered confounding factors in QOL.^36,37 Limiting our sample to women and records of dietary intake are a couple of the strengths of our study.

Conclusion

In this study, we discovered proof demonstrating significant effects of CoQ₁₀ on physical, social, and mental conditions in women with breast cancer. In short, the supplemented patients showed better QOL at the end of the study. Separate studies should be conducted in different age-groups and larger populations for longer periods to generalize the evidence gained.

Data-Sharing Statement

The data sets used and/or analyzed during this study are available from the corresponding author on reasonable request. Permission for use was received by the ethics committee of Ahvaz Jundishapur University of Medical Sciences.

Ethics Approval and Consent to Participate

This clinical protocol was approved by the Research Ethics Committee of the Ahvaz Jundishapur University of Medical Science (protocol number IRAJUMS.REC.1394.246, July 25, 2015) in accordance with the principles of the Declaration of Helsinki. Signed informed consent was obtained from all participants included in the study.

Author Contributions

All authors contributed to data analysis, drafting, and revising the article, gave final approval of the version to be published, and agree to be accountable for all aspects of the work.

Acknowledgments

This work is a part of Nazanin Zahrooni’s MSc thesis. Special thanks to staff of the Shafa Hematology Clinic Nutrition and Metabolic Disease Research Center, Ahvaz Jundishapur University of Medical Sciences.

Disclosure

The authors report no conflicts of interest in this work.

Additional information

Funding

This study was supported by an intramural grant of the Vice-Chancellor for Research at Ahvaz Jundishapur University of Medical Sciences.