Int J Reprod BioMed Vol. 14. No. 12. pp: 729-736, December 2016
Evidence based review
Antioxidant supplements and semen parameters: An
evidence based review
Sedigheh AhmadiP
1
P M.Sc., Reihane BashiriP
1
P M.Sc., Akram Ghadiri-AnariP
2
P M.D. Azadeh NadjarzadehP
1
P
Ph.D.
1. Nutrition and Food Security
Research Center, Shahid
Sadoughi University of Medical
Sciences, Yazd, Iran.
2. Diabetes Research Center,
Shahid Sadoughi University of
Medical Sciences, Yazd, Iran.
Corresponding Author:
Azadeh Nadjarzadeh, Nutrition
and Food Security Research
Center, Shahid Sadoughi
University of Medical Sciences,
Yazd, Iran.
Email:
60Tazadehnajarzadeh@gmail.com60T
Tel: (+98) 35 38209100
Received:
13 April 2016
Revised: 13 August 2016
Accepted: 7 September 2016
Abstract
Many studies have focused on male infertility. There is limited evidence about the
influence of nutrition on quality of semen. Approximately, 30-80% of infertility
cases are caused by oxidative stress and decreased level of seminal total antioxidant
capacity. This study was aimed to review the effects of oral antioxidant supplements
on improving major semen parameters such as sperm concentration, motility,
morphology, DNA damage, and fertility rate. Data were extracted from PubMed and
Google scholar database by using the terms “antioxidant”, “multivitamin”,
“carnitine”, “CoQ10”, “vitamin C”, “vitamin E”, “zinc”, “folic acid”, “N-acetyl
cysteine” and “selenium” combined with “male infertility”, “semen”, and “sperm” to
generate a set of relevant citations. Supplements such as CoQ10 and alpha-
tocopherol significantly improve sperm count. Also, carnitine has positive effects on
sperm motility and morphology. Simultaneous administration of vitamin E and
vitamin C reduces the sperm DNA damage. However, in some studies, one or more
factors have not changed substantially. In most of the studies, antioxidant
supplementation improved the number, motility, morphology and sometimes DNA
integrity of sperm. The present study showed that antioxidant supplements,
especially a combination of antioxidants such as vitamin C, vitamin E, and CoQ10
intake can effectively improve semen parameters in infertile men.
Key words: Male infertility, Semen, Antioxidants, Carnitine, Coenzyme Q10 (CoQ10),
Vitamins.
Introduction
nfertility is defined as not being able to
get pregnant despite having frequent,
unprotected sex for at least a year (1).
More than 70 million couples suffer from
infertility worldwide. Male infertility is a
controversial issue throughout the world.
Between 8 and 12% of couples suffer from
infertility, based on research (2). Male factors
account for at least 50% of all infertility cases
worldwide (3). Some factors such as radiation,
smoking, varicocele, infection, urinary tract
infection, environmental factors, nutritional
deficiencies and oxidative stress contribute to
male infertility (4, 5). Oxidative stress occurs
when the production of reactive oxygen
species (ROS) exceeds the body’s natural
antioxidant defenses (6).
The increased level of ROS can be
resulted from environmental factors such as
high temperature, electromagnetic waves, air
pollution, insecticides, alcohol consumption,
obesity and poor nutrition (7). There are
evidence that sperms are simply affected by
ROS and oxidative stress. There are a
number of studies that support the role of
ROS in male infertility theory (8-11). The
structure of the plasma membrane is unique
and consists of high levels of polyunsaturated
fatty acids (PUFAs) that improve membrane
flexibility. It makes them vulnerable to be
attacked by ROS (12-14). Lipid peroxidation
cascade can seriously compromise the
functional integrity of membrane cells,
decrease sperm motility, and subsequently
reduce fertility. ROS production pathologically
results in high levels of DNA damage that is
associated with properties of mitochondrial
membrane (15).
Ordinary antioxidants in semen include
vitamin E, vitamin C, superoxide dismutase,
glutathione and thioredoxin. These
antioxidants neutralize free radical activity and
protect sperm from ROS that already
produced (6). Evidence show lower
antioxidant capacity of semen in infertile men
that explain the reduced semen antioxidants
and high levels of ROS compared to fertile
men (16, 17). Semen analysis may identify
and characterize the following impairments in
male: oligozoospermia (low concentration of
I
Ahmadi et al
730 International Journal of Reproductive BioMedicine Vol. 14. No. 12. pp: 729-736, December 2016
sperm), asthenospermia (reduced sperm
motility), teratozoospermia (sperms with
abnormal morphology), and the combination
them (oligoasthenoteratozoospermia) (18).
Standard values of sperm parameters are as
follow: pH equal or greater than 7.2, semen
concentration equal or greater than 15 million
per milliliter, and semen volume 1.5 ml or
higher, sperm progressive motility of 32% or
higher, and normal morphology equal or more
than 4% (18).
In recent years, most attention is on the
effect of oxidative stress on the etiology of
male infertility and the role of oral antioxidant
supplements in improvement of semen
properties in infertile men. Majority of these
studies show a positive relationship between
antioxidants and improved male infertility.
However, some studies revealed paradoxical
results. The aim of this study was evaluating
the effect of antioxidant supplements on key
semen parameters such as sperm
concentration, motility, morphology DNA
damage, and fertility rate.
Data about effects of antioxidants on
improved sperm quality were extracted from
papers published between 2004 and 2015 in
electronic databases from two sites, PubMed
and Google scholar using the following
keywords: antioxidant, multivitamin, carnitine,
CoQ10, vitamin C, vitamin E, zinc, folic acid,
N-acetyl cysteine, selenium and male
infertility, semen and sperm. Searches were
limited to the title and abstracts of clinical trials
and meta-analysis. Animal and laboratory
studies were excluded from the study. Also,
studies that focused on the effect of
antioxidants in combination with drugs were
excluded to determine the positive effects of
antioxidant supplements. Table I shows the
clinical trials presented in this study.
Vitamin C and vitamin E
Ascorbic acid known as vitamin C is a
water-soluble antioxidant that acts as a key
cofactor in various hydroxylation and
amidation processes (19). It is utilized in the
synthesis of collagen, proteoglycan, and
components of the intercellular matrix along
with vitamin E (20). Vitamin C can be found in
high concentrations in seminal plasma (21,
22). As vitamin C intake increases its
concentration in seminal plasma rises and
prohibits DNA damage (23). Vitamin E is a fat-
soluble antioxidant that neutralizes free
radicals and protects cellular membrane
against O2 free radicals. It also prevents lipid
peroxidation and therefore improves functions
of other antioxidants (24). Vitamin E also
inhibits the production of ROS in infertile male
(25).
Gerco et al conducted an interventional
study on infertile men. Intervention group was
treated by 1 gr of vitamin E and 1 gr of vitamin
C. After two months, level of DNA damage
was reduced in intervention group (p<0.001).
However, no significant relationship was found
between vitamin E and C intake and major
semen parameters such as motility and
concentration (26). Results from intra-
cytoplasmic sperm injection (ICSI) and IVF
show that high levels of sperm DNA damage
results in lower fertility rate or infertility. Greco
and Colleagues stated that two-month
treatment with 1gr vitamin E and C improved
ICSI success rate in patients with sperm DNA
damage and reduced the level of DNA
damage in these individuals (27). Moslemi et
al studied 690 infertile men with idiopathic
asthenoteratospermia who received daily
supplement of selenium (200 μg) in
combination with vitamin E (400 IU) for at
least 100 days. They reported 52.6% (362
cases) total improvement in sperm motility,
morphology, or both, and 10.8% (75 cases)
spontaneous pregnancy in comparison with
no treatment (28).
Carnitine
L-carnitine (LC) or 3-aminobutyric acid is a
naturally occurring compound and also a
semi-essential vitamin like substance required
for human metabolism. LC involvement in
intermediary metabolism is essential for
bioenergetic processes, where it has a major
role in the formation of acyl carnitine esters of
long-chain fatty acids (29). The highest
concentrations of LC exist in epididymis which
is 2000 times higher than whole blood
concentration (30, 31). The high level of LC in
epididymis is resulted from an active secretory
process (29). Findings show a positive
relationship between initial sperm movement
and increased LC in epididymis and L-acetyl
in sperm (30, 32).
Some studies have examined the effect of
L-carnitine supplementation on male infertility.
Lenzi et al conducted a double-blind
controlled clinical trial to evaluate the effect of
LC on male infertility. A total of 60 infertile
men with oligoasthenoteratozoospermia were
divided into two groups (intervention and
control group). Intervention group received 2
gr/day LC and 1 gr/day L-acetyl carnitine
(LAC) for 6 months of therapy. A positive
relationship was observed between LC and
Antioxidants and semen parameters
International Journal of Reproductive BioMedicine Vol. 14. No. 12. pp: 729-736, December 2016 731
LAC and sperm motility in infertile men.
However, this relation was more significant in
men with lower sperm motility at the baseline
(33).
Balercia et al evaluated the effect of LC
and LAC or combined LC and LAC on the
semen motion kinetics and total oxygen
radical scavenging capacity (TOSC). This
randomized double-blind controlled trial
consisted of 60 men with idiopathic
asthenoteratospermia. A six-month
intervention showed that LC and LAC
increased sperm motility and TOSC in men
with asthenoteratospermia. Nine pregnancies
occurred in carnitine-treated patients during
therapy and that five of them were achieved
after combined LC plus LAC administration
(34). Sigman et al found no significant positive
relationship between LC and LAC therapy and
sperm motility and sperm concentrations, and
no statistical difference was observed
between two groups (35).
Garolla et al examined the effect of LC
therapy and Phospholipid hydroperoxide
glutathione peroxidase (PHGPX) therapy in
men with asthenoteratospermia. A total of 30
men with idiopathic asthenoteratospermia
underwent this double-blind study and were
divided into two groups based on PHGPX
levels. Patients received a placebo for 3
months, and then received LC 2 gr/day daily
for 3 months, too. Semen analysis showed
that LC therapy improved sperm motility in
patients with normal PHGPX levels (36). Wu
indicated that short-term administration of LC
can positively affect sperm count and leading
to successful pregnancy through ICSI (37).
Coenzyme Q10 (CoQ10)
CoQ10 also known as ubiquinone is an
antioxidant. As a component of the electron
transport chain, it participates in aerobic
cellular respiration, which generates energy.
This oil-soluble, vitamin-like substance is
present in cell membrane and lipoproteins
(38). In recent years, the role of this vitamin-
like antioxidant in male infertility has been
discussed widely. Balercia and colleagues
examined the effect of CoQ10 on sperm
motility in infertile men, which 60 men with
idiopathic asthenoteratospermia received
CoQ10 therapy in a double-blind controlled
trial.
After 6 months therapy, CoQ10 increased in
the semen of patients who received CoQ10,
and the sperm motility was improved in these
individuals. Twelve spontaneous pregnancies
were occurred (39). Another double-blind
controlled intervention by Safarinejad et al on
228 unexplained infertile men with abnormal
sperm concentration, motility and morphology,
showed that 28 wk treatment with ubiquinone
led to improvement in sperm density, sperm
motility and sperm morphology in the
intervention group compared to the control
group (40). Nadjarzadeh et al conducted a
double-blind placebo controlled clinical trial on
47 infertile men with
oligoasthenoteratozoospermia (OAT).
They were randomly assigned to receive
200 mg CoQ10 daily or placebo during a 16
wk period. The trial showed non-significant
changes in semen parameters such as
density, motility or morphology in CoQ10
group, whereas total antioxidant capacity was
increased significantly (p<0.05) (41). They
showed that three-month supplementation
with CoQ10 increased catalase and
superoxide dismutase (SOD) in semen of
OAT men compared with control group. There
was a significant positive correlation between
CoQ10 concentration and normal sperm
morphology, and also catalase and SOD
concentrations. A significant difference was
shown in seminal plasma 8-isoprostane in two
groups (p=0.003) after supplementation, too
(42).
Finally, it was found that the concentration
of CoQ10 was correlated with key semen
parameters such as sperm concentration,
motility and morphology because the total
antioxidant capacity improves. Thakur
suggested that daily administration of 150 mg
CoQ10 improved semen parameters in
infertile men (43). A meta-analysis showed
that supplementing infertile men with CoQ10
does not increase live birth or pregnancy
rates, but there is a global improvement in
sperm parameters such as sperm
concentration and motility and CoQ10
concentration in semen (8).
Zinc
Zinc is the second most abundant metal in
the body after iron. Although red meat, fish
and milk are rich sources of zinc, the world
health organization suggested that zinc
deficiency affects about one-third of the
world's population (44). It has been shown
that zinc supplementation normally protects
the spermatozoa against bacteria and also
prevents damage to chromosomes (45, 46).
Zinc plays an important role in testicular
development and sperm maturation (47).
Ahmadi et al
732 International Journal of Reproductive BioMedicine Vol. 14. No. 12. pp: 729-736, December 2016
Zinc deficiency is positively associated with
male hypogonadism and incomplete
development of sex characteristics in humans
(48). Decreased levels of zinc in the semen
were associated with reduced sperm
fertilization capacity (49). Ebisco and
colleagues revealed that patients who
received 5 mg of folic acid and 66 mg of zinc
for 26 wks reported improving sperm
concentration. However, no improvement was
observed in other semen parameters.
Furthermore, at baseline, positive correlations
were found between serum Zinc and sperm
concentration, motility and Inhibin B (50).
Hadwan and colleagues examined the
effect of zinc supplementation on quantitative
and qualitative characteristics of semen and
ligands attached to the zinc in men with
asthenoteratospermia. A total of 37 fertile
male and 37 infertile men that have been
adjusted for age, received 2 zinc sulphate
capsules (220 mg per capsule) per day for 3
months. Results showed that the volume of
semen, progressive sperm motility percentage
and total normal sperm count increased after
zinc supplementation. Zinc in seminal plasma
binds with 3 types of protein (low molecular
weight ligands, average molecular weight
ligands and high molecular weight ligands). In
this study, the percentage of high molecular
weight ligands in the semen was higher in
fertile men than in infertile men, and zinc
supplementation increased the percentage of
high molecular weight ligands in men with
asthenoteratospermia and raised low
molecular weight ligands above the normal
value (45).
Raigani et al did not show significant
improvements in sperm concentration, motility
and morphology after supplementation with
folic acid, zinc, and combination of them for 16
weeks (51). Hadwan et al also examined the
effect of zinc supplementation on the
peroxynitrite levels, arginase activity and
nitric
oxide (NO)
synthase activity in seminal plasma
in men with asthenospermia. They concluded
that peroxynitrite levels and NO synthase
activity were significantly higher in the infertile
patients compared to the fertile group.
Peroxynitrite levels, arginase activity and NO
synthase activity of the infertile patients were
restored to normal values after treatment with
zinc sulfate (46).
Selenium and N-acetyl-cysteine
Selenium is an essential trace element in
formation of sperm and testosterone
biosynthesis (52). At least 25 selenoproteins
have been identified in humans and animals.
Selenoproteins help maintain normal sperm
structure integrity. N-acetyl cysteine is a
naturally occurring compound which comes
from amino acid L-cysteine, and functionsas a
precursor of glutathione peroxidase (53).
Placebo controlled clinical trial carried out in
Iran and Tunisia showed that selenium
supplementation improved sperm counts,
concentration, motility and morphology as well
as sperm concentration in infertile men (54,
55).
Safarinejad et al investigated the effect of
selenium and N-acetyl-cysteine on 468
infertile men with idiopathic oligo-
asthenoteratospermia. They were followed by
a 30 weeks treatment period. In response to
treatment, serum follicle-stimulating hormone
decreased but serum testosterone and Inhibin
B increased. In addition, all semen
parameters significantly improved with
selenium and N-acetyl-cysteine treatment.
Administering selenium plus N-acetyl-cysteine
resulted in further beneficial effects in semen
parameters (55).
41TMulti41T-41Tantioxidant supplementation
Currently, multi-antioxidant supplementa-
tions are considered as an effective therapy
for male infertility. The synergetic effect of
multi antioxidants made them interesting for
researchers. Galatioto et al conducted a study
to determine the effectiveness of an
antioxidant therapy in the quality of seminal
fluid parameters and the natural pregnancies
in spouses of men with persistent
oligospermia (5-20 million/ml) 6 months after
retrograde embolization.
20 men with varicocele received
antioxidant therapy; NAC and vitamins-
minerals (containing vitamin C, vitamin E,
vitamin A, thiamine, riboflavin, biotin, B12,
magnesium, ferrous, manganese, copper,
zinc). After this therapy, significant statistically
increases were found in number of sperms
due to WHO index in treated groups. Also, no
significant relationship was observed between
multi-antioxidant supplementation and other
semen parameters like motility and
morphology. No spontaneous pregnancy was
occurred after 12 months (56).
Abad and colleagues also carried out a
study to determine the effect of oral
antioxidant treatment upon the dynamics of
sperm DNA fragmentation following in a
cohort of 20 infertile patients diagnosed with
asthenoteratozoospermia. All subjects
received 1500 mg of LC, 60 mg vitamin C, 20
Antioxidants and semen parameters
International Journal of Reproductive BioMedicine Vol. 14. No. 12. pp: 729-736, December 2016 733
mg CoQ10, 10 mg vitamin E, 10 mg zinc, 200
microgram folic acid, 50 microgram selenium,
and 1 microgram vitamin B12 during a period
of 3 months. Results showed that a proportion
of DNA degraded sperm was significantly
reduced and semen analysis data showed a
significant increase in concentration, motility,
vitality and morphology parameters. Also a
significant improvement of DNA integrity at all
incubation points was observed. Findings of
this study suggest that antioxidant treatment
improves sperm quality not only in terms of
key seminal parameters and basal DNA
damage, but also helps to maintain DNA
integrity. Therefore, administration of
antioxidants can help in new medical
treatments (57).
Gopinath stated that administration of
antioxidants lead to a significant improvement
in sperm count and sperm total motility at 90
days in men with oligoasthenoteratozoo-
spermia
compared with placebo (58).
Tremellen et al conducted a prospective
randomized double-blind placebo-controlled
trial in sixty couples with severe male factor
infertility. Participants were randomly assigned
to take either one capsule per day containing
6 mg Lycopene, 400 IU vitamin E, mg vitamin
C, 25 mg zinc, 26 microgram selenium, 5 mg
folate and 1000 mg garlic or taking a placebo
for three months prior to their partner's IVF or
ICSI cycle. The antioxidant group recorded a
statistically significant improvement in viable
pregnancy rates (38.5%) compared to the
control group (16%). No significant changes in
oocyte fertilization rate or embryo quality were
detected between the antioxidant and the
placebo groups (59).
Table I. Characteristics of clinical trials reviewed in the study
Author
Year
Number of participants/
Abnormality
Antioxidant type and dose Intervention
period
Controlle
d/ Blinded
Results
Lenzi
2004 (33)
60/
Oligoasthenoteratozoospermia
2 g/d LC plus 1 g/d LAC 6 months Yes/ Yes Increase in sperm motility
Balercia
2005 (34)
60/ Asthenozoospermia
a) 3 g/d LC
b) 3 g/d of LAC
c) 2 g/d of LC and 1 g/d LAC
d) Placebo
6 months
treatment and
1 month
follow up
Yes/ Yes
LCand LAC increased sperm motility and
TOSC. Nine pregnancies occurred in
carnitine-treated patients during therapy
and five of them were achieved after
combined supplement
Greco
2005 (26, 27)
64/ Unexplained infertility
with high DNA fragmentation
a) 1g/d vitamin E and 1g/d vitamin C
b) Placebo
2 months Yes/ Yes
No significant relationship was found
between vitamin E and C intake and sperm
motility or concentration but improved ICSI
in patients with sperm DNA damage and
reduced the level of DNA damage.
Ebisch
2006 (50)
47/ Fertile
40/ Subfertile
a) 5 mg folic acid and 66 mg zinc
b) Placebo
26 weeks Yes/ Yes
Improvement of sperm concentration with
no effect on other parameters
Sigman
2006 (35)
21/ Asthenozoospermia 2 g/d LCplus 1 g/d LAC 24 weeks Yes/Yes
No significant effect of LC / LAC and
sperm motility / concentrations
Galatioto
2008 (56)
42/ Oligospermia
a) 600 mg NAC plus vitamins-
minerals
b) no treatment
3 months Yes/ No
Increase in number of sperms in
intervention group with no differences in
other semen parameters
Balercia
2009 (39)
60/ Asthenozoospermia
a) 200 mg Co Q10
b) Placebo
6 months Yes/ Yes
Improvement in sperm motility and twelve
spontaneous pregnancies
Safarinejad
2009 (55)
468/
Oligoasthenoteratozoospermia
a) 200 µg selenium,
b) 600 mg N-acetyl-cysteine,
c) 200 µg selenium+ 600 mg N-
acetyl-cysteined) Placebo
30 weeks Yes/ Yes
All semen parameters significantly
improved with selenium and N-acetyl-
cysteine
Nadjarzadeh
2014 (41)
47/
Oligoasthenoteratozoospermia
a) 200 mg Co Q10
b) Placebo
3 months Yes/ Yes
Increase in seminal catalase and SOD with
a significant positive correlation between
CoQ10 concentration and normal sperm
morphology, catalase, and SOD
Safarinejad
2012 (40)
228/
Oligoasthenoteratozoospermia
a) 200 mg Ubiquinone
b) Placebo
26 weeks Yes/ Yes
Improvement in sperm density, motility and
morphology
Moslemi
2011
690/ Asthenoteratospermia 200 μg Selenium + 400 IU vitamin E 100 days No/ No
52.6% total improvement in sperm motility,
morphology, or both with 10.8%
spontaneous pregnancy
Hadwan
2012 (45)
37/ Fertile
37/ Asthenozoospermia
220 mg zinc sulfate bid 3 months Yes/ Yes
Increase in semen volume, sperm count and
motility
Raigani
2014 (51)
83/
Oligoasthenoteratozoospermia
a) 220 mg folic acid and 5 mg zinc
b) placebo
16 weeks Yes/ Yes
No significant improvements in sperm
concentration, motility and morphology
Abad
2013 (57)
20/ Asthenoteratozoospermia
1500 mg of LC, 60 mg vitamin C, 20
mg Co Q10, 10 mg vitamin E, 10 mg
zinc, 200 µg folic acid, 50 µg
selenium, and 1 µg vitamin B12
3 months No/ No
Significant increase in concentration,
motility, vitality and morphology of sperm.
Also a significant improvement of DNA
integrity was observed.
Nadjarzadeh
2011 (42)
47/
Oligoasthenoteratozoospermia
a) 200 mg Co Q10
b) Placebo
3 months Yes/ Yes
Improvement in seminal oxidative defense
but does not affect on semen parameters in
idiopathic oligoasthenoteratozoospermia
Hadwan
2014 (46)
60/ Fertile
60/ Asthenozoospermia
220 mg zinc sulfate bid 3 months
Increase in semen volume, forward motility
and sperm count
LC: L-carnitine
LAC: L-acetyl carnitine,
TOSC: total oxygen radical scavenging capacity
SOD: Superoxide dismutase