The
aim of this study was to evaluate the sperm-immobilizing properties of
lemon juice to determine if they are consistent with its traditional
contraceptive use. It was found that lemon juice supernatant (LJS) has
high osmolality (550–60 mOsm) and low pH (2.2–2.6) and that addition of
LJS to semen to give a final concentration of 20% v/v reduced the pH
from around 8.4 to 4.1. This acidification was associated with
irreversible cessation of all sperm movements within 1 minute. In
conclusion, lemon juice should be further evaluated for acceptability,
safety, and efficacy as a topical vaginal contraceptive agent.
Lemon
juice has been used as a traditional intravaginal contraceptive
throughout the Mediterranean region for hundreds of years. In Norman
Himes’s 1963 classic, Medical History of Contraception, he
stated that “the practice of some Constantinople women of soaking a
sponge in diluted lemon juice and using it as a vaginal tampon is
theoretically not surpassed in reliability by any modern clinical
contraceptive” ( 1). Even the great libertine Casanova advocated the use of half a lemon as a precursor to today’s cervical caps and diaphragms ( 1). Lemon juice douches are still in use today where more modern contraceptive techniques are unavailable ( 2 and 3). With such widespread traditional use, lemon juice must provide some protection against unwanted pregnancy.
The spermicidal properties of lemon juice are possibly due to the high concentration of citric acid (1). It is well documented that sperm are sensitive to low pH (4).
More recent studies clearly show that acidic solutions can immobilize
sperm within minutes. The immobilizing and spermicidal properties of
hydrochloric acid added to semen were linearly related to the resulting
hydrogen ion concentration in the mixture over a pH range of 7.5–4.0,
and the lowered extracellular pH rapidly induced acidification of the
intracellular compartment (5). Previous investigations have demonstrated that dynein ATPase in the sperm midpiece is required to energize the sperm tail (6). The acidic pH of lemon juice may immobilize sperm by denaturing dynein ATPase.
The
aim of this study was to examine the efficacy of lemon juice for
immobilizing human sperm in fresh semen. Lemon juice may provide a
simple answer to the vital need for a cheap, female controlled
contraceptive for use where condoms are unavailable, too expensive, or
socially unacceptable. In addition, lemon juice has significant
potential for reducing HIV transmission (7).
Lemon
juice supernatant (LJS) was prepared by centrifuging freshly squeezed
lemon juice at 2,000 Gmax for 5 minutes at room temperature. LJS was
stored at 4°C until use. LJS had an osmolality of 550–60 mOsm and a pH
of 2.2–2.6.
Fourteen normal semen
samples were obtained from consenting patients or sperm donors at the
Andrology Unit, Royal Women’s Hospital, Melbourne, Victoria, Australia.
The subjects signed a consent form containing a statement approved by
the Institutional Research and Ethics Committee regarding the use of
their semen for “nonfertilization research.” Collected semen samples
were liquefied by 30 minutes incubation at 37°C before use. Varying
volumes of neat LJS were then added to an aliquot of each ejaculate to
give final concentrations of between 0 and 20% (v/v). Sperm motility was
measured using computer-aided semen analysis with a Hamilton-Thorne
Motility Analyzer (Version 10.8 software, Hamilton Thorne Biosciences,
Beverley, MA 01915), while sperm viability was determined through dye
exclusion using the eosin-nigrosin membrane integrity stain.
Initial
observations showed that LJS at a 20% v/v mixture with semen reduced
the pH to 4.1 and resulted in zero motility of sperm within 1 minute. No
twitching or shuddering of sperm was observed. LJS at 10% v/v reduced
the pH to approximately 5.2 and resulted in zero progressive motility
within 15 minutes, but the sperm were observed to retain faint shudders
up until 3 hours of incubation, when no further movement was observed.
LJS at 5% v/v reduced the pH to approximately 6.5, and significant
progressive motility was retained at 15 minutes and 3 hours of
incubation at 37°C. For comparison, the pH of the original semen was
8.4.
A second experiment using 10%
LJS showed that at 1 minute sperm were still progressive, albeit
sluggish, but by 10 minutes there was no progression, only tiny
shudders. Dye exclusion using eosin-nigrosin showed that the sperm
retained their membrane integrity (two sperm samples gave 83% and 95%
viability when tested after 10 minutes incubation). The remainder of the
samples that had undergone the 10-minute incubation were washed once in
Tyrode solution containing 0.3% bovine serum albumin, which resulted in
restoration of good progressive motility, which was retained after 5
hours and overnight incubation. A third experiment using semen samples
from three individuals showed that 10% LJS reduced progressive motility
to zero in two samples and to <0.1% in the third sample after 10
minutes at 37°C. Washing readily restored progressive motility as was
found in the previous experiment, and the progressive motility was
retained on examination after a further hour of incubation. A total of
nine semen samples from different individuals were treated with 10% LJS,
with all responding in a similar way.
Another
experiment focused on the time of incubation with 10% LJS versus
motility restoration after subsequent washing. This showed that
incubation for up to 60 minutes with 10% LJS at 37°C allowed essentially
full motility recovery after washing, whereas 2 hours of incubation
resulted in only about 50% of the original motility being recovered, and
4 hours incubation resulted in no motility recovery.
An
experiment using 20% LJS showed that the semen-LJS mixture pH was 4.2
after 10 minutes incubation, resulting in zero progressive motility and
no shuddering. In addition, no motility was restored after washing.
However, most sperm had retained viability as assessed by dye exclusion.
Finally, the time course of sperm motility inhibition was measured for different concentrations of LJS (Table 1).
The highest concentration (20% LJS) stopped all sperm movements within 1
minute. The lower concentrations resulted in highly significant
motility reductions within 5 minutes, but 10% LJS took 30–60 minutes to
stop all sperm movements.
- TABLE 1. The effect of lemon juice supernatant on human sperm motility.
Hours at 37°C LJS (v/v%) in semen
0% 5% 10% 20% 0 52 (10.4) 32 (7.3) 5 (3.2) 0 1 48 (10.8) 25 (7.8) 0 0 4 39 (11.1) 13 (4.4) 0 0 16 1 (0.9) 0 0 0 - Note: The values represent the mean (SEM) for five semen samples from different men.
Clarke. Sperm immobilization by lemon juice. Fertil Steril 2006.
The
results obtained in this investigation are consistent with the
traditional use of lemon juice as a vaginal contraceptive since the
eighteenth century. They are also in agreement with previous scientific
studies that have shown that acidic conditions rapidly reduce sperm
motility. A previous study found that soft drinks containing lemon juice
immobilized all sperm within 1 minute (8),
but this is apparently the first report of the spermicidal properties
of lemon juice without additives, and we have found almost identical
results using lime juice. The results indicate that a minimum
concentration (v/v) of 20% lemon juice would be required to irreversibly
immobilize 100% of spermatozoa. The efficacy of this concentration of
lemon juice as a vaginal contraceptive would require adequate mixing of
the ejaculated semen and lemon juice during intercourse. Ejaculate
volume in normal men rarely exceeds 5 mL, so it would be necessary to
deliver at least 1.5 mL of lemon juice into the vagina to obtain the
desired concentration. A formal clinical trial of the acceptability,
safety, and efficacy of lemon juice as a cheap and widely available
vaginal contraceptive is urgently needed before its use can be promoted.
References
- 1
- Medical history of contraceptionGamut Press, New York (1963)
- 2
- Contraceptive knowledge, attitudes, and practice in Russia during the 1980s
- Stud Fam Plann, 24 (1993), pp. 227–235
- | |
- 3
- Use of lemon or lime juice douches in women in Jos, Nigeria
- Sexual Health, 2 (2005), pp. 237–239
- |
- 4
- Titrations of human seminal fluid with acids and alkalis and their effects on the survival of sperm motility
- Am J Physiol, 136 (1942), pp. 535–541
- 5
- The rate at which human sperm are immobilized and killed by mild acidity
- Fertil Steril, 73 (2000), pp. 687–693
- | | |
- 6
- Dynein structure and power stroke
- Nature, 421 (2003), pp. 715–718
- | |
- 7
- New ways of preventing HIV infection: thinking simply, simply thinking
- Philos Trans Roy Soc B (2006) in press
- 8
- The immobilization of all spermatozoa in vitro by bitter lemon drink and the effect of alkaline pH
- Contraception, 46 (1992), pp. 537–542
- | | |
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