ABSTRACT & COMMENTARY

Coital Lubricants and Natural Oils as Treatment for Vaginal Dryness

By Michael A. Thomas, MD

Professor, Reproductive Endocrinology and Infertility, Director, Division of Reproductive Endocrinology and Infertility, University of Cincinnati College of Medicine

Dr. Thomas reports no financial relationships relevant to this field of study.

SYNOPSIS: As a way to indirectly investigate the effects of lubricating products used by infertile women during intercourse on sperm quality, semen from 22 normospermic men was tested against several common lubricants (Pre-Seed®, Astroglide®, K-Y® Sensitive®, K-Y® Warming®, and K-Y® Tingling) and natural oils (baby, canola, sesame, and mustard) at 0, 5, 30 and 60 minutes. Pre-Seed and three of the oils (baby, canola, and mustard) had no deleterious effect on sperm.

SOURCE: Sandhu RS, et al. In vitro effects of coital lubricants and synthetic and natural oils on sperm motility. Fertil Steril 2014;101:941-944.

Vaginal dryness during intercourse is a common problem often combated with lubricating products. This study was initiated to determine whether over-the-counter lubricants and natural oils when applied intravaginally have an adverse effect on sperm motility in infertile couples. Donated semen samples were obtained from 22 normospermic men (mean age 25.9 ± 4.2 yrs). After centrifugation, the resulting sperm pellets were re-suspended in modified human tubal fluid (mHTF), a standard medium used in inseminations and in vitro fertilization procedures. Aliquots of sperm were standardized to contain a concentration of 20 million sperm per mL. These aliquots were then mixed with mHTF (control) or one of the "synthetic" (Pre-Seed®, Astroglide®, K-Y® Sensitive®, K-Y® Warming®, and K-Y® Tingling) lubricants or "natural" (baby, canola, sesame, and mustard) oils to a concentration of 10% (typical concentration of lubricant remaining in the vagina after intercourse). Total and progressive sperm motility was evaluated using a Makler counting chamber at incubation (0 min), and then at 5-, 30-, and 60-minute intervals.

Control samples co-incubated in mHTF showed no decline in total or progressive sperm motility after 60 minutes. In contrast, all of the synthetic commercial lubricants had a negative effect except Pre-Seed. Although Pre-Seed demonstrated a decline in both total and progressive motility, it did not affect total sperm motility at 60 min (P = 0.299). A minimal decrease in progressive motility was noted at 30 (4%) and 60 (7%) minutes (P < 0.01); however, this slight diminution in progressive motility was not thought to be clinically significant. The difference found between hHTF and Pre-Seed at these time points was within 2-4 percentage points.

Among the natural products, only sesame oil reduced total (18-22%) and progressive (24-28%) motility (P < 0.001). In contrast, baby and canola oils did not produce a change in any of the motility parameters of more than 7%. Incubation with mustard oil demonstrated a persistent hyperactivity of sperm in each of the 22 sperm donors.

COMMENTARY

Couples who are attempting to conceive will occasionally use one of the many over-the-counter lubricants or natural oils. The use of a supplemental aid is common among many couples, including couples having timed intercourse. Though vaginal moisturizers, like lubricants and oils, are marketed primarily to perimenopausal and menopausal women, young women also use these products. Lubricants,1-5 natural oils,1,6 and even saliva7 have been studied for their effect on sperm motility and/or chromatin integrity when applied in the vagina. Previously, Pre-Seed, baby oil, and canola oil were found to have minimal effects on sperm parameters.1,5,6 The newer K-Y jelly products (Sensitive, Warming, and Tingling) had not been investigated.

In a recent survey of 900 couples trying to get pregnant, vaginal dryness was a reported problem as "always" by 11%, "often" by 35%, and "occasionally" by 42%.8 Of the total number of respondents, 26% admitted that they often or always used a lubricant. Among those reporting lubricant use, 40% used K-Y jelly and 19% used Astroglide.

The current study was the first to evaluate multiple products (lubricants and oils) using a standardized approach that mimicked the natural vaginal environment (10% concentration of lubricant intravaginally). An additional strength of the study included the use of multiple donors and a consistent sperm concentration of 20 million sperm/mL. This eliminated variability between samples. Pre-Seed, baby oil, and canola oil were confirmed to be safe coital adjuvants when used for fertility purposes. The most unique finding was that mustard oil resulted in hyperactivation or exaggerated movement of sperm. We know that mustard oil contains allyl isothiocyante, which is an activator of the transient receptor potential (TRP) A1 channel.9 The TRP channels have been found to effect flagellar activity in human sperm. This may explain the hyperactive motion observed when the sperm came in contact with mustard oil. Sperm hyperactivity previously has been observed with caffeine, pentoxifylline, and 3-deoxyadenosine; however, these compounds were never utilized for routine clinical purposes by couples.10

Astroglide, the K-Y lubricants (Sensitive, Warming, and Tingling), and sesame oil all decreased total and progressive sperm motility. This provides strong evidence to recommend against their use by couples with fertility problems. Despite this adverse finding, it is unlikely that these specific lubricants and sesame oil would confer a contraceptive effect.

We know that 80-85% of reproductive-aged couples (with normal menstrual cycles) will conceive after 1 year of midcycle intercourse. For most couples experiencing a delay in conception, their primary care provider or gynecologist may suggest a different lubricant as low-level intervention that may result in pregnancy. This paper confirms that commonly used coital lubricants may affect sperm motility in a deleterious way. Having confidence that a lubricant will not affect fertility is important to the couple struggling with fertility since anxiety already takes its toll on intimacy. Now, the practitioner can have confidence that Pre-Seed and natural oils (baby, canola, and mustard) do not adversely affect sperm function and can be safely recommended. Whether the sperm hyperactivity documented with mustard oil would have an additional benefit to "boost" or "supercharge" sluggish sperm remains to be determined.

References

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  8. Ellington J, et al. Prevalence of vaginal dryness in trying-to-conceive couples. Fertil Steril 2003;79 (Supp 2):S21-S22.
  9. Castellano LE, et al. Transient receptor potential (TRPC) channels in human sperm: Expression, cellular location, and involvement in the regulation of flagellar motility. FEBS Lett 2003;541:69-74.
  10. Mbizvo MT, et al. The effect of the motility stimulants, caffeine, pentoxifylline, and 2-deoxyadenosiene on hyperactivation of cryopreserved human sperm. Fertil Steril 1993;59:1112-1117.