Friday, February 24th 2012
A woman's purse contents, including the ubiquitous emergency tampon. Image by Helga Weber, protected by a Creative Commons license.
Readers of this blog are already aware that their vaginas are at their best when they are on the acidic side. Vaginal flora is healthy, bacterial overgrowth is at a minimum, and any foreign bodies that want to pass through are firmly discouraged. Semen and douching can increase pH, douching especially so since the liquid used to douche not only has a relatively high pH but flushes out normal, good bacteria.
If there are substances that increase vaginal pH, might other substances decrease vaginal pH and thus encourage the growth of normal flora?
RepHresh thinks so. RepHresh is a company that makes pH-balancing gels and cleansers for your ladyparts. Recently, they started carrying a new product, RepHresh Brilliant, which is a pH-balancing tampon (hat tip to my undergraduate Sophia Bodnar for being the first to tell me about it). They claim that menses increases pH, and thus a tampon that decreases pH will keep bacterial overgrowth in check. The RepHresh Brilliant tampon contains strips of material that slowly release lactic acid and citric acid as they are saturated with menstrual fluid.
It certainly sounds like a good idea. Women in industrial and post-industrial environments menstruate far more often than we probably did under ancestral conditions, due in part to an energy surfeit (you know, eating too much chocolate while sitting at a desk, which is exactly what I was doing while drafting this post) and in part due to modern reproductive decisions (you don’t menstruate so much if you’re pregnant or breastfeeding all the time) (Strassmann 1997). So about 400 times in our lives, for several days at a time, we have a higher pH (somewhere between a 5.3-6.6 depending on the day according to Wagner and Ottesen 1982) than is ideal for housing beneficial vaginal flora.
But I want to know if this fancy tampon works. 1) Does it reduce pH, 2) does it do so without side effects, and 3) does it have an effect on vaginal flora?
Tl;dr version:1) yes, 2) probably, and 3) not sure.
RepHresh’s own research on the topic
A single paper tests the efficacy and safety of the RepHresh Brilliant tampon, and you can find a copy on the RepHresh site (Brzezinski et al. 2004). The authors found that participants who used the test-tampon (the one with strips that release lactic and citric acid) did not have significantly higher vaginal pH during menses (p = 0.0518), while participants who used a regular tampon did (p = 0.0011). Saying that first result isn’t statistically significant is adhering to the 0.05 alpha without honoring the spirit of the 0.05 alpha – it is not statistically significant but in a way that makes one question the meaning of statistical significance. (If you are new to statistics, usually a p-value that falls below 0.05 is considered significant, so a p-value of 0.0518 is pretty darn close, and in fact most people would drop those last two places and round to the hundredth, rendering that analysis p = 0.05, or statistically significant.) All that said, the difference between groups in intra-menstrual pH is statistically significant (p = 0.0025). And lowering menstrual pH by 0.5 isn’t bad.
Brzezinski et al 2004 Table 1
Further, according to Brzezinski et al (2004), no participants complained of vaginal irritation, which would be my big worry about an acid-producing tampon. And no participants in either group had abnormal vaginal flora during the study.
So, yay! Acid-increasing tampons for everyone! Kinda.
Nits to pick
First, the authors of this study did not use the gold standard method for assessing vaginal irritation or endothelial disruption, which is a colposcopy, or visual assessment of the vaginal tissue. Instead, the authors relied on self-report. Minor issues, or ones that could develop with repeated use over many cycles, would be caught in a longitudinal study that used this method. But this study only assessed side effects and pH reduction in a single cycle. And as far as I can tell, it is the only published study on the topic.
The second issue to consider is that all twenty eight participants had normal vaginal flora. The coincidence of all participants being perfectly healthy makes me wonder if a small sample size caught an abnormal number of normal women, or if they needed more rigorous testing of the bacterial swabs. But the study authors provide no detail about how they determined this or whether they assessed absolute and relative quantities of different bacteria that comprise normal flora. So, the normal flora in every single subject could just be that all twenty eight women were very healthy, but in every other study I read in preparing for this post, there were always a significant minority of participants who had or developed abnormal flora. I just wish the authors had provided more detail here.
Finally, this research was funded by Rostam Ltd Israel, a corporation that makes tampons. I did a little digging to try and figure out the relationship between Rostam and RepHresh. Rostam was bought by Albaad Massuot Yitzhak Ltd in 2010. Yet RepHresh has an article about the Rostam Ela tampon in the Wall Street Journal on the website from 2004. So my best guess (and someone with more business savvy than me could probably figure this out) is that RepHresh bought the Ela tampon from Rostam some time between 2004 and 2010, and is now marketing it as RepHresh Brilliant. Either way, part of the funding for the research was from a corporation invested in seeing the tampon gain FDA approval in the US. The 2004 article that RepHresh has on its site (scroll to the “Articles” and click the link for the pdf) explains that the testing for this tampon was simply to demonstrate it is as safe as effective as any regular tampon, since it is being categorized as a medical device.
I’m not worried about the lactic acid, since that is a product of Lactobacilli, which is not only present in normal vaginal flora but particularly good for the ladyparts (McLean and Rosenstein 2000; Onderdonk et al. 1986; Valore et al. 2002). But I am worried about the citric acid, since it produces moderate irritation and damage to the epithelium, and increases permeability and absorption rates when used to enhance drug delivery (Richardson et al. 1989). Maybe it’s shouldn’t be concerning in the particular way it is released in the RepHresh Brilliant tampon. I honestly don’t know.
I certainly am happy to see a company taking a woman’s actual vaginal pH into account in the making of their products. Give the tampon a try if you are so inclined, and let me know how it goes. I think I’m going to just let my vagina regulate itself, since vaginal flora repopulates naturally and quickly after menses on its own (Keane et al. 1997; Onderdonk et al. 1986; Wagner and Ottesen 1982).
References
Brzezinski A, Stern T, Arbel R, Rahav G, and Benita S. 2004. Efficacy of a novel pH-buffering tampon in preserving the acidic vaginal pH during menstruation. International Journal of Gynecology and Obstetrics 85(3):298-300.
Keane F, Ison C, and Taylor-Robinson D. 1997. A longitudinal study of the vaginal flora over a menstrual cycle. International Journal of STD and AIDS 8(8):489-494.
McLean N, and Rosenstein I. 2000. Characterisation and selection of a Lactobacillus species to re-colonise the vagina of women with recurrent bacterial vaginosis. J Med Microbiol 49:543-552.
Onderdonk A, Zamarchi G, Walsh J, Mellor R, Munoz A, and Kass E. 1986. Methods for quantitative and qualitative evaluation of vaginal microflora during menstruation. Applied and Environmental Microbiology 51(2):333-339.
Richardson JL, Minhas PS, Thomas NW, and Illum L. 1989. Vaginal administration of gentamicin to rats. Pharmaceutical and morphological studies using absorption enhancers. International Journal of Pharmaceutics 56(1):29-35.
Strassmann BI. 1997. The biology of menstruation in Homo sapiens: Total lifetime menses, fecundity, and nonsynchrony in a natural-fertility population. Current Anthropology 38(1):123-129.
Valore E, Park C, Igreti S, and Ganz T. 2002. Antimicrobial components of vaginal fluid. Am J Obstet Gynecol 187:561-568.
Wagner G, and Ottesen B. 1982. Vaginal physiology during menstruation. Annals of Internal Medicine 96(Part 2):921-923.
Thursday, February 23rd 2012
Kevin Zelnio’s #iamscience movement has launched a number of blogger origin stories and a Kickstarter project that has met its first funding goal (don’t stop donating yet though). Alongside this movement is one launched about the same time via a tumblr and related to SoNYC. My colleagues and I wanted to find a way to contribute our voices and show that there are many types of science, and many types of scientists. These colleagues smash gender stereotypes every day, what’s one more stereotype to add to our target hit zone?
Thirteen kickass rollers who also happen to be kickass scientists. Photo by Laura Fitch.
Thirteen University of Illinois, Urbana-Champaign scientists, all of whom skate for the Twin City Derby Girls.
Top row, left to right: Therafist, clinical psychologist; Anthrobrawlogist, biological anthropologist; Snarker Posey, legal information scientist; Doc Dementer, educational psychologist; Oh No Bobo, veterinarian; Killy Love-less, social scientist; MRSA, microbiologist.
Bottom row, left to right: Jo Holley, evolutionary ecologist; Gaya Jenda, family scientist; Mrs. T, educational psychologist; F1, developmental psychologist; Punchwrap Supreme, reproductive toxicologist; Polly Nator, evolutionary biologist.
Are we science? You better believe we are science. If you don’t…
Thirteen scientists who could seriously mess you up.
We will come for you.
Monday, February 13th 2012
Keeper and Diva cups. And yes, I recommend you try them! Image by Greencolander on flickr.
As many of you have already heard, I was a guest on Skeptically Speaking a few weeks ago, on the topic of why women menstruate. PZ Myers tackled the evolutionary perspective first, and then I got to answer audience questions and talk a little about my own research.
Because I think it’s important for listeners and readers to see where the evidence came from to support my claims, I am sharing references (and in several cases, past posts of mine that themselves contain references). That way you can look up these articles to learn more about each topic – using Google Scholar usually turns up whatever pdfs aren’t behind a paywall.
I want to thank Desirée Schell and K.O. Myers for their great work on the show. I had a great time and think that Skeptically Speaking is a truly fantastic way to share science. Schell was a wonderful host and I hope to be fortunate enough to be asked on again.
The history of the study of menstruation
Much of what I discussed in this section of the radio show can be found on my blog post “Menstruation is Just Blood and Tissue You Ended Up Not Using.”
I also think it’s important to point out that many hypotheses developed about menstruation often forget that the monthly cycle is a very modern occurrence. Not only are modern cycles in women in industrialized populations not necessarily 28 days in the first place (in fact, see my Guest Blog post about this from December 2010), but our ancestors very likely menstruated 50-100 times rather than the 400 or so that is our norm. The reason for this is first that they probably had neutral or negative energy balances (because they moved around so much more, and likely ate less), but also because they were pregnant and breastfeeding through most of their reproductive years. This also came up in the menstrual synchrony part of the conversation later.
Additional reading:
Strassmann, B. (1997). The Biology of Menstruation in Homo Sapiens: Total Lifetime Menses, Fecundity, and Nonsynchrony in a Natural-Fertility Population Current Anthropology, 38 (1) DOI: 10.1086/204592
Birth control pills (hormonal contraception)
This topic is always very popular, and women understandably have a lot of questions about hormonal contraception. It is ubiquitous and almost expected for most reproductively aged women in many industrial, western cultures. Yet women are poorly educated on how they work and their broader effects. This leads to a lot of ambivalence about something that a huge proportion of women take every single day for decades. Two posts over at my old blog that I will eventually migrate here have some good information: “Summer of the Pill: Why Do We Menstruate?” and “Summer of the Pill: The latest fashion accessory to hit your uterus: the IUD!”
Additional reading on the history of the pill:
Gladwell, M (2000). John Rock’s error. The New Yorker. March 13: 52-63. http://www.gladwell.com/pdf/johnrock.pdf
Additional reading on the biology behind the pill:
Bentley, GR. (1996) “Evidence for interpopulation variation in normal ovarian function and consequences for hormonal contraception” in Variability in human fertility, eds L. a. M.-T. Rosetta, C.G.N. (Cambridge University Press, Cambridge, UK), pp 46-65.
Vitzthum VJ, Spielvogel H, Caceres E, & Miller A (2001). Vaginal bleeding patterns among rural highland Bolivian women: relationship to fecundity and fetal loss. Contraception, 64 (5), 319-25 PMID: 11777494
Vitzthum VJ, & Ringheim K (2005). Hormonal contraception and physiology: a research-based theory of discontinuation due to side effects. Studies in family planning, 36 (1), 13-32 PMID: 15828522
Additional reading on adolescents and hormonal contraception:
My blog post, “Why We Shouldn’t Prescribe Hormonal Contraception to Twelve Year Olds.”
Deligeoroglou (2000). Dysmenorrhea. Annals of the New York Academy of Sciences 900(1): 237-244.
Vihko R, & Apter D (1984). Endocrine characteristics of adolescent menstrual cycles: impact of early menarche. Journal of steroid biochemistry, 20 (1), 231-6 PMID: 6231419
Additional reading on endometrial waves:
IJland M, Evers J, Dunselman G, van Katwijk C, Lo C, Hoogland H. 1996. Endometrial wavelike movements during the menstrual cycle. Fertil Steril 65(4):746-749.
IJland MM, Evers JLH, Dunselman GAJ, Volovics L, Hoogland HJ. 1997. Relation between endometrial wavelike activity and fecundability in spontaneous cycles. Fertility and Sterility 67(3):492-496.
Menstrual synchrony
Much of what I discussed on synchrony can be found on my blog post “Do Women in Groups Bleed Together? On Menstrual Synchrony.”
Effect of diet and activity on menstruation
Strangely enough, even though this is my own field of study, I don’t have any blog posts that discuss this!
Additional readings:
Clancy KBH, Ellison PT, Jasienska G, Bribiescas RG. 2009. Endometrial thickness is not independent of luteal phase day in a rural Polish population. Anthro Sci.117(3): 157-163.
Ellison PT. 2001. On Fertile Ground. Cambridge, MA: Harvard University Press.
Iron-deficiency anemia
This material comes from some of my own research on iron-deficiency anemia. I discuss it in the blog post “Iron-deficiency is Not Something You Get Just for Being a Lady.”
Menstruation and… camping?
One audience member asked if it was true that menstruating women should avoid going camping because of the risk that the smell of their menstrual blood would attract bears. I found a pretty fun study in the Journal of Wildlife Management that suggests that black bears, at least, couldn’t care less if exposed to tampons, menses-soaked tampons, or women during menstruation. Scicurious was inspired enough to discuss this topic for her Friday Weird Science.
I also am planning a separate post on the idea that menstruation makes wild game run away. As it turns out, there is a very interesting anthropological history to this idea, so stay tuned!
Toxic Shock Syndrome
Additional readings:
Davis JP, Chesney PJ, Wand PJ, LaVenture, M (1980). Toxic-Shock Syndrome. New England Journal of Medicine 303(25): 1429-1435. http://www.nejm.org/doi/full/10.1056/NEJM198012183032501
McCormick JK, Yarwood JM, Schlievert PM (2001). Toxic shock syndrome and bacterial superantigens: an update. Annual Reviews in Microbiology 55(1): 77-104.
Schlievert PM, Blomster DA, Kelly JA (1984). Toxic shock syndrome Staphylococcus aureus: effect of tampons on toxic shock syndrome toxin 1 production. Obstetrics and Gynecology 64(5): 666-671. http://ukpmc.ac.uk/abstract/MED/6436761
Shands KN, Schmid GP, Dan BB, Blum D, Guidotti RJ, Hargrett NT, Anderson RL, Hill DL, Broome CV, Band JD, Fraser DW (1980). Toxic-Shock Syndrome in Menstruating Women. New England Journal of Medicine 303(25): 1436-1442. http://www.nejm.org/doi/full/10.1056/NEJM198012183032502
Reproductive cancer
Additional readings:
Jasienska G, Thune I. 2001. Lifestyle, hormones, and risk of breast cancer. British Medical Journal 322:586-587.
Kahlenborn C, Modugno F, Potter DM, Severs WB. Oral contraceptive use as a risk factor for premenopausal breast cancer: a meta-analysis; 2006. Mayo Clinic. p 1290.
Strassmann BI. 1999. Menstrual cycling and breast cancer: an evolutionary perspective. Journal of women’s health 8(2):193-202.
Detecting menses in the voice
Additional readings:
HuffPo article on women’s voices through the menstrual cycle
