Wednesday, January 22, 2014

News Quickie: Running in Polluted Air Ramps Up Immune Defenses ✰ Retinol (Vitamin A) Protects Against Memory Decline ✰ Mean Penis Size (5.57") Not Race or Age Specific

In this quickie things that don't belong still find together ;-)
If it had not been much too long, I would probably have called today's SuppVersity article "Things You Want and Things You Don't Want to Know". I mean, chances that one of you is among the 45% of men who wanted their "best part" to be larger are high and I bet that many of these men won't really care that Janet Lever, David A. Frederick and Letitia Anne Peplau also found that 85% of the women were happy with the penis size of their male partners (Lever. 2006).

That's not really what you want to hear?

I see, you didn't really want to hear that!? Ok, let's not forget (all puns intended that there are other news in this quickie, as well. So, let's see what else we've got:
  • SuppVersity suggested read: "Child- hood Asthma: Children Born to Mothers Who Consume Semi-Skimmed Milk 8% More Likely, Kids of Whole Milk Drinking Mothers 15% Less Likely to Develop Asthma" | read more
    Lungs appear to adapt to running in polluted air, but ...: You may have read it in the SuppVersity Facebook News "California Imports Air Pollutants from China". Against that background it's good to know that our lungs - or, I should say the lungs of runners - appear to be able to cope with the continuous exposure to polluted air, by an increase in immune activity.

    What the recent paper by Sá et al. (2014) does not tell us, though, is whether this increase in immune-activity is also the cause of the ever-increasing rates of asthma. I mean, it's probably no coincidence that Cosca et al. write in their 2007 paper about common health problems in endurance athletes that "running is the most likely to precipitate exercise-induced asthma" (Costca. 2007); and we all know that the margin between appropriate (and controlled) immune and inappropriate (uncontrolled) auto-immune reactions is very narrow.
  • Vitamin A supplementation prevents age-related loss of memory: It's unfortunately just a rodent trial, but in view of the unwarranted condemnation of "real" vitamin A (retinol / retinoic acid) as the evil counter-part to the holy vitamin D, I guess it would not even have been deemed ethical to conduct a similar study in human being. The additional 300% vitamin A the rodents received over 2 months would bring a human being close to the upper tolerable limit (15,000IU), after all (Bonhomme. 2014).
Not relevant, because it's not a human study? I would not bet my brain on that. Researchers from the Central Middlesex Hospital London reported in 1992, already, that their comparison of Alzheimer's patients to healthy controls showed that the former had "significantly reduced" levels of retinol (-27%) in their blood (Zman. 1992)
  • Obviously I cannot tell you which consequences Damien Bonhomme and his colleagues would have observed in humans. What I can tell you, though, is that the rodents showed improvements “episodic-like” memory and that these effects were (probably) brought up / supported by the concomitant decrease in intrahippocampal stress (=cortisol) response - an effect that was by the way hardwired in the brain, and did not depend on a modulation of hippocampal 11β-HSD1 expression (this is what you would see as a result of "anti-cortisol" supplements). 
  • "How big is he?" Grown up scientists still interested in average penis lengths: This is one of the news, some of may not really want to hear, but I am not going to spare you the details ;-)

    As the "penis experts" from the Indiana University say, penile measurements are commonly conducted by having men or clinicians measure the length and circumference of the penis in a flaccid, stretched, or erect state. While stretched, compared with unstretched, measurements of the flaccid penis are a more accurate predictor of erect penile dimensions (Wessel. 1996). According to Wessel et al.'s "guidelines" from 1996, the good old saying that what you see in the men's dressing room ain't the real thing is thus not essentially correct; and still: What really matters is obviously the size in the size and circumference in the erect state Debby Herbenick and her colleagues measured in a sample of 1,661 healthy men from the US (see Figure 1; Herbnick. 2014).
    Figure 1: Average penis length and circumference (erect state) in 1,661 healthy US men (Herbenick. 2014)
    If you are pervert enough to scrutinize the data further, you will also realize that neither the size nor the length of every man's most precious body part differ between young and old men, dumbos and university professors, city dwellers or farmers, or men who were married vs. singles. For sexual orientation and race, there were minimal differences, but neither the fact that the gay men in the study had minimally shorter penises, nor the fact that those eight subjects who said that they were not sure if they liked men or women, as well as the 8 native Hawaiian/Other Pacific Islanders had the lowest penis circumference was statistically significant by any means.

    This does also mean that the average Caucasian, the average African-American, the average Asian, American Indian, native Hawaiin or Pacific Islander, all have a mean penis size of ca.  14.15 cm (SD=2.66; range=4 to 26 cm), and a mean erect penile circumference of 12.23 cm (SD=2.23; range=3 to 19). In view of standard deviations of >2cm and a range that's wider than 22cm the statement "we're all the same", still won't apply ;-)
Bottom line: It's pretty difficult to reconcile these studies, but if you want to you could argue that it would be a good idea to make sure you get at least your RDA (3,000IU) of retinol every day, to make sure you don't forget that 14.15cm is not short and running in a polluted city could put you at risk of allergic rhinitis and asthma. Ha? How about that?
Reference:
  • Bonhomme, Damien, et al. "Retinoic acid modulates intrahippocampal levels of corticosterone in middle-aged mice: consequences on hippocampal plasticity and contextual memory." Frontiers in Aging Neuroscience 6 (2014): 6.
  • Cosca, David D., and Franco Navazio. "Common problems in endurance athletes." Am Fam Physician 76.2 (2007): 237-44. 
  • Herbenick, Debby, et al. "Erect Penile Length and Circumference Dimensions of 1,661 Sexually Active Men in the United States." The journal of sexual medicine (2013).
  • Lever, Janet, David A. Frederick, and Letitia Anne Peplau. "Does size matter? Men's and women's views on penis size across the lifespan." Psychology of Men & Masculinity 7.3 (2006): 129.
  • Sá, Matheus C., et al. "Adaptation of Upper Airways in Urban Runners to Air Pollution." International Journal of Exercise Science: Conference Proceedings. Vol. 10. No. 1. 2014.
  • Wessells, Hunter, Tom F. Lue, and Jack W. McAninch. "Penile length in the flaccid and erect states: guidelines for penile augmentation." The Journal of urology 156.3 (1996): 995-997.
  • Zaman, Z., et al. "Plasma concentrations of vitamins A and E and carotenoids in Alzheimer's disease." Age and ageing 21.2 (1992): 91-94.