Man vs. Beast: Oral Hygiene Edition

"Don't worry," I often assure people whose face my dog is licking. "A dog's mouth is cleaner than a human's!"

Although I'm quick to invoke this rationale, it's never really convinced me. If the comparison were a dog's mouth and cantaloupe, an entity with which my mouth is regularly interacting, I'd stop and think. But since I rarely let strange humans lick my face, there's no good reason strange dogs should either.

So is my dog's mouth really cleaner than mine? I've consulted a few experts, and it seems like a question of semantics as much as a question of hygiene.

baileybananas.jpg +"They raid the garbage can. We give each other a peck on the cheek, they give each other a peck on the rear end. All you got to do is look, watch, smell and you'll realize that that is not true." [From Marty Becker, veterinarian and author of Chicken Soup for the Dog Owner's Soul]

+Truth is, oral bacteria are so species-specific that one can't be considered cleaner than the other, just different. [From LiveScience]

+If by cleaner you mean which mouth carries the least bacteria that would be harmful to a human, then a dog would probably be the answer. [From Indiana University's "A Moment of Science."]

Let's call it a draw. Go ahead and give your dog a big kiss to celebrate. Or some random person from your office.

[Thanks to Bailey for posing.]

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Feeling Down? Lifting Weights Can Lift Your Mood, Too
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There’s plenty of research that suggests that exercise can be an effective treatment for depression. In some cases of depression, in fact—particularly less-severe ones—scientists have found that exercise can be as effective as antidepressants, which don’t work for everyone and can come with some annoying side effects. Previous studies have largely concentrated on aerobic exercise, like running, but new research shows that weight lifting can be a useful depression treatment, too.

The study in JAMA Psychiatry, led by sports scientists at the University of Limerick in Ireland, examined the results of 33 previous clinical trials that analyzed a total of 1877 participants. It found that resistance training—lifting weights, using resistance bands, doing push ups, and any other exercises targeted at strengthening muscles rather than increasing heart rate—significantly reduced symptoms of depression.

This held true regardless of how healthy people were overall, how much of the exercises they were assigned to do, or how much stronger they got as a result. While the effect wasn’t as strong in blinded trials—where the assessors don’t know who is in the control group and who isn’t, as is the case in higher-quality studies—it was still notable. According to first author Brett Gordon, these trials showed a medium effect, while others showed a large effect, but both were statistically significant.

The studies in the paper all looked at the effects of these training regimes on people with mild to moderate depression, and the results might not translate to people with severe depression. Unfortunately, many of the studies analyzed didn’t include information on whether or not the patients were taking antidepressants, so the researchers weren’t able to determine what role medications might play in this. However, Gordon tells Mental Floss in an email that “the available evidence supports that [resistance training] may be an effective alternative and/or adjuvant therapy for depressive symptoms that could be prescribed on its own and/or in conjunction with other depression treatments,” like therapy or medication.

There haven’t been a lot of studies yet comparing whether aerobic exercise or resistance training might be better at alleviating depressive symptoms, and future research might tackle that question. Even if one does turn out to be better than the other, though, it seems that just getting to the gym can make a big difference.

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