How great would it be if shopping promoted dental hygiene?

… If sunbathing reversed signs of aging, martinis improved your IQ, and Egg McMuffins lowered your cholesterol? Sorry, sucker. The world is full of disappointments. Things that are fun are usually bad for you.

Except tap dancing. Word is out that it improves bone density.

And health benefits aside, tap is back. Blame Savion Glover, Britney Spears, the numerous dance studios that offer it, even your doctor. It may once have conjured images of Fred and Ginger, but tap dancing has gotten a makeover. (Did we mention how cute those shoes are?) And unlike spinning or aerobics, it’s as much a hobby as it is a workout. In other words, you can have fun while doing something good for you.

Tomorrow we’ll tell you about how creme brulee cures acne.

Tap classes are offered at Broadway Dance Center, 221 West 57th Street, fifth floor, between Broadway and Seventh Avenue (212-582-9304). A schedule of classes is available online at bwydance.com.

Men’s and women’s tap shoes are available online at capeziorvc.com.