Beauty is in the eye of the beholder. Still, there are some universal truths—among them, smooth, clear, glowing skin. Neither moist and wrinkled, nor dry and flaky, the middle ground of healthy skin features wrinkles at bay, not even wisened crow’s feet about.

Often overlooked as the body’s largest organ, the skin has long been seen as a target for topical applications—lotions, creams, balms, salves.

But consumers definitely see supplements as a way to also improve skin health from the inside-out. And while ceramides may be the current darling of sciency TV commercials, and vitamins like C and E remain stalwarts, the big winner among consumers is clearly collagen. Always marketed by twentysomethings with sterling skin. Do they actually really need skin-health products? Youth—wasted on the young!

The unique aspect of collagen as a nutritional aid is the way it works. Unlike most nutrients, which fill gaps in the body’s cells, tissues, organs and muscles, collagen is different. But it’s not the collagen protein per se, but the pieces of protein, fragments called peptides. These broken pieces of protein get consumed, and the body notices that collagen is broken down. Sensing that, the body kicks into gear to begin producing collagen all by itself. Sneaky!

Related:Which collagen source is best for dietary supplements?

So collagen has hit the big time and at just the right time—when smoothie nation is in full swing, and so what better powder to add to a bunch of fruits but a little protein?

Collagen used to be known as a cheap protein source, but thanks to a compelling list of published research showing specific peptides compel the body to make more endogenous collagen, it now finds itself atop the list of beauty-from-within ingredients.

Specific peptides from leading suppliers have been shown to reduce wrinkles, improve skin elasticity and improve nail health.

Also, collagen is not actually considered a complete protein. Some supplement brands make mention of that not-insignificant detail—that collagen powders do not, technically, count as protein. That’s because collagen contains 19 of the 20 amino acids the body needs, with tryptophan being the missing amino. Now, most people get tryptophan in their normal diets, even without the Thanksgiving turkey. Food sources of tryptophan include bananas, milk, cheese, chicken, peanuts and chocolate. But for labeling purposes, you still should not list collagen as a protein. Beauty? Sure—well, maybe, if you’ve got a researched peptide. Protein—no—well, maybe, if you consider that the average consumer is actually getting that missing tryptophan and so the collagen gets you 95% of the way there. But not for labeling purposes.

Related:Collagen: How to dose, who's your supplier?

For the complete insider’s guide to collagen —market size and growth outlook, which source works best in your supplement formulation, new science that could change your formulation dosage, and more – download the free Natural Products Insider digital magazine, “Collagenation.”