For decades, consumers have lined up for injections and creams that promise to plump, refresh, and smooth aging skin. But now, that same anti-aging crowd is dumping the shots and salves and going for snacks and smoothies instead.

A staple of skin care products—collagen—has moved to the newly trendy “functional foods,” as The Wall Street Journal recently pointed out. Instead of the standard anti-wrinkle creams and injectable fillers, people can try everything from collagen-packed powders to pre-made energy bars, chocolates, teas, shakes, and coffee creamers. The edibles tout all the same benefits of old stand-by cosmetics containing collagen—which is an abundant structural protein in the body, found in connective tissue. As we age, our bodies naturally produce less of the elastic, thread-like molecule that keeps our skin from sagging. Boosting and restoring your collagen levels with supplements “enhances” or “promotes” supple, youthful-looking skin, according to product labels and makers.

So far, the cosmetic-inspired consumables have been a hit. There are nearly 300 collagen-containing snacks now available, and sales reached more than $60 million in the past year. But scientists have been less eager to spoon up the food fad.

There’s little evidence that eating collagen will directly help renew aging skin or nails, hair, joints, or other aging bits. The few studies that have been done have often been backed by product manufacturers and/or done with animals or only a small number of humans for short periods of time. And there’s reason to be skeptical of the idea in general. Collagen is digested much like any other protein we eat. The collagen found in food products is derived from skin, bones, and cartilage of livestock, which is digested and processed into smaller snippets. (It has a “musty” taste, according to one user.)

“It’s not as if there is collagen that can be magically transported to the skin in its whole form,” Mary Sheu, a dermatologist at Johns Hopkins University, told the WSJ. “Dermal collagen is like a complex woven sweater. You can’t just throw a ball of yarn at it and expect it to get incorporated.”

And like all supplements, the Food and Drug Administration doesn’t approve or review products or their labels before they hit the market.