Is collagen really an anti-aging cure-all?

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Move over, protein bars. Hello, collagen bars? Collagen—which is sourced from the bones, cartilage, and skin of animals (including cows, chickens, and fish)—has been gaining popularity. This is in part thanks to the Paleo diet craze, which has sparked interest in “nose-to-tail” nutrition, or consuming more than just muscle meat from animals. Collagen is sold in powdered form, and also used in expensive protein bars, beauty gummies, and drinks. So is collagen the new must-eat superfood? Or is it a hyped-up trend not worth your hard-earned cash? Here's what you need to know.

Collagen isn't just found in animals. We produce it in our own bodies too. In fact, it's the most abundant structural protein in the human body, and the main component of connective tissue. It's found in our bones, tendons, ligaments, hair, skin, organs, muscles, and blood vessels.

Our bodies manufacture collagen from amino acids, which we consume in protein-rich foods. Research shows other nutrients are involved with collagen production too, including copper and vitamins A and C, along with plant pigments called anthocyanidins—which are found in deep red, purple, and blue produce (such as blueberries, blackberries, and raspberries).

As we age, we produce less collagen, which leads to wrinkles, sagging skin, and weakened joints. Certain lifestyle factors also interfere with collagen production, including consuming excess sugar and alcohol, sun exposure, and smoking.

Now, you may be wondering: If your body makes collagen itself, is there any benefit to eating the stuff?

The answer isn’t so straightforward. Some experts say that when you eat collagen, it's simply digested and absorbed as amino acids. In other words, eating collagen isn't any different from eating other protein-rich foods.

But the fact is, we don't know much about consuming collagen—which comes in many different types and forms—because there hasn't been much research on the subject. And most of the studies that do exist focused on supplements.

One 2014 study, for example, looked at the effects of collagen hydrolysate on women's skin. Sixty-nine participants between the ages of 35 and 55 were assigned to two groups: One group took the supplement once a day for eight weeks, while the second took a placebo. The first group experienced greater improvements in skin elasticity compared to the placebo group. And one month later, the effects were still statistically meaningful among the older women. (There were no notable differences when it came to skin moisture.)

Another study looked at the effect of collagen hydrolysate on fitness-related joint pain. The study involved 147 athletes, both male and female. Half of them took a liquid formula that contained collagen hydrolysate, and the other half took a liquid placebo. After 24 weeks, researchers found that the collage group had less joint pain at rest, and when walking, lifting, standing, and carrying objects, compared to the control group.

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But would you get similar results from adding a collagen powder to your morning smoothie instead of, say, whey protein powder? Or if you switched from a protein bar made with egg protein to a bar with collagen? And can collagen also reduce cellulite and stretch marks, improve gut health, make hair healthier, and promote better sleep and weight loss, like many products claim?

It's hard to know. Anecdotally, I've seen accounts online from people who say a daily collagen product led to improvements in their hair and skin. Others say they saw no results from taking collagen.

The lack of research also makes it difficult to predict potential side effects. One study in people with rheumatoid arthritis (RA) compared the effects of chicken collagen to a drug commonly used for RA. Researchers found fewer side effects overall in the collagen group. But the observed side effects included digestive upset and dizziness. It's unknown whether symptoms like this could occur in healthy people who consume collage powder.

The bottom line

I’m anxious to see more published research, especially studies that focus on the forms and amounts of collagen currently found in popular products—and compare them to placebos and other forms of dietary protein.

Until then, I advise my clients not to rely on collagen as a miracle food. For beauty benefits, joint health, gut health, and more, you’ll get the biggest bang for your buck from consistently eating a whole foods diet. That means plenty of veggies, lean proteins, plant based fat (avocado, EVOO, nuts, seeds), herbs, spices, and H2O, along with good carbs from fruit, whole grains, pulses, and starchy veggies (like sweet potato and spaghetti squash).

Eating this way provides a broad spectrum of nutrients, a healthy balance of macronutrients, and plenty of antioxidants and natural anti-inflammatory compounds. New trends are fun, but consistently eating a clean, healthy diet is the tried-and-true, big-picture approach to a healthier you.

Cynthia Sass is Health’s contributing nutrition editor, a New York Times best-selling author, and consultant for the New York Yankees.

This article originally appeared on Health.com.