Protein conversations typically revolve around muscle mass—but the ways in which protein is used in the body are vast and varied. “Protein plays a role in building bones, muscles, cartilage, skin, and virtually every body part and tissue,” says registered dietitian nutritionist Alex Larson, MS, RDN about the benefits of protein.
The skin, hair, and the nails are actually made up of several proteins, including keratin, collagen, and elastin. Keratin, collagen, and elastin are made up of amino acids (they’re commonly called the building blocks of protein). Where does our body get these amino acids, which then become keratin, collagen, and elastin? Consuming protein, be that from a plant or animal source.
“A sufficient amount of protein as part of a healthy diet is essential to support the body’s ability to synthesize proteins of all types, including those in the skin,” board-certified dermatologist Hadley King, M.D., told mbg about protein and the skin.
Essentially: By fueling the body with an adequate amount of high-quality protein, it can use the protein’s amino acids to build keratin, collagen, and elastin.
For example, hair growth is highly dependent on getting enough amino acids to make keratin, explains board-certified dermatologist Neera Nathan, M.D.
“We know in medicine from observation of people who have inherited disorders of vitamin metabolism deficiency or severe malnutrition that hair growth absolutely depends on basic nutrients and overall internal health. No questions there. So crash diets, restrictive diets, or diets completely void of protein can cause hair loss,” she says. “When your body goes into panic mode and is trying to conserve resources, your hair will be among the first to suffer because it’s not an essential function. Those resources are going to be routed elsewhere.One of the most important things you can do is get enough protein because it’s needed to make hair. Our hair is primarily keratin, which is protein. It’s that simple.”
Aging concerns may also be tied back to lack of protein in the diet.
“I have [someone in my life] who I’ve had some conversations with about her eating because I feel she’s not getting enough protein. She came to me the other day and said, ‘I’m getting a wrinkle here.’ I told her, you’re aging because you’re not getting enough of the collagen you need,” says board-certified integrative medicine physician Taz Bhatia, M.D.
While there isn’t a lot of human-focused research on the subject (just given the complexities of those studies and ethical implications), animal studies have shown that diets low on protein are linked to collagen decline as well as skin barrier damage. One study found that following a protein-free diet for eight days caused a “dramatic decrease in both types I and III collagen” in rats. Another showed that protein-lacking diets triggered atopic dermatitis and skin barrier issues in upwards of 89% of rat subjects.
Brittle, breakable nails have also been connected to protein concerns. “Nails are made of mainly hardened proteins,” says Amy Lin, the founder of sundays—a nail care salon focused on wellness. “When we’re low in protein, calcium, or other vitamins, that can sometimes show up on your fingernails”—be it as ridges, discoloration, or overall brittleness.