Slow-cooked bone broth has many of the constituents required to retain and replenish skin, bone and cartilage. Studies that have measured the effect of added collagen and gelatin in the diet, have shown that such components can increase skin elasticity , protect against sunburn  and increase the skin's ability to renew and repair itself . The latter applies to the inside of our bodies as well as the outside.
The surface of your intestines is your most important shield of protection against microbial attack from the outer world. Your ability to withstand disease depends on an intact intestinal layer. Glutamine, an amino acid abundant in broth, is important for intestinal cells to remain healthy .