When people see collagen in skin care products, they get excited. Plump, young looking skin can generally be attributed to layers of collagen underneath the surface. The collagen in skin care products doesn't actually penetrate the skin, but it does hold onto a lot of moisture. Similar to hyaluronic acid, it can help keep your skin hydrated for hours.

Collagen works the same way in hair care products -- it helps your hair and scalp hold onto moisture while making your hair look thicker and fuller. Try Sally Hershberger Collagen Volume Shampoo and Conditioner, $9 each, or Organix Thick & Full Biotin & Collagen Shampoo, $6. The Dr. Gross Root Resilience line also contains collagen.

You know you need sunscreen in your moisturizer, and you probably know why you need antioxidants. (They neutralize wrinkle-creating free-radicals caused by pollution and ultraviolet rays.) From green tea to pomegranate, just about every serum on the market contains some kind of antioxidant wonder ingredient.

Similarly, if you color your hair, you know that you need to protect your color from the sun. (There's a reason your color fades faster in the summer.) Most color-preserving shampoos, conditioners, and styling products contain UV filters that act like sunscreen for your hair, as well as antioxidants that neutralize free radicals. (In hair, free radicals contribute to brittleness and dullness.)

The Aveda Sun Care Protective Hair Veil, $27, has filters derived from wintergreen and cinnamon bark oils. Plus, it contains the antioxidants green tea, sunflower oil, and vitamin E to protect from free-radical damage to the scalp and hair. Another great option is Ouidad Biotin Lightweight Reparative Hair Serum, $42, which contains hair-strengthening biotin in addition to antioxidants.