As a veterinarian, I try to "follow the science" - as stated in the article below, there are no studies that show eating collagen is effective. The intestinal tract breaks it down and absorbs the amino acid components. I suppose if you eat a crappy diet and don't live a healthy lifestyle, collagen supplements may be of benefit, but just like glucosamine/chondroitin, these things don't magically get absorbed thru your gut in their original form and then go to your aching joints. You get the same amino acids eating a healthy diet.
https://my.clevelandclinic.org/health/articles/23089-collagen
As stated at the bottom of the article: "In the meantime, you can always help your body make collagen naturally by eating a well-balanced diet full of healthy foods. A well-balanced diet includes chicken, beef, fish, dairy, eggs, beans, leafy greens, other vegetables, whole grains and citrus fruits. To improve damage to the collagen in your skin, don’t smoke, avoid second-hand smoke and wear sunscreen every day."