ask: What are the best natural effective sources of collagen, if no natural sources what products offers high dose of collagen?

Great question! Here is what I know about natural collagen source.

Vitamin C is needed to promote the formation and maintenance of collagen which is the basis of connective tissue found in skin, ligaments, joint lining, etc. The best known natural sources of vitamin C are citrus fruits like oranges, lemons, grapefruit, etc. You can also obtain healthy amounts of vitamin C from papaya, rose hips, strawberries and from vegetables such as those red and green peppers, broccoli, brussel sprouts, tomatoes, parsley and cabbage to name a few.

In addition to the above food sources you can supplement your diet with vitamin C and Lysine supplements if you do not consume those foods.