How long does collagen take to make a difference?
Manufacturers generally suggest eight to twelve weeks of daily use. It is a slow one, and not worth judging after a fortnight.
Marine or bovine collagen?
Both are widely used. Marine is often chosen for a smaller peptide size and suits anyone avoiding beef; bovine tends to cost less. Neither is suitable for vegetarians.
Are these suitable for sensitive skin?
Salcura and Hope's Relief in particular were formulated with that in mind, and the absence of SLS helps. Sensitivity is individual, so check the ingredients and patch test.
Is there a vegan collagen?
Not really - collagen itself is an animal protein. What is sold as vegan collagen is usually a blend of vitamin C, amino acids and botanicals intended to support the body's own production. Vitamin C contributes to normal collagen formation.