Collagen for beauty, is it true?

Oral supplement with collagen is popular, especially for women. A lot of products are on sale every day. Collagen is a group of protein that keeps human skin smooth. So it is commonly said that taking collagen is beneficial for anti-aging.

However, effect of taking collagen for human skin is uncertain in the academic field.
It is obvious that collagen taken by mouth does not replace old skin. Collagen we ate are to be broken down into amino acids, and then they will be reconstructed to elements of human body. Therefore, taking vast collagen is not equal to supply collagen in human skin.

When I tell the story above to women, they are disappointed. Usually they say they feel the benefit of collagen-rich meal.
When a man strongly believes the effect of a certain material, it often has a real effect on him. This is called as “Placebo effect”. The placebo effect is somewhat confusing, but really beneficial for some patients.
On the other hand, it is sorry that a patient had to take a drug to be proved to have no effect for him. Some anti-arrhythmic drugs have been proved to useless in prolongation of life of patients who has arrhythmia. It is well known as an example of the dilemma between calculable effect and real outcome. In Japan, some drugs related to cerebral circulation were banished from the market, because of failure to show a significant effect in a makeup examination.

Today I saw a tweet about this issue. Someone wrote that there was a clinical trial on the effect of oral collagen for skin elasticity. Collagen is broken into amino acids through peptide. According to the description, some peptide may have a positive effect on human skin. It is an interesting hypothesis. Is feeling of women correct? Whether it is true or false is remain unknown. Indeed, only one quarter of academic articles are correct.
I am seeking the original article about this to investigate it by myself, but unfortunately I have not found it yet. Instead, vast articles about human skin and anti-aging are found. The desire for beauty is so strong.