This website mentions:
The makers of Alpecin Caffeine Shampoo must no longer advertise that the product can reduce hair loss after a watchdog ruled there was no adequate evidence to support the claim.
Ads for the product stated: "German engineering for your hair. Shampoo is too small a word for it. Alpecin provides caffeine to your hair, so it can actually help to reduce hair loss. Simply apply daily and leave on for 2 minutes ... to help the Caffeine Complex penetrate your hair and scalp."
Alpecin said its claims did not imply any medicinal action, but said topically-applied caffeine had a long history of use with individuals suffering from thinning hair or increased hair loss, claiming that caffeine was able to counteract the suppression of hair growth induced by testosterone and even stimulate hair growth to the normal level.
It provided eight full studies, several study summaries and a consumer opinion survey which it believed supported the claim that the shampoo could help to reduce hair loss.
The Advertising Standards Authority (ASA) said consumers would understand the claim to mean that using the product would result in a reduced rate and quantity of hair loss.
However it found that none of the information provided by Alpecin included adequate evidence that this was the case, noting that some results were measured using a "hair pull" test.
The ASA said: "Taking into account the body of evidence as a whole, we considered that we had not seen any studies of the actual product as used by consumers on their scalp using an accurate and objective analysis of hair growth, in a well-designed and well-conducted trial.
"We concluded that the claim 'it can actually help to reduce hair loss' had not been substantiated and was therefore misleading."
It ruled that the ad must not appear again, adding: "We told Alpecin not to state or imply that their product could reduce hair loss unless they held adequate evidence to support their claims."
So, does Alpecin Caffeine Shampoo help to reduce hair loss? Do anyone have the documents on the eight full studies to support the claim? or are there more reliable sources to support the claim?