You said that your friend was able to regrow hair on a previously large bald patch by a radical change in his diet. This is the diet that he attributed his success to:
_ strictly avoiding sugar, milk products, white flour and meat.
_ mantainin a strict alkaline diet consisting mainly of raw non processed food (legumes, fruits, nuts) and juices
_ 4 cl [cl is a centiliter]/day of fresh barley grass juice (he considers this as an essential ingredient in his personal "success formula")
I can understand avoiding milk products if one is lactose intolerant or meat if one is ideologically repelled by the slaughter of animals. There are, however, many important nutrients in milk products (yogurt) and meat (liver) that are important for hair follicle health. Living on legumes, fruits, nuts, and juices sounds great - getting back to nature - but can this diet really produce hair growth? It's a romantic notion I'll have to admit - Robinson Crusoe on a desert island growing hair down to his shoulders. I don't believe a word of it though. Sorry about my hard-boiled skepticism.
The diet does sound healthy though if one could add some small portion of meat occasionally. Iron is, after all, essential for living cells. A serving of plain yogurt with live and active cultures would not hurt either. These diets recommended by health gurus that exclude meat, dairy, whole wheat are eccentric. They appeal to a certain type of person - the ascetic who practices self-denial as a spiritual discipline. These damn ascetics all seem to have great hair though.