The first half of this post is a repeat of a response I made to a question about diet but I came here to give everyone the benefit (hopefully) of my experiences with this condition.  The second half is less related to diet and more related to my other experiences.  I am truly sorry for the length of this but I believe in being thorough.

About Me - skip if you just aren't that curious or don't have time :)
I'm 42 and I've had Alopecia for about 24 yrs. to varying degrees including eyebrows, eyeslashes, arms, and legs. I didn't worry about it for a long time since it seemed (and I was told) that it
was basically harmless and since I am a guy when it got really bad I
just shaved my head completely and no one thought anything of it. But
when my nose hairs fell out I came to the conclusion that this is not
harmless and there are probably other effects of which I am not even
aware of. So I went on a personal quest to find a cure for the root
cause (not the symptoms - ie hair loss).  My profession has always been to fix things that are broken.  I have been an auto mechanic, industrial millwright, and electrician, and electro-mechanical technician and I have found one thing is common - you do not fix anything by treating a symptom !!! A louder radio does not fix an engine noise and an engine noise generally leads to a complete failure of a component.  As an aside, (and an attempt to lend some credit to my personal conclusions ;), I also took some chemical engineering in university.

Diet - In my experience a definite factor
I read a booklet by David W. Rowland - One's Food is Another's Poison. It made a lot of sense to me. First of all I suspect that autoimmune diseases are systemic especially since if you have one type you are more than likely to have another. I have always had allergies and eczema as well as mild asthma but never got the Flu or any of the usual childhood diseases (chicken pox, mumps, etc). To make a long story short I have been off of gluten for about a year and have noticed more hair regrowth than I've had in about 8 yrs and I am just getting over a case of the chicken pox (which suggests to me that my immune system is not as active as it was). For me it seems to be gluten (and possibly dairy and chocolate - I'm going to try them next)
A few things to keep in mind from what I've learned:
- hair growth will most likely not happen immediately after a change since hair follicles go dormant for 3mths to a year
- also noticeable improvements are delayed because it takes time for your body to heal from the damage caused
- also damage cause by a food intolerance may cause other problems (such as bacterial or yeast infection) that may need to be resolved before symptoms improve
- most likely different foods for different people
- if you have intestinal irregularities (like I did - I just didn't know it wasn't normal) definitely investigate food as a culprit
- when you go off of a problem food you may notice some short term reactions ( I had a skin rash)
- when you've been off of a problem food for a long enough time you may have more immediate and obvious negative reactions - I've had wheat a few times by accident and experiment and I have no doubt that it's a problem for me
- in my case I suspect an under active thyroid as a contributing factor, I also feel cold, the way to test this is to take your temperature first thing in the morning. I just haven't gotten around to buying a thermometer, maybe tomorrow.
- changing your diet is NOT simple, gluten from wheat is used in most processed foods but due to lax labeling laws (to the point of immorality in my opinion) it is hidden in ingredients like spices, natural flavouring, and many many others. This is just one example, I would suggest that whatever food you choose to try that you research all the aliases used in the food industry.
- with above point in mind the easiest way is to eat fresh foods only prepared by you during the identifying process then when you have made a possible negative food list then do the research to ensure you have completely eliminated it.

My Self Diagnosis - So many possible causes.
-I was born allergic to pretty much everything and covered in eczema.  So I guess either there was some genetic issue or my mother was exposed to something that messed with her immune system and therefore mine.  I was allergic to my mother's milk. But had an even worse reaction to cows milk.  I lived on soybean formula for a couple years.
-From the age of about 2 to 18 I only had mild eczema and only ever got food poisoning as far as getting sick.  Although in hindsight I now wonder if that food poisoning was a response to gluten.
-I went from sleeping and eating on my own natural body clock (I slept through most of high school) to working in a greenhouse (exposure to humidity and fertilizers) to a woodworking factory, at which point my alopecia started (exposure to formaldehyde see footnote) followed by working in flat roofing (exposure to petrochemicals and way too much sun).  Another factor that increased significantly was that I took sandwiches for lunch at all these jobs.
-I went to Ireland about 4yrs ago and had the worst case of "food posioning" I've even had.  I suspect if I hadn't gone to the hospital I would have died or at least suffered severe long term damage.  I required 2 bags of IV electrolyte.  Ireland is very damp so there is a lot of mould even if it isn't visible.  Also I had been eating a lot of fast food which generally has a lot of wheat and MSG in it.  Keep in mind MSG is not related to gluten (so I'm told) but in my case I also have a reaction to MSG that I've known for some time - it makes me sleepy.
-Another possible reason for getting more food poisoning than most might be that my problems with wheat gluten caused damage to my intestines which made me suseptible.
-I am quite thin and despite eating lots of food and I always feel cold.  I believe the coldness is a symptom of an under active thyroid which runs in my family.  The thiness actually suggests an over active thyroid but could also be explained by malabsorbtion due to intestinal damage.  Also thyroid hormones are known to fluctuate which is why if you go to a doctor to get these levels tested you should be tested multiple times (possibly at different times of day).
-I seem to have a high threshold to responding to stress.  I've rock climbed without ropes and jumped out of planes without getting really overwhelmed.  From what I've read this could be due to low adrenaline production which, if I remember correctly, affects thyroid function.
-Apparently the immune system starts it's process by identifying an invader by it's protein.  If it's not your protein or it is but it doesn't "seem" like it to the identifying mechanism (possibly due to too low a body temperature) then a chain of events leads up to T-cells destroying the invading cells (as well as some of your surrounding cells as a normal way to prevent the spread of infection).  If you have an excess of foreign proteins floating around in your blood stream then you will have a wide spread immune response that would be highest where these proteins might accummulate, that last bit is my speculation.  Carrying along with my speculation, these proteins would vary from person to person depending on their diet, which proteins they can't break down, and where in the digestive tract the damage has occured.

My Treatments - one's I've tried and noticeable effects
Eliminating gluten: negative effects at first like rash then hair growth in the long term though complete foliation has not occured
Elimination diet: consisted of amino acids (pre-broken down proteins), fructose, vegetables, digestive enzymes, and multi-vitamins.  I was suprised at how much energy I had but I found I got agitated easy and craved a full stomach like crazy esp. when I was around other peoples food.  After this diet (not during) my bowel movements were more regular and consistent then they had ever been in my life and I felt generally better. If I did it again I eliminate the sugar and have more vegetables particularily more brocolli, spinach, and sweet potatoes.  I would use (I hope it's ok to refer) http://www.nutritiondata.com/
to ensure I was getting a proper caloric and nutritional intake.  It also has an Inflammatory Rating for each food.
Alpha-Lipoic Acid: Capsules I took as chelation therapy to remove mercury from old fillings now replaced with non-mercury fillings.  I started this due to a noticeable decline in my memory and mental function.  I noticed an almost immediate improvement which seemd to bring me to my former state with a lasting effect even though I don't take the capsules anymore. Although I do eat a lot of spinach which is a source of Lipoic acid - the natural equivalent of the synthesised Alpha-Lipoic acid.
Olive Oil Based Lotion: Seems to help the eczema and the generally condition of my skin - it tends to be dry.
Parasite Cleanse: Off the shelf pills with no dietary changes. Seemed to cause headaches while I was taking it and I notice no improvements or expelling of parasites.

The Nature of Alopecia - Most importantly systemic.
Since we are essentially a collection of many different parts and mechanisms linked in a web of interdependancy, I believe that damage to one part will lead to or be caused by damage in another part.  With respect to our condition (though I love analogies), the skin is the largest organ in our body and a frontline in defense against chemicals and micro-organisms.  How many different nasty things can we get exposed to, and how much damage can they cause to other organs - and not all the same from person to person, we each react differently.

Natural Remedies - I'm not an herbalist but ....
To my understanding herbs merely contain chemicals that have not been sythesized or extracted, price tagged and sold, or otherwise exploited by big Pharma.  Which is to also to say that I am not against big Pharma's treatments as long as they don't have negative side effects that outweigh the effects of the initial ailment.  READ THOSE LITTLE PAMPHLETES THAT COME WITH ANY MEDICATION.  I have never yet met a doctor who reads them out to me.  Specifically related to us: Cortisone injections will cause hair to grow with a side effect of weakening the heart muscle (probably all muscle of that type in fact - but the heart is enough for me to say "no thanks").  In the vein of a more "natural" remedy if you go on an elmination diet to find a food (natural or manufactured) make sure you are still getting all your vitamins, minerals, calories, etc. or you may cause yet another ailment.  Though I never have, I would suggest anyone consult a dietitian before embarking on any severe diet changes.  Or at least research it yourself.  Also research any natural substances you decide to try since, just like manufactured chemicals, these can have negative side effects or be overdosed on.  Natural does not neccessarily mean safe - just look at poison ivy :)  It is my guess that anything applied topically and seems to work is merely encouraging hair growth or supressing the immune system response in that area - not treating the cause of the immune reaction.

Some Misconceptions - Which we all have some about something.
Ignorance is not a derogatory term it is merely the lack of knowledge on a particular subject.  Just as I believe that these are misconceptions, I may also be wrong on some of these points as they are a result of my personal experiences and observations which may differ from yours.  So please excuse my ignorance :)
- "Our immune systems are weak", from what I've read our immune systems are working too strongly if anything.  This includes my personal experience - the only contagious diseases that I've ever suffered up until now is the flu twice and the chicken pox which I just caught now that I've been off of wheat for a year and my hair is starting to regrow.  That is not to say that they are not taxed and may weaken sooner than compared to a "healthy" person.
- "That's not a cause ... ", please add "in my case" unless you have done an in depth survey or a controlled experiment with a proper sample size.  Otherwise you may just be detering someone from trying something that may help them.
- "It's caused by stress", or at least not in my case :).  I lead one of the least stressed lifestyles of anyone I know.  I think I'd have to be a Buddist monk to be less stressed.  That said I do believe that stress can make any condition worse - it depletes the body of nutrients by setting in motion various chemical processes.
- "The main issue is asthetics", this appears to be a widely held medical opinion.  While I will acknowledge that it's a bigger issue for some than others, I believe that there are other effects that just show up later and are attributed to other things (or nothing at all)

Doctors - I'm not a doctor but ....
Doctors are like a lot of other professions in that they are expected to have a wide breadth of knowledge.  G.P.'s are the most extreme case of this since they have to know what tests to call for or what specialist to refer to for every concievable ailment.  Luckily our brains can evolve on the fly but there are limitations due to fundamental chemical processes and size.  A doctor who has not thoroughly investigated alopecia is of limited use to us since he can only provide the tools in his toolbox.  It seems to me that since we are communicating with each other in search for a cure for a condition with an UNKNOWN cause that a medical researcher in this field is of most use to us - but we have the least access to.  A medical researcher on a private companies payroll would be likely be subject to discipline for posting findings on a public forum such as this.

Footnote:
Formaldehyde is everywhere.  If you think it can't be the cause in your case because you've never been exposed - think again.  This stuff is nasty and the only reason it hasn't been eliminated from the consumer product stream is because of the sheer number of products that contain it (80% of U.S.A.'s GNP).  It is used as a binding agent (or emitted by binding agents) so paper towel, cardboard, partical boards (most modern furniture and house structures).  A chemist friend of mine was trying to find a water sample that had no formaldehyde in it to use as a blank for a test.  She couldn't find any. The lowest amounts were found in water from a pond and the highest were in bottle water!!!
It is a carcinegen and allergen and yet the most widely "acceptable" exposure is 0.2 parts per million per day.  The symptoms to exposure start at 0.1 parts per million and include eye irritation, tears, skin irritation, and respiratory tract irritation.  Do these symptoms sound "acceptable" to be experiencing on a daily basis.  It seems to me that acceptable is being used in the wartime concept of "acceptable losses" but in the context of protecting the business at the expense of unknowing civilians.  I don't believe this concept is ever acceptable.

If you gotten this far in the reading then I am amazed.  But also I would like to ask that you give a response citing what symptoms and successes.  That way I will know which are truly related to my alopecia.

Thank You for your time,
Neil