I've been doing some research on this, as a dear lady at my church also has this condition. The doctors don't know what causes it, so they 'practice' all sorts of medicine and techniques without much success.
According to one site, achalasia is "chronic spasms of the esophagus due to a stricture at the lower end of the esophagus." It's a condition in which the muscles are overactive.
I would refine this definition a bit to say that it's a hyperactivity of the lower esophageal sphincter
. A person may simultaneously have a hypoactive (underactive) esophagus, which indicates a lack of peristalsis; the involuntary muscle movements of the smooth muscle lining of the esophagus which moves food down to the stomach.
For a successful swallow, you have to have both the peristalsis and a simultaneous relaxation of the lower sphincter of the esophagus.
http://www.medicinenet.com/achalasia/page2.htm "In achalasia there is an inability of the lower sphincter to relax and open to let food pass into the stomach. In at least half of the patients, the lower sphincter resting pressure (the pressure in the lower sphincter when the patient is not swallowing) also is abnormally high. In addition to the abnormalities of the lower sphincter, the muscle of the lower half of the esophagus does not contract normally, that is, peristaltic waves do not occur, and, therefore, food and saliva are not propelled down the esophagus and into the stomach.
To the medical world, the cause is unknown.
I did some research on the smooth muscles, which line and power the esophagus, digestive system, hollow organs, the arteries...they regulate the blood pressure (fascinating!), and even the irises of the eyes. Smooth muscles are triggered by calcium entering the cell and a complex enzymatic process takes place that makes the muscles contract. The muscles relax when the calcium leaves the cell. sources
Since medical science is pretty mum on causes, I turned to homeopathic sources to look for causes or herbal remedies for achalasia. http://www.marysherbs.com/anatomy/anat-eso.shtml
This site gives some good ideas for supplements to help this condition including herbs, minerals and vitamins. It's a bit vague IMO, as it's a general 'herbal' site that doesn't specialize in achalasia, but it's a start none the less.
Since the sites that I found that discuss the contraction process of the smooth muscles state that calcium is the 'chemical' that causes them to respond, I would strongly suspect that a mineral defficiency or imbalance is at work here on some level.
Which leads me to my soap box on sugar. Processed sugars are stripped of their mineral content. The minerals were a part of the plant/natural sugar (put there on purpose by God) because they are needed by the body to metabolize the sugars. A processed sugar still 'needs' those minerals, and will rob the body of it's mineral stores during digestion. So eating and drinking a bunch of sweets, IMO, will only aggrevate the condition. Our American diet is so saturated with processed sugars, and years of abuse to our bodies can cause all sorts of neurological short circuits. Here is a good article on sugar:http://www.wholebodymed.com/library_education_details.php?pid=70
The byproduct of refined sugar is the 'waste product' called blackstrap molasses...and that's where all the good minerals end up. This page shows you what minerals are in the blackstrap molasses...all the good stuff originally found in the sugar cane: http://www.whfoods.com/genpage.php?tname=foodspice&dbid=118
I have started crystalized cane juice, which still has (some of) the natural minerals in tact. It is pretty much the exact same to use in the kitchen...it's just a cream color with a very faint fruity scent to it. As far as plant based foods, generally, the closer you can get to the raw, original 'God made' forms of food, the more nutritious it is. (With exceptions being made for some nuts and grains which are high in phytates and benefit from soaking).
As far as bumping up his nutrition, I would suggest a good liquid multi to start. We like the NOW brand Iron Free Liquid Multivitamin. It comes in berry or orange flavor. My kids like it and enjoy taking it. It's sweetened with Xylitol instead of sugar.
I did find a site that claims to have an 'all natural guaranteed herbal remedy' for achalasia. They listed the ingredients in latin or french or something, but I translated for you.
They obviously don't give proportions, but it consists of:
thymol (a substance found in the Bee Balm/Monarda Didymus family of herbs...an antifungal/antiseptic and relaxant)
and ginger tincture.
An interesting blend of stimulants and relaxants. They claim a money back guarantee (achlotab)...who knows. I would definitely look into researching these ingredients more and maybe including them in his diet if possible, or maybe even as an inhalent.
And finally, here is a page full of breakfast drink ideas. I think any one of these, coupled with the liquid multi that I recommended and your good milk would do the trick to get him off of the ensure. Homemade would inevitably be better nutritionally as well as cheaper than commercial preparations. Having a big variety of flavors is also a great thing if he'll be drinking them often and may get bored with only one flavor.http://www.mrbreakfast.com/subcategory.asp?subcategoryid=14&categoryid=4