Polly: Vitamin A is very important for healthy intestines and flora. According to Dr. Lars Hanson, in rats, vitamin A deficiency causes “a contaminated bowel syndrome, accompanied by a very abnormal immune response with IgE antibody formation to the bacteria, dyspagocytosis, increased translocation [leaky gut], and a number of other abnormalities, such as increased nitric oxide production.” 
Susan Owens, an autism researcher, points out one of the reasons that a lack of vitamin A can cause leaky gut.
“Vitamin A deficiency has been shown experimentally to produce an accelerated turnover of GAGs as well as their undersulfation.”
GAGs (glycosaminoglycans) form a protective barrier in the gut. When deficient or undersulfated, this can cause a leaky gut. 
Avandish: Stay away from the patented synthetic derivatives of Vitamin A like Accutane. Their slightly altered chemical structure makes them toxic. I’m now at this candida forum website because of these toxic effects. I have spent 6-7 years of my life trying to reverse this damage. I have experimented with numerous forms of vitamin A during this time period, and have spent countless hours in medical libraries trying to build an educated understanding of the biological activity of these products and vitamin A.
Polly: At the Roche pharmaceutical site, they have a long list of potential problems associated with Accutane. This list includes intestinal, liver and pancreas problems.  Avandish, it could very well have been the triggering factor in your case.
Avandish: If you would like to experiment with Vitamin A, read up on the side effects of excessive dosages, so that if you begin to experience any of them, you will be able to recognize them early and discontinue. For adults, start with 1000 IU a day (much lower than normally used). Gradually build to 5000 IU if tolerated. Larger doses although tolerated by many should not be necessary. A low consistent dose will be much more beneficial than high dosage vitamin A. Preformed chelates of vitamin A are easiest to absorb and most absorbable of the “Natural” vitamin A products. They are retinal succinate or retinal palmitate. These can be toxic as well so please read.
Polly: I agree that it is always good to start slow with vitamin A or any other supplement. However, if someone has an active measles infection in the gut (like many of the autistic), then perhaps more vitamin A than normal is necessary. You may want to get a doctor to monitor the vitamin A content of the blood in this situation. Also you must go by symptoms. It could be that the liver has plenty of vitamin A, but it is not releasing it to the blood.
Many parents of autistic individuals are trying to give children some fish oil for its retinol vitamin A content, in particular its 14- hydroxy-retro-retinol content. Dr. Megson says that for those with a damaged gut, the best-absorbed form of vitamin A is the retinol form of vitamin A, which is found in fish, butter and liver. She even suggests avoiding the palmitate. Dr. Megson implies that a good deal of the trouble we are in is due to substituting the palmiate for the retinol in the diet of infants and children. Yet, Avandish, you imply that this retinol form isn’t that well absorbed, and you prefer the palmitate. Why?
Avandish: If the retinol were extracted from the fish oil, its absorption would be easy. However, fish oil, as any polyunsaturated oil, requires the breakdown of the fats by lipase to allow digestion. Lipase from the pancreas digests fats. Micellization and emulsification can be used on cod liver oil to increase the surface area for lipase to act. This will improve absorption. (Micellization means the large fat-soluble nutrients have been broken down into tiny, stable, water-soluble particles called micelles, which are absorbed more easily. Bile essentially does the same thing. It emulsifies fatsmakes the fat particles very small.)
There is a problem with this emulsification technique though. The compounds used to emulsify can be different from different producers. For example: some use glycerin, some use lecithin, etc. These added ingredients are sometimes the sole reason a product becomes intolerable. Also many companies buy their vitamin A containing preservatives NOT listed on the label such as BHT, sodium benzoate, etc. If negative symptoms occur, you should discontinue and try another.
I can’t stress purity enough for people with any type of liver malfunction. If you have trouble getting pure Vitamin A without additives you may try College Pharmacy in Colorado Springs, Colorado, at (800) 888-9358. You MUST specify that you want a product with no additives because the pharmaceutical companies sell both to vitamin companies and pharmacies. The stuff with additives is easier to weigh and therefore more popular. You have to realize that 20,000 IU is smaller than a drop of pure A liquid. It must be diluted to measure it. You can have it diluted by this pharmacy with dilutents of your choice.
Polly: From what you just said, I assume adding bile salts and/or pancreatic enzymes might help absorption if someone were taking the cod liver oil. (You can purchase bile salts separately. *DEWS carries them. http://www.DEWSnatural.com phone (940) 243-2178) Maybe even an addition of the palmitic fatty acids from coconut would make the absorption easier too. There is some indication that the presence of phosphatidylcholine in the intestine will help the absorption of vitamin A.  Yet, just improving the absorption isn’t the total solution. A good portion of the autistic children are not able to tolerate cod liver oil. Faced with this problem, one mom tried micellized retinyl palmitate and noticed some improvement. Yet others are not able to tolerate the palmitate. Are there any other forms of vitamin A that they could try?
Avandish: You can bind or chelate retinol to just about anything. I have seen succinate, acetate, palmitate, and others. Thorne Research offers a preservative FREE retinyl palmitate. Biotics Research has also been tolerable for me. I would experiment with these before fish oil.
The retinol in fish oil must be converted in the liver to a form that can be distributed throughout the body. The palmitate and succinate require no further processing. When you give the liver any compound in which it can’t easily process, natural or not, it will put undo stress on that organ. In my situation the chelates have been much more tolerable and effective, while retinol from fish oil increased my symptoms associated with liver decline and increased the level of my liver enzymes. Also, if you look up vitamin A in any health book, or medical book it will generally advise against the use of cod liver oil in patients with clinical liver dysfunction.
Polly: Thank you, Avandish. That is very important information, and it is well expressed. Have a little more patience with me, and if possible, could you explain this quote by Dr. Mary Megson? Dr. Megson states, “… the enzyme that helps split vitamin A palmitate is in the microvilli of the gut, and if the child has a single adenoviral or rhinoviral infection before fifteen months of age, the mucosal cells are sloughed off so that enzyme might not be available for use. Vitamin A palmitate has to be in the presence of bile, and the right pH for absorption. [Sporn, M, Roberts, A, Goodman, D. The Retinoids: Biology, Chemistry and Medicine. Raven Press, 1994, page 231]” 
Avandish: It is my understanding that these intestinal cells actually chelate the retinol with palmitic acid for absorption. This step dose not occur automatically, but is carried out by the cells lining the intestine. I am not sure why there is so much conflicting information out there. I think that doctors often form hypotheses, that although sometimes get good results clinically, are not necessarily correct biochemically. I can’t say who is correct for sure. I would suggest having the vitamin A palmitate or any other vitamin A traced in the blood and tissues with a radioactive tracer or just simply test for those compounds in a sample to see if its present. I have, myself, had very poor bile secretion with these health problems, and poor fat metabolism. Yet palmitate has helped more than fish oil for me. If taken in high dosage, I experience symptoms of excess vitamin A. These symptoms should not occur body wide without proper absorption.
Every text I read on nutritional medicine, whether from one medical journal to another or from one nutritional text to another, contain conflicting information. After experimenting with this vitamin A thing for a while, I have come to the conclusion that palmitate is safer and more effective than fish oil for me. I have learned that the more you attempt to learn, the more you realize that everything should be questioned. Not very settling on the stomach.
Polly: Avandish, I’ve learned a lot from you, but I still feel uncomfortable with my level of understanding on this issue. Perhaps the key is not what form of vitamin A gets absorbed into the bloodstream the best, but what form of vitamin A heals the intestines the best. The intestines are designed to get most of their nutrition directly from the food in the gut. Hence the retinol form of vitamin A, which is the form normally found in food, might be the best way to let nature heal the gut. At least it is the first thing I’d try. Yet, if the retinol vitamin A from butter, fish, and liver didn’t help, then I’d certainly try the palmitate.
Vitamin A or Carotene?
Polly: An overdose of vitamin A can suppress thyroid, and be just as deleterious as too little vitamin A. Therefore, to be on the safe side, many people turn to a supplement of carotene. When you use carotene, the liver should convert the carotene into vitamin A as it is needed. This avoids the possible problem with an overdose of vitamin A. Most people assume that you can’t get too much carotene, so they feel that there is no problem with making this substitution. However, one cannot go too far with this logic without running into a few problems. A little carotene in your diet is fine, but too much carotene can interfere with liver function, and can block the action of vitamin A by competing with it. Also, if you are hypothyroid, it may be difficult for your liver to convert carotene into vitamin A. Especially for children, one needs to make sure they get some vitamin A instead of just carotene. In general, all children have a problem converting carotene into vitamin A.  Those with a phenol-sulfotransferase problem (many of the autistic and mercury poisoned) may have more trouble than most with carotene and other cartinoids. Therefore, I feel that a nominal supplement of vitamin A may be a better option than a carotene supplement, at least for many of us.
Please be careful if you give a child vitamin A supplements. A child will get very sick if you give them an adult dose of vitamin A on a regular basis. If your child is healthy, then just keeping butter in their diet should go a long way to keeping them healthy. If you want to add some insurance, you might consider a child’s vitamin supplement from Allergy Research/Nutricology. They are small capsules, and you use a number of them depending on the child’s weight — one capsule per 10 pounds of body weight or as directed by a physician. Each capsule contains 800 IU of vitamin A palmitate along with many other vitamins and minerals. Since the pills are capsules, they can be pulled apart, and the contents added to food. http://www.nutricology.com phone (800) 782-4274
Supplements of 25,000 IU of vitamin A per day is usually quite safe for adults More might be hard on the liver. However, there is currently some debate going on about using this much on a long-term basis. Adults can use higher doses on a short-term basis (eg 200,000 IU a day during an infection), but not necessarily for an extended period. Vitamin A supplements should be balanced with vitamin E because vitamin A tends to suppress the level of vitamin E.