Vitamins are a group of organic compounds occurring naturally in food and are necessary for good health. Lack of a vitamin may lead to a specific deficiency syndrome, which may be primary (due to inadequate diet) or secondary (due to malabsorption or to increased metabolic need), and it is rational to use high-dose vitamin supplementation in situations where these clinical conditions exist. Vitamin A comes pre-formed, as retinol in foods of animal origin, or in precursor form, as carotenoids in fruits and vegetables.
   Vitamins A is an essential, naturally occurring, fat-soluble nutrient involved in several important biological processes such as immunity, protection against tissue damage, reproduction, growth and development. Many people supplement with this vitamin and some do it in excess resulting in toxicity. More is not necessarily better.
   Retinyl palmitate, or vitamin A palmitate, is the ester of retinol (vitamin A) and palmitic acid.

Vitamin A and stomach cancer
 High intakes of vitamin A apparently reduce the risk of developing gastric cancer. Vitamin A may influence the development of stomach cancer through its role in controlling cell proliferation. Swedish researchers examined the records of 82,000 Swedish adults who had completed a food-frequency questionnaire in 1997 and were followed through June 2005. The average follow-up was 7 years. During that time, a total of 139 cases of gastric cancer were diagnosed. A significantly lower likelihood of developing gastric cancer was seen with high intakes of dietary and total vitamin A and retinol, and of alpha-carotene and beta-carotene. Compared with the lowest intakes, the highest consumption of these compounds was associated with about a 50 percent reduction in the risk of gastric cancer. Smoking affected how strongly vitamin A protected against stomach cancer, but alcohol drinking appeared to make no difference. American Journal of Clinical Nutrition, February 2007.

Infants in India
Vitamin A supplements given in the early newborn period in infants in India reduced the risk of infant deaths from diarrhea, fever and respiratory infections, but do not reduce the occurrence of these problems.

Vitamin A and cleft palate prevention
Getting adequate amounts of vitamin A during pregnancy may reduce the risk of having a child with cleft palate. A Norwegian study shows Infants born to women who consumed the most vitamin A were half as likely to have a cleft palate as children whose mothers consumed the least vitamin A. American Journal of Epidemiology, May 15, 2008.

Vitamin A deficiency from medications
Vitamin A deficiency can occur from the use of certain medications including Alli weight loss pill.

J Nutr. Feb 5 2014. Vitamin A Deficiency Is Associated with Gastrointestinal and Respiratory Morbidity in School-Age Children.

Supplement Research
Vitamin A intake and osteoporosis: a clinical review.
J Womens Health. 2004.
Crandall C. Department of Medicine, David Geffen School of Medicine at University of California, Los Angeles, Los Angeles, California
If osteoporosis is linked with vitamin A consumption, millions of people could be affected. A MEDLINE search was performed with keywords retinol, beta-carotene, and osteoporosis. Of 20 clinical studies, 3 were randomized controlled trials (RCTs), 14 were observational studies, and 3 were case reports. Most (8) observational studies were cross-sectional. Oral retinoyl palmitate in high doses induces fractures and radiographic osteoporosis in animals. Retinol intake from diet or supplements is negatively associated with lumbar, femoral neck, and trochanter bone mineral density (BMD). There is a graded increase in relative risk of hip fracture with increasing retinol intake, attributable primarily to retinol (either from diet or supplements) but not beta-carotene intake. Higher serum retinol levels are associated with higher risk of any fracture and with higher risk of hip fracture, whereas there is no evidence of harm associated with beta-carotene intake. The few RCTs involve serum markers of bone metabolism, not bone density or fracture outcomes. Observational studies are generally consistent in finding harm from either dietary or supplemental retinol intake on bone mineral density and hip fracture risk. Total vitamin A intake is more important than source in determining harm. Adverse effects may occur at a level of retinol intake that is only about twice the current recommendation for adult females. It is not yet possible to set a specific level of retinol intake above which bone health is compromised. Pending further investigation, vitamin A supplements should not be used with the express goal of improving bone health.

Supplement pill questions
Q. Does a vitamin A supplement help with coronary artery disease?
   A. I doubt if it, by itself, will make much of a difference.

Q. I an interested in buying the Eyesight Rx formula. I know vitamin A is good for the eyes but I am worried about getting a vitamin A overdose. How much vitamin A does Eyesight RX have? Is it okay to take it with cod liver oil which is also full of vitamin A?
   A. Eyesight Rx has very little vitamin A. Taking Cod-Liver-Oil together with Eyesight Rx is fine.

Q. It just occurred to me to ask why, since Dr. Sahelian recommends not supplementing with vitamin A, does the MultiVit Rx have it?
   A. Supplements of vitamin A usually have 10,000 units or more per capsule. Taking 2 or 3 of these is not healthy nor necessary for long term use. The amount of vitamin A (not beta carotene) in MultiVit Rx is 2500 per four capsules and most people only need one or two capsules a day. Hence, this small amount of vitamin A could be beneficial. Concern arises when people take more than 10,000 or 20,000 units a day for prolonged periods.

I am presently taking Macular Protect Complete. I have read that 25,000 IU of Vit A is reaching a toxic level. Am I getting too much of this when considering what I also get from food? Macular Protect Complete contains this high dosage.
    We prefer long term use of vitamin A in supplement form to be less than 15,000 units a day but different people may have different needs.

High levels of beta-carotene can turn the skin orange. Do you know exactly how much beta-carotene you have to consume in terms of Vitamin A? Will 5,000 IU a day start to tan the skin? I also thought that high levels of Vitamin A was toxic is this true?
    Yes, very high amounts of vitamin A intake can be toxic. It would take tens of thousands of units of beta carotene daily for several weeks to turn the skin orange.