Vitamin A (Retinoid)
Why I take it:
Mostly for vision.
Forty years ago, when I was in my late 20s, I began taking large doses of vitamin A to combat pimples. I had not had a significant amount of acne in my teens, and am uncertain why I was having difficulty then, but in any case, I knew that vitamin A is an infection fighter, so I thought I would try it. Results were positive enough for me to believe that it was working, and I kept increasing the amount I was taking.
One day, after perhaps three months of large doses (probably 50,000 IU per day), I realized that I could see better. In fact, marvelously well. I was unable to remember ever having been able to focus for any distance, and had worn glasses for about fifteen years - half my life - at that time; but now, suddenly, I could actually see individual leaves on distant trees. I hadn’t know that was possible.
I also discovered that driving became easier, not just because my eyes could focus, but because sunlight and headlights no longer bothered me.
I stopped wearing glasses altogether shortly after that, and have not worn them since except occasionally for driving at night, and recently for near distance (because my eyes are aging).
Based on 40 years of experience, observation, and talking with other people, I believe that in almost all cases light contrast difficulty (such as headlights at night or sun in your windshield) is due the eye being unable to adjust itself properly because of lack of vitamin A.
How much I take:
Usually 10,000 IU (one gel cap) per day. I find that this isn’t really quite enough for me, and occasionally (when I feel that my eyes aren’t adjusting properly) take a megadose of about 8 gel caps.
What WebMD says about it:
Vitamin A is key for good vision, a healthy immune system, and cell growth. There are two types of vitamin A. This entry is primarily about the active form of vitamin A -- retinoids -- that comes from animal products. Beta-carotene (next) is among the second type of vitamin A, which comes from plants. …
High doses of antioxidants (including vitamin A) may actually do more harm than good. Vitamin A supplementation alone, or in combination with other antioxidants, is associated with an increased risk of mortality from all causes, according to an analysis of multiple studies. (Note: association does not prove cause. Personally, I think it likely that something else is happening. For instance, people diagnosed with a major illness may take a lot of vitamin A in hopes of improving their condition. Or perhaps their condition prevents them from using the vitamin A in their system, leaving an apparent surplus.)
Topical and oral retinoids are common prescription treatments for acne and other skin conditions, including wrinkles. Oral vitamin A is also used as a treatment for measles and dry eye in people with low levels of vitamin A. Vitamin A is also used for a specific type of leukemia.
Vitamin A has been studied as a treatment for many other conditions, including cancers, cataracts, and HIV. However, the results are inconclusive.Most people get enough vitamin A from their diets. However, a doctor might suggest vitamin A supplements to people who have vitamin A deficiencies. People most likely to have vitamin A deficiency are those with diseases (such as digestive disorders) or very poor diets. (Note: personally, I believe that the typical American diet is deficient in nearly all nutrients including vitamin A.)