Vitamin A

Vitamin A represents a number of related compounds: retinol, retinal, retinoic acid, and a vitamin A precursor beta (b)-carotene. Vitamin A is important for night vision, for fighting infection (body immunity), and for regulating the genes to ensure their proper functioning.

Vitamin A

Dietary sources

Orange and yellow vegetables such as carrots, cod liver oil, fortified cereal, cantaloupe, whole milk, spinach, and eggs are examples of vitamin A rich foods.

Vitamin A Deficiency aftermath

Early vitamin A deficiency leads to impaired night vision, and advanced vitamin A deficiency can lead to corneal ulcers and scarring and blindness. In developing countries, vitamin A deficiency is an important cause of blindness among children. These children are also more likely to develop diarrhea and respiratory infections

Vitamin A: Respiratory infections

Why are supplements beneficial?

There is NO evidence that taking vitamin A supplements can prevent cancer or heart attacks. In the ATBC trial, subjects given beta-carotene had higher incidence of lung cancer than subjects not given beta-carotene.

Toxicity

Vitamin A can be toxic in high doses (Usually 10 times RDA). Symptoms of vitamin A toxicity include nausea, dry itchy skin, headache, and loss of appetite, bone and joint pain. High doses of vitamin A can also cause liver toxicity. Elderly people and people who drink alcohol heavily are more susceptible to vitamin A toxicity.

Vitamin A: Joint pain

Tips for supplements

Eat a balanced diet and take one multivitamin daily. (Most multivitamins contain 5000 IU of vitamin A, generally in the form of beta-carotene). Additional vitamin A supplements are currently NOT recommended. Pregnant women should not take additional vitamin A supplements without medical supervision. Pregnant women should also avoid skin acne medications derived from natural and synthetic retinoids such as tretinoin (Retin-a), isotretinoin (Accutane), and psoriasis medications such as etretinate and acitretin.

Vitamin A: Pregnancy

Comments

Hashim21 Sunday, December 25, 2011

What is the ideal timing for getting exposed to sun for vitamin D benefit and how far long exposure especially for those with Osteoporosis ?

nobody57 Monday, May 7, 2012

I'm not a doctor. I'd say long enough to maintain a healthy full-body tan. Skin tone is a mechanism that the body uses to prevent excess D production. Now it's likely that nobody is going to do this [I won't], which means we all need some degree of supplement in or with our diets. For osteoporosis? Remember that D pulls calcium into the blood, but it also pulls it out of the bone. You want both D and something to put that calcium where you want it (vit K2?).

guest Tuesday, March 11, 2008

I have had kidney stones since I was 14 years old. Now the doctor tells me that my body is making to much calcium and that is the reason I am getting kidney stones. Is there a doctor who I can see that can fix this problem? I am wanting someone who can treat the calcium problem not my kidney stone problem.

Most Popular on Medindia