Vitamin A: The Real Deal
Why We Need Vitamin A
Vitamin A is necessary for healthy surface linings of the nose, throat, lungs and intestines.
Other key functions of this vitamin include:
Promotes healthy development of bones and teeth
Aids in proper wound healing
Increases resistance to infection
Some experts also say that vitamin A may help prevent some cancers and deter night blindness.
Food Sources of Vitamin A
Vitamin A in our diets comes from both animal and plant sources. Vitamin A found in food from animal sources is called preformed vitamin A, also called retinoids. Rich animal sources of vitamin A include:
- Liver and other organ meats
- Fish
- Egg yolks
- Milk and Cream
- Butter
Vitamin A that is found in plants is called provitamin A, also known as carotenoids. Carotenoids are what give yellow, red and orange fruits and veggies their color.
Beta-carotene is the most potent of the carotenoids, and also acts as a powerful antioxidant in the body. Plant sources of vitamin A include:
- Orange and yellow vegetables and fruits
- Dark green leafy vegetables
How Much Vitamin A Do We Need?
Current RDAs (recommended daily allowances) are as follows:
- 1000 micrograms daily for men
- 800 micrograms daily for women
Those at Risk for a Deficiency
Though vitamin A deficiency is rare in most developed countries, it is not unheard of. Individuals most at risk include:
- Persons following very low-fat diets
- Those who have fat absorption problems due to illness or recent surgical procedures
- Persons whose diets are deficient in protein or zinc
- Individuals who regularly make poor food choices
Can We Get Too Much Vitamin A?
Yes, preformed vitamin A can be toxic in high doses. As a rule, most animal foods don't contain exorbitant amounts of preformed vitamin A.
Supplements are most often the culprits when toxicity issues become a problem.
There are exceptions to every rule, of course. For instance, 3 ounces of polar bear liver is estimated to have about 60,000 micrograms of preformed vitamin A.
That's 60 times the RDA for adult males! So, if you happen to be a fan of polar bear liver--BEWARE!
Symptoms of vitamin A toxicity:
- nausea or vomiting
- headache, dizziness or blurred vision
- lack of muscle coordination
- weight loss
- muscle and joint pain
- bone abnormalities
- liver damage
- dry scaly lips
- skin rashes
Please note that preformed vitamin A toxicity can occur with repeated doses of just 10 times the RDA.
However, provitamin A, found in plant foods, is non-toxic. Experts say this is because our bodies decrease the absorption of carotenoids when we consume them in high doses.
So if you plan on supplementing with vitamin A please get the advice of a trusted medical professional first. Better to be safe than sorry.
To Your Health!
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