How Do I Know If I Need a Vitamin A Supplement?

Vitamin A is a micronutrient necessary for your eyes, skin, lungs, digestive and urinary system, as well as immunity. You may need a vitamin A supplement if you are showing signs of vitamin A deficiency.

Vitamin A is a micronutrient necessary for your eyes, skin, lungs, digestive and urinary system, as well as immunity. This vitamin also helps with wound healing and cell multiplication. Vitamin A deficiency is a public health problem in developing countries but rarely occurs in the U.S., so you should only take vitamin A supplements if you truly need them and accurately follow the dose your doctor prescribes. 

You should get vitamin A from both plant and animal sources, but you may need vitamin A supplements if you're deficient. Bear in mind that vitamin A is a fat-soluble vitamin, which means the body can't remove excess amounts in the urine. Additionally, since it is stored in the body, you needn't consume vitamin A every day. 

In the U.S., breakfast cereals and other foods are often fortified with this vitamin, and almost everyone gets enough of it. Read on, though, to learn how you can tell when you might not be getting enough.

Vitamin A is also known as retinol. It is a fat-soluble vitamin, much like vitamin D, vitamin E, and vitamin K. It has several essential functions in your body.

Eye health

Vitamin A is crucial to eye health. It is a component of rhodopsin, the light-sensitive eye pigment. Rhodopsin enables you to see in low light.

Vitamin A is also necessary for corneal health. Severe deficiency of this vitamin causes a condition called xerophthalmia, one of the most common causes of loss of sight worldwide.

Immunity

Vitamin A helps your immune system to function. Consequently, children who are deficient in vitamin A have a higher risk of dying of infections such as measles and diarrhea.

Other functions of vitamin A

• Wound healing
• Keeping skin and mucous membranes (like the lining of your nose) healthy
• Cell multiplication

The daily recommended amount of vitamin A is expressed using retinol activity equivalents (RAE) because different forms and sources have differing potencies:

• Men: 900 micrograms RAE
• Women: 700 micrograms RAE
• Pregnant adults: 770 micrograms RAE
• Breastfeeding adults: 1,300 micrograms RAE

Vitamin A is plentiful in food, so you should be able to get your requirements from your diet. Additionally, it's a fat-soluble vitamin, and your body stores it in the liver. If you eat more of it one day, it will be stored and used if you don't have enough on another day.

Retinol is the active form of vitamin A. One microgram of retinol is 1 RAE. Beta-carotene, meanwhile, is a precursor of this vitamin that has to be converted into an active form in the body. One RAE of dietary beta-carotene is equivalent to 12 micrograms, though 2 micrograms of beta-carotene within supplements will equal 1 RAE. 

You may find vitamin A requirements and supplements labels mentioning international units (IU) instead of retinol activity equivalents (RAE). One IU of retinol is equal to 0.3 micrograms RAE.

Vitamin A occurs in two forms in nature. Animal sources mainly contain retinol, while plant-based foods have beta-carotene. Retinol is found in:

• Eggs
• Milk
• Liver
• Margarine

Beta-carotene is found in:

• Carrots
• Apricots
• Cantaloupes
• Mangoes
• Sweet potatoes
• Tomatoes
• Spinach

Liver and liver pâté are particularly rich in vitamin A. If you eat these even once a week, you may get too much of this vitamin. Unlike water-soluble vitamins (vitamins B and C), vitamin A can't be removed by the kidneys, so if you eat liver frequently, avoid any supplements and multivitamins that contain vitamin A.

Vitamin A is a heat-stable vitamin. Cooking does not reduce the amount of vitamin A in food. In fact, cooking can increase the availability of vitamin A by breaking cell walls in food and releasing the vitamin.

If you're not getting enough vitamin A from your food, the first symptoms are usually related to your vision. You'll realize you can't see well at night, and driving after sunset is difficult. Your eyes might be dry and irritated. If you don't receive treatment soon, you may lose your sight permanently.

Other common symptoms include:

• Dry, bumpy, or itchy skin
• Broken nails
• Dry hair
• Dry mouth
• Frequent infections

Vitamin A deficiency is rare in Americans with a normal diet. However, if you have a malabsorption syndrome or cystic fibrosis, you may not be able to absorb vitamin A present in your food.

If you have symptoms of vitamin A deficiency, your doctor will ask for a blood test to confirm it. Retinol blood levels of less than 20 micrograms per deciliter indicate moderate vitamin A deficiency. Levels less than 10 micrograms per deciliter indicate severe vitamin A deficiency.

Your doctor will prescribe vitamin A supplements if you have a deficiency. Supplements are available in both the active form (retinol) and the precursor (beta-carotene). Most vitamin A supplements provide 3,000 micrograms RAE. Multivitamin supplements that contain vitamin A usually provide 750 to 1,050 micrograms RAE.

Too high a dose of vitamin A supplements can harm your baby, so always ask your doctor before starting vitamin A during pregnancy. Retinol supplements are a hazard at doses of more than 3,000 micrograms a day. Beta-carotene consumption is safer.

If you are planning a pregnancy or are pregnant, you shouldn't eat liver more than once a week. Stop taking all supplements that contain vitamin A, including fish liver oil and multivitamins. Too much retinol during pregnancy can cause birth defects, including abnormalities of the skull, eyes, heart, and lungs.

Too much vitamin A from supplements can also cause severe headaches, nausea, dizziness, blurred vision, and muscle aches. Very high doses can cause unconsciousness and even death.

It can be dangerous to take vitamin A supplements if there is already plenty in your diet. Vitamin A collects in your body, and having more than 1,500 micrograms a day for a long time affects your bones, potentially resulting in fractures. This is a significant risk for the elderly, who are already at risk for osteoporosis.