欧博abgHypervitaminosis A
Hypervitaminosis A can be diagnosed using blood tests to check your vitamin A levels. Most people improve simply by decreasing their intake of vitamin A.
Hypervitaminosis A, or vitamin A toxicity, occurs when you have too much vitamin A in your body.
This condition may be acute or chronic. Acute toxicity occurs after consuming large amounts of vitamin A over a short period of time, typically within a few hours or days. Chronic toxicity occurs when large amounts of vitamin A build up in your body over a long period of time.
Symptoms include changes to vision, bone pain, and skin changes. Chronic toxicity can lead to liver damage and increased pressure on your brain.
Causes of hypervitaminosis A
Excess amounts of vitamin A are stored in your liver, and it accumulates over time.
Most people develop vitamin A toxicity by taking high dose dietary supplements, possibly due to megavitamin therapy. A megavitamin therapy involves consuming very large doses of certain vitamins in an attempt to prevent or treat diseases.
It may also be caused by long-term use of certain acne treatments that contain high doses of vitamin A, such as isotretinoin (Sotret, Absorica).
Acute vitamin A toxicity is usually the result of accidental ingestion when it occurs in children.
Getting the right amount of vitamin A in your diet
Vitamin A is important for eye health in children and adults. Vitamin A is also important in the development of the heart, ears, eyes, and limbs of fetuses.
You can get most of the vitamin A your body needs from a nutritious diet alone. Vegetables contain beta carotene, which the body converts small amounts of into vitamin A. Foods that contain vitamin A include:
liver
fish and fish oils
milk
eggs
Foods that contain beta-carotene include:
dark fruits
leafy, green vegetables
orange and yellow vegetables (sweet potatoes, carrots)
tomato products
some vegetable oils
fortified foods (which have added vitamins) like cereal
How much vitamin A do you need?
According to the National Institutes of Health (NIH), the recommended dietary allowances for vitamin A are:
0 to 6 months old400 micrograms (mcg)
7 to 12 months500 mcg
1 to 3 years300 mcg
4 to 8 years400 mcg
9 to 13 years600 mcg
14 to 18 years900 mcg for males, 700 mcg for females
14 to 18 years/pregnant females750 mcg
14 to 18 years/breastfeeding females1,200 mcg
19+ years900 mcg for males, 700 mcg for females
19+ years/pregnant females770 mcg
19+ years/breastfeeding females1,300 mcg
Taking more than the recommended daily allowance for several months can cause vitamin A toxicity. This condition can occur more quickly in infants and children because their bodies are smaller.
Symptoms of hypervitaminosis A
Symptoms vary based on whether toxicity is acute or chronic. Headaches and rash are common in both forms of the illness.
Symptoms of acute vitamin A toxicity include:
Symptoms of chronic vitamin A toxicity include:
In infants and children, symptoms may also include:
During pregnancy, defects in their baby can result with too much vitamin A.
If you’re pregnant, don’t take more than one prenatal vitamin each day. There’s enough vitamin A in prenatal vitamins. If you need more iron, for example, add an iron supplement to your daily prenatal vitamin. Don’t take two or more prenatal vitamins, as the risk of deformities in your baby increases.
If you’re pregnant, don’t use retinol skin creams, which are very high in vitamin A.
The correct amount of vitamin A is crucial for the development of a fetus. However, excess vitamin A consumption during pregnancy is known to cause birth defects that may affect a baby’s eyes, skull, lungs, and heart.
Potential complications
Potential complications of excess vitamin A include:
Diagnosing hypervitaminosis A
Your doctor will start by asking you about your symptoms and medical history. They’ll also want to know about your diet and any supplements you’re taking.
Your doctor may order blood tests to check the levels of vitamin A in your blood as well.
How hypervitaminosis A is treated
The most effective way to treat this condition is to stop taking high dose vitamin A supplements. Most people make a full recovery within a few weeks.
Any complications that occurred from the excess vitamin A, such as kidney or liver damage, will be treated independently.
Long-term outlook
Recovery depends on the severity of the vitamin A toxicity and how quickly it was treated. Most people make a full recovery once they stop taking vitamin A supplements. For those who develop complications, such as kidney or liver damage, their outlook will depend on the severity of the damage.
Talk to your doctor before you begin taking any supplements, or if you’re concerned that you aren’t getting enough nutrients from your diet.
As well, contact your doctor if you’re experiencing any of the symptoms of hypervitaminosis A.