Vitamin A is a crucial class of fat-soluble essential molecules for many different functions in the body. One of the most important roles of vitamin A is keeping our eyesight healthy. Vitamin A is necessary for the proper development and function of the retina, the light-sensitive tissue at the back of the eye. Vitamin A also helps protect the surface of the cells, including the eye lens and cornea, and regulates bone growth and maintenance, immune function and hormone production.
Where Is Vitamin A Found?
The human body readily absorbs two forms of vitamin A: preformed vitamin A and provitamin A.
Preformed vitamin A (retinol, retinyl esters) is found in animal products, such as liver and cod liver oil, dairy products, eggs, rice bran oil, salmon, trout (including their livers), mackerel (including their livers), beef liver and butter.
Provitamin A, converted to retinol, is found in plant products, colorful fruits and vegetables (e.g., carrots, sweet potatoes) and leafy green vegetables (e.g., kale).
A diet rich in organ meat, especially liver from different animals such as fish and beef, along with salads with carrots and kale, is a great way to keep your levels of vitamin A at an optimal level.
Why Is Vitamin A Good for You?
Vitamin A has many roles in the body. It helps maintain healthy vision and skin, helps with cell growth and differentiation, protects against infection and helps the body process calcium. In addition, vitamin A helps form red blood cells, hormones and enzymes.
Vitamin A Deficiency
A deficiency of vitamin A can lead to several health problems, including blindness, dry skin, chronic diarrhea, poor physical growth and increased susceptibility to infections.
Several groups are at risk of vitamin A deficiency, such as children and pregnant women in developing countries, premature infants and cystic fibrosis patients.
Vitamin A deficiency is more common in developing nations, owing to a higher prevalence of diets lacking in vitamin A. Clinical vitamin A deficiency rarely occurs in infants and is only seen in those with malabsorption problems. Preterm infants do not have adequate liver reserves of vitamin A at birth, and their retinol levels are normal only after two to four weeks of age; for full-term infants, retinol levels rise to normal in two weeks.
The onset may be gradual or sudden for those with acquired vitamin A deficiency disorders. The symptoms of vitamin A deficiency are mostly subtle, but they manifest themselves with several conditions associated with vision loss and night blindness, such as cataracts, aniridia and retinitis pigmentosa.
According to Harvard Health Publishing, the current recommended daily intake of vitamin A is 2,330 IU (700 mcg) for females and 3,000 IU (900 mcg) for males.
Is Vitamin A Good for Acne?
Vitamin A deficiency has been linked to acne because it can cause dryness and excessive sebum production (i.e., the natural oil produced by the body and found on the skin). In children with severe vitamin A deficiency, hair may fall out because vitamin A is needed for healthy hair growth.
Vitamin A Supplementation
A person with a healthy diet does not need vitamin A supplementation because they will get enough from their diet alone. However, vitamin A supplementation is beneficial to individuals with an inadequate or limited diet and those with a disease requiring vitamin A in high doses. Examples are retinitis pigmentosa and xerophthalmia.
Supplementation may also be used in cases of malabsorption and dietary restriction. Those with malabsorption may benefit from taking a supplement that helps to increase the absorption of this vitamin.
WHO does not recommend vitamin A supplementation in children under the age of six months because they are at risk of developing a vitamin A deficiency called xerophthalmia, which causes permanent vision loss and may even lead to death.
Having Too Much Vitamin A
Vitamin A toxicity is more prevalent in developed nations than a vitamin A deficiency, owing to the high doses of preformed vitamin A (retinol) found in certain supplements. Vitamin A is also fat-soluble, which means any amount that isn’t immediately required by the body is absorbed and stored in fat cells or the liver.
The liver converts the vitamin into retinol so other parts of the body can use it. If you take too much vitamin A, your liver may not be able to convert enough of it into retinol. This oversaturation leads to hypervitaminosis A, which causes liver damage and even death if left untreated.
Acute hypervitaminosis A is a condition with symptoms including irritability, drowsiness, nausea, abdominal pain, a feeling of pressure on the brain and vomiting.
Chronic hypervitaminosis A symptoms include mouth ulcers, swelling of the bones, cracked fingernails, bone pain, loss of appetite, cracked corners of the mouth and blurry vision.
Some cases of hypervitaminosis A may result in acute psychosis and death. The main causes of hypervitaminosis A are excessive consumption of vitamin A-rich food, including:
- Eating liver or raw fish;
- Taking supplements without checking the label for ingredients that might contain vitamin A (such as retinol);
- Using ointments with high retinol levels such as tetracycline;
- Taking supplements that are not considered safe by the FDA.
The symptoms of hypervitaminosis are usually reversible upon cessation of excess intake.
Large doses of preformed vitamin A, beta-carotene and other provitamin A carotenoids have not been linked to significant health risks. Beta-carotene is not as fat-soluble as vitamin A and cannot be stored in large quantities by the body. It is mainly excreted through the feces, so it should not lead to hypercarotenosis. However, beta-carotene supplements have been linked to an increased risk of lung cancer in smokers.
Vitamin A Interaction with Medications
Orlistat (Alli, Xenical)
Orlistat is a weight-loss drug that interferes with vitamin A absorption. While taking this medicine, your doctor may advise you to take a multivitamin with beta-carotene and vitamin A every day to ensure adequate intake. Orlistat may also be prescribed for patients with chronic pancreatitis or gastroparesis, in which the stomach takes too long to empty its contents into the small intestine.
Hepatotoxic Drugs
Taking high doses of vitamin A supplements and other medicines may heighten the risk of liver disease. Examples of hepatotoxic medications are statins, steroids, antifungal drugs, acetaminophen (also known as paracetamol) and arthritis drugs such as methotrexate or azathioprine.
Retinoids
Retinoids are vitamin A-derived compounds that have multiple skin benefits. They provide several advantages, including reduced inflammation, unclogged pores, reduced wrinkle appearance and controlled cell growth on the skin’s surface.
Retinoids and vitamin A supplements may increase the risk of hypervitaminosis A when taken together. You should regularly check your vitamin A blood levels if you take these oral medications together.
A Parting Reminder
Vitamin A is essential for the proper functioning of the body, especially for our eyes. A healthy, balanced diet of both animal and plant products can help you meet your daily vitamin A requirements. Animal products, which contain preformed vitamin A, and plant products, which contain provitamin A, will ensure your body receives enough of this essential vitamin.
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