Retinol or Vitamin A is an essential fat-soluble nutrient that plays a significant role in human development, eyesight, and the maintenance of healthy skin. Retinoic acid is needed in the growth and development of embryos and is a key element in the differentiation of stem cells. It is also vital for the proper working of epithelial cells and for maintaining healthy epithelial tissues and skin, which function as a physical barrier to diseases. The nutrient is required in the production of red blood cells and the human growth hormone.
Retinol plays a vital role in night vision and eye health by maintaining a clear cornea and protecting against eye diseases like age-related macular degeneration (AMD). It is also important for preserving fertility, immunity and healthy tooth and bone development. Retinol also works as an antioxidant, which is a protective compound that may lower the risk of certain types of cancer.
Dietary sources of vitamin A include:
These are active forms that are immediately usable in the body. These sources include:
- Cod liver oil
- Dairy products: milk, butter, cheese
- Liver, beef, pork, fish, chicken, turkey
These are precursors or provitamins and must be transformed into active forms by the body. They are found in fruits and vegetables with orange, dark green and yellow pigments, including carrots, sweet potatoes, broccoli, pumpkins, etc.
Retinol is also available as a dietary supplement. It was identified in 1909, isolated in 1931 and produced in 1947. It features on the List of Essential Medicines by the World Health Organization (WHO), the most effective and safest medicines necessary in a healthy system.
Vitamin A deficiency (VAD) is a lack of vitamin A in the tissues and blood. It is more common among women of childbearing age and children in the developing world. Its signs and symptoms include pale, dry skin, keratomalacia and night blindness. VAD is the leading cause of preventable blindness in children. It can also reduce the ability to fight infections. Even mild, subclinical deficiency may be an issue because of increased risk of the children developing diarrheal and respiratory diseases, slow bone development, reduced growth rate, and decreased chances of survival from a severe illness.
- Prescription medication
- Over the counter supplements
Retinol is used in the prevention and treatment of hypovitaminosis A or VAD, particularly xerophthalmia. It is an eye disorder where the patient's eye can't produce tears. The condition is caused by severe VAD and leads to morbid dryness of the conjunctiva and cornea. If not treated, can result in ulceration of the cornea leading to blindness from corneal and retinal damage.
Retinol is also useful in the treatment of many conditions, including:
- Breast cancer
- Oral leukoplakia
- Retinitis pigmentosa
- Complications after childbirth
- Inflammatory bowel disease (ulcerative colitis)
Retinol is also regarded as the gold-standard of anti-aging skincare. It is famous for its rejuvenating and reparative effects. It is added to skin and eye creams and serums. Retinol helps to boost the amount of collagen the body makes and transports it to the surface, which cuts down wrinkles and fine lines. It can also reduce acne, mottled patches and improve skin tone and color. Retinol is also considered a powerhouse ingredient that can work wonders to enhance the appearance of the under-eye area.
Mode of Administration
Retinol may be taken by mouth or applied on the skin. If it is required in high doses the doctor will inject it into a muscle.
The anti-aging skincare products are best applied at night, followed by moisturizer and sunscreen in the morning.
The Recommended Daily Intake for vitamin A per day:
- Up to six months - 400 mcg
- Seven to twelve months - 500 mcg
- One to three years -300 mcg
- Four to eight years - 400 mcg
- Eight to thirteen years - 600 mcg
- 14 to 18 years - 900 mcg
Pregnant girls between 14 and 18 years - 750mcg
Lactating girls between 14 and 18 years - 1,200 mcg
Adults above 25 years
- Male - 900 mcg
- Female - 700 mcg
Potential Side Effects
Retinol at the recommended doses is well tolerated. However, high doses may be harmful or fatal. It may lead to the toxicity of the optic nerve and cause permanent vision loss. It can also cause dry skin, hair loss, enlarged liver, or hypervitaminosis. Excess vitamin A can also increase bone loss, suppress bone rebuilding, and raise the risk of osteoporosis and lung cancer.
High doses of vitamin A during early pregnancy can be harmful to the baby and are linked to a significant rise in congenital disabilities. It's not safe for pregnant women to use retinol or any form of vitamin A.
Using the topical products can make the top layer of the skin dry and flaky. Retinol can be an irritating ingredient to some causing increased skin sensitivity, itchiness, redness, and peeling, even at low percentages.
One should consult a doctor, pharmacist, or dermatologist before using retinol topical products.
Patients being treated with any of the following medications should consult the doctor before taking vitamin A supplements:
- Neomycin (Mycifradin)
- Tetracycline antibiotics
- Orlistat (Alli) and Olestra
- Anticoagulants (blood thinners)
- Cholesterol-lowering medications (bile acid sequestrants)
Patients with any of the following conditions should also see a doctor before taking vitamin A:
- Acne vulgaris
- Kidney or liver disease
- Problems with alcohol abuse
- Conditions that affect the patient's ability to absorb nutrients from food
Symptoms of Overdose
Symptoms of sudden vitamin A overdose include:
- Skin peeling
- Stomach pain
- Increased pressure in the area between the skull and the brain
Carotenosis is a significant sign of vitamin A toxicity. It is a condition which causes the palms and soles of the feet to have a deep orange or yellow color. Other long-term vitamin A toxicity symptoms include:
- Dry skin
- Itchy skin
- Coarse hair
- Cracked lips
- Severe headache
- Sunlight sensitivity
- Thinning eyebrows
- Visual disturbances
If one experiences the overdose or toxicity symptom they should stop taking the supplements and consult a doctor.