Vitamin A deficiency can result from various causes, including insufficient intake of vitamin A-rich foods, poor fat absorption, or liver disorders. This deficiency may weaken the immune system, impair blood formation, cause skin rashes, dryness of the conjunctiva, and affect the eye’s lens.
Vitamin A deficiency is the leading cause of preventable blindness in children. It also significantly raises the risk of severe illnesses and death from common infections such as diarrhea. For pregnant women, especially in the last trimester, deficiency can cause night blindness and increase mortality risk. The World Health Organization classifies vitamin A deficiency as a public health issue in over half of the world’s countries, particularly in Africa and Southeast Asia. Around one-third of children aged 6 to 59 months were affected in 2013, with children and pregnant women in developing countries being the most vulnerable.
Symptoms of Vitamin A Deficiency
Dry Skin
Vitamin A deficiency is linked to eczema development, characterized by irritated, dry, itchy skin, and other skin disorders such as scaling and thickening. This vitamin plays a vital role in skin cell growth and repair and helps fight inflammation associated with these conditions. For example, studies have shown that alitretinoin, a form of vitamin A, can reduce symptoms of hand eczema and enhance the effects of conventional treatments.
Deficiency is also associated with thickened pores, skin peeling, and keratinization, particularly in mucous membranes of the respiratory, digestive, and urinary tracts.
Dry Eyes
One of the earliest signs of vitamin A deficiency is dry eyes or inadequate tear production. Severe deficiency can lead to complete blindness or corneal death, identified by Bitot's spots. A study in Nepal showed that vitamin A supplementation over 16 months reduced conjunctival dryness in children by 63% and lowered the risk by 62%. However, research on vitamin A’s role in treating dry eyes remains limited.
Night Blindness
Severe vitamin A deficiency can cause night blindness. This condition is most prevalent in developing regions like South Asia. Supplementing vitamin A in women with night blindness has been shown to improve their ability to see in low light after six weeks of treatment.
Reproductive Issues and Pregnancy Complications
Vitamin A deficiency can cause infertility in both men and women. Animal studies indicate severe deficiency impairs pregnancy and increases birth defects. Vitamin A is essential for male reproductive health and sperm formation, as well as embryonic development. Oxidative stress is linked to infertility, and vitamin A, as an antioxidant, may play a role. Low levels of vitamin A have also been observed in women with recurrent miscarriages.
Women planning pregnancy who have low vitamin A levels are advised to correct this deficiency beforehand.
Growth Delay in Children
Vitamin A is crucial for normal growth. Deficiency can stunt growth, especially in children from developing countries. Studies indicate that vitamin A supplementation, alone or combined with other micronutrients, improves growth in children aged 6 to 48 months with low blood retinol levels.
Throat and Chest Infections
Vitamin A deficiency increases susceptibility to infections, particularly in the throat, chest, and abdomen. Some studies suggest beta-carotene (a vitamin A precursor) may reduce respiratory infections in older adults. In children with low weight, weekly vitamin A doses lowered respiratory infection risks. However, excessive supplementation in preschool children might increase respiratory infections, so vitamin A should be given only to those deficient.
Slow Wound Healing
Vitamin A promotes collagen formation, essential for skin health. Deficiency may delay wound healing after injury or surgery. Research shows oral vitamin A can enhance collagen production and control chronic wounds, especially in patients on corticosteroids for inflammatory diseases.
Acne
Vitamin A helps reduce acne severity by promoting skin growth and fighting inflammation. Lower vitamin A levels have been linked to worse acne. Isotretinoin, a well-known oral vitamin A derivative, is effective against acne but may cause side effects such as mood changes and birth defects.
Other Symptoms
Early vitamin A deficiency symptoms include dry hair, dry mouth, brittle nails, fatigue, cracked lips, mouth sores, diarrhea, urinary tract infections, and tear deficiency. Severe deficiency can lead to permanent blindness.
Groups Most at Risk
- Children: Deficiency leads to severe vision impairment and increases risks of serious infections and death.
- Pregnant Women: Especially in developing countries during late pregnancy, deficiency raises night blindness risk and possibly affects HIV transmission.
- Premature Infants: Often have low vitamin A stores, increasing risks of eye, lung, and digestive diseases.
- Cystic Fibrosis Patients: Due to pancreatic insufficiency, they have difficulty absorbing fats, increasing deficiency risk.
Treatment of Vitamin A Deficiency
Treatment depends on the severity of deficiency. Mild cases may be managed by increasing dietary intake of vitamin A-rich foods. More severe cases require medical supplementation under professional supervision.
Recommended Vitamin A Intake
| Age Group | Recommended Daily Intake (µg) |
|---|---|
| 0-6 months | 400 |
| 7-12 months | 500 |
| 1-3 years | 300 |
| 4-8 years | 400 |
| 9-13 years | 600 |
| Boys 14-18 years | 900 |
| Girls 14-18 years | 700 |
| Pregnant 14-18 years | 750 |
| Lactating 14-18 years | 1200 |
| Adults male (19+) | 900 |
| Adults female (19+) | 700 |
| Pregnant 19-50 years | 770 |
| Lactating 19-50 years | 1300 |
Sources of Vitamin A
Dietary Sources
Vitamin A comes in two main forms: Preformed vitamin A (retinol) found in animal products such as liver, fatty fish, and cheese; and Provitamin A (beta-carotene) found in fruits and vegetables like papaya, mango, and leafy greens.
| Food | Vitamin A Content (µg per serving) |
|---|---|
| Sweet Potato (whole) | 1,403 |
| Beef Liver (85g, fried) | 6,582 |
| Boiled Frozen Spinach (½ cup) | 579 |
| Raw Carrots (½ cup) | 459 |
| Fresh Cantaloupe (½ cup) | 135 |
| Red Bell Pepper (½ cup) | 117 |
| Boiled Egg (large) | 75 |
| Cooked Sockeye Salmon (85g) | 59 |
| Boiled Broccoli (½ cup) | 60 |
Supplements
Vitamin A supplements are rarely needed due to its abundance in foods. Excessive intake above 10,000 µg daily may cause toxicity, with symptoms such as headaches, dizziness, nausea, and vision problems. Chronic excess (hypervitaminosis A) can damage the liver, bones, and cause birth defects.
Carotenoid supplements are considered safer antioxidants but may cause skin to turn orange in high doses. It is generally better to consume carotenoids through a healthy diet rather than supplements.
Overview of Vitamin A
Vitamin A (retinol and retinoic acid) is a fat-soluble vitamin essential for vision, reproduction, growth, cell division, and immune function. It supports organs like the heart, lungs, and kidneys and has antioxidant properties that protect cells from damage by free radicals. Beta-carotene is converted in the body to vitamin A and contributes to the orange color in foods like carrots. Adequate vitamin A supports eye health but does not replace corrective lenses for vision correction.
If you want me to add any other details or adjust style, just let me know!
Leave a comment
Your email address will not be published. Required fields are marked *
