Vitamin A deficiency (VAD) or hypovitaminosis A is a lack of vitamin A in blood and tissues. It is common in poorer countries, especially among children and women of reproductive age, but is rarely seen in more developed countries. Nyctalopia i.e. night blindness is one of the first signs of VAD. Xerophthalmia, keratomalacia, and complete blindness can also occur since vitamin A has a major role in phototransduction. The three forms of vitamin A include retinol, beta-carotene, and provitamin A carotenoids. Looking at the risk factors of Vitamin A deficiency, Siddha Spirituality of Swami Hardas Life System appeal to our valuable readers to read this informative article for well-being.
Vitamin A Meaning
The word “vitamin” was coined in 1911 by the Warsaw-born biochemist Casimir Funk (1884-1967). At the Lister Institute in London, Funk isolated a substance that prevented nerve inflammation in chickens raised on a diet deficient in that substance. He named the substance “vitamine” because he believed it was necessary to life and it was a chemical amine. The “e” at the end was later removed when it was recognized that vitamins need not be amines.
Vitamin A Definition
Vitamin A is retinol. Carotene compounds are gradually converted by the body to vitamin A (retinol). A form of vitamin A called retinal is responsible for transmitting light sensation in the retina of the eye. Vitamin A deficiency leads to night blindness.
The letters (A, B, C, and so on) were assigned to the vitamins in the order of their discovery. The one exception was vitamin K which was assigned its “K” from “Koagulation” by the Danish researcher Henrik Dam. The various vitamins include:
An antioxidant that protects cells against oxidation damage that can lead to cancer. Beta carotene is converted, as needed, to vitamin A. Food sources of beta carotene include vegetables such as carrots, sweet potatoes, spinach, and other leafy green vegetables; and fruit such as cantaloupes and apricots. Excessive carotene in the diet can temporarily yellow the skin, a condition called carotenemia, commonly seen in infants fed largely mushed carrots.
Riboflavin, essential for the reactions of coenzymes. Deficiency causes inflammation of the lining of the mouth and skin.
Folate (folic acid)
Folic acid is an important factor in nucleic acid synthesis (the genetic material). Folate deficiency leads to megaloblastic anemia.
Ascorbic acid, important in the synthesis of collagen, the framework protein for tissues of the body. Vitamin C deficiency leads to scurvy, characterized by fragile capillaries, poor wound healing, and bone deformity in children.
Steroid vitamin that promotes absorption and metabolism of calcium and phosphorus. Under normal conditions of sunlight exposure, no dietary supplementation is necessary because sunlight promotes adequate vitamin D synthesis in the skin. Deficiency can lead to osteomalacia in adults and bone deformity (rickets) in children.
It is a fat-soluble nutrient found in many foods. In the body, it acts as an antioxidant, helping to protect cells from the damage caused by free radicals. Free radicals are compounds formed when our bodies convert the food we eat into energy. However, Vitamin E deficiency can lead to anemia.
An essential factor in the formation of blood clotting factors. Deficiency can lead to abnormal bleeding.
Vitamin A deficiency Risk factors
Many people in developing countries do not get enough vitamin A. Those at the highest risk of deficiency are pregnant women, breastfeeding mothers, infants, and children. Cystic fibrosis and chronic diarrhea may also increase your risk of deficiency.
Vitamin A deficiency Symptoms
The most common cause of blindness in developing countries is Vitamin A deficiency (VAD). The WHO estimated in 1995 that 13.8 million children had some degree of visual loss related to VAD. Night blindness and its worsened condition, xerophthalmia, are markers of Vitamin A deficiency (VAD).
VAD can also lead to impaired immune function, cancer, and birth defects.
Night blindness is the difficulty for the eyes to adjust to dim light. Affected individuals are unable to distinguish images in low levels of illumination. People with night blindness have poor vision in the darkness but see normally when adequate light is present.
VAD affects vision by inhibiting the production of rhodopsin, the eye pigment responsible for sensing low-light situations.
Because the body cannot create retinal in sufficient amounts, a diet low in vitamin A leads to a decreased amount of rhodopsin in the eye, as the retinal is inadequate to bind with opsin. Night blindness results.
Along with poor diet, infection and disease are common in many developing communities. Infection depletes vitamin A reserves which in turn make the affected individual more susceptible to further infection.
Increased incidence of xerophthalmia has been observed after an outbreak of measles, with mortality correlated with the severity of eye disease. In longitudinal studies of preschool children, susceptibility to disease increased substantially when severe VAD was present.
Vitamin A deficiency Causes
Iron deficiency can affect vitamin A uptake; other causes include:
- Pancreatic insufficiency
- Inflammatory bowel disease
- Small-bowel bypass surgery
- Protein-energy malnutrition
- Suppressed synthesis of retinol-binding protein (RBP)
Excess alcohol consumption can deplete vitamin A, and a stressed liver may be more susceptible to vitamin A toxicity. People who consume large amounts of alcohol should seek medical advice before taking vitamin A supplements. In general, people should also seek medical advice before taking vitamin A supplements if they have any condition associated with fat malabsorption such as:
- Cystic fibrosis
- Tropical sprue
- Biliary obstruction
Other causes of vitamin A deficiency are inadequate intake, fat malabsorption, or liver disorders. Deficiency impairs immunity and hematopoiesis and causes rashes and typical ocular effects e.g. xerophthalmia, night blindness.
Vitamin A deficiency Diagnosis
Several methods of assessing bodily vitamin A levels are available, with HPLC the most reliable. Measurement of plasma retinol levels is a common laboratory assay used to diagnose VAD. Other biochemical assessments include measuring plasma retinyl ester levels, plasma, and urinary retonioic acid levels, and vitamin A in breast milk.
Vitamin A deficiency Treatment
Treatment of VAD can be undertaken with both oral vitamin A and injectable forms, generally as vitamin A palmitate.
As an oral form, the supplementation of vitamin A is effective for lowering the risk of morbidity, especially from severe diarrhea, and reducing mortality from measles and all-cause mortality. Vitamin A supplementation of children under five who are at risk of VAD can reduce all-cause mortality by 23%. Some countries where VAD is a public-health problem address its elimination by including vitamin A supplements available in capsule form with national immunization days (NIDs) for polio eradication or measles.
Maternal high supplementation benefits both mother and breast-fed infant: high-dose vitamin A supplementation of the lactating mother in the first month postpartum can provide the breast-fed infant with an appropriate amount of vitamin A through breast milk. However, high-dose supplementation of pregnant women should be avoided because it can cause miscarriage and birth defects.
Genetic engineering is another method that could be used to fortify food, and golden rice is a genetic engineering project designed to fortify rice with beta-carotene (which humans can convert into vitamin A) and thereby prevent and/or treat VAD.
Dietary diversification can also control VAD. Nonanimal sources of vitamin A like fruits and vegetables contain preformed vitamin A and account for greater than 80% of intake for most individuals in the developing world. The increase in consumption of vitamin A-rich foods of animal origin has beneficial effects on VAD.
The richest animal sources of vitamin A (retinol) are livers (beef liver – 100 grams provides around 32,000 IUs, and cod liver oil – 10 g provides around 10,000 IUs).
Researchers at the U. S. Agricultural Research Service have been able to identify genetic sequences in corn that are associated with higher levels of beta-carotene, the precursor to vitamin A. They found that breeders can cross certain variations of corn to produce a crop with an 18-fold increase in beta-carotene. Such advancements in nutritional plant breeding could one day aid in the illnesses related to VAD in developing countries.
Good sources of Vitamin A
Most Americans get enough from their food, but moms-to-be might want to add an extra helping because it helps the baby grow. Red peppers are an excellent source: A half-cup gives you almost half of what you need for a single day.
There are two kinds of vitamin A: Preformed vitamin A — from meat, poultry, fish, and dairy — arrives in your body ready to use.
The second kind, provitamin A, comes from certain fruits and veggies, like spinach. Your body has to process it before it can go to work.
It may not be the meal you crave, but it’s full of vitamin A, which gives your immune system a huge boost — it keeps the cells that protect you against infection working the way they should. It also helps make the antibodies that fight off any threats that get past other defenses.
Here’s a good reason to load up your plate with these versatile veggies: They’re a great source of vitamin A. One baked sweet potato gives you more than one and a half times the amount you need each day.
Which sounds better: a cup of ice cream or 14 servings of tuna? Believe it or not, both have the same amount of vitamin A (about 20% of what you should get each day).
Vitamin A helps your heart, lungs, and kidneys do their work. So if you’re having dessert, think about a slice of pumpkin pie. It has plenty of beta-carotene, an antioxidant your body turns into vitamin A.
Vitamin A keeps your eyes working the way they should. People who don’t get enough — it’s mainly a problem in Africa and Southeast Asia — can have night blindness. So keep an eye out for chances to get your daily dose. Just a half-cup of raw carrots will give you half of what you need in a day.
If it’s tough for you to get all the A you need from food, you might try fortified foods. They have an extra helping of the vitamin. These foods include cereals, condiments, sugar, and milk. You’ll also find it in supplements. Talk to your doctor about the right amount for you.