Get the right amount of VITAMIN A
VITAMIN A is a fat-soluble vitamin, also known as retinol because it produces the pigments in the retina of the eye.
Vitamin A plays essential roles in vision, growth and development of a person, maintaining healthy teeth, skeletal and soft tissue. It also plays essential roles in the development and maintenance of healthy skin, hair, and mucous membranes, immune functions, reproduction and breastfeeding. Retinol is an active type of vitamin A. It is found in animal liver, whole milk, and some fortified foods.
Although normal foetal development requires sufficient vitamin A intake, consumption of excess preformed vitamin A (retinol) during pregnancy is known to cause birth defects. Since a number of foods are fortified with preformed vitamin A, pregnant women should avoid multivitamin or prenatal supplements that contain more than a certain level of vitamin A.
Both vitamin A excess and deficiency are known to cause birth defects. Vitamin A deficiency among children in developing nations is the leading preventable cause of blindness. The earliest evidence of vitamin A deficiency is impaired dark adaptation or ‘night blindness’. Mild vitamin A deficiency may result in changes in the conjunctiva (corner of the eye) called Bitot’s spots. Severe or prolonged vitamin A deficiency causes a condition called xeropthalmia (dry eye), characterized by changes in the cells of the cornea (clear covering of the eye) that ultimately result in corneal ulcers, scarring, and blindness.
Sources of Vitamin A
Eating a variety of foods that contain vitamin A (and carotene) is the best way to get an adequate supply. Healthy individuals who eat a balanced diet rarely need supplements.
What are the other sources of Vitamin A?
Vitamin A is found naturally in many foods such as the following
• Butter • Sweet pepper • Collard greens
• Eggs • Broccoli • Carrots
• Kale • Pumpkins • Sweet potatoes
Vitamin A deficiency and infectious disease
Vitamin A deficiency can be considered a nutritionally acquired immunodeficiency disease. Even children who are only mildly deficient in vitamin A have a higher incidence of respiratory disease and diarrhoea, as well as a higher rate of mortality from infectious disease, than children who consume sufficient vitamin A. Supplementation of vitamin A has been found to decrease the severity of, and deaths from, diarrhea and measles in developing countries, where vitamin A deficiency is common.
HIV infected women who are vitamin A deficient have been thought to be three to four times more likely to transmit HIV to their infants. The onset of infection reduces blood retinol levels very rapidly. This phenomenon is generally believed to be related to decreased synthesis of retinol binding protein (RBP) by the liver. In this manner, infection stimulates a vicious cycle, because inadequate vitamin A nutritional status is related to increased severity and likelihood of death from infectious disease.
Symptoms of Vitamin A deficiency
Night blindness, corneal drying (xerosis), triangular gray spots on eye (Bitot’s spots), corneal degeneration and blindness (xerophthalmia), impaired immunity, hypokeratosis (white lumps at hair follicles), softening of the cornea (keratomalacia).
Symptoms of Vitamin A overdose
As vitamin A is fat-soluble, disposing of any excesses taken in through diet is a lot harder than with water-soluble vitamins B and C. As such, vitamin A toxicity can result. This can lead to nausea, jaundice, irritability, vomiting, blurred vision, headaches, muscle and abdominal pain and weakness, drowsiness and altered mentality. In chronic cases, hair loss, drying of the mucous membranes, fever, insomnia, fatigue, weight loss, bone fractures, anaemia, and diarrhoea can all be evident on top of the symptoms associated with less serious toxicity.
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