Role of Vitamin A in Human Metabolic Processes
As we all know, vitamins are essential for carrying out the structure of normal metabolic processes. The deficiency of any of these substances can lead to serious diseases. In order to avoid such circumstances, one should take enough vitamins according to their sex, age and weight. Vital role in the normal course of metabolic processes has vitamin A.
Vitamin A
It is a fat-soluble vitamin that exists in two forms. The first one is found only in animal products and is known as a complete vitamin A (retinol – a name given in connection with the participation of this compound in the functions of the retina of the eye). The second form is known as provitamin A(carotene) and is found in both animal and in plant products. Vitamin A is also called “anti-infective” vitamin because of its role in supporting the immune system.
Vitamin A plays a role in a variety of metabolic functions throughout the body, such as:
- vision
- gene transcription
- immune function
- embryonic development and reproduction
- bone metabolism
- haematopoiesis
- skin and cellular health
- antioxidant activity
Vitamin A, and more specifically, retinoic acid, appears to maintain normal skin health by switching on genes and differentiating keratinocytes (immature skin cells) into mature epidermal cells. This is why Vitamin A supports growth and regulates the metabolic processes in epithelial tissue. It is also responsible for skin’s good condition, focusing on qualities such as strength, elasticity, smooth and fresh complexion. It is essential for maintaining normal vision and eye health, because it is an important component of the visual pigment rhodopsin in the human retina. Night vision also depends on it.
People dealing with physical work and power sports have greater need for vitamin A. If you are an athlete, Vitamin A is important for you because it helps burning body fat. Combination with vitamin B-group vitamins D and E, calcium, phosphorus and zinc is optimal.
Vitamin A accumulates in human body, so it is not necessary to supply your body with it every day. It is good for the development and protection of certain body cells, for the development of bone structure, and teeth and gums formation. It participates in the regulation of metabolism.
It is a fact that Vitamin A has a prophylactic effect against certain types of cancer; it contributes to reducing the harmful cholesterol. There is sufficient evidence for its preventive function in terms of heart disease. It is especially needed in the autumn and winter, since it increases the body’s resistance against respiratory infections, strengthens the immune system and shortens the duration of disease.
Vitamin A is available in foods such as milk, egg yolk, liver, eggs, butter, and fish oil. Many vegetable oils, vegetables such as dark leafy greens, tomatoes, red peppers, carrots, and fruits – apples, peaches, apricots, some kinds of melon, are extremely rich in carotene. It is high concentrated in citrus fruits as well.
The recommended daily dose of Vitamin A (RDA) by the Food and Nutrition Board of the U.S. National Academy of Sciences are:
- Infants up to 1 year old – 1,250 IU per day
- Children 1 through 3 years old – 1,333 IU per day
- Children 4 through 6 years old – 1,667 IU per day
- Children 7 through 10 years old – 2,333 IU per day
- Males 11 years and older – 3,333 IU per day
- Females 11 years and older – 3,333 IU per day
- Pregnant/Lactating 1st 6 months – 4,333 IU per day
- Pregnant/Lactating 2nd 6 months – 4,000 IU per day
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