(Extraído de Biology Site)
Vitamins are important to the normal growth and development of humans from its conception. A fetus needs certain vitamins in precise quantities at various stages in order to properly form skin, bones, and muscle. If one or more of these vitamins is deficient in the diet of the mother, the baby may suffer from various deficiency diseases which can cause permanent damage to the health of the child.
After the birth of a child, healthy doses of selected vitamins continue to be important in maintaining good health throughout life. Humans obtain most vitamins from food, but some are obtained by other means. As an example, Vitamin D is synthesized by a person's skin when it is exposed to natural sunlight!
VITAMIN DEFICIENCY DISEASES
There are two categories of vitamin deficiency - primary and secondary. Primary vitamin deficiency occurs when there is a shortage of a certain vitamin in the diet. Secondary vitamin deficiency occurs when there is some sort of underlying factor that prohibits the body from absorption of the vitamins in food. Such factors include the use of certain medications, excessive alcohol consumption, and smoking.
In the so-called "developed" world, vitamin deficiencies are uncommon because most people have access to adequate food supplies and many common foods are "fortified," or have had vitamins and minerals added to them during processing.
Following is a list of known vitamin deficiency diseases:
Vitamin A - Night-blindness, Hyperkeratosis, Keromalacia
Vitamin B1 - Beriberi, Wernicke-Korsakoff syndrome
Vitamin B2 - Ariboflavinosis
Vitamin B3 - Pellagra
Vitamin B5 - Paresthesia
Vitamin B6 - Anemia, Peripheral neuropathy
Vitamin B7 - Dermatitis, enteritis
Vitamin B9 - Neural Tube birth defects
Vitamin B12 - Megaloblastic anemia
Vitamin C - Scurvy
Vitamin D - Rickets, Osteomalacia
Vitamin E - Mild hemolytic anemia in newborns
Vitamin K - Bleeding diathesis
The current RDA for vitamins is as follows:
Vitamin A -- 5000 IU
Vitamin C -- 60 mg
Vitamin D -- 10 mcg (400 IU)
Vitamin E -- 10 mg (15 IU)
Vitamin K -- 80 mcg
Thiamin -- 1.5 mg
Riboflavin -- 1.8 mg
Niacin -- 20 mg
Vitamin B-6 -- 2 mg
Folate -- 400 mcg
Vitamin B-12 -- 2 mcg
Biotin -- 30 to 100 mcg
Panthothenic acid -- 4 to 7 mg
DO I HAVE A VITAMIN DEFICIENCY?
The following health conditions are often (but not always) caused by vitamin deficiencies:
Premature graying - Deficiencies in Pantothenic acid (B5)
Hair loss - Deficiencies in Folate, B5, B6, or B-complex
Dandruff - Deficiencies in B6 or B-complex
Tooth decay - Deficiencies in B6
Bleeding gums - Deficiencies in vitamin C
Cracks at the corners of the mouth - Deficiencies in B2 (riboflavin) or B-complex.
Sore tongue (glossitis) - Deficiencies in B12 or folate, zinc or iron.
Dark circles under eyes - Deficiency in vitamin C
Dry skin - Deficiencies in vitamin A or vitamin E
Small red bumps on back of arms - Deficiencies in vitamin A or vitamin E
Slow wound healing - Deficiencies in vitamin A or vitamin C
Easy bruising - Deficiencies in vitamins K, C, or E
Cold hands - Deficiencies in niacin (B3), vitamin E, or B12
It should be noted, however, that the only sure way to determine if you have a vitamin deficiency is to have your physician run blood tests, which should be a part of your regular physical examinations..
Generally, if you consume a varied, balanced diet, vitamin supplements may not be necessary. Many people, though, have made the taking of vitamin supplements part of their daily routine. If supplements are part of your routine, it is important that you ensure you get at least 100% of the Recommended Daily Allowance (RDA) of any vitamin.
Earl Mindell's New Vitamin Bible
One of the best resource guides on vitamins/supplements! Includes information on how to maximize the effectiveness of your vitamins/supplements and avoid problems by taking them in the right combinations, new warnings about potentially drug interactions, expanded sections on nutraceuticals, homeopathy and aromatherapy, and information on how to personalize your dietary regimen to fit your lifestyle and health profile.
Nutrient A-Z: A User's Guide to Foods, Herbs, Vitamins, Minerals & Supplements
This book is an excellent quick reference guide to vitamins, minerals and other food supplements. Each entry provides a definition, i.e. what it is, where it comes from, the form it takes, how to prepare or take it, the medicinal and health benefits and the recommended daily use.