Vitamin A : Daily Requirement, Warnings, Side Effects, Sources, Benefits, and Deficiency

Vitamin A : Daily Requirement, Warnings, Side Effects, Sources, Benefits, and Deficiency



Basic Overview about Vitamin A: It is an antioxidant that protects our cells from free radicals. There are two main sources of vitamin A – retinol which comes from animal products such as liver, egg yolk, and milk; and beta carotene, which comes from plant sources and they are provitamin A. Others include retinal  and retinoic acid. It is fat soluble.

Other alternative names: 3-Dehydroretinol, Axerophtholum, Retinol Acetate, Retinol Palmitate, Retinyl Acetate, Retinol; Retinal; Retinoic acid; and Carotenoids.

Usage Information; it is indicated for: essential for normal function of retina, as a cofactor in enzyme systems, necessary for growth of bone, testicular and ovarian function, embryonic development, regulation of growth and differentiation of tissues.

Warnings and Precautions: Don’t take if you are allergic to any preparations containing vitamin A and don’t take doses greater than the RDA if you are planning a pregnancy or are pregnant.

Consult doctor if you have: cystic fibrosis, diabetes, intestinal disease with diarrhea, kidney disease, liver disease, overactive thyroid function, and pancreas related illnesses, viral hepatitis, chronic alcoholism, pregnant, and are lactating.

Over 60s: dosage must be taken carefully to avoid possible toxicity.

Pregnancy: Exceeding normal daily doses can lead to growth retardation and urinary tract malformation of the fetus.

Side effects of adverse reactions: abdominal pain, appetite loss, bone or joint pain, discomfort, tiredness or weakness, may increase risk for osteoporosis or  hip joint fracture in older people, drying or cracking of skin or lips, fever, hair loss, headache, increase frequency of urination, increased sensitivity of skin to sunlight, irritability, vomiting, yellow-orange patches on soles of feet or palms of hands or skin around nose and lips.

Overdose or Toxicity can result in: gum bleeding, mouth sore, bulging soft spot on head in babies, confusion or hallucination, diarrhea, dizziness, double vision, headache, irritability, dry skin, hair loss, peeling skin on lips and palms, seizures, nausea or vomiting, enlarged liver and spleen, and yellow and orange colored skin. If you have a type of high cholesterol condition called Type V hyperlipoproteinemia, it might increase your chance of vitamin A poisoning. Excessive amount can turn skin color to yellow-orange. Symptoms usually appear gradually and about 7 hours after overdose ingestion. If these occur, discontinue the supplement and consult doctor. For accidental overdose, call 911 or Poison Control Center.

Interactions with other medications such as antibiotics (when taking  along with very large amounts of vitamin A, it can increase the chance of a serious side effect called intracranial hypertension), vitamins, minerals, supplements and substances: antacids, mineral oil neomycin, olestra-fat substitute, tobacco, and cholestyramine decrease the absorption; using warfarin (Coumadin) simultaneously may increase the chances of bruising and bleeding; calcium effects may be decreased; and alcohol abuse interferes with transport and use. High intake of vitamin-A can even interfere with working benefits of Vitamin D.

Available forms: Extended release capsules or tablets and oral solutions.

Is prescription needed? No.

How much required by our body? Probable Optimal Intake or Daily Value is 5,000IU; Eating 5 servings of fruits and vegetables per day can provide more than half of the daily vitamin A requirements by an adult body.

Infants (average intake): 0 – 6 months: 400 micrograms per day (mcg/day) and 7 – 12 months: 500 mcg/day. Children (RDA): 1 – 3 years: 300 mcg/day; 4 – 8 years: 400 mcg/day; and 9 – 13 years: 600 mcg/day

Recommended Dietary Allowances (RDA) Men 900mcg and Women 700mcg.

Natural Sources besides prescriptions and supplements are: apricots, asparagus, beef, broccoli, calf, cantaloupe, carrots, cheese, chicken liver, cod liver oil, collard greens, dandalion greens, eggs, raw endive, kale, leaf lettuce, fish liver oils, mango, milk, mustard greens, pea, pumpkin, spinach, winter squash, sweet potatoes, tomatoes, watermelon, and yogurt. The more intense the color of the fruits and vegetables have higher beta-carotene content found in them.

Storage: store in cool, dry place away from direct light, but don’t freeze. Store safely out of children reach. Don’t store in bathroom medicine cabinet since heat and moisture may change the working action (pharmakokinetics).

Benefits: Why do people take it?

Vision: aids in treatment and prevention of some eye disorders including night blindness and formation of visual purple of eye. It is involved in the formation of rhodopsin, which is a light absorbing molecule for both scotopic vision and color vision. It produces pigments in the retina.  May help control glaucoma or age related macular degeneration.

Bone: promotes bone health and teeth growth and development. Vitamin A is involved in remodeling bone.

Tissues: helps form and maintain healthy skin, mucous membranes and hair. It may help treat acne, impetigo, boils, carbuncles and open ulcers when applied topically. May speed healing of cuts, lesions and wounds.

Immune system: builds body’s resistance to respiratory and other infections.

Hormone: possible treatment for hyperthyroidism.

Reproduction: it is also needed for reproduction and breast feeding a baby. Women use vitamin A for heavy menstrual periods, premenstrual symptoms (PMS), vaginal or yeast infections, “lumpy breasts” (fibrocystic breast disease), and to prevent breast cancer. Men use to increase sperm count.

Other uses in people with:

Inadequate caloric consumption or nutritional dietary intake resulting in malnourishment, increased nutritional requirements, abuse of drugs and alcohol, prolonged fever, chronic wasting illness, excess stress persistently, fast recovery from recent undergone laser surgery, severe burns or injuries, and impaired immunity.

Signs and Symptoms of Deficiency; you may be lacking this supplement if you have one of the following conditions present: night blindness, decreased tear secretion, susceptible to infectious disease, dry and rough skin, weight loss, poor bone growth, weak tooth enamel, diarrhea, slow growth, acne, insomnia and fatigue. Primary deficiency is caused by low intake of vitamin A; whereas secondary deficiency is due to malabsorption.

Tests to detect deficiency: plasma vitamin A and plasma carotene, dark-adaptation test, electronystagmogram, and electroretinogram.

References:

Feskanich D, Singh V, Willett WC, Colditz GA. Vitamin A intake and hip fractures among postmenopausal women. JAMA. 2002; 287:47-54.

Michaelsson K, Lithell H, Vessby B, Melhus H. Serum retinol levels and the risk of fracture. New England Journal Medicine. 2003; 348:287-94.

Sarubin Fragaakis A, Thomson C. The Health Professional’s Guide to Popular Dietary Supplements. 3rd ed. Chicago, IL: American Dietetic Association, 2007.

Azais-Braesco V, Pascal G. Vitamin A in pregnancy: requirements and safety limits. American Journal of Clinical Nutrition. 2000; 71:1325S-33S.

Albanes D, Heinonen OP, Taylor PR, et al. Alpha-Tocopherol and beta-carotene supplements and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study: effects of base-line characteristics and study compliance. Journal of Nattionl Cancer Institute. 1996; 88:1560-70.

Terms of Use: The information presented here is only for general use and not intended as a medical advice; it may not be up to date or even include some errors. Please seek help of your doctor or health care professional regarding healthy or any medical advice.


| Published on May 2nd, 2013 at 1:28 am | Article of: food and drinks, Health | Resource for: , |

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