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Clinician’s Corner: Vitamin-A

Now we start our journey through the fat-soluble vitamins of A, D, E, K.  These vitamins can accumulate and cause adverse effects.  Rarely does someone get excess fat-soluble vitamins from the diet, but excess supplementation may cause accumulation and potential serious side effects.


What it does: Vitamin A is necessary immune function, vision, reproduction, and cellular communication. Vitamin A is critical for vision to absorb light in the retinal receptors in the back of our eyes.  Vitamin A also supports cell growth and differentiation, playing a critical role in the normal formation and maintenance of the heart, lungs, kidneys, and other organs

  • Dietary sources: fish liver oils, egg yolks, green leafy, orange & yellow vegetables.

Deficiency States:

  • Night blindness: early sign of Vitamin-A deficiency. May progress to dryness & ulceration of the cornea. May progress to blindness.
  • See decrease in heath and integrity of skin

Adverse effects from excessive doses: dry mucus membranes, cracking of the lips, yellowing of skin, fatigue, nausea, hair loss, headache, dizziness, blurred vision, birth defects, loss of muscular coordination, dry scaly skin.

  • Multivitamin supplements typically contain 2,500–10,000 IU vitamin A
  • Excess Vitamin-A supplementation: massive headache, dizziness, nausea, skin irritation, pain in joints and bones, coma, and even death.

Smokers should avoid Vitamin-A supplements. Taking beta-carotene seems to increase the risk of lung cancer in people who smoke (especially those smoking more than 1 pack per day), former smokers, asbestos exposure, and those who use alcohol (one or more drinks per day) in addition to smoking. Beta-carotene from the diet does not seem to have this adverse effect.

Because of the risk of excessive Vitamin-A supplementation, it is very important to consult your Thompson Pharmacist before supplementing with Vitamin-A alone.  Go Ahead and ASK… at Thompson Pharmacy, it’s all for YOU!