Vitamin Deficiencies | What You Need to Know

vitamin deficiencies


At the most fundamental level, vitamins are organic molecules that act as vital micronutrients to sustain many essential biological processes. Here, we talk about vitamin deficiencies and what biological effects they’re linked to.

As part of your next clinical pharmacy exam, you will be expected to have a rounded knowledge of vitamins, their names and effects, as well as the supplemental versions of these vitamins that are used to treat a wide range of conditions.

Vitamins can be divided into water-soluble and fat-soluble vitamins:

  • B complex and vitamin C are water-soluble vitamins. Because they are water soluble, they are readily eliminated from the body and so more consistent dietary intake is needed.
  • Fat soluble vitamins include A, D, E and K. With the help of lipids, these vitamins are readily absorbed from the intestinal tract.

Vitamins have innumerable biochemical functions:

  • Vitamins C and E are antioxidants
  • B vitamins function as enzyme cofactors (or are precursors to them)
  • Vitamin D acts in a hormone-like capacity with bone metabolism
  • Vitamin A is a regular of cell and tissue growth, repair and differentiation

With this classification and these biochemical functions in mind, let’s now turn our attention to what happens when deficiency arises.

Let’s begin with B complex vitamins.

B Vitamins

B vitamins are water-soluble vitamins that play an enormous role in the regulation of aspects of cellular metabolism.

Below, we’ve put together the various types of B vitamin, their standard name, as well as what effects manifest from deficiency.

B VitaminNameEffects
Vitamin B1ThiamineDeficiency causes beriberi – symptoms of which include Wernicke encephalopathy, limb weakness and weight loss.

Chronic thiamine deficiency is linked to alcohol Korsakoff syndrome.

Vitamin B2RiboflavinDeficiency causes ariboflavinosis – characterised by cheilosis, angular cheilitis, photosensitivity, glossitis, pharyngitis and edema of the throat and oral cavity.
Vitamin B3NiacinDeficiency causes pellagra (often with a deficiency of tryptophan); symptoms include insomnia, weakness, aggression, confusion and, in advanced cases, dementia.
Vitamin B5Pantothenic acidRare, but can lead to acne and paresthesia.
Vitamin B6PyridoxineVitamin B6 deficiency can lead to seborrheoic dermatitis, peripheral neuropathy and epilepsy.
Vitamin B7BiotinIn infants, biotin deficiency can lead to impaired growth / neurological damage. Symptoms rare in adults.

Previously known as vitamin H.

Vitamin B9Folic acidDeficiency causes macrocytic anemia and high homocysteine levels. Birth defects may occur in pregnant women.
Vitamin B12CobalaminPernicious anemia is a common cause of vitamin B12 deficiency. Cobalamin deficiency can lead to megaloblastic anemia. Peripheral neuropathy may also result.

Other Vitamins

Vitamin C – like the B vitamins above – is a water-soluble vitamin.

All other vitamins tabled below – namely, A and D and E and K – are fat soluble vitamins that are readily absorbed through the gastrointestinal tract. Let’s quickly review these vitamin deficiencies.

Vitamin CAscorbic acidVitamin C deficiency is today rare, but can lead to scurvy which is characterised by bleeding gums, connective tissue damage, weight loss, weakness, generalised aches / pains, and skin bleeding.
Vitamin ARetinolDeficiency can cause night blindness, or nyctalopia and keratomalacia. If left untreated, it can lead to permanent blindness.
Vitamin DCholecalciferol (D3)

Ergocalciferol (D2)

Vitamin D deficiency often linked to a lack of sun exposure. Very little vitamin D is obtained from the diet. Deficiency leads to rickets and other bone-related diseases, such as osteoporosis and osteomalacia.
Vitamin ETocopherols


Very rare. When it occurs, it’s usually a product of impaired fat absorption / metabolism. Symptoms of deficiency include impaired nerve conduction, myopathies, hemolyticanemia and retinopathy.
Vitamin KPhytomenadione (K1)

Menaquinone (K2)

Deficiency leads to impaired blood coagulation (Koagulation, from the German, where its name derives). It can also be caused by impaired fat absorption.

As part of your NAPLEX exam, or other clinical pharmacy test, candidates are expected to have a thorough knowledge of vitamins deficiencies, as well as how medicinal supplement versions should be administered, and what side effects and drug interactions they’re linked to.

As part of our online pharmacy course, we’ve put together a comprehensive range of NAPLEX questions that address each of these topics – complete and effective preparation for this part of your clinical pharmacy examination.

If you haven’t already, take a few minutes to become a registered member of NAPLEX Study Guide and receive instant access to all these learning tools.


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