The vitamins have been identified since the early 20^th century and occur naturally and mostly in diets. Thirteen vitamins exist that are classified as fat-soluble (easily dissolvable in fats) and water-soluble (easily dissolvable in water). The fat-soluble vitamins are Vitamin A, D, E and K.

Vitamin A, also known as retinal, retinol or retinoic acid, is important organic nutrient integral to visual system, maintenance of immune system and development. It is a component of B-carotene, which is found in plants, algae and fungi.  Typical vegetables and fruits with increased contents are carrots, cauliflower and tomatoes.  Those with vitamin A deficiency, especially children, are afflicted with xerophthalmia (dry eyes), corneal ulceration, blindness, and increased mortality¹.  In Sub-Saharan Africa, and other developing countries, it is postulated that 1/3 of children under the age of 5 suffer from vitamin A deficiency.

Another fat-soluble vitamin is calciferol (Vitamin D), which is present in both plants and animals.  About 50-90% of it is produced when sunlight strikes the skin and converts a precursor to calciferol. Its presence is necessary for the calcium equilibrium in order to prevent osteopenia and osteoporosis. Adequate vitamin D level has also been associated with enhancement of the immune system, control of diabetes mellitus, prevention of cardiovascular conditions and cancer.  Fatty fish, such as mackerel, tuna are abundant in vitamin D as well as dairy products, egg yolks, beef liver, and soymilk.  Vitamin D deficiency is not as prevalence as vitamin A but has a host of complications, with approximately 1 billion of people suffering from diminished stores. Obesity, hypertension, rickets, osteoporosis, depression, fibromyalgia and certain cancers have all conditions that are linked to low calciferol levels.

Alpha tocopherol, the only human nutritious part of 8 components of Vitamin E, is the third fat-soluble vitamin. It is typically absorbed in the small intestine. It has important implications as an anti-oxidant, immunomodulator and anti-platelet agent. It is one of the fat-soluble vitamins that are least likely to be deficient in human; its deficit is typically due to malabsorption of fats in developed countries.  In developing countries, the lack of Vitamin E is due to dietary insufficiencies. Tocopherol is found in leafy vegetables, whole grains, nuts, seeds, vegetable oils and fortified cereals.  Individuals who are low chronically with Vitamin E suffer from gait abnormalities (ataxia), difficulty with upward gaze and diminished reflexes.  More severe problems include cardiac arrhythmias, blindness and dementia. As well, low tocopherol levels have also been associated with increased rates of ischemic heart diseases and atherosclerosis (deposits of fat plaques in arteries).

Vitamin K , also known as naphthoquinone, exist as two subcategories, K₁ and K₂, that will not be discussed here. In short, they naturally occur in green leafy fermented foods.  Population that are at risk for deficiency are newborns, as they are depleted from their maternal storage as soon as they are born, patients with liver cirrhosis and those with inflammatory bowel disease.  In developing countries, where access to nutritious food is sparse, complications are readily observed. Deficiency can causes easy bruising, nonfatal and fatal bleeds, and subsequent anemia. Osteoporosis and heart disease are associated with Vitamin K₂ deficiency.

The complications of these fat-soluble vitamins could readily reversed in most cases by readily administering supplements and appropriate nutrition support. If support could be obtained early in childhood, in certain cases, in the neonatal period, neurological deficits could be avoided.  If we could aid developing countries in the acquisition and sustainability of appropriate nutrients and agriculture, then these complications would be eradicated.

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Bird JK, Murphy RA, Ciappio ED, McBurney MI. Risk of Deficiency in Multiple Concurrent Micronutrients in Children and Adults in the United States. Nutrients. 2017;9(7):655. Published 2017 Jun 24. doi:10.3390/nu9070655

Fitzpatrick TB, Basset GJ, Borel P, et al. Vitamin deficiencies in humans: can plant science help?. Plant Cell. 2012;24(2):395-414.

Kemnic TR, Coleman M. Vitamin E Deficiency. [Updated 2019 Feb 14]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK519051/

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Monicka Felix

Dr. Monicka Felix, MD is an academic hospitalist in Internal Medicine with a passion for Global Health. Her focus is on healthcare disparities in both developed and developing countries. She is set to obtain a Master’s in Public Health with a concentration in epidemiology. She is originally from Montreal, Quebec Canada but now currently resides in the Tampa Bay area in Florida.