The body needs an adequate amount of vitamins to meet its daily requirements and function effectively. A diet that lacks proper nutrients in the form of vitamins and minerals that meet the body’s requirements leads to diseases are associated with malnutrition.
On the contrary, excess vitamin intake can also be harmful as this can cause toxicity in the body, especially in the case of fat-soluble vitamins that can accumulate in the body tissues. Such a condition is referred to as hypervitaminosis.

Usually, long-term deficiency of a vitamin is referred to as avitaminosis or hypovitaminosis, which can be classified as a primary deficiency when caused by inadequate vitamin intake. An underlying disorder like malabsorption due to defects in the metabolism can also lead to vitamin deficiency, which can be classified as a secondary deficiency. Sometimes, lifestyle choices like smoking and alcohol increase the need for vitamins to balance their influence on the body. This article discusses some of the diseases caused by the deficiency of vitamins:

• Vitamin A deficiency causes nyctalopia or night blindness. Keratomalacia is another disease that will lead to permanent blindness if left untreated. This is a preventable childhood disease that affects 250,000 to 500,000 malnourished children in the world every year. About half of the children succumb to the disease within a year of blindness as this disease also compromises the immune system.
• Severe vitamin B1 (thiamine) deficiency causes beriberi. It may affect the cardiovascular system and the nervous system in the adults. Acute beriberi causes loss of appetite, vomiting, changes in heart rate, and enlargement of the heart in malnourished babies. This deficiency also leads to Wernicke encephalopathy and Korsakoff syndrome.
• Vitamin B2 (Riboflavin) deficiency is also called ariboflavinosis, and this deficiency results in stomatitis.
• Vitamin B3 (Niacin) deficiency causes pellagra.
• Vitamin B5 (pantothenic acid) deficiency causes paresthesia.
• Vitamin B6 (pyridoxine) deficiency is a rarity seen in instances of end-stage renal diseases or malabsorption syndromes. Some of the signs and symptoms include microcytic anemia, electroencephalographic abnormalities, dermatitis depression, and confusion.
• Vitamin B7 (biotin) deficiency is rare, but it can sometimes be seen in alcoholics and during pregnancy and breastfeeding. Biotin deficiency affects hair growth and skin health.
• Vitamin B9 (folate) deficiency is associated with numerous health problems, including neural tube defect. This deficiency may develop due to genetic factors.
• Vitamin B12 (cobalamin) deficiency can lead to anemia, the Lichtheimia disease, and methylmalonic acidemia, among other conditions.
• Scurvy is typically associated with the deficiency of vitamin C. This deficiency can lead to fatigue, loss of body weight, and body pain.
• Vitamin D deficiency causes rickets and is linked to increasing the risk of a number of health conditions, including cardiovascular diseases.
• Often, abnormalities in metabolism or dietary fat absorption cause vitamin E deficiency. It is a very rare condition that is generally not a result of following the wrong diet. This deficiency causes nerve problems.
• A deficiency of vitamin K leads to impaired coagulation and is also linked with osteoporosis.