Vitamins

Vitamins are categorized as either fat soluble or water soluble. Water-soluble vitamins taken in excess are excreted and pose no threat to the body’s health. Fat-soluble vitamins are stored in the body and, if taken in excess, can lead to toxicity referred to as hypervitaminosis. If fat intake is too low, or if fat absorption is compromised by a disease such as cystic fibrosis or through the use of certain drugs, the absorption of fat-soluble vitamins is inhibited. The following tables provide an overview of the vitamins and their functions.

Table 6.1 Water-Soluble Vitamins 

Vitamin	Source	Function
B12 (cobalamin)	Meat, fish, seafood, eggs, milk, dairy products	Cell development, nerve function
B1 (thiamine)	Pork, whole grains, breads and cereals, legumes, seeds, nuts	Energy and nerve function
B2 (riboflavin)	Milk and dairy products, green leafy vegetables, whole grains	Metabolism, vision, skin health
B3 (niacin)	Meat, poultry, fish, breads, cereals, peanut butter, green leafy vegetables	Metabolism, digestive and nervous system function and health
B6 (pyridoxine)	Meat, fish, poultry, fruits, vegetables	Protein metabolism and red cell production
C (ascorbic acid)	Citrus fruits, vegetables in the cabbage family	Immunity, iron absorption, protein metabolism, antioxidant
Folic acid	Green leafy vegetables, orange juice, seeds, legumes	Red blood cell production, liver health

Table 6.2 Fat-Soluble Vitamins

Vitamin	Source	Function
A	Animal sources, dairy products, liver, dark orange vegetables and fruits	Vision, bone, mucous membrane, and tooth health; immunity
D	Egg yolks, fortified milk, liver, fatty fish, sun exposure	Calcium absorption
E	Plant oils, green leafy vegetables, whole grains, nuts, seeds	Antioxidant, cell health
K	Green leafy vegetables, with smaller amounts in fish, liver, eggs, and cereals	Blood clotting

Vitamins can behave in different ways in different bodies:

• Alcoholics are prone to a secondary vitamin B6 deficiency. 
• Individuals with a vitamin B12 deficiency are likely lacking an intrinsic factor in the stomach. If pernicious anemia is diagnosed, these patients require an injection of B12 on a monthly basis.
• Infants are born with a low level of vitamin K. An injection of this vitamin is administered shortly after delivery to enhance clotting and deter intracranial bleeding associated with the trauma of delivery.