Webster's New World Medical Dictionary

vitamin B3
470
vitamin B3
Niacin, a water-soluble vitamin, which
is a component of coenzymes that are important in
body metabolism. Vitamin B3 is found primarily in
liver and yeast, and it is easily destroyed by cooking.
Deficiency of vitamin B3 causes inflammation of the
skin, vagina, rectum, and mouth, as well as mental
slowing. Also known as nicotinic acid. The daily adult
requirement is 16 milligrams.
vitamin B5
Pantothenic acid, a water-soluble, B
vitamin that is widely distributed in nature.
Pantothenic acid is virtually ubiquitous. It is present
in foods as diverse as poultry, soybeans, yogurt, and
sweet potatoes. No naturally occurring disease due to
a deficiency of vitamin B5 has been identified, due to
the ease of obtaining this vitamin. An experimental
deficiency of pantothenic acid has, however, been
created by administering an antagonist to pantothenic
acid. This experiment produced disease, thereby
demonstrating that pantothenic acid is essential to
humans.
vitamin B6
Pyridoxine, a water-soluble vitamin,
which is a cofactor for enzymes. Vitamin B6 is
found primarily in liver and yeast, and it is easily
destroyed by cooking. Deficiency of vitamin B6
leads to inflammation of the skin and mouth, nau-
sea, vomiting, dizziness, weakness, and anemia.
The daily adult requirement is 2 milligrams.
vitamin B12
Cobalamin, a water-soluble vitamin,
which is an essential factor in nucleic acid synthesis.
Vitamin B12 may affect vitamin C absorption. It is
found primarily in liver and yeast, and it is easily
destroyed by cooking. Deficiency of vitamin B12
leads to megaloblastic anemia, as can be seen in per-
nicious anemia. The daily adult requirement is 2
micrograms.
vitamin C
Ascorbic acid, a water-soluble vita-
min that is important in the synthesis of collagen,
the framework protein for tissues of the body.
Vitamin C is found in citrus fruits, tomatoes,
berries, potatoes, and most vegetables. It may
affect vitamin B12 absorption. Minor deficiency
can cause gum bleeding, joint pain, nosebleeds,
and easy bruising. Extreme deficiency can lead to
scurvy, characterized by fragile capillaries, poor
wound healing, and bone deformity in children.
Overdose is not possible with this water-soluble
vitamin, but overuse can cause diarrhea, painful
urination, rash, and nausea. The daily adult
requirement is 60 milligrams.