Water-Soluble Vitamins
University of Hawai‘i at Mānoa Food Science and Human Nutrition Program and Human Nutrition Program
All vitamins play a different kind of role in energy ; they are required as functional parts of enzymes involved in energy release and storage. Vitamins and minerals that make up part of enzymes are referred to as and , respectively. Coenzymes and cofactors are required by enzymes to catalyze a specific reaction. They assist in converting a substrate to an end-product. Coenzymes and cofactors are essential in pathways and play a role in many pathways too. In addition to being essential for metabolism, many vitamins and minerals are required for blood renewal and function. At insufficient levels in the diet these vitamins and minerals impair the health of blood and consequently the delivery of nutrients in and wastes out, amongst its many other functions. In this section we will focus on the vitamins that take part in metabolism and blood function and renewal.
Figure 9.7 Enzyme Active Site for Cofactors
Vitamin C
, also commonly called ascorbic acid, is a water[-soluble micronutrient essential in the diet for humans, although most other mammals can readily synthesize it. Vitamin C’s ability to easily donate makes it a highly effective . It is effective in scavenging reactive oxygen species, reactive nitrogen species, and many other . It protects lipids both by disabling free radicals and by aiding in the regeneration of .
In addition to its role as an antioxidant, vitamin C is a required part of several enzymes like signaling molecules in the brain, some hormones, and ]amino acids. Vitamin C is also essential for the synthesis and maintenance of collagen. Collagen is the most abundant protein in the body and used for different functions such as the structure for ligaments, tendons, and blood vessels and also scars that bind wounds together. Vitamin C acts as the glue that holds the together and without sufficient levels in the body, collagen strands are weak and abnormal. (Figure 9.8 “The Role of Vitamin C in Collagen Synthesis”)
Figure 9.8 The Role of Vitamin C in Collagen Synthesis
Vitamin C levels in the body are affected by the amount in the diet, which influences how much is absorbed and how much the kidney allows to be excreted, such that the higher the intake, the more vitamin C is excreted. Vitamin C is not stored in any significant amount in the body, but once it has reduced a free radical, it is very effectively regenerated and therefore it can exist in the body as a functioning antioxidant for many weeks.
The classic condition associated with vitamin C deficiency is . The signs and symptoms of scurvy include skin disorders, bleeding gums, painful joints, weakness, depression, and increased susceptibility to infections. Scurvy is prevented by having an of fruits and vegetables rich in vitamin C.
Figure 9.9 Bleeding Gums Associated with Scurvy
Cardiovascular Disease
Vitamin C’s ability to prevent disease has been deba