Both vitamins and magnesium are nutritionally essential in human metabolism. Essential nutrients are those which you cannot synthesize yourself, and must be obtained through the diet. Therefore, since they are absolutely required for metabolism, essential nutrients must be consumed at adequate levels to avoid deficiency and possible metabolic dysfunction. Beyond there similar nutritional importance, however, the 16 vitamins and magnesium are very different in their chemistry and function in human metabolism.
Magnesium
The metallic element magnesium is the 11th most common element in the human body, with the average 70 kg person containing approximately 19g, according to the Emsley's "The Elements." Magnesium is required for the proper function of an estimated 300 enzymes in plants and animals. One of the reasons that magnesium is so frequently required as a enzyme cofactor is that in cells, the chemical energy molecule adenosine triphosphate --ATP-- is normally stabilized by magnesium ions. Therefore, metabolic pathways that use ATP for energy, like those involved in muscle contraction or DNA synthesis, also require magnesium as part of their chemistry.
B-vitamins
Vitamins of the B-complex have a wide range of functions in human metabolism. The family of B-vitamins includes thiamine, riboflavin, niacin/niacinamide, pantothenic acid, pyridoxine and its derivatives, biotin, folic acid, choline, and cobalamins; in some cases para-aminobenzoic acid and inositol are included in this list. In human metabolism, B-vitamins function as cofactors for enzymes in a diverse collection reactions that synthesize and break down amino acids, fats, and carbohydrates, generate cellular energy, construct cell membranes, produce neurotransmitters and hormones, and detoxify potentially harmful chemicals.
Vitamin A, C and E
Although Vitamins A, C and E are chemically unrelated and metabolically distinct, all have a common function as antioxidants in human metabolism. Antioxidants are important for mitigating oxidative damage, which is a natural, but potentially detrimental chemical cascade that can cause permanent damage to cells and genetic material. Vitamin C, a water-soluble vitamin, works to protect the aqueous compartments of the body, while the fat-soluble vitamin A precursor beta-carotene and vitamin E protects fats and cell membranes from oxidation. Vitamins E can also be found in LDL and HDL cholesterol particles, protecting them from damage as they travel though the bloodstream. Aside from its antioxidant role, vitamin C is a cofactor for the enzymatic reactions that make collagens, the most abundant proteins in the body. Vitamin A, in the form of retinal, is a cofactor for the vision protein rhodopsin.
Vitamin D
Vitamin D differs from other vitamins in that it is not strictly essential in human metabolism. You can make your own vitamin D by the action of UV light on cholesterol stored in skin cells. Vitamin D is actually a hormone, with a predominant role in the uptake of calcium from the gut and the balance of minerals in the blood. Vitamin D is most often recognized by its role in skeletal health and the maintenance of proper bone mineral density, however, it also is needed for proper function of the kidneys and cardiovascular system. Despite our ability to make it, vitamin D is deficiency is probably the most prevalent vitamin deficiency in the United States, as many people are unable to get the year-round sun exposure required for optimal levels of the vitamin.
Vitamin K
Vitamin K is a family of fat soluble vitamins that are needed for the activation of certain proteins that are involved in blood coagulation (Koagulation in German, hence vitamin "K"), as well as the binding of calcium in bone and other tissues. Vitamin K deficiency is rare (usually manifested as impaired blood clotting), but depletion of plasma and liver K stores can occur rapidly if dietary sources --mostly green leafy vegetable--are absent. Vitamin K has been for its ability to increase bone mineral density and reduce fracture risk, according to a meta-analysis in the Archives of Internal Medicine.
References
- "The Journal of Nutrition" Circulating 25-Hydroxyvitamin D Levels Indicative of Vitamin D Sufficiency: Implications for Establishing a New Effective Dietary Intake Recommendation for Vitamin D", B. W. Hollis, 2005
- "Archives of Internal Medicine", Vitamin K and The Prevention of Fractures: Systematic Review and Meta-analysis of Randomized Controlled Trials, S. Cockayne et al., 2006
- "The Elements, 3rd Edition", J. Emsley, 1998
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