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Vitamin K is a family of structurally similar, fat-soluble vitamers found in foods and marketed as dietary supplements. [1] The human body requires vitamin K for post-synthesis modification of certain proteins that are required for blood coagulation ("K" from Danish koagulation, for "coagulation") or for controlling binding of calcium in bones and other tissues. [2]
Diagnosing Vitamin B12 Deficiency and Cancer [38] If cancer is suspected as the cause of vitamin B12 deficiency, several diagnostic steps are necessary: Blood tests: A blood test can measure vitamin B12 levels, along with other markers such as homocysteine and methylmalonic acid, which may also indicate a deficiency.
Humans can produce some vitamins from precursors they consume: for example, vitamin A is synthesized from beta carotene; and niacin is synthesized from the amino acid tryptophan. [54] Vitamin C can be synthesized by some species but not by others. Vitamin B 12 is the only vitamin or nutrient not available from plant sources.
In the case of the simians, it is thought that the loss of the ability to make vitamin C may have occurred much farther back in evolutionary history than the emergence of humans or even apes, since it evidently occurred soon after the appearance of the first primates, yet sometime after the split of early primates into the two major suborders ...
A high capacity for long-term storage of retinol means that well-nourished humans can go months on a vitamin A-deficient diet, while maintaining blood levels in the normal range. [4] Only when the liver stores are nearly depleted will signs and symptoms of deficiency show. [4]
(Many animal species can synthesize vitamin C, but humans cannot.) Certain vitamin-like compounds that are recommended in the diet, such as carnitine , are thought useful for survival and health, but these are not "essential" dietary nutrients because the human body has some capacity to produce them from other compounds.
Folate is required for the body to make DNA and RNA and metabolise amino acids necessary for cell division and maturation of blood cells. [1] [8] As the human body cannot make folate, it is required in the diet, making it an essential nutrient. [9] It occurs naturally in many foods.
Biotin (also known as vitamin B 7 or vitamin H) is one of the B vitamins. [ 1 ] [ 2 ] [ 3 ] It is involved in a wide range of metabolic processes, both in humans and in other organisms, primarily related to the utilization of fats, carbohydrates, and amino acids. [ 4 ]