Micronutrients, vitamins and minerals, comprise a group of over 20 unrelated compounds that serve physiologic functions essential to life. Many of them cannot be synthesized by the human body and must be obtained through a balanced diet. However, certain vitamins, namely, vitamins K, A, and B-12, can be made by us, either through precursor hormones in the body or in association with beneficial bacteria in the gut.
Vitamin K
Vitamin K is a fat-soluble vitamin that serves as a coenzyme in the formation of various blood clotting factors. Although it is found plentifully in vegetables such as cabbage, cauliflower and spinach, as well as in egg yolk and in liver, vitamin K is also extensively synthesized by probiotics in the gut. These beneficial bacteria can produce at least half of the estimated requirement of 100 mg/day.
Vitamin A
Vitamin A is the name given to a family of retinoid molecules essential for vision, reproduction, growth and the maintenance of skin. Liver, kidney, cream, butter and egg yolk are good sources of preformed vitamin A. Yellow and dark green vegetables and fruits are good dietary sources of the carotenes that serve as precursors for vitamin A. Of these, beta-carotene can be converted in the intestine into vitamin A in quantities sufficient to meet metabolic needs.
Vitamin B-12
Cobalamin, as this vitamin is also called, is essential to the metabolism of amino acids and fatty acids, and is important for the proper function of the nervous system and blood cells. Vitamin B-12 is synthesized only by microorganisms; it is not present in plants. Most animals obtain the vitamin preformed from their natural bacterial flora, and though the bacteria in your colon produce B-12, you are not able to absorb it and so must obtain in the diet from foods such as liver, whole milk, eggs, fish or fowl.
References
- "Biochemistry"; Pamela C. Champe et al.; 2005
- "Pathologic Basis of Disease"; Kumar et al.; 2005
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