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Thursday, September 23, 2010

2.10 Introduction to Vitamins & Minerals

Physician's Notebooks 2  - http://physiciansnotebook.blogspot.com - See Homepage
2.10: Introduction to Vitamins & Minerals (Update 03 Dec 2017)
Vitamins and Minerals (V&M) are no-calorie. Many vitamins act as enzymes. Vitamin D acts as a hormone. Minerals are used much as structural units (calcium and phosphorus in bone, iron in hemoglobin, cobalt in vitamin B12) or function as electrolytes  (Na+, K+, Ca2+, Mg2+, Clin body fluids and or intracellular messengers in nerves  (Mg2+, Ca2+) or as parts of enzymes. Vitamins are complex organic chemical compounds; "minerals" in nutritional term are simple inorganic ions. In the naming, a simple chemical element name is used (calcium, phosphorus, lithium) but actually we never eat a pure element. 
Absorption of V&M: Vitamin or mineral taken by mouth several times a day is better absorbed into blood than same 24-hr amount. Some V&M, if taken as pill, tablet or powder, are best absorbed on empty stomach with water. But fat soluble vitamins (A, D, E, K) require a little fat. Iron absorption is enhanced by vitamin C. Calcium does well with food and vitamin D.
Dosage – Physiologic vs. Pharmacologic Dose: All vitamins and some minerals function in small amount (milligram, microgram) often in enzyme that speeds chemical reaction but is not used up in it. This is physiologic dose. Some vitamins have a medicinal or pharmacologic effect at doses hundreds or thousands of times higher. Example is niacin used medically to lower high cholesterol and taken at gram levels compared to its physiologic milligram. This has slopped over into vitamin with no known medicinal function but taken in megadose in hope it will have good medicinal effect. (Vitamin C 5 to 15 grams a day) 
Excretion & Absorption: V&M are excreted in urine (Many vitamins cause deep yellow urine) or feces (Iron or Bismuth cause black feces). There is threshold of intestinal absorption and excretion above which a high-dose vitamin user defeats its purpose. If you take vitamin C more than 10 grams a dose, much of it goes right out of you into the toilet water. 
Advisory on Essential Nutrients: The US National Academy last updated the Dietary Reference Intakes, and Food & Nutrition Board (FNB) and published it as Recommended Daily Allowances (RDA; Recommended Dietary Allowances: 10th Edition 2011), Adequate Intakes (AI), and Upper Limits (UL was Tolerated Upper Limits). Every V&M the FNB considers essential has an RDA or AI. The RDA of an essential nutrient is said to meet the need of almost all healthy persons while Adequate Intake (AI) is used where data are insufficient for RDA. Upper Limit (UL) is the estimated max level of nutrient considered to pose no risk. If no UL is given for a nutrient, it means data are insufficient. The RDA, AI and UL are given for infants, children, by gender and each within age groups, and for pregnancy and breast feeding. The doses I recommend are usually for adults in range found in the lists. For specific RDA, AI and UL by age, gender, state of body See www.cc.nih.gov/ccc/supplements. 
Toxicity of V&M can be by dose (vitamin C is nontoxic at physiologic dose but can form kidney stone at megadose), by interaction with other chemical (Folic acid is harmless at any dose but can cause neurological illness when taken without vitamin B12), by age (Old person more prone to deficiency and more sensitive to toxic effect), by medical condition (diabetes or gout may make a vitamin toxicity at low dose), by pregnancy (breast feeding mom, infancy usually increase the need), and by genetic inheritance. Constant ingestion of certain foods or substances may up the need for a vitamin or mineral (Alcohol drinking for thiamine, niacin, folic acid, calcium and magnesium)  
Metabolic Diseases: Genetic condition may make a nutrient toxic. (Phenylketonuria requires low-phenylalanine protein diet and to avoid the Aspartame sweetener a.k.a. Nutrasweet). Oppositely, genetic loss of enzyme leads to need for high dose of vitamin or mineral. Worst case is obvious from birth. More often, a condition leads to low enzyme resulting in unrecognized dangerous rise in toxic substance in blood (eg, homocysteine rise leading to coronary heart attack from combined folic acid, B6 & B12 borderline deficiencies) or high-mineral daily intake for optimal health. Only an alerted person can head it off by blood testing and then taking the high-dose essential nutrient. Suspect it if your DNA relative has metabolic illness or if you show deficiency despite adequate intake or RDA.
        Need for Vitamins & Minerals in Normal Nourished Persons:
     Here I am writing about supplements as pills, powders, and even injections taken by normal persons. By "normal" I mean adults from ages 20-60 with normal nutrition, which means normal weight and generally good health and no excessive bad habits like alcoholism. Such normal persons do not need to take any supplements; they are presumably getting their vitamins and minerals in their food. Aging brings on a need for vitamins and minerals even in normally nourished persons and the following sections will go into that need.
          Non Vitamin, Essential Nutrient: The Essential Fatty Acids and Essential Amino Acids are like vitamins in being required in diet in small amount but are also nutrients with calorie values. Of particular interest is tryptophan, a cyclic amino acid that can substitute for Niacin (Vitamin B3) to prevent or cure pellagra. Also the omega-3 fatty acids found in fish oils and marketed as "nature-made odorless fish oil" 1200 mg capsules, which may up the HDL (good) cholesterol in blood test. These will be further discussed in later sections.
 END OF CHAPTER. Next, click 2.11a Start of Vitamins -Intro; Biotin and Cholin...

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