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Unformatted text preview: Vitamins and Minerals: A General Overview Vitamins: Essential Organic Substances Two types: Fat soluble or water soluble 4 fat-soluble: Vitamins A, D, E, and K 9 water-soluble: Vitamin C and the B Vitamins All are organic (i.e. carbon-containing) compounds Vitamins are Vital to life primary function: enable necessary chemical reactions in body ALL ARE ESSENTIAL but needed in only tiny amounts Yield no energy, but facilitate energy-yielding reactions Fat-Soluble Vitamins Dissolve in organic solvents Not readily excreted; thus, can cause toxicity Absorbed along with fat Transported like fat in chylomicrons, VLDL, LDL Water-Soluble Vitamins Dissolve in water Generally readily excreted Absorbed along with carbohydrates and proteins Transported by blood like carbs and proteins Fat-Soluble vs. Water-Soluble Vitamins: Toxicity Fat-soluble are generally stored; thus, elevated risk of toxicity except vitamin K Water-soluble are generally excreted; thus, lowered risk of toxicity except vitamin B12 and B6 Minerals: Essential Inorganic Substances Minerals inorganic (non C-containing) substances existing in gourps of 1 or more of same atoms Two types: major minerals and trace minerals Classification based on dietary need Critical to nervous system function, mantainence of water balance, and structural (ex. Skeletal) systems ALL ARE ESSENTIAL, but needed in only tiny amounts Yield no energy, but facilitate energy-yielding reactions Mineral Toxicity Easy to reach toxic levels: some minerals potentially toxic at intakes not much above UL's Excess mineral supplementation can greatly diminish absorption and metabolism of other minerals Vitamin/Mineral Supplementation: Health Risks and Benefits Many Americans unwilling to change diets to ensure proper dietary nutrient intake; therefore, supplementation recommended for these individuals Supplements cannot fix poor diet in all respects; benefits derived from supplementation do not compare to those derived from food, ex. few to no supplements contain fiber or phytochemicals Vitamin/Mineral Supplementation: Harmful Effects Toxicity: adverse health effects arising from ingestion of too much of a particular nutrient(s) Causes: supplementation, increased storage/decreased excretion Most nutrient toxicity a result of supplement use Vitamin Deficiency Deficiency: adverse health effects arising from ingestion of not enough of a particular nutrient(s) Deficiency is opposite of toxicity Two types: Primary and Secondary Primary caused by lack of consumption of a nutrient in the diet Seconday caused by metabolic imbalance or failure to absorb nutrients Vitamin Deficiency Diseases Nearly always seen in context of general malnutrition Therefore, treatment with single nutrient generally insufficient Malnutrition: failing health that results from longstanding dietary intake that fails to match nutritional needs, includes both under- and overnutrition Two types: historical deficiency diseases and contemporary deficiency diseases Historical Deficiency Diseases Rarely seen/no longer prevalent in U.S. due to: 1. Enriched and fortified foods 2. Fruit/Vegetable processing techniques (allowing them to be more readily available): Vitamin D (Rickets) Thiamin (Beriberi) Niacin (pellagra) Vitamin C (Scurvy) Iodine (Goiter) Contemporary Deficiency Diseases Primarily seen as deficiencies in iron, calcium, or protein Individuals who may be at risk for: Iron deficiency - women who are pregnant or breastfeeding, women with excessive bleeding during menstruation, people with very low energy intakes, and strict vegetarians. Calcium deficiency women who are pregnant or breastfeeding, people with lactose intolerance, and strict vegetarians. Protein deficiency people with very low energy intakes, children who are "picky eaters," and very strict vegetarians. Dieting-Induced Deficiencies Adherence to "fad" diets may result in certain vitamin/mineral deficiencies Examples: Low- or Restricted-Carbohydrate diets. Low carb dieting AKA "Atkins Diet" may result in potassium deficiency as well as extreme reduction in body water, fiber, and antioxidant phytochemicals. Common Micronutrient Deficiencies Worldwide Nutrient deficiencies primarily the result of undernutrition/starvation: Iron Zinc Vitamin A Iodine Assessment of Nutritional Status The Dietary Reference Intake (DRIs) Broad "umbrella" term encompassing a number of dietary standards used to evaluate nutrient intake in large populations Encompasses 4 sub-sets of nutritional standards What 4 standards fall under DRI "umbrella"? Estimated Average Requirements (EAR's) Recommended Dietary Allowances (RDA's) Adequate Intakes (AI's) Tolerable Upper Intake Levels (UL's) The Recommended Dietary Allowances (RDAs) "Recommended intakes of nutrients that meet the needs of almost all healthy people of similar age and gender" ---- the Food and Nutrition Board of the National Academy of Sciences RDA's Designed to prevent deficiency and chronic disease in ~97% of healthy individuals in a given gender/age group Accommodate for people having increased nutritional needs: values ~20% above those required by the average person - thus RDA's are generous allowances Based upon multiple of EAR value, however not all nutrients have EAR, thus RDA currently set for (only) 19 nutrients More About RDAs... Improvements in health not expected if person consumes more than the RDA amount Goal is to eat close to the RDA amounts; however, short-term deficiencies in RDA-specified nutrients appear harmless Adequate Intakes (AIs) Used when not enough research information available to determine RDA for a particular nutrient Based on observed or experimentally determined estimates Set for some vitamins and minerals Planned for children under the age of 1 Tolerable Upper Intake Levels (UL's) Maximum level of daily intake without causing adverse health effects in almost all people in a population (97%-98%) Applies to daily use Set to protect even very susceptible people in population - thus set lower than actual "upper intake" for most individuals Not a goal, but a ceiling below which nutrient intake should remain Uses for the DRIs Diet planning for the healthy population using RDAs or AIs Do not exceed the ULs Applicable to ~97% of HEALTHY population; thus, may be used amongst broad range of individuals The Daily Reference Values (DRVs): Standards For Food Labeling DRIs cannot be used on food labels since they are gender and age specific; therefore, FDA developed the Daily Reference Values (DRVs) using two standards: Reference Daily Intake (RDI) and Daily Reference Value (DRV) However, these standards do not appear individually on nutrition label - DV's, combination of both standards, on label instead Only used on food labels Allow for comparison shopping Why use DV's? DRI's cannot be used on food labels since specific to gender and age groups Thus, DV's developed as generic standards for use on food labels Express nutrient content of food as percentage of DV - thus, percentages are point of reference for evaluation Allow for comparison shopping How do DV's work? Percent DV on Nutrition Facts Panel determined by comparing nutrient content of particular food to FDA's standard nutrient-intake reference DRV for 2000 kcal Food Component Fat Sat. Fat Protein Cholesterol CHO Fiber Sodium Potassium DRV 2000 kcal <65 g < 20 g 50 g < 300 mg 300 g 25 g <2400 mg 3500 mg ...
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- Fall '08