Vitamin requirements/recommendations

However, it is recommended that the NRC (1994) derived values for mineral and vitamin requirements be adopted without modification, to help ensure correct skeletal growth and avoidance of foot and leg problems. Conventional diets are usually formulated with higher levels of minerals and vitamins but this approach is not suggested for organic diets, to try and minimize nutrient levels above those required for normal growth and reproduction. 

Folate is a water-soluble vitamin. The recommended daily allowances (RDAs) of folate for the adult man and woman are 20fJ and 101) pg, respectively. The RDA is defined in the Preface. Folate is critically important for growth, and for this reason it is required in increased amounts during pregnancy (400 pg. The need for dietary folate remains elevated after pregnancy and during lactation because of the Irans-... 

Vitamins are complex biochemically and functionally and may be classified many ways. This chapter acknowledges the traditional solubility model but focuses on functionality. Un-fortunately,the loose regulation of nutritional products in the United States has led to misleading promotion of these items to the lay public, such that individuals are confused as to what can be called a vitamin. General criteria for deciding if a substance truly is a vitamin are presented. Another problem is to decide r whether a patient actually has a vitamin defi-J ciency. As noted in the next section, this can be l cornplex question. Finally, deciding how ifaich of a particular vitamin should be consumed has moved from the familiar Recommended Dietary Allowance (RDA) to four different ways to evaluate vitamin requirements and consumption. These are called the Dietary Reference Intakes (DRIs). 

Little information is available concerning alterations in vitamin requirements in ARF. Reduced plasma concentrations of vitamin A, ascorbate, vitamin D, and vitamin E have been reported in patients with ARF, whereas vitamin K concentrations are relatively increased. Losses of vitamins via dialysis also must be considered. Traditional HD clears several water-soluble vitamins such as folic acid, vitamins C and B12, and pyridoxine, but not the highly protein-bound vitamins A and D. The clinical significance of these findings in ARF is unknown. Currently, it seems prudent to administer vitamins at least daily in doses recommended by the Nutrition Advisory Group of the American Medical Association for patients receiving PN (see Chap. 137)." Administration of ascorbic acid should be restricted to under 200 mg/day to avoid secondary oxalosis which may worsen renal function." If the enteral route is used for nutritional support, vitamin administration should at least meet the recommended daily allowances (RDAs). 

Recently, a great deal of emphasis has been placed on vitamin supplements to combat stress, prevent the common cold, protect against various kinds of cancer and heart disease, offset the s)mptoms of premenstrual syndrome, delay the aging process, and improve one s sex life Most nutritionists believe that a well-balanced diet provides all the nutrients, including the vitamins, required by the body. Indeed, when associations such as the American Cancer Society suggest that certain vitamins might help prevent cancers, they recommend that they be obtained from the natmal food sources, rather than from vitamin supplements. 

The best known use of vitamin C is as a nutritional supplement, taken to ensure that one receives his or her daily minimum requirement of the vitamin. The recommended daily allowance (RDA) of vitamin C for adults is 60 milligrams per day. Anyone who eats a well-balanced diet that includes citrus fruits, tomatoes, and green leafy vegetables probably does not need to take a vitamin supplement. However, the amount of vitamin C one normally receives from a supplement is unlikely to cause any harm. 

At the present time, there is no concrete information as to the intravenous vitamin requirements of the infant. Table 6 shows a comparison of the recommended allowances for vitamins compared with the levels found in one ml of MVI (USV Pharm.). It is apparent that the amount of vitamin A is slightly on the high side while vitamin D is on the low side of the recommended dose. The water soluble vitamins are markedly in excess of the recommended dosage. 

Vitamins A, D, and E are required by mminants and, therefore, their supplementation is sometimes necessary. Vitamin A [68-26-8] is important in maintaining proper vision, maintenance and growth of squamous epitheHal ceUs, and bone growth (23). Vitamin D [1406-16-2] is most important for maintaining proper calcium absorption from the small intestine. It also aids in mobilizing calcium from bones and in optimizing absorption of phosphoms from the small intestine (23). Supplementation of vitamins A and D at their minimum daily requirement is recommended because feedstuffs are highly variable in their content of these vitamins. 

To obtain optimal performance of farm animals, foHc acid supplementation is required (86) and as is the case with most of the vitamins, the majority of worldwide consumption is as feed supplements. The foHc acid requirement for chickens and pigs is about 0.2—0.5 mg of foHc acid/kg diet and 0.3 mg/kg diet, respectively. Increased amounts, 0.5—1.0 mg/kg feed for chickens and 0.5—2.0 mg/kg for swiae, are recommended under commercial production conditions (87). The degree of intestinal foHc acid synthesis and the utilization by the animal dictates the foHc acid requirements for monogastric species. Also, the self-synthesis of folaciais dependent on dietary composition (88). 

Animals exposed to sunlight for extended lengths of time do not require substantial dietary vitamin D. Current livestock management practices place an emphasis on high productivity, and most feed manufacturers recommend vitamin D supplementation of diets. Recommendations for practical levels of vitamin D in feeds for various animals, as recommended by feed manufacturers, are listed in Table 10. 

The recommended daily allowance for vitamin E ranges from 10 international units (1 lU = 1 mg all-rac-prevent vitamin E deficiency in humans. High levels enhance immune responses in both animals and humans. Requirements for animals vary from 3 USP units /kg diet for hamsters to 70 lU /kg diet for cats (13). The complete metaboHsm of vitamin E in animals or humans is not known. The primary excreted breakdown products of a-tocopherol in the body are gluconurides of tocopheronic acid (27) (Eig. 6). These are derived from the primary metaboUte a-tocopheryl quinone (9) (see Eig. 2) (44,45). 

So far, it is not possible to give any recommendations concerning the vitamin C intake required for the prevention of osteoporosis, cataracts, cancer, or cardiovascular disease. 

The mean dietary intake of soy isoflavones in Asian populations consuming soy-based diets ranges from 20-40 mg isoflavones/day, with upper percentile consumer intakes of 70 mg/day (corresponding to around 1 mg/kg body weight). In the six month intervention studies in Western postmenopausal women, the effective dose for improved BMD was around 80-90 mg/day, while in the one year, randomized, double-blind, placebo controlled clinical trial, the effective dose was 54 mg/day. Overall, the dietary recommendation is to consume 50 mg isoflavones/day in combination with standard nutritional requirements for calcium and vitamin D. 

Daily calcium and vitamin D requirements are highest in postmenopausal women and elderly men 1500 mg elemental calcium and 400 to 800 IU vitamin D (see Table 53-4). When these requirements cannot be achieved by diet alone, appropriate calcium and/or vitamin D supplementation is recommended. 

The water-soluble and fat-soluble vitamins in the parenteral multivitamin mix are essential cofactors for numerous biochemical reactions and metabolic processes. Parenteral multivitamins are added daily to the PN. Patients with chronic renal failure are at risk for vitamin A accumulation and potential toxicity. Serum vitamin A concentrations should be measured in patients with renal failure when vitamin A accumulation is a concern. Previously, vitamin K was administered either daily or once weekly because intravenous multivitamin formulations did not contain vitamin K. However, manufacturers have reformulated their parenteral multivitamin products to provide 150 meg of vitamin K in accordance with FDA recommendations. There is a parenteral multivitamin formulation available without vitamin K (e.g., for patients who require warfarin therapy), but standard compounding of PN formulations should include a parenteral multivitamin that contains vitamin K unless otherwise clinically indicated. 

Polymeric formulas typically have low osmolality of 300 to 500 mOsm/kg. These formulas also usually supply essential vitamins and minerals in amounts similar to the Adequate Intakes or Recommended Dietary Allowances for these nutrients when the formula is delivered in amounts adequate to meet the macronutrient requirements of most patients. Many polymeric formulas are inexpensive relative to oligomeric formulas. Most polymeric formulas are lactose-free and gluten-free, as are most modern tube feeding products. Products designed to be used as oral supplements generally are polymeric and often have sucrose or other simple sugars added to improve taste. 

While the dog is a carnivore, it is able to adapt to an omnivorous diet. Requirements for dietary sources of energy, amino acids, glucose precursors, fatty acids, minerals, vitamins, and water have been established based on recommendations by the National Research Council (NRC, 1985). Adult beagles maintained in a laboratory environment function well with one feeding of standard laboratory chow per day. In safety assessment testing, however, some compounds may induce serious dietary deficiencies through induced loss of appetite, malabsorption, or vomiting, and, in these cases, it may be advisable to provide a dietary supplement. 

Human adult needs for this vitamin (vitamins) are not established quantitatively. Most human studies have involved preventing or curing rickets in infants or children, and the recommended daily allowance of the Food and Nutrition Board is 400 units. Even among "normal" children, however, there is evidence of variation in vitamin D needs. According to Spies and Butt,38 "The activated milk does not exhibit sufficient potency in vitamin D for the prevention of rickets in cases in which a susceptibility exists" (italics added). They note that "susceptible" children may require 5,000 to 10,000 units daily. 

Osteoporosis, a condition in which bone becomes porous and weak (potentially leading to fractures), is a far more prevalent disease than osteomalacia. While modest levels of serum 25-hydroxyvitamin D will prevent osteomalacia, these levels may not be sufficient to minimize the risk of osteoporosis. Clinical studies have demonstrated that bone mineral density is directly related to serum 25-hydroxyvitamin D levels up to 40 ng/ml. It has also been demonstrated that in elderly women given unusually high doses of calcium and vitamin D3 the risk of both hip and vertebral fractures is substantially reduced. Optimizing bone health in both young and old may require higher levels of vitamin D activity than are typically achieved at recommended doses. This story will play out over time. 

These are classified as those with a requirement below one pg (microgram) per day. Elements in this class include boron, chromium, fluoride, iodine, molybdenum, nickel, selenium, cobalt and manganese. Cobalt is part of vitamin (see above). However, there appear to be no recommended dietary intakes for any of these except molybdenum. 

Reference Intakes (DRIs). In the past, the recommended dietary allowances (RDAs), which are the levels of intake of essential nutrients that are considered to be adequate to meet the known nutritional needs of practically all healthy persons, were the primary reference value for vitamins and other nutrients. The DRIs also include other reference values, such as the estimated average requirement (EAR) and the adequate intake (AI). The RDA, EAR, and AI reference standards define nutritional intake adequacy. Since these recommendations are given for healthy populations in general and not for individuals, special problems, such as premature birth, inherited metabolic disorders, infections, chronic disease, and use of medications, are not covered by the requirements. Separate RDAs have been developed for pregnant and lactating women. Vitamin supplementation may be required by patients with special conditions and for those who do not consume an appropriate diet. 

Geriatric Considerations - Summary Primidone is poorly tolerated in older adults avoid use if possible. Dosage adjustments are required in renal impairment. Numerous drug interactions with primidone exist. Primidone may reduce bone mineral den-sitybyinterferingwith vitamin D catabolism. Calcium and vitamin D supplementation and monitoring of bone mineral density are recommended for older adults taking this drug. 

Dietary Reference Intakes for vitamins and minerals in individuals one year and older. EAR = Estimated Average Requirement RDA = Recommended Dietary Allowance ... 

Vitamins are chemically unrelated organic compounds that cannot be synthesized by humans and, therefore, must must be supplied by the diet. Nine vitamins (folic acid, cobalamin, ascorbic acid, pyridoxine, thiamine, niacin, riboflavin, biotin, and pantothenic acid) are classified as water-soluble, whereas four vitamins (vitamins A, D, K, and E) are termed fat-soluble (Figure 28.1). Vitamins are required to perform specific cellular functions, for example, many of the water-soluble vitamins are precursors of coenzymes for the enzymes of intermediary metabolism. In contrast to the water-soluble vitamins, only one fat soluble vitamin (vitamin K) has a coenzyme function. These vitamins are released, absorbed, and transported with the fat of the diet. They are not readily excreted in the urine, and significant quantities are stored in Die liver and adipose tissue. In fact, consumption of vitamins A and D in exoess of the recommended dietary allowances can lead to accumulation of toxic quantities of these compounds. 

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