Nutritional requirements

Introduction of Nutritional requirements ( according to RDA data ), different methods for assaying nutritional requirements, interaction with other nutrients and Antagonists & Analogues of vitamins.

1. NUTRITIONAL REQUIREMENTS, METHOD OF ASSAY, INTERACTION WITH OTHER NUTRIENTS, ANATGONISTS AND ANALOGUES OF VITAMIN KOMAL OJHA PH.D 1 st YEAR

2. INTRODUCATION The amount of each nutrient needed is called the nutritional requirement. These are different for each nutrient and also vary between individuals and life stages, e.g. women of childbearing age need more iron than men. Each nutrient has a particular series of functions in the body and some nutrients are needed in larger quantities than others. For example , protein is needed in gram (g) quantities. Vitamin C is needed in milligram (mg) quantities (1/1000 gram) and vitamin B 12  is needed in microgram (µg) quantities (1/1000000 gram). Individual requirements of each nutrient are related to a person’s age, gender, level of physical activity and state of health. Also, some people absorb or utilize nutrients less efficiently than others and so will have higher than average nutritional requirements, e.g. among older people, vitamin B 12  absorption can be relatively poor .

3. General Principles for deriving human nutrient requirements Several methods have been employed over the years to arrive at the requirement of different nutrients for individuals of different physiological groups and some of these methods have improved with time. The general principles underlying these methods are: Dietary intakes This approach is used to arrive at the energy requirement of children. Energy intakes of normal growing healthy children are used for this purpose. Currently it is not in use as it is considered to overestimate the requirement and not yield correct figures . Growth : Daily intake of breast milk and its nutrient content are utilized to define the nutrient requirement during early infancy (0-1y). This approach is also no longer in use as it leads to an overestimation of the requirement during early infancy. However, the mode of satisfying the nutrient requirement in early infancy ( up to 6 months) is only through breast milk intake.   Nutrient balance: The minimum intake of a nutrient for equilibrium (intake = output) in adults and nutrient consistent retention with satisfactory growth in infants and children, for satisfactory maternal and foetal growth during pregnancy, satisfactory breast milk output during lactation have been used widely in arriving at the protein requirements.

4.   Frame work for nutrient requirements 1. Dietary Reference Values In the UK, estimated requirements for particular groups of the population are based on advice that was given by the Committee on Medical Aspects of Food and Nutrition Policy (COMA) back in the early 1990s. COMA examined the available scientific evidence and estimated nutritional requirements of various groups within the UK population. These were published in the 1991 report Dietary Reference Values for Food Energy and Nutrients for the United Kingdom. Since this time, COMA has been superseded by the Scientific Advisory Committee on Nutrition (SACN). Rather than reviewing all the nutrients in one go, SACN is focusing on nutrients about which there is cause for concern, e.g. iron, folate , selenium and vitamin D, and has published reports on each of these. SACN is also considering whether energy requirements need adjustment. Population groups for which dietary reference values have been set include: Boys and girls  (aged 0-3 months; 4-6 months; 7-9 months; 10-12 months; 1-3 years; 4-6 years; 7-10 years) Males  (aged 11-14 years; 15-18 years; 19-50 years; 50+ years) Females  (aged 11-14 years; 15-18 years; 19-50 years; 50+ years; pregnancy and breastfeeding) 2. Dietary Reference Values (DRVs) Meaningful estimates of nutritional requirements must take account of the distribution of requirements within a population or group. To achieve this, the COMA panel used four Dietary Reference Values (DRVs) (Figure 1). DRVs are estimates of the requirements for groups of people and are not recommendations or goals for individuals.

5. CONTD… Estimated Average Requirement (EAR):  This is an estimate of the average requirement for energy or a nutrient - approximately 50% of a group of people will require less, and 50% will require more. For a group of people receiving adequate amounts, the range of intakes will vary around the EAR. Reference Nutrient Intake (RNI):  The RNI is the amount of a nutrient that is enough to ensure that the needs of nearly all the group (97.5%) are being met. By definition, many within the group will need less. Lower Reference Nutrient Intake (LRNI):  The amount of a nutrient that is enough for only the small number of people who have low requirements (2.5%). The majority need more. Safe intake :   This is used where there is insufficient evidence to set an EAR, RNI or LRNI. The safe intake is the amount judged to be a level or range of intake at which there is no risk of deficiency and is below the level where there is a risk of undesirable effects. There is no evidence that intakes above this level have any benefits - and in some instances they could have toxic effects.

6. SUMMARY OF RDA FOR INDIANS – 2020

7. METHOD OF ASSAY Assessment of nutritional status of community is one of the first steps in the formulation of any public health strategy to combat malnutrition. The principle aim of such an assessment is to determine the type, magnitude and distribution of malnutrition in different geographic areas to identify ‘at risk’ groups and to determine the contributory factors Nutritional status can be assessed by the following methods: Direct Methods Indirect Methods Anthropometry Vital health statistics Clinical Examination Food balance studies Biophysical or radiological examination Agriculture data Functional assessment Use of growth charts

8. CONTD… 1. Anthropometry - Anthropo means ‘human’ and metry means ‘measurement’. Use several different measurements including length, height, weight and head circumference. Length Height    Weight Mid-Upper Arm Circumference (MUAC) Head and Chest Circumference Skin Thickness Measurements Arm Anthropometry  

9. INTERACTION WITH OTHER NUTRIRNTS Nutrient interaction means, the impact of the nutrient on other nutrient’s bioavailability. Nutrient bioavailability includes two important components, absorption and utilization. Absorption is the process by which a nutrient moves from the intestinal lumen into the body . Utilization of the absorbed nutrients includes transport to various parts of the body, assimilation by cells, and conversion to biologically active forms. Nutrient-nutrient interactions may affect – Bioavailability in either in positive or negative way. May either enhance or inhibit nutrient absorption or utilization. High or low levels of one or more nutrients may affects bioavailability of other nutrient. Interaction can affect all the major categories of nutrients; protein, carbohydrates, fats, vitamins and minerals. Interactions of nutrients with non-nutrient components of foods can alter availability. Protein   Interaction of protein with other nutrient Various proteins bind and carry certain vitamins and minerals including iron, copper, calcium, vitamin A, vitamin D, fat. Inadequate protein intake may impair the function of these nutrients.  

10. CONTD… Carbohydrate Interaction of Carbohydrate with other nutrient Carbohydrates present in the body require thiamine for their metabolism, as thiamine pyrophosphate is a coenzyme for the oxidative decarboxylation of pyruvic acid, the main breakdown product of carbohydrate. Presence of excess carbohydrate in diet increase thiamine requirement also helps in functioning of fat and protein. Dietary fiber Interaction of dietary fiber with other nutrient It reduces the absorption and/or increase the excretion of several minerals, including calcium and iron.   Fat Interaction of fat with other nutrient The presence of excess fat in diet decreases thiamine requirement addition of essential fatty acid to a low pyridoxine diet offers protection against the development of deficiency sign due to pyridoxine deficiency.   Lipoic acid Interaction of Lipoic acid with other nutrient Vitamins C and E, coenzyme Q, glutathione, and NADH all require lipoic acid for their efficient recycling isulfur -containing amino acids, like cysteine and taurine , can also prevent lipoic acid synthesis in our cells.n the body. Deficiency of these antioxidant nutrients will reduce synthesis of lipoic acid in the body. Lipoic acid gets its two sulfur atoms primarily from the sulfur-containing amino acid methionine . For this reason, methionine deficiency can reduce the body's ability to make lipoic acid. Deficiency of other  

11. VITAMINS Interaction of Vitamin A with other nutrient- The transport and utilization of vitamin A is dependent upon several vitamin A binding proteins. Sufficient dietary intake of protein is required for the manufacture of these binding proteins, inadequate protein intake may result in vitamin A deficiency. Adequate intake of dietary fat and zinc is necessary for the absorption and utilization of vitamin A. Because vitamin A deficiency causes anemia, it is believed that vitamin A impacts the metabolism of iron. Excess vitamin A interferes with the absorption of vitamin K, a fat-soluble vitamin necessary for blood clotting. Interaction of Vitamin B2 with B1 and other nutrient Vitamin B2 status is strongly affected by intake of vitamin B1. Adequate supplies of vitamin B1 can help increase levels of vitamin B2. However, very high levels of vitamin B1 intake can increase the loss of vitamin B2 in the urine. Other nutrients, especially iron, zinc, folate , vitamin B3 and vitamin B12 are not fully available in the body without adequate supplies of riboflavin

12. Niacin-B3 Interaction of vitamin B3 with other nutrient B3 supply comes from conversion of the amino acid tryptophan. Tryptophan deficiency can therefore increase risk of vitamin B3 deficiency. (Tryptophan deficiency is likely to occur in any individual with poor overall protein intake.) Conversion also requires the presence of vitamins B1 and B6, and when B1 and/or B6 are deficient, B3 can also become deficient. Vitamin B3 deficiency also appears to be related to vitamin B12 status, since even mild deficiencies in vitamin B12 can increase loss of vitamin B3 in the urine. Pantothenic acid - B5 Interaction of pantothenic acid with other nutrient In animal studies, vitamins B12, folate , and biotin are required for proper use of vitamin B5 in the body's biochemical pathways. In addition, vitamin C appears to help prevent B5 deficiency. Folate   Interaction of folate with other nutrient   Vitamins B1, B2, and B3 must be present in adequate amounts to enable folic acid to undergo metabolic recycling in the body. Excessive amounts of folic acid, however, can hide a vitamin B12 deficiency, by masking blood related symptoms.  Vitamin B12   Interaction of vitamin B12 with other nutrient   Vitamin B6 is required for proper absorption of vitamin B12, and deficiency of vitamin B6 has been shown to impair B12 absorption in animal studies. Conversion of vitamin B12 from its non-active into its biologically active form requires the presence of vitamin E. Vitamin E deficiency may show signs of vitamin B12 deficiency as well. Excessive intake of folic acid can mask B12 Deficiencies  

13. Vitamin C   Interaction of Vitamin C with other nutrient   Vitamin C has significant interactions with several key minerals in the body. Supplemental intake of vitamin C at gram-level doses can interfere with copper metabolism. Conversely, vitamin C can significantly enhance iron uptake and metabolism, even at food-level amounts. Vitamin C also has important interactions with other vitamins. Excessive intake of vitamin A is less toxic to the body when vitamin C is readily available. Vitamin C is involved in the regeneration of vitamin E, and these two vitamins appear to work together in their antioxidant effect.   Vitamin D Interaction of vitamin D with other nutrient  It plays a role in maintaining normal blood levels of calcium. It impacts the absorption and storage of calcium. It also stimulates the absorption of phosphorus. Vitamin D is believed to regulate the production of certain calcium-binding proteins that function in the bones and kidneys. Because these binding proteins are dependent on vitamin K. It has also been theorized that iron deficiency results in decreased vitamin D absorption

14. Vitamin E The recycling of vitamin E in the body is intricately connected to four other nutrients: vitamin C, glutathione, selenium, and vitamin B3. Vitamin C is required to keep vitamin E in its metabolically active form. glutathione (a very small protein molecule called a tripeptide and consisting of three amino acid building blocks) is required to keep vitamin C in its active form. Selenium (a micromineral ) and vitamin B3 (in a special form called NADPH) are required to keep glutathione in its active form. At moderately high levels of 1,000 milligrams or more, vitamin E can interfere with the bodily activities of vitamin K. The potential injury to vitamin K metabolism was largely the reason why the National Academy of Sciences, in the year 2000, set a Tolerable Upper Limit (UL) of 1,000 milligrams per day for vitamin E.   Vitamin K   Research on nutrient-nutrient interactions with vitamin K has traditionally focused on the major fat-soluble vitamins-A, E, and D. Persons undergoing treatment with anticoagulant drugs have clearly been shown to have their anticoagulant therapy and their vitamin K status impacted by high doses of vitamin E. For this reason, intake of both vitamin K and vitamin E for persons undergoing treatment with anticoagulant medications needs to be determined with the help of a healthcare provider. In healthy persons, no food intake of vitamin E has been shown to compromise vitamin K status. However, under some circumstances, higher supplement intake of vitamin E (above 1,000 milligrams) has been shown to interfere with vitamin K function and, in some cases, to promote hemorrhaging. Since calcium metabolism can be greatly affected by both vitamin D and vitamin K, researchers suspect some key interactions between these two fat-soluble vitamins. However, the exact nature of this interaction has yet to be determined.  

15. Vitamin Antagonisms An anti-vitamin is a substance which makes the vitamin unavailable or ineffective within the body. Specifically these substances block the action of some vitamins. Sometimes, the antagonism may not be direct but indirectly they may increase the requirements of target vitamins because of their excessive intake. Vitamin A and D are mutually antagonistic to each other. Vitamin A reduces the toxic effects of vitamin D. Vitamin A enhances the absorption or retention potassium and phosphorus. It has been reported that vitamin B1 can have an antagonistic action against vitamin. The antagonistic relationship between vitamin C and vitamin B12 is an indirect one. Vitamin C neither directly affects B12, nor destroys this vitamin. Vitamin C enhances iron absorption. Increased amount of iron in body leads to deficiency of cobalt, which is an integral part of vitamin B. This is however a rare occurrence and may affect only a small segment of the population who may suffer from iron overload disorders. Vitamin A antagonists Blood-thinning medications and other drugs, including aspirin, phenobarbital , arsenicals and dicumarol (a drug used medically to retard blood clotting) destroy vitamin A in the body. Vitamin A is also depleted when nitrosamines are formed in the stomach from the union of nitrites with secondary amines and when the mucous membranes of our respiratory passages are exposed to air pollutants such as carbon monoxide, ozone, sulphur dioxide, nitrogen dioxide, lead, hydrocarbons, etc

16. Vitamin K Vitamin K is necessary for blood to coagulate effectively. Patients with a vitamin K deficiency have an increased risk of uncontrolled bleeding. There are some postulations which suggest that vitamin E inhibit the vitamin K dependent carboboxylase activity and subsequently inhibit the coagulation cascade. Therefore, high amount of vitamin E decrease the activity of vitamin K in coagulation. α- tocopheryl hydroquinone is an oxidized product of α- tocopherol and an efficient antioxidant. Vitamin E quinine is a potent anticoagulant as inhibitor of vitamin K dependent carboxylase that controls blood clotting. Vitamin B Antagonists Cortisone is an antagonist of vitamin B6 (pyridoxine). Since the body needs B vitamins to metabolize sugars, B vitamins are depleted when refined sugar or flour is consumed as refined sugar and flour are devoid of B vitamins that existed in the beet, cane or grain before refining. Specifically, the body’s supply of vitamin B1, vitamin B2, biotin, choline , niacin and the mineral magnesium are depleted when refined sugar and flour are consumed. Alcoholic beverages are antagonists of thiamin and the other B-complex vitamins. Coffee is another popular beverage that is a B vitamin antagonist, because it contains caffeine and other noxious substances like chlorogenic acid. Inositol deficiency may occur among coffee drinkers along with deficiency of biotin and thiamin. Raw fish and raw shellfish, including oysters, are also B-complex antagonists as raw fish contains the enzyme thiaminase which destroys thiamine. This is one of many reasons not to eat the Japanese dish, sashimi (raw fish) or any other raw seafood.

17.   Vitamin C and vitamin E interactions Vitamin C and vitamin E are both antioxidants and protect against reactive oxygen species. These substances are of parallel interest as water-soluble vitamin C regenerates lipid soluble vitamin E in an outside the cell of the organism. There is much evidence indicating that vitamins C and vitamin E may also have a physiologically relevant interaction. In guinea pigs, vitamin C deficiency led to reduced levels of vitamin E and administration of oxidized frying oil, large doses of vitamin C increased the level of vitamin E in the liver, kidney, spleen, and lungs. In inherently scorbutic rats, vitamin C deficiency led to reduced vitamin E levels in the liver, kidney, and heart. In normal rats, vitamin C supplementation increased plasma vitamin E level Contradicting to this Hruba et al.14 reported that vitamin C deficiency did not affect the plasma vitamin E level in guinea pigs. The excessive doses of vitamin C may reduce plasma vitamin E levels. The estrogen in oral contraceptives is also an antagonist of vitamin E. Vitamin C reacts with several alien substances in the bloodstream. All drugs and pollutants can be considered as vitamin C antagonists. Some of the foremost vitamin C antagonists include ammonium chloride, stribesterol , thiouracil , atropine, barbiturates and antihistamines. All stresses (surgery, emotional outbursts and upsets, acute pressures, extremes of heat and cold and all drugs) as well as alcoholic beverages are vitamin C antagonists. Anemia is often observed in vitamin C deficient patients. A normocytic or macrocytic anemia is generally observed, though megaloblastic has been reported sometimes in same patients. The presence of megaloblastic anemia in some scorbutic patients has given rise to the consideration that either a dietary deficiency of folic acid existed or that folate metabolism was impaired in vitamin C deficiency. In some instances the megaloblastic anemia was effectively treated with ascorbic acid alone, while in other reports, additional amounts of folic acid supplementation were required.  

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