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Nutrition Tools  
  
1102   11:46 صباحاً   date: 7-12-2021
Author : Denise R. Ferrier
Book or Source : Lippincott Illustrated Reviews: Biochemistry
Page and Part :

Nutrition Tools


A set of tools has been developed that gives consumers information about what (and how much) they should eat as well as the nutritional content of the foods they do eat. Additional tools allow medical professionals to assess whether or not the nutritional needs of an individual are being met.
A. MyPlate
MyPlate was designed by the U.S. Department of Agriculture (USDA) to graphically illustrate its recommendations as to what food groups and how much of each should be consumed daily. In MyPlate, the relative amounts of each of five food groups (vegetables, grains, protein, fruit, and dairy) are represented by the relative size of their section on the plate (Fig. 1). The number of servings depends on variables that include age and sex. [Note: MyPlate replaced MyPyramid in 2011.]

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Figure 1:  MyPlate.
B. Nutrition facts label
Most types of packaged goods are required to have a Nutrition Facts label, or “food label” (Fig. 27.24), that includes the size of a single serving, the Cal it provides, and the number of servings per container. In addition, a percent daily value (%DV) is shown for most nutrients listed. [Note: The %DV is based on a 2,000-Cal diet for healthy adults.]

Figure 2: Nutrition Facts label (food label).
1. Percent daily value: The %DV compares the amount of a given nutrient in a single serving of a product to the recommended daily intake for that nutrient. For example, the %DV for the micronutrients listed, as well as for total carbohydrates and fiber, are based on their recommended minimum daily intake. Thus, if the label lists 20% for calcium, one serving provides 20% of the minimum recommended amount of calcium needed each day. In contrast, the %DV for saturated fat, cholesterol, and sodium are based on their recommended maximum daily intake, and the %DV reflects what percentage of this maximum a serving provides.
There is no %DV for protein because the recommended intake depends on body weight (see p. 367). [Note: “Sugars” represents mono- and disaccharides. The remainder of the carbohydrate (total carbohydrate –[fiber + sugars]) is the oligo- and polysaccharides.]
2. Proposed revisions: In 2014, the USDA proposed the following changes to the Nutrition Facts label for implementation by 2018: Added sugars, vitamin D, and potassium are to be included; vitamins A and C, total fat, and Cal from fat are to be removed; and serving size is to be adjusted to reflect the amounts people are now consuming. Additionally, design changes to highlight key parts of the label were proposed (Fig. 3). [Note: The proposed addition/removal of certain micronutrients is based on newer data on the risk for underingestion.]

Figure 3: Nutrition Facts label showing changes proposed in 2014 for implementation by 2018.
C. Nutrition assessment
Nutrition assessment evaluates nutritional status based on clinical information. It includes (but is not limited to) dietary history, anthropometric measures, and laboratory data. [Note: Assessment findings may result in medical nutrition therapy, which is the treatment of medical conditions through changes in diet (for example, replacement of long-chain TAG with medium-chain TAG in malabsorption disorders) and/or the method of intake (for example, enteral [tube] or parenteral [IV] feeding).]
1. Dietary history: This is a record of food intake over a period of time. For a food diary, the specific types and exact amounts of food eaten are recorded in “real time” (as soon as possible after eating) for a period of 3–7 days. Retrospective approaches include a food frequency questionnaire (for example, what fruits were eaten and how often they were eaten in a typical day, week, or month) and a 24-hour recall of the specific foods and the amounts eaten in the last 24 hours.
2. Anthropometric measures: These are physical measures of the body. They include (but are not limited to) weight, height, body mass index (an indicator of obesity, see p. 349), skin-fold thickness (an indicator of subcutaneous fat), and waist circumference (an indicator of abdominal fat). [Note: Ideal body weight can be calculated using the Hamwi method: 106 lb (for males) or 100 lb (for females) for the first 5 ft of height + 5 lb for every inch over 5 ft, with an adjustment of −10% for a small frame and + 10% for a large one.]
3. Laboratory data: These are obtained by tests performed on body fluids, tissues, and waste. They can include plasma LDL-C (for cardiovascular risk), fecal fat (for malabsorption), red cell indices (for vitamin deficiencies), and N balance and serum proteins (such as albumin and transthyretin [prealbumin]) for protein–energy status. [Note: These proteins are made in the liver and transport molecules such as fatty acids and thyroxine  through blood. Low albumin levels correlate with increased morbidity and mortality in hospitalized patients. The short half-life (2–3 days) of transthyretin as compared to that of albumin (20 days) has led to its use in monitoring the progress of hospitalized patients.]
Nutritional insufficiency can be the result of inadequate nutrient intake (caused, for example, by an inability to eat, loss of appetite, or decreased availability), inadequate absorption, decreased utilization, increased excretion, or increased requirements.




علم الأحياء المجهرية هو العلم الذي يختص بدراسة الأحياء الدقيقة من حيث الحجم والتي لا يمكن مشاهدتها بالعين المجرَّدة. اذ يتعامل مع الأشكال المجهرية من حيث طرق تكاثرها، ووظائف أجزائها ومكوناتها المختلفة، دورها في الطبيعة، والعلاقة المفيدة أو الضارة مع الكائنات الحية - ومنها الإنسان بشكل خاص - كما يدرس استعمالات هذه الكائنات في الصناعة والعلم. وتنقسم هذه الكائنات الدقيقة إلى: بكتيريا وفيروسات وفطريات وطفيليات.



يقوم علم الأحياء الجزيئي بدراسة الأحياء على المستوى الجزيئي، لذلك فهو يتداخل مع كلا من علم الأحياء والكيمياء وبشكل خاص مع علم الكيمياء الحيوية وعلم الوراثة في عدة مناطق وتخصصات. يهتم علم الاحياء الجزيئي بدراسة مختلف العلاقات المتبادلة بين كافة الأنظمة الخلوية وبخاصة العلاقات بين الدنا (DNA) والرنا (RNA) وعملية تصنيع البروتينات إضافة إلى آليات تنظيم هذه العملية وكافة العمليات الحيوية.



علم الوراثة هو أحد فروع علوم الحياة الحديثة الذي يبحث في أسباب التشابه والاختلاف في صفات الأجيال المتعاقبة من الأفراد التي ترتبط فيما بينها بصلة عضوية معينة كما يبحث فيما يؤدي اليه تلك الأسباب من نتائج مع إعطاء تفسير للمسببات ونتائجها. وعلى هذا الأساس فإن دراسة هذا العلم تتطلب الماماً واسعاً وقاعدة راسخة عميقة في شتى مجالات علوم الحياة كعلم الخلية وعلم الهيأة وعلم الأجنة وعلم البيئة والتصنيف والزراعة والطب وعلم البكتريا.