Macro Nutrients Carbohydrates From Mc Ardle W Katch
Macro Nutrients Carbohydrates From Mc. Ardle, W. Katch, F. Katch, V. Essentials of exercise Physiology (5 th edition) 2016 Wolters Kluwer • Found in Most living cells, • Plant sources provide all CHO except for lactose (milk) & a small amount of glycogen which is found in animals
Monosaccharide - basic unit of Carbohydrate • Glucose – dextrose / blood sugar • Formed in plants a) when carbon, hydrogen, water & chlorophyll combine with sunlight b) through breakdown /digestion food (hydrolysis) a) Immediate Cell energy b) Can be Stored energy (glycogen) in muscle liver c) Can be converted & stored for later use as fat or d) Provides carbon to synthesize non essential amino acids • Fructose - considered the sweetest found in honey, tree & vine fruits, root vegetables, berries & flowers • a) Energy source b) travels fast in body & readily turns to fat but also glucose in liver • Galactose – milk sugar (lactose) & readily converts to glucose for energy metabolism
Carbohydrates • Stored in liver & muscles as glycogen 1 g CHO either as glucose or glycogen = 4 kcal of energy • Muscle glycogen = main source of energy for all physical activities • Limited storage capacity & the upper limit = 15 g / Kg of body weight Average size person • Stores between 1, 500 & 2, 000 kcal of CHO • Well-nourished 80 kg person stores 500 g CHO 400 g in muscle 100 g in liver & 2 - g in blood as glycogen = energy to run 20 miles on level ground
Disaccharide Two Monosaccharides Combined • Sucrose = glucose + fructose a)occurs naturally b) found in beet, cane, sugar, & brown sugar, maple syrup & honey • Lactose = glucose + galactose a) naturally in milk (milk sugar) • Maltose = glucose + glucose fund in cereals & germinating seeds
Polysaccharides Plant & Animal Based Plant polysaccharides Starch – hundreds of sugar molecules large granules in seed, corn cells & grains (breads cereals pastas potatoes roots) Fiber – Non starch = cellulose (most abundant organic molecule on earth a) Provides structure of plant roots stems leafs seeds & fruit coverings b) found in cell walls as (cellulose) gums, pectin, lignins c) Resist hydrolysis in digestive tract important because fiber has beneficial physiological effects
Health Benefits of Fiber Characteristics & Role of Fiber 4) Provided fuel to cells of colon 5) lower levels of obesity, type II diabetes, hypertension, heart disease & intestinal disorders & • https: //www. mayoclinic. org/diseasesconditions/divert iculitis/symptoms-causes/syc-20371758 • Functional Fiber = nondigestible CHO Nutrient rich, low energy (caloric) & dense food that 1) Holds water & adds volume to food In our gut 2) Contributes to satiety (feeling full) 3) Reduces constipation, diverticular disease & colon cancer by moving food through digestive track 6) Reduces blood glucose & lipid (fat) levels ü Water soluble – preferred & help reduce cholesterol levels & blood lipid levels ü Found in rolled oats / oat bran, citrus fruits, apples, carrots, peas ü Insoluble fibers = cellulose, wheat bran lignin ü 3: 1 intake of water soluble to insoluble fiber preferred ü 20 -40 g daily advised
Obesity / Fiber Link Glycemic index – Relative guide as to various carbohydrates ability to raise blood glucose levels High processed low in fiber foods (simple sugar) affect absorption rates of carbohydrates (high glycemic index) High glycemic index foods enter blood fast & elevate blood sugar levels Affects how hormones (insulin) regulates blood sugar 25% of adults produce excessive insulin Excessive insulin cause obesity because higher levels of glucose oxidation happen instead of fatty acid oxidation Insulin surge causes abnormal decrease in blood glucose, (hypoglycemia) Insulin stimulates fat storage in adipose tissue Hypoglycemia causes urge to eat & very possibly to overeat
Glycemic Index Vs. Glycemic Load Glycemic Index • Indicator of CHO containing foods ability to raise blood glucose levels • Standard for measurement = white bread or glucose & given a value of 100 or 1 • Measurement • Eating 50 g of CHO or food containing CHO • Ability to raise blood glucose levels in comparison for a 2 hour time period • Apples = glycemic index of 39 • Eating 50 g apple = 50 g will raise blood glucose level to 39% of eating 50 g of glucose or white bread • High glycemic index food can be considered healthy (carrots, brown rice, corn) Glycemic Load Quantifies serving sizes of foods or the available CHO per serving & its glycemic index Reflects greater ability to raise a) blood glucose levels b) Insulin release in response Frequent eating of high glycemic load foods are associated with a) Increased risk to type II diabetes b) Coronary artery disease
Dietary Trends & Industrialized Nations American diets • Generally high in fiber free refined, + animal based & coupled with low levels of plant foods • 12 -15 g of fiber consumed daily National Academy of Sciences (NAS) Recommendations – men = 38 g, women = 25 g up to age of 50 then 30 g & 21 g respectfully • Water Soluble = pectin, guar gum & found in apples, carrots, berries, • Beans, peas, Legumes, Barley & brown rice • Non soluble= cellulose, lignin, hemicellulose wheat bran did not reduce cholesterol levels Current General Consensus • Consume 20 -40 g of fiber daily at a ratio of 3: 1 water soluble to insoluble fibers obesity / low fiber link https: //www. nationalacademies. org/fnb/food-and-nutrition-board
Exercise & Carbohydrates • Primary Role= energy source for activity – especially intense • Readily converted to fat when Intake exceeds glycogen storage capacity Finding Your Estimated Storage Capacity (grams) Wt. in lb divided by 2. 25 Pound to kg Conversion = body. X 15 Intense Physical Activity
Carbohydrates Primary Source of Body’s Energy Only macronutrient used in both aerobic (long lower intensity) & anaerobic (short higher intensity) metabolism Stored glycogen = primary energy source form rest to initial activity Fast source of energy – twice the rate as fats for work done 1 st 20 minutes of activity = 40%-50% of energy Long bouts of activity causes glycogen depletion & more fats are used Approximately ½ of energy supplied for light & moderate activity Needed “primer” for fat metabolism as well Helps to prevent protein & tissue breakdown in the body (Catabolism)
CHO & the Brain CHO (glucose) impact on the brain & CNS. CHO Structure = 3 carbon compound Brains primary & almost exclusive fuel source consumes about 120 g / 420 kcal (1760 k. J) daily (2) Approximately 60% of the utilization of glucose by the whole body in the resting state (2) Fatty Acids cannot cross the blood brain barrier Brain, Speech & Importance of Glucose for Tasks Taken from http: //communica. co. cr/en/ Intensive brain tasks – simultaneous interpretation consecutive interpretation or document interpretation Recommended interpreters require adequate supply of glucose Exam taking – may be important as well ask teachers if that is why hard candy / sweets are sometimes given during exams Image from “Interpreters & Translators Need to consume sugar (glucose)” http: //communica. co. cr/en/
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