Metabolic Integration and Nutrition

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Metabolic Integration and Nutrition

• Medical Biochemistry
• Lecture 57

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Nutrients There are Three Macronutrients

• Macronutrients
• Fat
• Protein
• Carbohydrate
• Micronutrients
• Vitamins
• Minerals
• Macrominerals
• Ca, P, Na, Cl, K, and Mg
• Microminerals

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Macronutrients Units of Measure

• Sucrose
• molecular weight of 342
• mmol 342 mg .34 g
• Starch
• Very large glucose polymer
• Variable molecular weight
• Hundreds to thousands of residues

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Macronutrients Units of Measure

• Each residue will contribute 162 daltons
• M.W. glucose (180 mg/mmol) - M.W. water (18
  mg/mmol)
• 162 mg/mmol of residues x 1,000 residues
  162,000 mg 162 g
• gt 500 times as much food and fuel as one mmol of
  sucrose

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Macronutrients Units of Measure

• Grams?
• US diet is approximately
• 40 fat
• 40 carbohydrate
• 20 protein
• of energy provided

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Heats of Combustion Energy Available from Major
Food Sources
Energy kcal/g (kJ/g)
Heat of Combustion (Bomb Calorimeter)
Human Oxidation
Standard Conversion Factors
5.4 (22.6)
4.1 (17.2)
4 (17)
9.3 (38.9)
9.3 (38.9)
9 (38)
4.1 (17.2)
4.1 (17.2)
4 (17)
7.1 (29.7)
7.1 (29.7)
7 (29)
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How Many g Protein Consumed?
20 of 40 kcal
kg d
1 g protein
8 kcal protein x
kg d
4 kcal protein
2 g protein
kg d
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Macronutrient IntakeAssume 70 kg consuming 3000
kcal/d
Intake (g/kg)
Energy (kcal)
Content (kcal/g)
Intake (g)
40 CHO
4
300
4.3
1200
40 Fat
1200
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133
1.9
20 Protein
4
150
600
2.1
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Energy Protein Requirements
Energy Requirement
Protein Requirement
Baby
110 kcal/kg/d
1.1 g/kg/d
Adult
40 kcal/kg/d
0.8 g/kg/d
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Pregnant
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25
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Lactating
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Essential Dietary Amino Acids

• Quality of dietary protein
• Human milk
• Dairy products and meats
• Vegetarian diets
• Plant sources of protein can be mixed and matched
• Offsetting deficiencies (e.g., lysine in wheat
  and methionine in beans)

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The following macronutrients contain substances
that are structurally essential to humans

• A. Carbohydrates
• B. Lipids
• C. Proteins
• Your Choices
• 1. A and B
• 2. B and C
• 3. A and C
• 4. All of the above

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Correct Answer 2. B and CLipids and Proteins

• Lipids contain essential fatty acids

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EFA Deficiency
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Correct Answer 2. B and CLipids and Proteins

• Lipids contain essential fatty acids
• Proteins contain the essential dietary amino
  acids
• Carbohydrates are not structurally required

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Fatty Acids
Triose phosphate
Phosphoenolpyruvate
Pyruvate
Acetyl-CoA
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Carbohydrate
(
Glycogen Glucose
(
Phosphoenolpyruvate
Oxaloacetate
Citric Acid Cycle
Aspartate
Citrate
Fumarate
?-Ketoglutarate
Isoleucine
Succinyl-CoA
Propionyl-CoA
Propionate
Odd Chain
Methionine
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Protein-energy Malnutrition Definition

• Combined deficiency of energy, protein, vitamins,
  and minerals
• Marasmus
• Kwashiorkor protein deficiency edema
  (kwashi is squashy)

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Biosynthesis of Malonyl-CoA(Enz, acetyl-CoA
carboxylase)
CH3 CO S CoA
-OOC CH2 CO S CoA
Acetyl-CoA
Malonyl-CoA
Enz biotin
Enz biotin COO-
ATP HCO3-
ADP Pi
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Regulation of Ketogenesis
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Regulation of LC FA Oxidation in the Liver
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Liver
Major Function
Service for the other organs and tissues
Most - gluconeogenesis ß-oxidation ketogenesis
lipoprotein, uric acid, urea, bile acid, and
cholesterol synthesis
Major Pathways
Major Substrates
Free fatty acids, glucose (well fed), lactate,
glycerol, fructose, amino acids
Glucose, VLDL(triacyglycerol), HDL, ketone
bodies, urea, uric acid, bile acids, plasma
proteins
Major Products
Specialist Enzymes
Glucokinase, glucose-6-phosphatase, glycerol
kinase, PEP carboxykinase, fructokinase,
arginase
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Brain
Major Function
Coordination of the nervous system
Major Pathways
Glycolysis, amino acid metabolism
Glucose, amino acid, ketone bodies (in
starvation) Polyunsaturated fatty acids in
neonate
Major Substrates
Major Products
Lactate
Specialist Enzymes
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Heart
Major Function
Pumping of blood
Aerobic pathways, e.g., ß-oxidation and citric
acid cycle
Major Pathways
Free fatty acids, lactate, ketone bodies, VLDL
and chylomicron triacylglycerol, some glucose
Major Substrates
Major Products
Specialist Enzymes
Lipoprotein lipase, respiratory chain well
developed
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Adipose Tissue
Major Function
Storage and breakdown of triacylglycerol
Esterification of fatty acids and lipolysis
lipogenesis
Major Pathways
Major Substrates
Glucose, lipoprotein triacylglycerol
Major Products
Free fatty acids, glycerol
Specialist Enzymes
Lipoprotein lipase, hormone-sensitive lipase
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MuscleFast Twitch, Slow Twitch
Major Function
Rapid movement. Sustained movement
Glycolysis. Aerobic pathways, e.g.,
ß-oxidation and citric acid cycle
Major Pathways
Major Substrates
Glucose Ketone bodies, triacylglycerol in VLDL
and chylomicrons, free fatty acids
Major Products
Lactate
Specialist Enzymes
Lipoprotein lipase. Respiratory chain well
developed.
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Kidney
Major Function
Excretion and gluconeogenesis
Major Pathways
Gluconeogenesis
Major Substrates
Free fatty acids, lactate, glycerol
Major Products
Glucose
Specialist Enzymes
Glycerol kinase, phosphoenolpyruvate
carboxykinase
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Erythrocytes
Major Function
Transport of O2
Glycolysis, pentose phosphate pathway. No
mitochondria and therefore no ß- oxidation or
citric acid cycle.
Major Pathways
Major Substrates
Glucose
Major Products
Lactate
Specialist Enzymes
(Hemoglobin)