Lecture 4- Carbs Flashcards
Function if carbs
- provide energy
- spare protein
- provide fiber
- provide sweetness
Carbohydrates
- carbon
- oxygen
- hydrogen
- also called saccharides
Simple carbs
- monosaccharide
- disaccharide: common form found in nature
Complex carbs
- 3 or more monosaccharides
- oligosacchrides (3-10 monosaccharides)
- polysaccharide (hundreds of monosacharides)
Monosaccharides
Glucose: must abundant sugar molecule in our diet; good energy source (not often found alone)
Fructose: sweetest natural sugar; found in fruit, high-fructose corn syrup
Galactose: does not occur alone in foods; binds with glucose to form lactose
Galactose + glucose
Lactose
Glucose + glucose
Maltose
Glucose + fructose
Sucrose
Polysaccharides
- Starch: storage forn of glucose in plants; food source include grains, legumes, amd tubers
- Glycogen: storage form of glucose in animals; stored in liver and muscles
- fiber: forms the support structure of leaves, stems, and plants
Insoluble fiber
- does not dissolve in water
- part of plants cell wall
- not metabolized by bacteria
- contributes bulk to stool
- ex. Cellulose
- good source: whole grains
Health benefits to insoluble fiber
- promote regular BM and decrease constipation
- help prevent hemorrhoids, diverticulitus
• diverticula: bulging pockets in colon - may lower the risk of colon cancer
Soluble fiber
- dissolves in water, is viscous and gel- forming
- found in plant cells
- bacteria metabolize them easily
Ex. Gums, pectin - found in oatmeal, beans
Health benefits to soluble fiber
Lowers cholesterol
Total fiber and health benefits
- may improve blood glucose levels in diabetics
• delay nutrient absorption and release of glucose into the blood stream - high fiber diet may promote weight loss
• food high in complex carbs= low in fat an sugar= lower calories
• fiber an water= bulk, dense food - delays gastric emptying
- increase satiety
Whole grain
- Bran: fiber(insoluble) , vitamins
- Germ: vit E, healthy fats, protein, fiber, B vit
- endosperm: starch, small anounts of protein, minimal vits and min
Grain Enriched
Add back nutrients that were lost in processing
- refined grains with riboflavin, niacin, thiamin, iron
- not with fiber, vit E, UFA, phytochemicals
Grain fortified
Add ingredients that were not originally in the product
- folate, sterols, omega3 fatty acids, vit D in milk, extra iron
What enzymes break down Carbs
Salivary and pancreatic amylase
- lactase, amylase
Brush border enzymes
- sucrose
Absorptions of carbs
- monosaccharide: glucose, fructose, galactose are absorbed into the entrocyte
- enter capillaries and bloodstram —> liver
- in liver cells, fructose and glactose —> glucose
The fate of glucose
- used for energy in liver and travelto other cells for energy production
- stored in liver and muscles as glycogen
- in consumed in excess of energy needs —> synthesize fatty acids
- used to maintain blood glucose levels to ensure adequate glucose for thr cells to make energy
Carb metabolism
- glycolysis produces pyruvate
- pyruvate in the presence of O2 and with coenzymeA forms acetyl CoA
- acetyl CoA enters citric acid cycle
- these steps reduce coenzymes
- reduced coenzymes transport electrons to the ETC
- by product: ATP, water, CO2, oxidized coenzymes
Oxidation
Loss of an electron
Reduction
Gain if an electron
Carbs in the body: stored as glycogen
If glucose is not needed for energy it is stored ad glycogen
- storage form of glucose
- used during sleep, fasting, excercise
- made and stored by liver and muscle tissues
- liver ~100g glycogen (400 Kcal) used to maintain BG to provide fuel for brain and RBC
- muscles: ~350g (1400 Kcal) used to meet muscle needs
• is not released into the blood for use
Excess carbs stored as fats
Lipogenesis: making fat from nonfat substances
- mostly occurs in liver cells
- travels to adipose cells for storage
Blood glucose levels
-blood glucose: sugar in blood
- function of blood glucose is ti provide a circulating steady supply of fuel for cells
• immediately available so it can be taken up bu cells and used for energy
• peferred fuel for brain and only fuel for red blood cells
• used by muscles in aerobic excercise
Pancreatic hormonrs that regulate blood glucose levels
- insulin
- glucagon
Insulin
- cellular uptake of glucose (actuvr transport)
- uptake by liver and muscles to store as glycogen
- anabolic hormone
- secreted by pancreas
Glucagon stimulates liver to…
- convert stored liver glycogen yo glucoose (glycogenesis)
- convert amino acids to glucose (gluconeogenesis)
- catabolic hormone
- secreted by pancreas
Needs of carbs
- the RDA: 130g/day
- AMDR: 45-65% of energy
• 2000 calories= 225-324 g - AI for fiber:
• 38g/d for 19-50 adult men
• 25g/d for women - AHA recommends:
• 100 kcal-6 tsp for women
• 150 kcal-9 tsp for men
Diabetes
- inability to regulate blood glucose levels within the normal range
- if blood sugar level is less than 100mg that you are okay!
- if between 100-125 then considered prediabetes
- 126 and over, you have diabetes
Type 1 diabetes
Autoimmune disease: own immune system destroys yhe insulin producing beta cells of pancreas
Type 2 diabetes
Decrease sensitivity or response to insulin
Symptoms and outcome of diabetes
Immediate symptoms
- frequent urination and unusual thirst: BG excreted in urine
- unusual weight loss -BG not entering cells, use pro/fat
- extreme hunger
- type 2: frequent infection and slow healing, blurred vision, numbness in hands and feet
- type 1: fruity odor breath, ketone production
Long term complications:
- damage to large blood vessels
- damage to small blood vessels (eyes: blindness, kidneys: kiney failure)
- amputation: nerve damage and increase blood glucose= microbial growth
Diseases related to hypoglycemia
- low blood sugar (glucose) causing shakiness, sweating, anxiety
- reactive hypoglycemia: pancreas secretes too much insulin after a high- carb meal
- regualr small meals
Glycemic index
- a food’s potential to raise blood glucose
- compared with standard amount of glucose or white bread
- increase glycemic index= rapid increase in blood glucose levels
- influenced by carb content, type of carb, the way it i prepared, fat and fiber content
- under 55 is low and over 77 is high
- glycemic load: GI x carbs in a typical portion
- possibly important for people with diabetes but total carb is important
Polysaccharides: starch
Amylose: straight chain
Amylopectin: branched chain
- contain digestable alpha binds
