Lecture 09 - Carbohydrates

Phenylketonuria

PKU is an inherited condition attributed to a defective gene

Protein-energy malnutrition (PEM)

PEM is used to refer to the continuum of protein deficiency conditions ranging from mostly protein deficiency, called kwashiorkor, to overall energy deficiency, called marasmus. most protein-energy malnutrition is a combination of the two.

Kwashiorkor

sever protein deficit; often accompanied by infections or other diseases

Kwashiorkor Characteristics

edema, mild to moderate weight loss, maintenance of some muscle and subcutaneous fat, growth impairment (60-80% of normal weight for age), rapid onset, fatty liver

Marasmus

severe energy and protein deficit

Marasmus characteristics

severe weight loss, wasting of muscle and body fat (skin and bones appearance), severe growth impairment (less than 60% of normal weight for age), develops gradually

Types of vegetarian diets

semi-vegetarian, lacto-ovo vegetarian, vegan

Health benefits of vegetarian eating

less fat, saturated fat, and cholestrol

Health risks of vegetarian eating

restrictive diets may lack nutrients; careful planning needed for children, pregnant women

Nutrients Supplied by Plant and Animal Foods

Animal products provide sources of protein, B vitamins and minerals such as iron, zinc, and calcium

- however, animal products are low in fiber and can be high in fat

- plant sources of protein are also a good source of B vitamins, iron, zinc, and fiber and calcium, but in less absorbable forms

Food Protein Allergies

foot proteins (allergens) cause an immune response, creating an allergic reaction

8 foods account for 90% of food allergies: peanuts, tree nuts, milk, eggs, fish, shellfish, soy, and wheat

Too much protein can lead to...

heart disease, obesity, cancer, osteoporosis, kidney stones, hydration and kidney function

Hydration and Kidney Function

When protein intake increases above the amount needed, so does the production of protein breakdown products, like urea, which must be eliminated from the body by the kidneys. to do this, more water must be excreted in the urine, increasing water losses

Kidney Stones

the increase in urinary calcium excretion associated with high-protein diets has lead to speculation that a high protein intake may increase the risk of kidney stones.

Heart disease and cancer

high protein diet is related more to the dietary components that accompany animal vs plant proteins. typically, high protein diets are also high in animal products; this dietary pattern is high in saturated fat and cholesterol and low in fiber

Celiac disease

wheat-gluten intolerance (found in wheat, rye, and barley)

Photosynthesis

sunlight energy goes the plant, carbon dioxide and water goes into plant, carbohydrates are formed, and oxygen is released by the plant

Carbohydrates

macronutrient; 4kCal/g

carbon, oxygen, hydrogen (C+H20)

Glucose: C6H12O6

Carbohydrates functions

provides energy

spares protein

provides sweetness

provides fiber

enhance functions of many proteins

Carbohydrate Type: Simple

Monosaccharides (ex. glucose, fructose)

Disaccharides (sucrose "sugar" = glucose + fructose)

Carbohydrate Type: Complex (3+ monosaccharides)

Oligosaccharides

Polysaccharides (starch, fiber, glyocen)

Glucose Molecule

most abundant sugar molecule in our diet; good energy source

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 (milk sugar)

Glucose + Glucose

Maltose: join in food to form starch molecules; by-product of fermentation process

Glucose + Fructose

Sucrose: found in sugarcane, sugar beets, and honey

Lactose Intolerance

not enough lactase in the SI to digest lactose

symptoms: diarrhea, bloating, intestinal gas

Oligosaccharides

3-10 monosaccharides, indigestible molecular bonds, colonic bacteria digest = gas, short chain fatty acids (SCFA)

Amylase

pancreatic enzyme that breaks down carbohydrates (starch) into sugars which are more easily absorbed by the body; also found in saliva;

shortage may lead to diarrhea due to effects of undigested starch in the colon

Digestion and absorption in the small intestine

1) pancreatic amylase digests starch to double sugars and short glucose chains

2) fiber, which cannot be digested by human enzymes, passes to the large intestine

3) enzymes in the microvilli digest double sugars into single sugars, which are absorbed into the blood

Fates of Glucose

monosaccharides enter capillaries, travel to liver

in liver cells, fructose & galactose > glucose

Glucose

used for energy in liver, passed into the blood for other cells to use for energy, store in liver and muscles a glycogen, if consumed in excess energy needs > synthesis fatty acids

Insoluble Fiber

part of cell wall

do not dissolve in water

contributes bulk to stool

ex. cellulose, hemicellulose

good sources: whole grains, fruits, vegetables

Soluble fiber

dissolve in water, are viscous and gel-forming, bacteria metabolize-like oligosaccharides

ex. gums, pectin

good sources: fruits, berries, oats, and beans

Polysaccharides: starch

storage form of glucose in plants; food sources include grains, legumes, and tubers

Polysaccharides: glycogen

storage form of glucose in animals; stored in liver and muscles

Polysaccharides: fiber

forms the support structures of leaves, stems, and plants

Fiber: Health Benefits

promote weight loss, promote regular bowel movements, prevent constipation, prevent hemorrhoids and diverticulitis, lower the risk of colon cancer

Soluble Fiber: Health Benefits

lowers cholesterol

- soluble fiber binds with bile

- decreases reabsorption of bile acids

- increase hepatic cholesterol > bile acids

- increases LDL uptake by liver

delays rise in blood glucose

- fiber in food 'traps" nutrients

-delays nutrient absorption

-stabilizes blood sugar level

Enterohepatic Circulation of Bile

in gallbladder, bile is stored > in small intestine, bile emulsifies fats (in the colon bile that has been trapped by viscous fibers is lost in feces) > bile reabsorbed into the blood > in the liver, bile is made from cholesterol

Whole grains (unrefined grains)

contain

- bran layers: good source of fiber and vitamins

- germ: good source of vegetable oils and vitamin E

- endosperm: contains starch and some protein

but processing removes the bran and germs, loss of nutrients