Carbohydrates Used as energy source in the body Some can be stored as glycogen (a storage polymer) in the liver and muscles and quickly converted back.

14.4 NUTRITION

CarbohydratesUsed as energy source in the bodySome can be stored as glycogen (a storage

polymer) in the liver and muscles and quickly converted back to glucose

Excess is converted by the body to be stored as fat

Carbohydrates

• Glycemic index: a measure of how quickly a carbohydrate is digested and glucose is absorbed from the small intestine to the bloodstream. The higher the GI, the quicker the release of glucose.

CarbohydratesCarbohydrates with a low GI (55 or less)

don't make our blood glucose levels rise very high for very long. They provide sustained energy.

Carbohydrates with a high GI (70 or more) are the ones that cause our blood glucose levels to go higher for longer. High blood glucose may cause damage to vital organs.

CarbohydratesSimple carbohydrates:

○ Quick to break down – sugar released quickly○ High glycemic index○ E.g. potatoes, white flour

Complex carbohydrates:○ Slower to break down – sugar is released

slowly○ Lower glycemic index○ E.g. whole grains, oats, beans

ProteinsUsed to build enzymes, muscle tissue,

plasma proteins, hormonesExcess cannot be stored and is converted to

fat with nitrogenous waste begin disposed of in urine

Eight essential amino acids (body cannot make, must be consumed in diet)

20 amino acids totalHigh protein foods include: meat, beans,

dairy, eggs, nuts

LipidsUsed as high energy sourceInclude fats, oils, and cholesterolServe as high energy source: each gram of

a lipid contains 2.5 times more calories than a gram of protein or carbohydrate

Essential fatty acids○ Fatty acids the body can’t make must be in

diet

Lipids

Two general categories of fatty acids:Unsaturated fatty acids

○ Liquid at room temp.○ Oils, plant fats (generally)

Saturated fatty acids○ Solid at room temp.○ Butter, animal fats (generally)

Lipids

Types and Functions of LipidsTriglycerides

○ crucial in the body for energy storageSteroids

○ benefit the body by helping determine and control the structure of plasma membrane

LipidsPhospholipids

○ key role in constituting cell membranes.Glycolipids

○ play an important role in boosting the body’s immune system

Lipoproteins (cholesterols)○ help fat move around the body in the

bloodstream ○ exist in the form of Low Density Lipoprotein

(HDL) and High Density Lipoprotein (LDL)

VitaminsAre organic compounds (other than carbs,

lipids or proteins) that the body needs for metabolic processes, but is unable to produce in adequate quantities on its own

Some vitamins are fat soluble, such as Vitamins A, D, E, and K

VitaminsOthers are water soluble, such as Vitamin C

○ need to take these with food b/c body can’t absorb them otherwise and they may make you feel ill.

Too little or too much of a vitamin can have harmful effects.○ E.g. too little Vitamin D causes Rickets, bone

decalcification and weakening (osteoporosis), but too much can cause calcification of soft tissues, diarrhea, possible renal (kidney) damage

Dietary Supplements

Dietary SupplementsAre nutrients and plant products used to

enhance healthIronic fact: most people who take

supplements don’t need them. Why might that be?

MineralsAre non-organic compounds that the body

needs to function properly.Examples: calcium, potassium, sodium

Minerals

○ CalciumFunction: strong bones, teeth, nerve

conduction, muscle contractionFood sources: dairy, leafy green

vegetablesToo little: stunted growth in children,

low bone density in adultsToo much: kidney stones, interferes

with iron and zinc absorption

Minerals○ Potassium

Function:Food sources:Too little:Too much:

○ SodiumFunction:Food sources:Too little:Too much:

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