Glycogen —> Stores carbohydrates in the liver and muscle until needed

Major source of energy for ppl all over the world

Made up of elements carbon (C), hydrogen (H), oxygen (O)

Each gram of carbohydrates provides 4 calories

Protein sparing action

• function of carbohydrates

• spare proteins for their primary function of building and repairing body tissues

Normal fate metabolism

• requires an adequate supply of carbohydrates.

• When there isn’t enough carbohydrates —> ketones are produced.

  • Ketones are acids that accumulate in the blood, urine.

    • Less hungry

  • Ketoacidosis —> a serious condition whereby the levels of ketones reach abnormally high level

Principal sources of carbohydrates

• Cereal grains

  • Dietary staples in nearly every part of the world

  • Rice is the basic food

  • Contains vitamins, minerals and some proteins.

  • When a nutrient that has never been part of a grain is added, the grain is said to be fortified

• Vegetables

  • Substantial amounts of carbohydrates in the form of starch

  • Provide dietary fiber, vitamins and minerals

• Fruits

  • Provide fruit sugar, fiber, vitamins and minerals

• Sugars

  • Table sugar, honey and syrup.

  • Provide carbohydrates in a form of sugar with few other nutrients except for fat

  • Low nutrient dense foods

• Milk (only animal source)

Monosaccharides

Simplest form of carbohydrates

Require no digestion and can be absorbed directly into the bloodstream

Glucose (AKA dextrose)

• All other forms are converted into this for metabolism.

• Found naturally

• Central nervous system, the red blood cells and the brain use only glucose as fuel

• Needed constantly

• Furnish E, Spare proteins and prevents ketosis

• Deficiency symptoms —> Fatigue and Weight loss

Fructose (AKA fruit sugar, levulose)

• Found with glucose in fruits and in honey

• Sweetest of all the monosaccharides

• Provide vitamins, minerals and fiber

Galactose

• Product of the digestion of milk

• Not found naturally

• Found in lactose

Disaccharides

Pairs of the three sugars; sweet and must be changes to simple sugars before they can be absorbed

Sucrose

• Composed of glucose and fructose

• form of carbohydrate present in granulated, powdered and brown sugar and also molasses

• sweetest and least expensive sugars

• Function - Furnish Energy, Spare Proteins and prevent ketosis

Maltose

• produced by enzyme action during the digestion of starch in the body.

• created during the fermentation process that produces alcohol

Lactose

• sugar found in milk; not found in plants

• help the body absorb calcium

Lactose Intolerance

• Ppl that are unable to digest lactose and get an severe allergy reaction.

• caused by insufficient lactase (an enzyme required for digestion of lactose

Polysaccharides

Complex carbohydrates

Starch

• Found in grains and vegetables.

• Storage form of glucose in plants

• Takes the body longer to digest

• Supply E over a long period of time.

Starch is found mainly in the endosperm (center part of the grain)

The tough outer covering of grain kernels is called the bran

The germ is the smallest part of the grain and is rich source of B vitamins, vitamin E, minerals and proteins

Intact grains —> When these three layers are present

Refined grains

• Bran and germ layers removing, only leaving the endosperm

• Less healthful, rapidly digested

• Quicker blood sugar response.

Glycogen —> Storage form of glucose in the body

Fibers

Dietary Fiber (roughage) —> indigestible because it cannot be broken down by digestive enzymes.

Cellulose —> Primary source of dietary fiber

• Found in the skins of fruits, leaves and stems of vegetables and legumes

• No energy value

Hemicellulose —> Found in mainly whole-grain cereal; some are soluble and some aren’t

Lignins —> Woody part of vegetables and aren’t a carbohydrate

Mucilage —> gel-forming dietary fiber

Pectin —> Some hemicellulose, gums and mucilage are soluble in water and form a gel that helps provide bulk for the intestines

• Useful because they bid cholesterol —> reducing the amount of blood can absorb

Help lower blood glucose levels; prevent some colon cancers; prevent constipation, hemorrhoids, diverticular disease

Optimal for fiber intake is 20-35 grams per day

Recommended fruit intake is 2 cups a day and vegetables at 2.5 cups a day —> Someone who needs to consume 2,00 calories a day.

Eating too much fiber in a short time can produce discomfort, abdominal gas and diarrhea.

Digestion and Absorption

Monosaccharides are simple sugars that may be absorbed from the intestine directly into the bloodstream

• Carried to the liver where fructose and galactose are changed into glucose

• Blood then carries glucose to the cells

Disaccharides require an additional step of digestion

• Converted to the simple sugar before they can be absorbed into the bloodstream

• accomplished by enzymes of sucrase, maltase and lactase.

Polysaccharides are more complex and their digestibility varies

• Cellulose wall is broken down, starch is changed to the intermediate product called dextrin.

• Changed to maltose (Disaccharide) and then glucose.

• Cooking also changes starch into dextrin

Digestion of Starch

1. Enzyme salivary amylase begins to change starch to dextrin —> Happens in the mouth

2. Food is mixed with gastric juices —> Occurs in the stomach

3. Digestible carbohydrates are changed to simple sugars by enzyme action of pancreatic amylase and are subsequently absorbed into the blood —> Occurs in the small intestine

Metabolism and Elimination

All carbohydrates are changed to the simple sugar glucose before metabolism can take place

After being carried by the blood to cells, it can be oxidized.

When more glucose is ingested than the body can either use immediately or store in the form of glycogen, it is converted to fat and stored as a adipose (fatty) tissue

Process of glucose metabolism is controlled by the hormone insulin

• which is secreted by the islets of Langerhans in the pancreas.

Hyperglycemia —> When blood glucose is more than 126mg/dI; When there is too much glucose in the body

Hypoglycemia —> Blood glucose is less than 70 mg/dI; When there is not enough glucose in the body

The waste products of carbohydrate metabolism —> Carbon dioxide and water

Dietary Requirements

There is no specific daily dietary requirements for carbohydrates

Mild Deficiency of carbohydrates can result in weight loss, fatigue, cause ketosis.

Ketosis —> A stage in metabolism occurring when the liver has been depleted of stored glycogen and switches to a fasting mode —> Fat is being used to synthesize glucose

Obesity is a major health problem in US

• Caused by eating way too much carbohydrates —> Refined carbohydrates and the sugar fructose

Rapidly digested carbohydrates lead to precipitous swings in blood sugar —> high insulin resistance

• This resistance is a major driver of obesity, high blood pressure and type 2 diabetes.