notes/education/nutrition/Carbohydrates.md

- Carbohydrates are a class of nutrients that is a major source of energy for the body
	- Can also server as a glue that holds cells togehter
	- Classified as simple or complex
- Plants are rich sources of carbohydrates
There are 3 categories of carbs.

# Sugars
- A **monosaccharide** is a simple sugar that is the basic molecule of carbohydrates:
	- Glucose: Primary fuel for muscles, nerves, and other cells, the most common.
	- Fructose: In **fruits**, honey, and certain vegetables
	- Galactose: Component of lactose
- A **disaccharide** is a simple sugar comprised of two monosaccharides.
	- Maltose: Disaccharide composed of two glucose molecules "malt sugar"
	- Sucrose: Disaccharide composed of a glucose and fructose molecule "table sugar"
	- Lactose: Disaccharide composed of a glucose and a galactose molecule "milk sugar"

- High fructose corn syrup is a syrup obtained from the processing of corn
- No conclusive evidence that the use of HFCS causes poor health and disease
- Excessive calories from beverages sweetened with HFCS contributes to increased risk for diabetes and heart disease
- Nutritive sweeteners are substances that sweeten and contribute energy to foods
- Each gram of mono or disaccharide supplies 4 kcal
- Added sugars are sugars added to foods during processing or prep
	- The main source of added sugars in the American diet is sugar sweetened beverages.
- Alternative sweeteners are substances that sweeten foods while providing few or no calories
- Sugar alcohols are alternative sweeteners use to replace sucrose in some some sugar free foods:
	- Sorbitol, xylitol, mannitol
	- Not fully absorbed by the intestinal tract
	- Supply 2kcal/g
	- Can cause diarrhea when consumed
- Non-nutritive sweeteners are a group of synthetic compounds that are intensely sweet tasting compared to sugar
	- Examples include Aspertame, Saccharin, Acesulfame-K, Neotame, and Sucralose
	
- Glycogen = storage form of glucose
	- A highly branched storage polysaccharide in animals
	- Muscles and liver are major storage sites
# Starches
Complex carbs have 3 or more monosaccharides bonded together
- Starch is a storage polysaccharide in plants.
	- Composed of amylose and amylopectin
	- Rich sources include:
		- Bread and cereal products made from wheat, rice, barley, and oats

# Fiber
- Plants also use complex carbohydrates to make supportive and protective structures
- Dietary fiber is non-digestible plant material
	- Most types are polysaccharides
	- Soluble fiber
		- Forms of dietary fiber that dissolve or swell in water. includes pectins, gums, mucilages, and some hemicelluloses
		- Delays stomach emptying, slows glucose absorption and lowers blood cholesterol
	- Insoluble fiber
		- Forms of dietary fiber that generally do not dissolve in water: Includes cellulose, hemicelluloses, and lignin
		- Helps with bowel movements and fecal bulk
# Consumption
- In developing nations, diets supply 70% or more of energy from unprocessed carbs
- In industrialized nations, people tend to eat more highly refined starches and added sugars
- Americans consume about 30% of energy from added sugars (600 kcal/day)
- Regular soft drinks and energy drinks are major sources of added sugars in Americans' diets
- According to the dietary guidelines, people should limit their added sugar to 

# Digestion
- Salivary amylase is an enzyme secreted by salivary glands that begins work in the mouth, stops working soon after food enters the stomach
- The small intestine is the main site for carbohydrate digestion and absorption
	- Pancreatic amylase
		- Enzyme secreted by the pancreas that breaks down starch into maltose molecules
	- Maltase
		- Enzyme that splits maltose molecules
	- Sucrase
		- Enzyme that splits sucrose molecules
	- Lactase
		- Enzyme that splits lactose molecules
1. Dietary carbohydrates are delivered from 
- Fructose and galactose are converted to **glucose** in the liver.