Bio 28: NutritionInstructor: Paul Nagami

Laney College

Jan. 28, 2014

Carbohydrates, pt. 1

Today’s Agenda• Reminders• What Are Carbohydrates?• Simple and Complex Sugars• Sources of Carbohydrates • Wrap-Up, Add Codes

What Are Trees Made Of?

Every year, the General Sherman sequoia adds on over a cubic meter of wood – enough to make a new 15-meter (50-foot) tall tree!

Where does all of this dry mass come from?

Take a guess:Most of the General Sherman tree’s dry mass is derived from….A) Water and minerals from the soil.B) Organic matter from the soil.

C) Energy from the sun.

D) Gas from the air.

All Our Energy Ultimately Comes from the Sun. Our Carbon Comes from CO2

Monomers and dimers• Many biological molecules, such as proteins and complex carbohydrates, are made of repeating pieces.• Each piece is a monomer. Sticking two monomers together makes a dimer.

Monomerone + piece

Dimertwo + pieces

Glucose

Monosaccharides (Simple Sugars)

• Simple sugars are made out of one sugar “piece” (monomer.) They are not chains of sugar.

* These are the three most common monosaccharides (name means “one sugar”) :

Fructose is “fruit sugar.” It’s found in fruits, vegetables, and honey.

Glucose is “blood sugar.”It’s the main circulating energy storage molecule in the body.

What do these names (glucose, fructose, galactose) have in common?

Galactose is part of milk sugar, and is also found in fruits and vegetables.

Disaccharides (Simple Sugars with Two Parts)

• Disaccharides (“two sugars”) are made out of two parts. Most of the sugar we eat that is not starch is in the form of disaccharides.

• Sucrose = “table sugar”

• Lactose = “milk sugar”

• Maltose = “malt sugar”

SourcesSources of mono- and disaccharides

Syrup sweeteners used to contain more glucose…

…and now are closer to 55% fructose/45%

glucose. Is that a problem in itself?

Natural sources of fructose: fruits,

vegetables.

Milk contains lactose, made of

glucose and galactose

Starch is made out of

simple sugars

The HFCS (High Fructose Corn Syrup) Controversy

Agree or disagree?“High fructose corn

syrup is worse for the body than table

sugar.”

Fructose: 16% of American Calorie intake.

Quick poll: How much soda have you drank in the last 24

hours?20 oz. soda: 65 g of sugar (16 teaspoons!)

12 oz soda: 39 g of sugar

Lactose Intolerance

Disaccharide

Monosaccharide

Lactose-Intolerant DietsRegardless of myplate.gov’s recommendations, dairy is not necessary for a healthy diet (though nonfat milk is quite healthy), provided calcium sources are available.Some people can tolerate low-lactose dairy products, such as cultured yogurt (where the bacteria break down the lactose), yet have trouble with other dairy products.

If you drink soy milk or almond milk, be sure to get fortified products that add back the missing nutrients.

PolymersOrganisms can chain together smaller monomers to make polymers! Examples of polymers include proteins and starch.

The polymers can then be broken down later into their parts to recycle them or harvest chemical energy.

PolysaccharidesStarch

Glycogen

Cellulose

Dietary FiberDietary fiber is (mostly) carbohydrates that are not starch – ones that your body can’t break down (unless you’re a termite!)There are two categories of dietary fiber: soluble and insoluble dietary fiber.

Soluble dietary fiber:Pectins and mucilage

Sources: Oats, some fruits, legumes, potatoesLowers blood cholesterol by getting rid of bile!

Insoluble dietary fiber:Cellulose, lignin, etc.

Sources: Seeds, beans, wheat bran, etc.Helps digestion; lowers colon cancer risk.

Benefits of Fiber

Reduces “transit time” through intestines (though that varies normally!)Softens stool and reduces constipation.

Increases satiety (because it holds water, fiber makes you feel more “full.”)Displaces calories.

Lowers cholesterol

Reduces risk of colon polyps

Whole Wheat vs. White Bread

Outer layer: BranHigh in fiber, with some B vitamins.Not present in white bread, only whole grain.Developing embryo: Germ

Rich in vitamins, minerals, and oil. Not easy to store/preserve.

Energy source for embryo: Endosperm. Most of white flour. High in starch, not in other nutrients.

What About Low-Carb Diets?Recommended calories from carbs: 50-60% of dietLow-carb diets can result in weight loss, but at least some of this is due to the removal of empty calories from the diet. (Foods like sugar that aren’t very nutrient dense).Low-carb diets can also result in shortages of fiber, and can cause the body to break down muscle for energy.

However, for some people, a well-balanced low-carb diet, set up with a nutritionist’s advice, can be beneficial, especially for controlling blood sugar in diabetics!