Lecture 3 Flashcards
What provides energy for the brain & nervous system, help keep the digestive system healthy, help keep the body lean?
Carbohydrates
Where do carbohydrate-rich foods come from (3)?
- Plants (almost exclusively) (whole grains, legumes, vegetables and fruit)
- Milk products (only animal-derived foods that contain significant carbohydrate) (milk, yogurt, sour cream)
- Concentrated sugars (soft drinks, candies, cake, etc.)
What are the categories of carbohydrates?
- Simple Carbohydrates (monosaccharides and disaccharides)
- Complex Carbohydrates (polysaccharides – chains of monosaccharides)
What are the three monosaccharides?
- Glucose
- Fructose
- Galactose
Which monosaccharide is mildly sweet, essential energy source for body activities, one of the two sugars of every disaccharide, and the almost exclusive ingredient of polysaccharides?
Glucose
Which monosaccharide is a component of milk products, not sweet at all, generally occurs only as one of the two single sugars in milk products, and found occasionally as a single sugar (in fermented milk products like yogurt and aged cheese)
Galactose
Which monosaccharide is the sweetest, sometimes called fruit sugar, occurs naturally in fruits and honey, and commercially high-____ corn syrup is often used in soft drinks, cereals, and desserts?
Fructose
What are the three disaccharides?
Lactose, maltose, and sucrose
What is lactose made up of?
glucose + galactose
What is maltose made up of?
glucose + glucose
What is sucrose made up of?
glucose + fructose
Disaccharides are joined together through ____ reactions and split by ____ reactions
condensation, hydrolysis
What is known as milk sugar?
Lactose (principle carbohydrate of milk – provides about 1/2 kcal in skim milk)
Which sugar is produced during starch breakdown, only occurs in a few foods (barley), and occurs during the process of alcohol fermentation?
Maltose
Which sugar is the sweetest disaccharide; occurs naturally in fruits, vegetables, and grains; and whose most common form is table sugar?
Sucrose
What happens when monosaccharides are ingested?
They are absorbed directly into the blood
What happens when disaccharides are ingested?
Digested before absorption – split into monosaccharides by enzymes
What is the most used nutrient in the body?
Glucose
Where do most of the energy in fruits and vegetables come from?
Sugar
What do fruits contain, overall?
Fibre, phytochemicals, vitamins and minerals
What are the polysaccharides?
Starch, glycogen, and fibre
What are polysaccharides (complex carbohydrates) made up of?
Many strands of glucose units
What is the storage form of glucose in plants, long chains of glucose molecules linked together, and nutritive (we get energy from it)?
Starch
List some rich food sources of starch
Grains, tubers (yams and potatoes), legumes (peas and beans)
What is a storage form of glucose in animals, highly branched glucose chains (rapid hydolysis), and meat does not contain a significant amount of carbohydrate since ___ breaks down rapidly when animal is slaughtered?
Glycogen
Where is glycogen stored?
2/3 in muscle
1/3 in liver
What is found in vegetables, fruit, whole grains and legumes; provide support and structure to plants; retain water to protect seeds from drying out; are mostly polysaccharides; and whose bonds that hold together the sugar units cannot be broken down by the human digestive enzymes?
Fibre
How can bacteria in the human large intestine digest fibres to varying degrees?
By fermenting them. Short chain fatty acids that the colon absorbs
Define prebiotics
Foods that are not digested (such as fibres) but promote bacterial growth by acting as food for the bacteria
What are the characteristics of soluble fibres?
Dissolve in water
Form gels (are viscous)
Can be digested by bacteria in the human colon
Are associated with a lower risk of chronic disease – decrease blood cholesterol
Slow glucose absorption
Soften stool
Used as thickening agent
Gums, pectin, psyllium, some hemicelluloses
What is important to remember when increasing fibre absorption?
Need to increase water intakes so you don’t lose water
What are some rich sources of soluble fibres?
Barley, legumes, oats, apples, citrus fruits
What are the characteristics of insoluble fibres?
Do not dissolve in water
The outer layers of whole grains, the strings of celery, etc. contain insoluble fibres such as cellulose
Retain their structure & texture even after hours of cooking
Ease elimination, can alleviate constipation, speed passage of feces through colon
Are less easily fermented (not easily broken down by bacteria in the gut) & do not form gels
Fats are not normally used as fuel by the ___ & ____ but glucose is
brain, central nervous system
The DRI recommends an AMDR of what percentage of daily kcalories?
45%-65%
When excess carbohydrates are absorbed, what does the body do?
Converts it to fat, even though it is metabolically costly.
Why are fibre-rich foods recommended?
Fill people up
Generally supply vitamins, minerals & phytochemicals
Generally contain little or no fat
Soluble fibres (e.g., in apples) have a significant cholesterol-lowering effect
Maintenance of healthy bowel function
Helps maintain a healthy body weight
Modulation of blood glucose concentrations
What is pectin?
A soluble fibre
Diets rich in complex carbohydrates (fibres) may help with what?
Protect against heart disease and stroke
Blood glucose control
Maintenance of Digestive Tract Health
Constipation
Lower rates of colon cancer
Healthy weight management
How do carbohydrates (fibres) contribute to blood glucose control?
Viscous fibres trap nutrients and delay their transit through the digestive tract, so glucose absorption slows – helps steady levels of blood glucose & insulin
Lower glycemic index
How do carbohydrates protect against heart disease and stroke?
Low in saturated & trans fats and cholesterol, high in fibres, vegetable proteins & phytochemicals
Viscous fibres lower blood cholesterol by binding with cholesterol-containing bile & carrying it out w the feces
Bacterial fermentation of fibre produces a small fatty acid which travels to the liver where it may help reduce cholesterol synthesis
How do complex carbohydrates (fibres) help maintain digestive tract health?
Fibre & fluid intake play a role in maintaining colon function and preventing & alleviating constipation (enlarge & soften stools, speed passage through the intestine, and easier elimination)
How do complex carbohydrates (fibres) help with constipation?
- Fibre helps prevent constipation
- Large, soft stool ease elimination helping prevent hemorrhoids
- Fibre helps prevent compaction of intestinal contents (such compaction could obstruct the appendix & permit bacteria to invade & infect it (appendicitis)
- Fibre stimulates the GI tract muscles so they retain their strength & resist bulging out into pouches (diverticula)
What is diverticulitis?
The inflammation of diverticula
Abnormal bulging pockets formed in the colon wall. These pockets can entrap faces and become painfully infected and inflamed, requiring hospitalization, antibiotic therapy, or surgery.
How do complex carbohydrates (fibres) help with colon cancer?
- Fibre rich foods contain nutrients & phytochemicals
- Fibres dilute & speed the removal of cancer-causing agents from the colon
- Fibre-rich diets promote bacterial reproduction, binding nitrogen & carrying it out of the body in feces
- Bacteria ferment soluble fibres in to short chain fatty acids
How do complex carbohydrates (fibres) help with healthy weight management?
Foods rich in complex carbohydrates tend to be low in fats & added sugar (less energy & creates feelings of fullness/delays hunger)
Pure fibre compounds usually not necessary
What is the recommended fibre intake for females and males aged 19-50?
25g/day & 30g/day
What are Canada’s Food Guide’s recommendations that would increase fibre?
- Choose protein foods that come from plants more often
- Have plenty of vegetables and fruit
- Choose whole grains