Lecture 3 Flashcards
1
Q
What provides energy for the brain & nervous system, help keep the digestive system healthy, help keep the body lean?
A
Carbohydrates
2
Q
Where do carbohydrate-rich foods come from (3)?
A
- 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.)
3
Q
What are the categories of carbohydrates?
A
- Simple Carbohydrates (monosaccharides and disaccharides)
- Complex Carbohydrates (polysaccharides – chains of monosaccharides)
4
Q
What are the three monosaccharides?
A
- Glucose
- Fructose
- Galactose
5
Q
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?
A
Glucose
5
Q
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)
A
Galactose
6
Q
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?
A
Fructose
7
Q
What are the three disaccharides?
A
Lactose, maltose, and sucrose
8
Q
What is lactose made up of?
A
glucose + galactose
9
Q
What is maltose made up of?
A
glucose + glucose
10
Q
What is sucrose made up of?
A
glucose + fructose
11
Q
Disaccharides are joined together through ____ reactions and split by ____ reactions
A
condensation, hydrolysis
12
Q
What is known as milk sugar?
A
Lactose (principle carbohydrate of milk – provides about 1/2 kcal in skim milk)
12
Q
Which sugar is produced during starch breakdown, only occurs in a few foods (barley), and occurs during the process of alcohol fermentation?
A
Maltose
13
Q
Which sugar is the sweetest disaccharide; occurs naturally in fruits, vegetables, and grains; and whose most common form is table sugar?
A
Sucrose
14
Q
What happens when monosaccharides are ingested?
A
They are absorbed directly into the blood
15
Q
What happens when disaccharides are ingested?
A
Digested before absorption – split into monosaccharides by enzymes
16
Q
What is the most used nutrient in the body?
A
Glucose
17
Q
Where do most of the energy in fruits and vegetables come from?
A
Sugar
18
Q
What do fruits contain, overall?
A
Fibre, phytochemicals, vitamins and minerals
19
Q
What are the polysaccharides?
A
Starch, glycogen, and fibre
20
Q
What are polysaccharides (complex carbohydrates) made up of?
A
Many strands of glucose units
21
Q
What is the storage form of glucose in plants, long chains of glucose molecules linked together, and nutritive (we get energy from it)?
A
Starch
21
Q
List some rich food sources of starch
A
Grains, tubers (yams and potatoes), legumes (peas and beans)
22
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
23
Where is glycogen stored?
2/3 in muscle
1/3 in liver
24
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
25
How can bacteria in the human large intestine digest fibres to varying degrees?
By fermenting them. Short chain fatty acids that the colon absorbs
26
Define prebiotics
Foods that are not digested (such as fibres) but promote bacterial growth by acting as food for the bacteria
27
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
28
What is important to remember when increasing fibre absorption?
Need to increase water intakes so you don't lose water
29
What are some rich sources of soluble fibres?
Barley, legumes, oats, apples, citrus fruits
30
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
31
Fats are not normally used as fuel by the ___ & ____ but glucose is
brain, central nervous system
32
The DRI recommends an AMDR of what percentage of daily kcalories?
45%-65%
33
When excess carbohydrates are absorbed, what does the body do?
Converts it to fat, even though it is metabolically costly.
33
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
34
What is pectin?
A soluble fibre
35
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
36
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
37
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
38
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)
39
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)
40
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.
41
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
42
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
43
What is the recommended fibre intake for females and males aged 19-50?
25g/day & 30g/day
44
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
45
What are some examples of plant-based protein sources?
Beans, lentils, legumes opposed to meat, which has zero fibres
46
What happens when too much fibre is ingested?
- Can lead to a blocked intestine especially if too little fluid.
- Binders in some fibres act as chelating agents (bind minerals & carry them out of the body, which may limit the absorption of iron, zinc, and calcium.
- Can limit food intake & cause both nutrient & energy deficiencies
- Fibres remove water from body, so can contribute to dehydration.
47
What is bran largely made out of?
Cellulose
48
What is endosperm (generally what is used in refined flour)?
Largely starch grains embedded in a protein matrix.
49
What is the germ?
Part where new grain develops. Majority of fat in the grains are located here. Often left out of processing to avoid rancidity.
50
What does modern milling do?
Removes the germ & bran -- whiter, smoother-textured flour increasing the starch content & lowering the fibre content
51
White bread meant a loss of nutrients. What happened in the mid 1970s?
Mandatory addition of riboflavin, thiamin, niacin & iron to bleached white flour.
52
What happened in the late 1990s?
Mandatory addition of folic acid (important for healthy pregnancy)
53
Starch digestion begins in the mouth. How?
Salivary amylase, which becomes deactivated by stomach acid.
54
Starch digestion resumes in the small intestine. How?
Pancreatic enzymes: split starch into smaller polysaccharides and disaccharides.
Intestinal enzymes: split these into monosaccharides
55
Starch found in what food is rapidly broken down to glucose which is then absorbed?
Refined grains
56
Resistant starch, found in what food is digested more slowly & releases glucose later in the digestive process?
Cooked beans
57
Resistant starch behaves like what?
Fibre
58
What is resistant starch found in?
Raw potatoes, unripe bananas, and inside the unbroken husks of swallowed seeds.
59
Most resistant starch remains intact until what stage?
The bacteria of the colon break it down
Sometimes classified as insoluble fibre
60
So, what is a summary of how digestible carbohydrates are split into monosaccharides before they are absorbed?
Pancreatic amylase splits most starch to disaccharides
Small polysaccharides and disaccharides are split by enzymes attached to the cells lining the small intestine (lactase, sucrase, and maltase).
61
What is a biproduct of intestinal bacteria fermenting fibres?
Odourous gases
62
Why do some people have trouble digesting milk?
Some people produce less lactase.
Lactose is a disaccharide, which must be broken down into two monosaccharides: glucose and galactose.
Problem: deficiency in lactase (enzyme which breaks down lactose). The bacteria feed off of everything that is passed all the way through till the intestine, which causes cramping, discomfort, etc.
63
Lactase deficiency may also occur because of damage to intestinal villi due to what?
Disease, malnutrition, medications, or prolonged diarrhea.
64
How is the severity often overestimated for ability to digest lactose?
Many can tolerate 1-2 cups of a milk a day
Often can tolerate lactose-reduced milk
Yogurt and aged cheeses are often tolerated
Hard cheese is very low lactose
Drinking milk with other foods may increase lactose tolerance (food slows the transit time of milk through the digestive tract)
Treat the products with over-the-counter enzyme pills or drops
Not tolerating any lactose at all is very rare.
65
Is milk allergy the same as lactose intolerance?
No. It is an allergic reaction to the protein in milk. These people cannot tolerate any milk products, so they must find nondairy calcium sources (fortified foods)
66
Inside a cell, what releases energy from glucose?
Glycolysis and Krebs cycle
67
What is the minimum intake to feed the brain & reduce ketosis?
130 grams a day for an average adult -- RDA 130g/day
More is recommended (AMDR: 45%-65% of total energy) to maintain health & glycogen stores.
68
What happens when one does not meet this minimum?
Body fat cannot be converted into glucose to feed the brain.
When severe, uses protein to make glucose - gluconeogenesis.
69
Fat fragments usually combine with a compound derived from what before being used for energy?
Glucose (or protein).
70
Without this compound that fat usually combines with before being used for energy, what happens?
Fat fragments combine with each other producing acidic ketone bodies. The accumulation of these in the blood (ketosis) can disturb normal acid-base balance.
71
Adults with chronic ketosis may face what symptoms?
- Vitamin & mineral deficiencies
- Loss of bone minerals – osteopenia and osteoporosis
- Altered blood lipids
Increased kidney stone risk
- Constipation, nausea and vomiting
- Glycogen stores that are too low to meet a metabolic emergency or support maximal high-intensity muscular work - no instant energy
72
How does eating affect blood glucose?
Eating increases blood glucose
73
What happens with high blood glucose?
Insulin is secreted from pancreas
74
What does insulin stimulate?
Uptake of glucose into cells
Storage of glucose into glycogen
Excess glucose into fat
75
What happens when cells use glucose & a low blood glucose is found?
Glucagon is secreted from the pancreas
76
What does glucagon stimulate?
Breakdown of glycogen therefore glucose released into bloodstream (opposite goal of insulin -- bring up blood sugar/glucose)
77
What is the glycemic index (GI)?
A measure of the ability of a food to elevate blood glucose & insulin levels
Scored against standard (usually white bread or glucose whose score=100)
78
What types of foods have a high glycemic index?
Sugary things with a quick break down & peaks blood sugar quite quickly.
A refined item like cornflakes would be the highest as opposed to cashews, peanuts, kidney beans, etc.)
78
How is excess glucose stored?
Glycogen
78
Where is glycogen stored?
2/3 in muscle (and used by it)
Remainder is in the liver with a small emergency store in the brain
79
What happens if there is still excess glucose?
The liver converts it into fats then it is stored in fat tissues.
Fat cells may also convert glucose to fat
Fat cells can store practically unlimited quantities of fats.
80
Diabetes impairs a person's ability to regulate what?
Blood glucose normally
81
What is type 1 diabetes?
Little or no pancreatic secretion of insulin
Often diagnosed in childhood (or young adults)
Less common (up to 10% of cases) but is on the rise (leading chronic disease among children & young adults)
82
What does the treatment of type 1 diabetes entail?
An external source of insulin
Meal planning to balance blood insulin & glucose concentrations
83
Why is insulin given by injection or pump and not ingested orally?
If we ate it, our stomach would denature it as it is a protein, so it would not function.
84
What is type 2 diabetes?
Body produces insulin at first, then insulin resistance
As blood glucose rises, so does blood insulin (eventually, pancreas may become less able to make insulin)
Often diagnosed in adulthood
Most prominent type of diabetes (90%)
85
If drugs are necessary for type 2 diabetes, what might they do?
May stimulate insulin secretion
May improve tissue uptake of glucose
External source of insulin may also be used
86
Who is more likely to get type 2 diabetes?
Those with a family history
Indigenous people (colonisation effects)
Obese people (increase in weight leads to increase in resistance)
87
What is impaired glucose tolerance?
Pre-diabetes. Blood glucose levels higher than normal but not high enough to be diagnosed as diabetes.
88
Tighter glucose control = less severe the complications. What are some of these complications?
- High Blood pressure
- Impaired circulation/amputation
- Kidney disease (requiring dialysis or kidney transplant)
- Cataracts, retinopathy
- Nerve damage (peripheral neuropathy), skin damage
- Strokes & heart attacks
89
The same diet that best controls diabetes also helps control body weight & supports physical activity. What does this diet entail?
- Adequate in nutrients
- Adequate fibre
- Moderate in added sugars
- Provides a controlled amount of total carbohydrates
- Low in saturated fat & provides unsaturated oils
- Adequate but not too high in protein
90
What are two recommendations to heighten tissue sensitivity to insulin?
Increasing physical activity and weight loss
91
What are some dietary patterns that would be helpful to type 2 diabetes patients?
- Mediterranean-style dietary pattern to reduce major CV events and improve glycemic control
- Vegan or vegetarian dietary pattern to improve glycemic control, body weight, and blood lipids, including LDL-C and reduce myocardial infarction risk
- DASH dietary pattern to improve glycemic control, BP and LDL-C and reduce major CV events
- Dietary patterns emphasizing dietary pulses (e.g. beans, peas, chickpeas, lentils) to improve glycemic control systolic BP and body weight
- Dietary patterns emphasizing fruit and vegetables to improve glycemic control and reduce CV mortality
- Dietary patterns emphasizing nuts to improve glycemic and LDL-C
92
What is hypoglycemia?
Low blood glucose. Very rare in healthy people
93
What is fasting hypogycemia?
Too long in between meals
Can be seen with cancer, pancreatic disease, diabetes, liver damage.
94
What should one do if they are struggling with hypoglycemia?
Regularly timed, balanced, protein-containing meals.
Avoid switching between low-carb dieting & sudden, large, refined carbohydrate doses & minimize alcoholic beverages (liver busy regulating alcohol instead of glucose).
94
What causes low blood sugar in people with Diabetes?
More physical activity than usual
Not eating on time
Eating less than you should have
Too much medication
Drinking alcohol
95
What does the DRI committee recommend as an AMDR?
45%-65% of kcalories (225-325 grams carbohydrate/day (2000 kcals)
96
What does the DRI recommend as an RDA?
Minimum 130g/day
97
What are free sugars?
Sugars that have been added and sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates. Free sugars do not include the naturally occurring sources of sugars found in intact or cut fruit and vegetables, and (unsweetened) milk
98
What are added sugars?
All sugars added to foods and beverages during processing or preparation. All added sugars are also free sugars.
99
What are total sugars?
Account for all sugars present in foods and beverages regardless of the source. This includes added, free, as well as the naturally occurring sources of sugars found in intact or cut fruit and vegetables, and unsweetened milk.
100
What does the DRI committee suggest as a daily intake of added sugars?
25% of calories or less from added sugars (WHO, Diabetes Canada, and The Heart and Stroke Foundation recommend below 10).
101
What does Canada's Food Guide recommend for decreasing sugar intake?
Prepare meals and snacks using ingredients that have little to no added sodium, sugars, or saturated fat.
Replace sugary drinks with water.
102
What are the two ways to replace sugar?
Energy-yielding sugar alcohols (nutritive sweeteners)
No energy artificial sweeteners (nonnutritive sweeteners)
103
What are some characteristics of sugar alcohols?
Do not contain ethanol or any other intoxicant
Provide energy
Produce a low glycemic response: body absorbs them slowly
Gas, abdominal discomfort, and diarrhea from large quantities
Do not contribute to dental caries.
104
What are some sugar alcohols (need to recognize names & know they produce energy but less than sugar)?
Erythritol
Isomalt
Lactitol
Maltitol
Sorbitol
Xylitol
105
What are some characteristics of artificial/alternative sweeteners?
Make foods taste sweet
Do not promote tooth decay
Provide very little food energy, if any at all
Can be toxic if consumed in high enough doses.
106
What are some sugar substitutes?
Advantame
Acesulfame potassium
Aspartame
Monk fruit extract (Luo Han Guo extract)
Neotame
Saccharin
Seviol glycosides (Stevia)
Sucralose
Thaumatin
Tagatose
107
Which sweetener is approximately 200 x sweeter than sucrose, holds up well during cooking, and is excreted unchanged by the kidneys?
Acesulfame-K (Potassium)
108
Which sweetener is known as splenda, is approximately 600 x sweeter than sucrose, useful in cooking, baking, and as a tabletop sweetener, passes through body unchanged, and is the only artificial sweetener made from sucrose?
Sucralose
109
Which sweetener is approximately 200x sweeter than sucrose, is not heat stable, and provides 4 kcalories per gram (same as sugar, as it is made up primarily of two amino acids/proteins)?
Aspartame
Can be linked to cancer. Didn’t result in any change because recommendations were to use well below that amount anyways
110
If people have PKU, which alternative sweetener should they not have?
Aspartame, as it is made up of phenylanine, which is a problem for those with PKU as it is a hereditary inability to dispose of excess phenylalanine.
111
Which substitue is 300x sweeter than sucrose and is a naturally sweet herb?
Stevia
111
What changes will be made to labelling of sweeteners by January 1st, 2026
No longer need to appear on front of package label. Aspartame must still include a statement that will now appear in bold at the end of the list of ingredients, "Aspartame contains phenylalanine"
112
What are some strategies for using artificial/alternative sweeteners?
Moderation is key
Use does not automatically lower energy intake
Probably do not hinder weight-loss efforts
Safer for teeth
