NTRN 201 Exam 1: Nutrition Foundations, Carbohydrates, and Lipids

six major categories of essential nutrients

carbohydrates, proteins, fats, vitamins, minerals, water

what are nutrients

substances essential for health that the body cannot make or makes in quantities too small to support life

functions:

• provide energy

• promote growth and development

• regulate body processes

macronutrients

needed in large amounts

• carbs, lipids, proteins, water

micronutrients

needed in small amounts

• vitamins, minerals

which macronutrients provide energy and how many calories does each provide per gram

carbohydrates, protein, fat

carb = 4 calories per gram

protein = 4 calories per gram

fat = 9 calories per gram

carbohydrates

obtained from fruits, vegetables, grains, beans

provide 4 kcal/g

simple and complex forms:

• sucrose, blood glucose, starch, glycogen (muscles & liver), fiber

lipids

insoluble in water

provide 9 kcal/g

fats are lipids that are solid at room temp

oils are lipids that are liquid at room temp

triglycerides = major energy source for body

proteins

main structural components in the body

provide 4 kcal/g

formed from bonding of amino acids

vitamins

enables chemical reactions to occur

helps release energy

fat-soluble vs. water-soluble vitamins

fat-soluble:

• more likely to accumulate & cause toxicity

• found in dairy, nuts, seeds, oils, breakfast cereals

water-soluble:

• more likely destroyed by cooking

• excreted from body more readily

• found in fruits and veggies

minerals

inorganic substances

not destroyed by cooking

yield no energy

required for normal body function

2 groups: major minerals & trace minerals

water

needed in the largest quantity of all nutrients

functions:

• solvent

• lubricant

• transports nutrients

• regulates body temp

how does the body store excess energy from carbohydrates?

1. Blood glucose gets stabilized first — carbs are absorbed as glucose, which raises blood sugar, triggering insulin release.

2. Glycogen stores fill first. Insulin drives glucose into the liver and muscle, where it's packaged into glycogen (storage form of carbohydrate). This happens in both organs, but glycogen storage capacity is limited.

3. Once glycogen stores are full, any additional excess carbohydrate gets converted into fat and stored in adipose tissue.

glucose → glycogen (liver + muscle) → once full, excess converts to fat

how does the body store excess energy from fats?

Dietary fat that isn't used for energy or other functions is stored directly as body fat (triglycerides) in adipose tissue.

define the acceptable macronutrient distribution range (AMDR) + know the AMDR for carbohydrate, protein, and fat

the range for keeping carb/protein/fat intake in, expressed as % of total calories, to maintain good health

carbohydrate 45-65%

protein 10-35%

fat 20-35%

of total calories

explain the purpose of dietary reference intakes (DRIs)

recommendations for a healthy population (NOT individual requirements)

• differ by life stage: age group, gender (after age 9), pregnancy, lactation

explain the meaning of a Tolerable Upper Intake Level (UL)

maximum chronic daily intake of nutrients that is unlikely to cause adverse health effects (e.g. neurologic damage) in almost all people in a specific life stage

• closer to UL, higher risk for toxicity

• protects those susceptible in the healthy population

• not every nutrient has a tolerable UL

• No UL established ≠ safe in unlimited amounts — it usually just means there isn't enough research to set one

define energy density + explain characteristics of low-energy-density foods

energy density: calories per gram of food

energy-dense foods = high in calories but weigh very little

• nuts, cookies, fried foods, snack foods, peanut butter

• often high in fat

low-energy-dense foods = contain large amounts of water and few calories

• fruits, veggies, stews, oatmeal

• help keep calorie intake under control

naturally occurring sugars vs. added sugars

naturally occurring sugars are part of the food itself, packaged w/ other healthy nutrients

added sugars are introduced during manufacturing, cooking, or food prep

• may have nutrients but high diet of added sugar increases risk for cardiovascular disease & inflammation

e.g. fruits (orange) vs. jelly beans

explain the purpose of daily values (DVs)

generic standards developed by FDA

• standardized 2000-calorie diet → NOT tailored to your age, sex, size, or activity level

found on the nutrient facts panel on food label

compares amount of nutrients in the food w/ set of standards

distinguish daily values from individualized nutrient requirements

• DVs are not individualized nutrient requirements

  • It is an average/standard approach to helping ppl understand their food labels

what is the 5% and 20% daily value rule

≤5% DV = low source

≥20% DV = high source

e.g., 5% vitamin C = low source of vitamin C

examples of foods that can contain fat even when not visibly apparent

hidden fat: foods can contain fat w/o looking greasy

e.g. cake, mayo, nuts, ice cream

monosaccharides vs. disaccharides vs. polysaccharides

monosaccharides = one sugar unit (basic unit of carbs)

• glucose, fructose, galactose

• all are absorbed as glucose

disaccharides = two sugar units

• sucrose

polysaccharides = many glucose molecules linked together

• starch, glycogen, fiber

• takes longest to digest since more chains must be broken down

difference in quickness of digestion & absorption

• monosaccharides are quickest

• mono & di are simple sugars

starch, dietary fiber, and glycogen are all what?

complex carbohydrates / polysaccharides

starch

digestible polysaccharide

storage form of glucose in plants

e.g. legumes, tubers, grains (potatoes, rice, pasta, beans)

glycogen

digestible polysaccharide

stored form of carbohydrate for animals & humans

stored in the liver & muscles

liver glycogen can replenish blood glucose

• when blood glucose drops, the liver breaks down its glycogen & releases glucose into bloodstream

muscles retain for muscle use only. muscle glycogen does not replenish blood glucose.

resistant starch

dietary fibers that resist digestion in the small intestine, fermenting in the large intestine instead

• fermentation produces healthy gut microbiota

• promotes satiety, reduce risk of colon cancer, improve glucose metabolism

• natural sources: green bananas, cashews, pinto/black beans, uncooked oats

in which form are digestible carbohydrates absorbed?

as monosaccharides (simple sugar units)

what is the protein-sparing function of carbohydrate?

If there isn't enough carbohydrate available, the body will break down protein for energy instead of using it for its normal jobs (building/repairing tissue).

Adequate carb intake "spares" protein for that purpose (prevents proteins from being broken down for fuel)

factors that influence how quickly carbohydrates are digested and absorbed

• chain length (mono vs. poly)

• what the carb is eaten with — protein & fat in meal slows digestion down

• speed of eating

• insulin sensitivity — controls quickness of sugar clearance from bloodstream

• fiber content — more fiber slows digestion, absorption, and flattens/delays glucose peak

what must happen to digestible carbohydrates before absorption?

By organ:

• Mouth — small amount of digestion begins

• Stomach — small/negligible amount

• Small intestine — major site of absorption

• Large intestine — fiber and resistant starch end up here (fermentation, not digestion)

Describe the role of each digestive organ in carbohydrate digestion. (Little or no digestion, some digestion, or serves as a major site of digestion)

Mouth	Some — chewing plus salivary amylase starts starch breakdown.
Stomach	Little/none — acid halts amylase activity.
Small intestine	Major site — pancreatic amylase and brush-border enzymes finish breaking carbs down to monosaccharides for absorption.
Large intestine	No digestion by human enzymes — fiber and resistant starch arrive here and are fermented by bacteria.

what organs are important in blood glucose control?

LIVER

• determines amount of glucose needed to enter the bloodstream after a meal

• stored as glycogen for later use

PANCREAS

• secretes insulin (gets glucose out of blood into cells)

• secretes glucagon (produces glucose to get back to normal levels)

Normal physiological responses to increased insulin (after a meal)

insulin is released after eating, when blood glucose levels are high

• lowers blood glucose

• increases glucose uptake into muscle cells

• stimulates glycogen synthesis (liver & muscle)

• stimulates protein synthesis

• forms triglycerides (fat storage)

• inhibits breakdown of fat, deposits fat

glucagon

released if no dietary carbohydrates are present, blood glucose levels have fallen

promotes increased breakdown of glycogen, gluconeogenesis

blood glucose levels return to normal

what energy reserve helps maintain blood glucose early in a fast?

blood glucose is maintained by liver glycogen.

• Insulin is low, glucagon is high.

• Liver breaks down its glycogen stores and releases glucose into the bloodstream.

soluble vs. insoluble fiber

SOLUBLE FIBERS - fermentable

• dissolves in water

• found inside & around plant cells

• decreases cholesterol, controls blood sugar b/c slow to absorb

• healthy gut fiber

• e.g. oats, skin/flesh of fruits (apples), legumes, psyllium

INSOLUBLE FIBERS - non-fermentable

• does not dissolve in water

• adds water to stool → healthy gut via bowel movements (prevents constipation)

• increase digestion rate

• e.g. seeds, whole grains, veggie skins, nuts

dietary & functional fiber

indigestible polysaccharides

dietary fiber - found naturally in plant foods

• comes packaged w/ other nutrients (vitamins, minerals, water)

• e.g. oats, beans, whole grains, veggies, nuts

functional fiber - added to foods in manufacturing

• stimulates growth or activity of beneficial bacteria in the large intestine

• metabolically helpful but less beneficial than naturally occurring fiber

• e.g. psyllium, inulin, chicory root fiber; found in candies, ice cream, yogurts

what characteristics of foods can help support a healthy gut microbiota?

• high in natural fiber (plant-based foods, prebiotics)

• rich in polysaccharides

• fermented foods (resistant starch - yogurt)

saturated fats vs. unsaturated fats

saturated fats

• NO DOUBLE BONDS (filled w/ hydrogen)

• solid at room temp

• found in animal sources

• raise blood cholesterol levels (bad)

• can lead to CV disease

unsaturated fats

• has DOUBLE BONDS

• liquid at room temp

• found in plant sources

• healthier

• raises good cholesterol

examples of saturated and unsaturated fats

Saturated fats (mostly animal-based, solid at room temperature)

• Butter, cheese, whole milk

• Bacon and fatty red meat

• Exception: coconut oil and palm oil (plants, but mostly saturated)

Unsaturated fats (mostly plant-based, liquid at room temperature)

• Avocado

• Olive oil and canola oil

• Nuts (almonds, peanuts, walnuts)

• Sunflower, corn, and soybean oil

essential fatty acids

unsaturated fatty acids that must be supplied by the diet:

• linoleic acid (omega-6)

• alpha-linolenic acid (omega-3)

roles:

• structural components of cell walls

• regulate blood pressure

• regulate nerve transmission

found in vegetable oils and fish

examples of omega-3 and omega-6 foods

Omega-3 examples

• Fatty fish: salmon, mackerel, sardines, herring, trout

• Walnuts

• Flaxseed and ground flaxseed

• Chia seeds

• Canola and soybean oil (smaller amounts)

Omega-6 examples

• Vegetable oils: soybean, corn, sunflower, safflower

• Sunflower seeds and pumpkin seeds

• Walnuts, almonds, and other nuts

• Mayonnaise and salad dressings made with these oils

trans fatty acids

• unsaturated fats that have been processes from cis form to trans form

  • saturated but not fully saturated

• stabilized by adding hydrogen (hydrogenation) → causes them to last a long time

• found in deep-fried foods, baked snack foods, solid fats

• health risk

how does the number of double bonds differ among saturated, monounsaturated, and polyunsaturated fatty acids? 

saturated = zero

monounsaturated = one

polyunsaturated = more than one, many

general differences b/w common plant-derived & animal-derived fats

animal: saturated = solid at room temp

plant: unsaturated = liquid at room temp

e.g. avocado vs. bacon

plant based are predominantly unsaturated fats

• exception = coconut oil (plant-based but predominantly saturated)

contribution of each organ to fat digestion

Organ	Contribution
Mouth	None in adults (lingual lipase plays a role for infants).
Stomach	None meaningfully — gastric lipase contributes very little.
Small intestine	Most — bile emulsifies, pancreatic lipase digests.
Large intestine	Negligible amount of fat left to process.

digestion vs. absorption

digestion = chemical breakdown

absorption = uptake of the breakdown products into intestinal cells

health benefits of dietary fiber

1. Prevents constipation. Insoluble fiber makes stool absorb water and adds bulk

2. Lowers blood cholesterol. Soluble fiber is gummy (viscous) and binds cholesterol

3. Controls blood glucose. Soluble fiber slows digestion and absorption, so blood sugar rises more gradually and the glucose peak is lower.

4. Supports a healthy gut microbiota. Fiber and resistant starch reach the large intestine, where bacteria ferment them into short-chain fatty acids.

5. Promotes fullness. Fiber adds bulk and slows digestion