NUTR 2100 Exam 2

Functions of Carbs

Functions of Carbs

Provides quick energy

Regulates blood glucose

Spares protein

Prevents ketosis

Flavor, sweetening, anti-spoilage

Regulates digestion (fiber)

Feeds gut bacteria (fiber)

Carbohydrates

Sugar, starch, fiber & glycogen

Made up of carbon, hydrogen, & oxygen

Simple & complex

Simple Carbohydrates

Smaller, 1-2 molecules (table sugar), more sweet.

Monosaccharides

Disaccharides

Monosaccharides

1 sugar molecule and can be directly absorbed into bloodstream to be brought to liver for energy (ATP) or storage:

Glucose

Fructose

Galactose

Disaccharides

2 sugar molecules:

Sucrose

Maltose

Lactose

Complex Carbohydrates

Larger, several sugar molecules (vegetables), less sweet.

Starches

Fiber

Glycogen

Not dietary, built in the body from carbs we eat, & is how carbs are stored. Process of production known as glycogenesis where glucose molecules are combined.

Glucose

Basic unit of many sugars & primary energy source for all cells. Necessary for blood contents (blood sugar).

Fructose

Naturally found in fruits, honey & some vegetables. Tastes sweeter than glucose, converted to glucose in the body.

Galactose

Not commonly found in foods, except milk (component of lactose).

Refined Sugars

Must be limited, less nutritional value, mostly added just for taste.

Polysaccharides

10+ monosaccharides bound together (starches & fiber), nutritive.

Nutritive

Contributes energy to our foods (4kcal for carbs).

Carbohydrate Storage

Animals: glycogen, can only produce so much and will begin to store as fat when in excess.

Plants: starch/fiber

Fiber

Supportive structures in plants, most are not digestible by the human body (cellulose, pectin, & lignins). Better to increase slowly.

Functions of Fiber

Feeds gut bacteria

Reduces blood cholesterol

Slows glucose absorption

Reduces constipation

Prevents diverticulitis

Soluble Fiber

Dissolves, forms a gel during digestion

Slows absorption of sugar

Delays stomach emptying so you feel fuller

Can lower blood cholesterol

(oatmeal, fruits, seeds)

Insoluble Fiber

Does not dissolve well in water

Adds bulk to digestive tract

Helps movement through GI tract

Prevents or alleviates constipation

(rice, wheat, vegetables)

Fermentability

Ability to be fermented/eaten by gut bacteria in order to provide energy for gut bacteria (not us), leading to a healthy gut microbiome. Byproducts may provide us with health benefits.

Lactose

Disaccharide that is broken down by lactase in the small intestine to form glucose and galactose.

Maltose

Disaccharide that is broken down by maltase in the small intestine to form glucose.

Sucrose

Disaccharide that is broken down by sucrase in the small intestine to form glucose and fructose.

Adipose Tissue

Carbohydrates are stored in this way when all glycogen has been made.

Insulin

Hormone produced by the beta cells in the pancreas, travels through the bloodstream, and acts as a key to allow certain cells to absorb and store glucose. When in lack, glucose cannot enter certain cells, and as a result, collects in the blood.

Glycogenesis

Production of glycogen to store extra glucose energy.

Lipogenesis

Production of fat to store extra glucose.

Blood Glucose

70/110 mg/dl, regulated by insulin. Cells need energy from glucose in the blood stream in order to function.

Symptoms of High Blood Sugar

Thirst

Headaches

Trouble Concentrating

Blurred Vision

Frequent Urination

Fatigue

Can lead to diabetes, heart disease, or damage to blood vessels

Symptoms of Low Blood Sugar

Shaking

Sweating

Headaches

Hunger

Fatigue

Fainting

Can lead to death in severe cases because cells need energy to function

When Blood Glucose is Low

1. The pancreas is alerted of low glucose levels

2. Alpha cells in the pancreas release glucagon

3. Glucagon stimulates cells to release glucose (from glycogen) into the blood

4. Blood glucose is regulated

When Blood Glucose is High

1. The pancreas is alerted of high glucose levels

2. Beta cells in the pancreas release insulin

3. Insulin stimulates cells to absorb glucose

4. Blood glucose is regulated

Glucagon

Secreted by the alpha cells in the pancreas when glucose levels are low. Activates glycogen to be broken down and used to energize cells.

Glycogenolysis

Breakdown of glycogen to form glucose.

Lipolysis

Breakdown of fat molecules.

AMDR for Carbohydrates

45-65% of total calories should come from carbohydrates (roughly half, or slightly more).

Type I Diabetes

Autoimmune disease that damages beta cells of the pancreas, therefore, little to no insulin can be produced. Can continue to have a normal diet but must be conscious and use insulin.

Hypoglycemia

Low blood glucose (< 70 mg/dl), can result from taking too much insulin.

Type II Diabetes

Beta cells can successfully produce insulin, but cells do not respond and are unable to absorb glucose (insulin resistance). No certain cause, but it’s necessary to be conscious that carb intake is spread throughout the day. Diet and exercise is also beneficial.

Hyperglycemia

High blood glucose; can cause complications and lead to blood vessel damage in untreated cases.

Gestational Diabetes

Diabetes formed during pregnancy. Often resolves post-partum, but increases the risk of developing type II diabetes.

Lipids

Not soluble in water and associates with self (in droplets). Oils, spreads, dairy, fatty fish, avocados, and nuts.

Functions of Lipids

Reserves energy \n Cushions organs \n Insulation \n Signal transduction \n Cell membrane structure & function \n Component of other compounds (e.g., bile, \n vitamin D) \n Absorption & transport of fat-soluble vitamins

Fatty Acids

Chains of carbon, hydrogen & oxygen that can be saturated of unsaturated.

Short-Chain Fatty Acids

SCFA, 2-4 carbons.

Medium-Chain Fatty Acids

MCFA, 6-10 carbons.

Long-Chain Fatty Acids

LCFA, 12-24 carbons. Most naturally-occurring fatty acids in food are long-chain with an even number of carbons.

Saturated Fat

Full, no room for more hydrogens. There are no double bonds in the fat molecule, meaning molecules can lay flat against one another and form a solid substance.

Unsaturated Fat

The fat molecule has one or more double bonds, creating a bend in the molecule’s shape and a more liquified substance.

Monounsaturated Fat

MUFA, there is one double bond and is liquid at room temperature, but will become solid if refrigerated (olive oil, canola oil, peanut oil, sesame oil).

Polyunsaturated Fatty Acids

PUFA, two or more double bonds resulting in a liquid substance at room temperature or when refrigerated. Usually of plant origin (corn oil, safflower oil).

Essential Fatty Acids

Long-Chain, PUFA fatty acids that must be obtained from the diet. Omega-3 and Omega-6 help with cell communication, inflammation, and blood clotting.

Omega-3

Linolenic acid; mostly anti-inflammatory and prevents blood clotting (poultry, eggs, avocado, nuts, cereals, whole-grain breads, and vegetable oils). 0.6-1.2% of daily kcals.

Omega-6

Linoleic acid; pro-inflammatory, anti-inflammatory, and promotes blood clotting (fatty fish, human milk, fortified eggs, flaxseed, walnut, canola, and soybean). 5-10% of daily kcals.

Trans Fatty Acids

Unsaturated; do not serve a useful purpose in the body but used for rancidity resistance, spreadability, and higher smoking point in food production.

Partial Hydrogenation

Process of forming trans fats, adding hydrogen to the molecule to flip the double bond and make the shape more straight.

Total Fat

AMDR is 20-35% of daily calories.

Triglycerides

TG; major form of fat in foods and storage of lipids. Contains 3 fatty acids and can be broken down to form ATP.

Glycerol

3 carbon molecule that binds tryglycerides.

Functions of Tryglycerides

Provides energy (9 kcal/gram)

Allows body to store energy

Pads organs

Insulates the body

Visceral Fat

Fat surrounding the organs.

Phospholipids

Forms structure of cell membrane (lipid bilayer). Facilitates nerve function, transportation of fat-soluble nutrients, and emulsification. Head is hydrophilic (interacts with water), and tails are hydrophobic (repels water).

Sterol

Large, lipid molecules. Gives cell membranes flexibility and makes bile, vitamin D, and hormones.

Cholesterol

No specific recommendation, but minimize intake within context of a healthy diet. Body can make its own cholesterol (made by liver).

Stomach

Begins lipid digestion by clumping contents together through mechanical digestion.

Lingual Lipase

Enzyme that leads to minor lipid digestion in the mouth (mostly in infants).

Small Intestine

Where most lipid digestion occurs. Lipids are emulsified by bile and digested by lipase into absorbable fatty acids.

Emulsification

Breaking lipids down into smaller droplets.

Micelles

Emulsified lipid droplets surrounded by water in the small intestine.

Bile

Made up of cholesterol and phospholipids to emulsify lipids.

Pancreatic Lipase

Made in the pancreas and active in the small intestine to break triglycerides into fatty acids and then glycerol.

Chylomicron

Lipoprotein package of reassembled lipids made up of cholesterol, proteins, and phospholipids to transport lipids to lymphatic system and ultimately the blood stream.

Adipocytes

Adipose/fat cells; we can continue to store almost endless amounts of fat as energy. Fat cells continue to grow until they divide to form new ones.

Fed State

Anabolic (building up) state after a meal. Excess energy, increased glucose levels, and insulin released. Insulin encourages adipocyte production/lipid storage.

Fasting State

Catabolic (breaking down) state between meals or during exercise. Lack of energy and glucagon released. Glucagon encourages lipolysis and ATP production.

Lipogenesis

The creation of fat storage (adipocytes).

Lipolysis

The break down of fat storage.

LDL Lipoproteins

Low-density lipoproteins; carry cholesterol and are harmful in excess. Releases cholesterol into the bloodstream for cells to absorb.

HDL Lipoproteins

High-density lipoproteins; carry cholesterol and are less detrimental to health when in excess. Fill up with cholesterol to transport excess in the bloodstream.

Consequences of Too Little Fat

Infertility

Amenorrhea

Decreased bone density

Poor cognitive development & concentration

Decreased immunity & growth

Poor vision

Consequences of Too Much Fat

Cardiovascular Disease (leading cause of death in U.S.)

Diabetes

Cancer

Cardiovascular Disease

Leading cause of U.S. adults (1/4). Characterized by blood vessels clogged with excess lipid, damaged vessels, or other heart issues.

Atherosclerosis

First stage of CVD. Buildup of fats, cholesterol, and other \n substances in and on artery walls; forming “plaques” and restricting blood flow.

Cardiovascular Disease Risk Factors

High blood pressure

High LDL cholesterol

Smoking

Diabetes (blood vessel damage)

Overweight and obesity

Poor diet (high trans/sat fat, high cholesterol, low omega 3)

Physical inactivity

Excessive alcohol use

Protein

Made up of amino acids, about 50,000 kinds in our bodies. Is not stored beyond body’s usage, but made whenever necessary. 1+ polypeptides linked and folded into a 3D shape.

Function of Proteins

Structure/movement

Molecule/nutrient transport

Facilitate chemical reactions

Support immune system

Allow body to adapt

Maintain fluid balance in bloodstream

Protein Recommendations

Vary sources

5.5oz daily

8oz seafood weekly

5oz nuts/seeds/soy products weekly

lbs / 2.2 = kg, kg x 0.8 = #g

Athletes, malnourished, energy restrictive diets, and older adults need more

Sources of Protein

Meat

Fish

Dairy

Eggs

Soy

Quinoa

Amaranth

Typical Protein Intake (for Americans)

Males: >100g/day

Females: >70g/day

Too much!!!

Protein Deficiency Diseases

Occur when there is a lack of protein in the diet (Protein Malnutrition). Common in those with wasting diseases, with anorexia, in impoverished areas, U.S. homeless, children of the working class/poor.

Kwashiorkor

Type of protein energy malnutrition where there is an inadequate protein intake or severe infection. It is acute and more common in young children. Caloric/other macronutrient intake may be adequate, but protein is not. Symptoms include:

Muscle wasting

Edema

Fatty liver

Inability to heal wounds

Loss of hair pigmentation

Edema

Build up of fluid in the interstitial space (between blood and cells) that leads to swelling when there is a lack of protein. Protein creates pressure in the bloodstream and maintains the distribution of fluids.

Marasmus

Chronic protein energy malnutrition characterized by a general lack of food/energy intake, not just protein. Symptoms include:

Impaired growth

Little subcutaneous fat*

Slowed metabolism/lower body temp

Impaired brain development

Impaired immunity

Amino Acids (AA)

Amino “nitrogen containing” acids are the basic unit of proteins. 20 are essential (from diet), 11 are made in the body. Every protein you eat is digested into amino acids. Each amino acid has a very specific structure and function.

Amino Acid Structure

Contain an amino group, an acid, a carbon, and an “R Group” that determines the type of amino acid.

Methionine

Usually first AA in a protein, donor of methyl groups.

Phenylalanine/Tyrosine

AA that makes epinephrine, melanine, and thyroid hormone.

Tryptophan

Synthesizes serotonin into melatonin.

Peptide Bonds

Bind amino acids together to form a peptide; which is then folded into a protein.

Transcription

Creating a copy of the DNA with mRNA and transporting it out of the nucleus so that the DNA does not have to leave the nucleus.

Translation

A ribosome binds to the RNA at a specific codon to use tRNA to make amino acids.