Test 3 Flashcards
Lipids
Category compouds containing Carbon, Hydrogen and Oxygen that are hydrophobic.
Function in foods
- Give flaky texture to baked goods
- Make meats tender
- Provide flavor and aromas
- Contribute to satiety
Lipid Function in the body
- Energy Storage
- Insulation
- Transport of proteins in blood
- Cell membrane structure
Fatty Acids
Chain of Carbon and Hydrogen atoms with acid group
-COOH at one end
Over 20 different fatty acids
Saturated Fatty Acids
All Carbons bonded to hydrogen
Example: stearic acid, solid at room temperature
Unsaturated Fatty acids
1 or more double bond between carbons (less saturated with hydrogen)
Monosaturated fatty acid: one double bond
Example: Oleic acid (olive oil)
Polysaturated fatty acid: more than one double bonds
Example: Linoleic and alpha linoleic acids (soybean oil)
Triglycerides
Three fatty acids connected to glycerol backbone
Most common lipid in foods and body
Referred to as fats:
Saturated fat have mostly saturated fatty acids
Unsaturated fat have mostly unsaturated fatty acids
Phospholipids
Have a glycerol backbone but two fatty acids abd a phosphorus group.
Phosphorus containing head is hydrophilic
Fatty acid tail is hydrophobic
Cell membranes are made of phospholipid bilayer.
Lecithin is the major phospholipid in cell membrane, and is also used in foods like salad dressing.
Sterols
Are compromised mainly of four connecting rings of carbon and hydrogen.
Example: Cholesterol
Important role in cell membrane structure
precursor of important compounds in body
not required in diet
Digestion of Lipids
Mouth: Chewing, lingual lipase
Stomach: gastric lipase: diglyceride and one fatty acid
Small intestine:
** Bile acids**: emusify fat
** Pancreatic lipase:** 2 fatty acids and glycerol
** Lecithin** in bile is packaged with monoglycerides and fatty acids to create micelles for absorption.
** Short- chain** fatty acids enter the blood stream and travel to the liver
** Long-chain** fatty acids enter the lymph and need transport carriers.
Lipoproteins
Transport fat through the lymph and blood.
Chylomicrons: carry digested fat through lymph into the blood stream.
Very-Low Density lipoprotein (VLDL): deliver fat made in the liver to the cells.
Low-density lipoprotein (LDL, good cholesterol): deposit cholesterol n walls of arteries.
High-density lipoprotein (HDL, bad cholesterol): remove cholesterol from body and deliver to the liver for excretion.
Use of Fat in your body
- An energy-dense source of fuel: 9kcal/gram.
Glucagon also stimulates release of fat from fat cells to fuel heart, liver and muscle.
- Is needed for absorption of fat-soluble vitamins A, D, E, K and carotenoids.
- Insulates the body
- Cushions bones, organs, nerves
Eicosanoids
Made by fatty acids
Cholesterol
Hormone like substances involved in inflamation, blood clotting and blood pressure
- Linoleic acid used to make arachidonic acid
Deficiency interferes with growth and causes inflamation.
- Alpha linoleic Acid (omega 3 fatty acids): needed for healthy cell membranes (nerves and retina)
Deficiency results in scaly skin
Cholesterol is part of the cell membranes and is precursor for vitamin D, bile acids, sex hormones
How much fat you should eat
20-35% of daily calories
For healthy heart no more than 10% should come from saturated fats and trans fats.
Linoleic Acid: 5-10% daily calories
Alpha Linoleic Acid: 0.6-1.2% of daily calories
Linoleic and Alpha linoleic acid ratio
Cholesterol intake
Too much linoleic acid can inhibit the conversion of alpha linoleic acid to DHA.
Too much alpha linoleic acid can inhibit conversion of linoleic to arachidonic acid
Cholesterol doesn’t need to be consume in diet
For heart health should be limited to 300mg/day
Sources of fat
Unsaturated Fats
Vegetable oils (soy bean, canola, corn)
Soybeans, walnuts, flaxseeds, wheat germ.
Saturated Fats: Avoid
Animal Sources: fatty meats, whole milk dairy products and skin on poutry
Plant sources: coconut, palm, palm kernal oils
Cis
Trans
Cis - hydrogens are on the same side of the double bonds
Trans - Hydrogens are on opposite sides of the double bond
Hydrogenation
Process of adding hydrogen to unsaturated fatty acid to make it saturated, more solid at room temperature and more resistant to rancidity.
Causes double bonds of unsaturated fatty acids to change from cis to trans
Trans fats should be kept as low as possible because they raise the levels of LDL and lower HDL
Unsaturated fats are more susceptible to rancidity (decomposion due to oxidation)
Atherosclerosis
narrowing of arteries due to build up of plaque (hardened debris of cholesterol laden foam cells, platelets, calcium, cellular waste products)
- Though to begin with injury to lining of arteries, contributed by high cholesterol levels, and smoking.
- Increase chance of blood clots blocking the vessel, causing heart attack or stroke
Risks of Heart Disease you can control
- Regular exercise can help lower LDL, and raise HDL cholesterol
- Lossing excess weight and quitting smoking can help increase the HDL levels
Syndrome X: group of risk factors, including insulin resitence that increases the risk of heart disease.
What can you do to lower cholesterol
- Minimize saturated fats, trans fats, cholesterol.
- Eat more fish, plant foods, including soybeans and canola oils, flaxseeds, nuts, legumes, oatmeal, fruits, vegetables and tea.
- Get plenty of exercise and manage your weight
- Moderate use of alcohol may reduce risk of heart disease but some should avoid alcohol
Mercury and Fish
Methylmercury is a toxic chemical especially harmful to the nervous system of unborn children.
Accumulates in larger fish with longer life span.
Examples: swordfish, shark, king mackerel, tilefish
FDA recommends women of childbearing age and young children to avoid these four types of fish
Pregnant women/ chidbearing age: up to 12oz of other fish a week Canned tuna has more mercury than light tuna: 6oz/week limit.
Mediterranean Diet
Lower risk of heart disease and cancer:
- Very active lifestyle as well as long, relaxing family meals, afternoon siestas, supportive community.
- Plant-based diet of whole grains, fruits and vegetables, legumes and nuts.
- With olive oil, low fat dairy, water
- occasinal fish, poultry, eggs, meat, sweets, wine
Proteins
Are made of amino acids
Contain Carbon, Hydrogen, Oxygen and Nitrogen
Each amino acid has:
- Acid group: -COOH
- Amine group: -NH2
- Side chain: unique
Types of amino acids
9 essential amino acids
- Cannot be made by the body
- It is essential to obtain them from diet
11 nonessential amino acids
- Can be synthesized by the body from other amino acids or by adding nitrogen to carbon-containing structures
Conditionally essential amino acids.
- Under certain conditions, some nonessential amino acids cannot be made by the body - stress, diseases, babies
Building proteins
Peptide bonds hold amino acids together.
- Acid amino group of one acid connected to the amine group of another amino acid
- 2 amino acids= dipeptide; 3 amino acids = tripepetide.
- Many amino acids= polypeptide
Protein may contain 100-10,000 amino acids.
- Form specific 3D shapes due to interactions between side chains of amino acid
- 3D shape is critical to protein function
Denaturation
Unfolding of protein shape by heat, acids, bases or salts - SHAKING.
Start loosing shape
- Change of protein shape alters its function
- Examples: cooking meat, eggs change texture
- stomach acid untangles protein to aid in digestion
Digestion of Proteins
Dietary proteins are digested and absorbed in the stomach and small intestine
- Stomach acids denature protein
1. Active pepsin, which breaks down protein into shorter polypeptides. - In the small intestine, polypeptides broken down into tri, dipeptides and amino acids
- Amino acids enter the blood and travel to the liver
Where do amino acids come from?
- Diet
- breakdown of proteins in the body
- A limited supply is stored in “amino acid pools” in blood and cells for needed protein synthesis
Protein Turnover
process of continuous breakdown and synthesis of protein from its amino acids
How are amino acids used by the body
Amino acids are used to make:
- Body protein
- non-protein sunstances
- examples: thyroid hormone, melanin
After amino groups removed, converted to urea, excreted in urine, amino acids can also be:
- burned for energy
- stored as fat
- made into glucose
DNA directs Synthesis of New Protein
- DNA in the cell nucleus contains instructions for protein synthesis
- Gene: DNA segment that codes for specific protein
- Specialized RNA molecules carry out instructions for protein synthesis
- Gene mutations can result in errors in protein synthesis.
- Example: sickle-cell anemia
* only one amino acid out of place makes hemoglobin carry only 30 instead of 40
How does the body uses protein
How much protein do we need and where to find them?
- Protein quality varies among food sources
1. Depends on digestibility and amino acid profile - Complete proteins contain all the essential amino acids along with the nonessential one
1. Examples: animal protein, soy protein - Incomplete proteins are low in one or more essential amino acids
1. Example: plant food
Protein Quality
Plant proteins “upgraded” to complete proteins by:
- Consuming modest amounts of soy or animal protein, or
- Being complemented with other plant proteins which provide enough of the limiting amino acid
Protein Digestibility Correct Amino Acid Score (PDCAAS)
- Measure of protein quality taking into account digestibility and amino acid profile
- Basis of protein as % daily value on foods
Protein Requirements determine by nitrogen studies
- Nitrogen Balance: Amount of protein consumed = amount of protein used.
- Nitrogen Imbalaces:
- Positive Nitrogen Imbalance: more nitrogen is retained (for protein synthesis) than is excreted
Examples: infants, children, pregnant women
- Negative Nitrogen Balance: more nitrogen is excreted than consumed (body protein broken down)
Examples: starvation, serious injury or illness
Protein Intake
DRI
- 10-35% of total daily calories from protein
- Average intake is 15%
Calculating daily protein needs:
- Convert weight to pounds by dividing by 2.2
- weight in kg x 0.8g = protein daily intake in gr.
Too much protein and too little
Eating too much protein:
- Can increase risk of heart disease, kidney stones, calcium loss from bones.
- Can displace other nutrient- and fiber rich foods associated with reduced risk of chronic diseases:
- Whole grains fruits and vegetables.
Eating too little:
- Low protein diets associated with loss of bone mass
Protein Energy Malnutrition (PEM)
- Inadequate calories and/or proteins
- More common in children, because they are growing
- Factors: poverty, poor quality food, insufficient food, unsanitary living conditions, ignorance, stopping lactation too early
Protein Energy Malnutrituion
- Kwashiorkor: severe deficiency of dietary protein
1. Seen in children weaned to low-protein cereals - Marasmus: severe defiency of calories
1. Signs: emaciation, lack of growth, loss of fat stores - Marasmic Kwashior: worst of both conditions
1. Medical treatment and food: three step approach - LOST OF ORGANS
How do vegetarians meet their protein needs
- Variety of plant foods
- Protein rich meat alternatives
- Soy
- Dried beans and legumes
- nuts
- eggs and dairy (lacto-ovo- vegetarians)
Types of vegetarians
Benefits of soy
- high quality protein source
- low in saturated fat
- contains isoflavones (phytoestrogens)
- May have anticancer functions
- May relieve menopausal symptoms’
- Lowers blood cholesterol levels
- may reduce risk of heart disease, certain cancers
Types of soy products
- edamame
- tofu
- soy milk soy flour tempeh
- miso
- soy meat analogs texture soy protein
Benefits and risks of vegetarian diet
Benefits:
- May reduce risk of heart disease, high blood pressure, diabetes, cancer, stroke, obesity
Risks:
- Potential deficiencies of nutrients found in animal foods
1. Protein, iron, zinc, calcium, vitamin D, riboflavin, vitamin B12, and A, Omega 3 fatty acids
What are vitamins
They are essential nutrients
- tasteless, organic compounds needed in small amounts
- a deficiency will cause physiological symptoms
- Consuming too much of some vitamins will cause adverse effects
Types of Vitamin
Fat-soluble
- Are absorbed with dietary fats
- Can be stored in body
- Vitamins A,D.E,K
Water soluble
- Absorbed with water
- Not stored in the body, but excess still harmful
Vitamins can be destroyed
Proper food preparation techniques can reduce loss.
- Don’t expose produce to air
- A little water is enough
- Water soluble vitamins leech into the water
* Reduce cooking time - Microwave, steam, or stir fry vegetables until just tender
* Refrigeration delays vitamin loss
Vitamin A
retinoids (retinol, retinal, retinoic acid)
- Performed vitamin A only found in animal foods: liver, eggs, fortified milk, cheese
- Some plants contain provitamin A carotenoids, which are converted to retinol in the body.
- Carotenoids, including beta-cartotene, are pigments which give color to carrots, cantaloupe, sweet potatoes, spinach and broccoli
Functions of Vitamin A
- Essential for healthy eyes
- Involved in cell differenctiation, reproduction and immunity by promotig gene expression for:
- Healthy skin
- bone growth
- fetal development
- white blood cells to fight harmful bacteria
Too Much or Too Little
Vitamin A
Too much
- Excessive amounts of preformed vitamin A can accumulate to toxic levels
- Carotenoids in foods are not toxic
- Excess of Carotenoids can cause nonthreatening condition: CAROTENODERMIA
Too litlle
- Chronic vitamin A deficiency causes night blindness
- # 1 cause of preventable blindness in children in developing country
- Associated with stunting of bone
Vitamin E
Alpha-tocopherol is most active form in body
FUNCTION:
- Act as a powerful antioxidant
1. Protects cell membranes, prevents oxidation of LDL cholesterol - acts as an anticoagulant, inhibiting formation of harmful clots inside bloodstream
FOOD SOURCES: vegetable oils, nuts, seeds, fortified cereals, some green leafy vegetables
Too much or Too little
Vitamin E
Too much:
- No problems if overconsuming vitamin E naturally
- Synthetic overconsumption, increases the risk of hemorrhage
Too little:
- Although rare, chronic deficiency of vitamin E can cause nerve problems, muscle weakness, and free radical damage to cell membrane
Vitamin K
Two forms:
- Menaquinone synthesized by intestinal bacteria
- Phylloquinone found in green leafy plants
FUNCTIONS:
- Essential for blood clotting
1. involved in four blood clotting factors - Important for bone health
1. Enables bone protein osteocalcin to bind with calcium
FOOD SOURCES:
green vegetables such as broccoli, aspargus, spinach, salad greens, brussels sprouts, cabbage; also vegetable oils and margarine, green tea
Too Much or Too Little
Vitamin K
Too much:
- No problems of over consuming vitamin K
- People taking anticoagulant medications such as Warfin need to keep vitamin K intake consistent
- Changes in intake can increase or deacrease drug effectiveness
Too little:
- May affect blood clotting, but is extremely rare
1. At risk: people with problems absorbing fat.
Vitamin D
- Cholesterol- cointaing coumpound in skin is converted to inactive form of vitamin D
- People with insufficient sun exposure must meet needs through diet; vitamin D in foods is also in inactive form
- Inactive form converted to circulating form in liver to active form in kidneys
Vitamin D Functions
- Regulates two important bone minerals: calcium, phosphorus
- Stimulates intestinal absorption of Ca and P to maintain healthy blood levels and build and maintain bones
- When dietary calcium is inadequate, vitamin D and parathyroid hormone cause calcium to leave bones to maintain necessary blood levels
- May prevent type 2 diabetes and some cancers
FOOD SOURCES: fortified milk, and yogurt, fortified cereals, fatty fish (sardines, salmon, tuna)
Too much or too little
Vitamin D
Too much:
- Overuse of supplements may lead to hypervitaminosis D, which causes hypercalcemia.
1. Damaging calcium deposited in kidneys, lungs, blood vessels, heart.
Too little:
- Rickets: vitamin deficiency in children
- On the rise in the US due to decresead milk consumption
- the bones of children with rickets aren’t adequately mineralized with calcium and phosphorus, causing them to weaken and leading to bowed legs.
- Ostemalacia: adult equivalent of rickets
Vitamin B and C
Are water soluble, not stored in body
- excess excreted in urine
- however routine intake of excessive amounts can be harmful
Vitamin B
- share common role as coenzymes
1. help many enzymes produce chemical reactions in cells
Enzymes: speeds up reactions, makes sure reactions will occur
Thiamin
Vitamin B1
FUNCTIONS:
- Transmission of nerve impulses, electrical and quemical
- Metabolism of carbohydrates and certain amino acids
- plays a role in breakdown of alcohol in bidy
FOOD SOURCES: enriched and whole grain products, pork
Too much or too little
Thiamin
Too much:
- Not toxic
Too little:
- Beriberi: thiamin deficiency disease (loss of appetite, weight, memory, confusion)
- Rare in the US, due to enriched grains
- Chronic alcohol abuse can lead to advanced form: Wernicke-Korsakoff syndrome, progressively damaging brain disorder
- Due to thiamin-deficient diet, and alcohol interferes with thiamin absorption
Riboflavin
Vitamin B2
Light-sensitive vitamin, abundant in milk
- Opaque containers preserve riboflavin content
FUNCTIONS:
- Important for energy metabolism
- keeps cells healthy
- Enhances functions of other B vitamins, such as niacin and B12
FOOD SOURCES: milk, yogurt, enriched cereals and grains
Too much or too little
Riboflavin
Too much:
- Excess riboflavin excreted in urine: bright yellow color
Too litlle:
- Deficiency symptoms rarely seen in healthy individuals eating a balanced diet
1. Sore throat, swelling inside mouth, inflamed and purplish- red tongue, dry and scaly lips
Niacin
Vitamin B3
Active forms: nicotinic and nicotinamide
FUNCTION:
- neeeded for energy metabolism
- synthesize fat and cholesterol
- keep skin cells and digestive system healthy
Sometimes prescribed in high doses by physicians to decrease blood cholesterol LDL and triglycerides, increase HDL
Can be made in the body from the amino acid tryptophan: daily needs expressed in niacin equivalents NE
Tryptophan: stimulates the production of HDL
makes you fall asleep (turkey)
FOOD SOURCE: meat, fish, poultry, enriched whole grain breads, fortified cereals
- Protein rich foods are a good source of tryptophan
Too much or too little
Niacin
Too much:
- niancin supplements can cause flushing, nausea, vomiting, be toxic to liver, raise blood glucose levels - DESTROY LIVER-
Too little:
- Pellagra: known as four Ds
- dermatidis, diarrhea, dementia, death
- once common in the south due to corn based diet
Vitamin B6
FUNCTIONS:
- works as coenzymes for over 100 enzymes in protein metabolism, needed to:
- Make nonessential amino acids, convert tryptophan to niacin and hemoglobin in red blood cells
- Keep immune and nervous system healthy
- Metabolize fats and carbohydrates and break down glycogen
FOOD SOURCES: Meat, fish, poultry, fortified cereal (no bread), nuts, legumes, peanut butter, many fruits and vegetables
Too much or too little
Vitamin B6
Too much:
- Nerve damage
Too little:
- Sore tongue, skin inflammation, depression, confusion, anemia
- Those with alcoholism at risk for deficiency due to poor diet and alcohol causes body to lose B6
Folate
Vitamin B9
- Naturally occuring form in foods
- Folic acid: synthetic form of folate added to foods and supplements
FUNCTIONS:
- Vital for DNA synthesis
- To create and maintain new cells, including red blood cells
- to help body use amino acids
- reduces risk of some cancer
FOOD SOURCES: enriched grains, legumes, broccoli, aspargus, leafy greens such as spinach
Too much or too little
Folate
Too much:
- Too much folic acid makes vitamin 12 deficiency anemia
Too little:
- During pregnancy can result in neutral tube birth defects
- Folate deficiency can lead to macrocytic anemia
cytic= cells
vegetarians eat a lot of B9, so they are more prone to macrocytic anemia
Vitamin B12
Also known as COBALAMINE, because it contain cobalt
- Requires instrict factor protein made in stomach, in order to be absorbed in small intestine
- Pernicious anemia results in people who cannot make intrict factor: treatment requires B12 injection to bypass intestine
- Symptoms may take years to appear since B12 is stored in liver
Instrict factor: synthesis and absorption of protein
Vitamin B12
Function
- To make DNA
- To use certain fatty acids and amino acids
- For healthy nerves and cells, especially red blood cells
FOOD SOURCES:
- Only found in animal products, meat, fish, poutry and dairy
- Syhthetic B12 is found in fortified foods such as soy milk and some cereals
Too Much or too little
Vitamin B12
Too much:
- Not toxic, no UL
Too little:
- Macrocytic anemia, because folate can’t be utilized properly
- Lack of instrict factors cause pernicious anemia, involves nerve damage
Vitamin C
Ascorbic acid
FUNCTIONS:
- coenzyme to synthesize and use certain amino acids
- Needed to make collagen, most abundant protein in body, present in connective tissue. - Important for healthy bones, skin, blood vessels, teeth
- Also acts as an antioxidant
- Helps absorb iron from plants
- breaks down histamine, cause of inflammation.
Too much or too little
Vitamin C
Too much:
- nausea, stomach cramps, diarrhea
- Peple with history of kidney stones or hemochromatosis (body stores too much iron) should avoid excess
Too little:
- Scurvy: inflammation skin and gums
