-In the mouth lipase, an enzyme that breaks down fats is released in the saliva.
-It is not activated, however, until it reaches the acidic environment of the stomach, where it breaks down a small amount, about 10 percent, of fats consumed.
-When chyme enters the duodenum, bile released from the gallbladder acts on large fat molecules in a process called emulsification and mixes them in the watery environment of the small intestine.
-This mixing allows the enzyme pancreatic lipase to break down the fat molecules into smaller molecules—fatty acids and glycerol
-Once inside the cells of the small intestine, the smaller molecules rejoin to make triglycerides. Some free fatty acids enter the capillaries, but the larger triglycerides must enter the larger vessels of the lymphatic system.
-Remember that fat and water don't mix. Therefore, before the larger triglycerides can be transported through the body they are formed into special carriers, called chylomicrons, that enable the fat to travel in the watery environment of the blood.
-The triglycerides can then pass into the cells of the body to be broken down and used for energy or stored as fat.
-After the fat is absorbed, the bile continues through the intestine and most is reabsorbed in the ileum or bound by fiber and excreted.
-Protein digestion begins in the stomach when pepsinogen is released from the wall of the stomach and converted to its active form, pepsin, when exposed to stomach acid.
-The enzyme pepsin then breaks the peptide bonds in proteins into smaller units.
-Stomach acid also assists in the digestive process by denaturing the proteins, or unraveling their three-dimensional shape.
-The smaller units then empty into the small intestine, where enzymes secreted by the pancreas break them into still smaller units.
-Then, enzymes from the wall of the small intestine act on the peptides to break off one amino acid at a time, and the individual amino acids are absorbed
-The amino acids then travel through the blood to the liver.
-Once in the liver, their fate depends on several circumstances, such as how many carbohydrates you have consumed. The absorbed amino acids can be used to make proteins, or glucose if you have not consumed enough carbohydrates, and a small amount is kept in the blood for a short time in the amino acid pool.
-Any amino acids in excess of the body's needs can be made into fat and stored.
-Excessive intake can be toxic (3,000 μg per day)
-Retinol is most active form, stored in liver
-Plays important role in vision, bone growth, disease resistance and gene regulation
-Food sources: animal foods and products; fortified milk, cheese, cream, butter, eggs, liver, and margarine with vitamin A added; apricots, cantaloupe, squash, carrots, sweet potatoes, and pumpkins
-exposure to sunlight is crucial
-plays role in bone health
-Deficiency leads to rickets(bowlegged children)
-Found in Sunlight, oily fishy products, milk, cereal, fortified juices
-fights off free radicals (cancer, heart disease, aging)
-enhances immune system and is needed for nerve cell development
-deficiency of this vitamin leads to anemia
-Found in vegetable oils, nuts, seeds, leafy greens
-Helps with blood clotting (production of Fibrin)
-Found in Bacteria in Large Intestine, green leafy vegetables, vegetable oils, soybean
-also known as ascorbic acid
-Helps with healing wounds and maintaining structure of blood cells
-deficiency results in scurvy and anemia
-Food sources: fruits and vegetables
VITAMIN B1 (THIAMIN):
-Releases energy from carbs & amino acids
-Integrity of nerve and muscle tissue
-Found in Pork, Whole Grains, Cereal, Enriched Grains and Pasta, Beans, Milk, Peanuts/Seeds, Orange Juice, Organ Meats
VITAMIN B2 (RIBOFLAVIN):
-Helps with the release of Energy from foods.
-Found in Milk, enriched bread, Cereal, Pasta.
VITAMIN B3 (NIACIN):
-Can be synthesized from Tryptophan (essential amino acid)
-Helps release energy from macronutrients and synthesis of fatty acids.
-Found in red meat, dairy products, nuts, seeds, bananas, tuna, shellfish, turkey, soy
VITAMIN B5 (PANTOTHENIC ACID):
-Involved in Synthesis of
-Easily destroyed in food processing
-has seven forms
-converts one amino acid into another
-helps convert tryptophan into niacin (B3)
-synthesis of glucose and other lipids
-important in the production of serotonin from tryptophan, and in hemoglobin synthesis
-Food sources: meats, baked potatoes, bananas, broccoli, spinach, watermelons, salmon, and navy beans.
VITAMIN B7 (BIOTIN):
----Fatty Acid Synthesis
----Breakdown of Amino Acids
-Found in Liver, soy, fish, beans, whole grains.
VITAMIN B9 (FOLATE):
-helps with cell division and developing the central nervous system
-Found in orange juice, leafy greens, organ meats, beans, sprouts, veggies, cereal, breads.
-found only in animal products.
-Converts Folate Coenzymes into active form.
-Amino Acid Metabolism
-Synthesis of DNA
-Found in-Milk, Cheese, poultry, seafood, meat, cereals, soy.
-Most abundant macromineral in human body
-can lower risk for hypertension
-Found in spinach, Kale, milk, soybeans, seafood.
-Second most abundant macromineral.
-Part of bones and teeth, DNA and RNA, helps balance Ph Levels.
-Found in ,eat, fish, poultry, eggs, beans, milk, cereals, grains, coffee, tea, chocolate, soft drinks
----Protein Synthesis and Growth
----Affected by Stress
----Protects against free radicals
----Effect on taste and smell
-Found in Meat, turkey, eggs, grain, cereal
Lipids perform various functions in human nutrition, including:
-supplying essential fatty acids,
-absorbing and transporting fat-soluble vitamins,
-protecting and insulating vital organs,
-providing flavor in foods and, promoting satiety,
-providing cell membrane structure, and
-serving as a precursor to steroid hormones
-Fats are found in both animal and plant products. Meats, butter, and other dairy products contain significant levels of triglycerides with saturated fatty acids.
-help prevent tissue inflammation, heart disease, and the formation of blood clots.
-from plant sources include soybean and canola oils, walnuts, and flaxseed.
eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA):
-important omega-3 fatty acids in addition to linolenic acid
-Fish that naturally contain more oil (e.g., salmon, trout, herring) have higher concentrations of EPA and DHA than leaner fish (e.g., cod, haddock, catfish)
body growth, maintenance and repair, and fluid balance
The specific order of the amino acids is part of what determines a protein's shape, which in turn dictates its function.
-Why does the order dictate the shape?
Recall from our previous discussion that the R groups give the protein its unique and specific qualities. The charge of each amino acid influences how it interacts with the other amino acids in the protein and therefore its shape.
Because a protein's shape determines its function, we can change a protein's ability to function by altering its shape.
-This occurs when we cook food, when we sterilize items such as bandages or a baby's bottle, or when we break down protein during digestion.
-A protein's structure and function can be changed by heat, acid, enzymes, agitation, or alcohol in a process called denaturation.
-Similarly, when we eat proteins we denature them with stomach acid. Stomach acid unravels the three-dimensional structure just as cooking does.
-can lead to anemia due to inadequate intake of iron or vitamin B12
-Lacto-vegetarians: dairy but avoid eggs, seafood, and meat
-Lacto-ovo vegetarians: eggs and dairy products, but no meat or seafood.
-Macrobiotic vegetarians: whole grains, vegetables, soy, legumes, fruits, and nuts and seeds/sometimes include fish but avoid meat, poultry, eggs, and dairy.
-semivegetarians (or flexitarians): occasionally eats meat and seafood, mostly practice a vegetarian diet
-only plant food/ NO animal products
-low in zinc, calcium, protein, vitamin B6, and B12
-can lead to anemia due to inadequate intake of iron or vitamin B12