The Water-Soluble Vitamins- Chapter 8

Vitamin C Function: Collagen

- Collagen molecule---> (vitamin C) strong, healthy, cross linked connective tissue - Collagen molecule---> (no vitamin C) weak, abnormal connective tissue

Folate Deficiency: Macrocytic Anemia

- Red blood cell precursor---> (folate adequate) normal cell division---> red blood cells - Red blood cell precursor---> (folate deficient) cells are unable to divide aka megaloblast---> macrocytes

Dietary Supplements

-Another source of vitamins in the modern diet -Contain some combination of vitamins, minerals, herbs, botanicals, amino acids, enzymes or extracts -Cannot replace the benefits of a diet containing a wide variety of foods

Water soluble vitamins

-B vitamins and vitamin C -Vitamin B ---Thiamin (B1) ---Riboflavin (B2) ---Niacin (B3) ---Biotin ---Pantothenic acid ---Vitamin B6 ---Folate ---Vitamin B12

Thiamin Deficiency

-Beriberi

Biotin

-Biotin functions as a coenzyme in energy metabolism -Avidin in raw eggs destroys biotin -Dietary sources are liver, egg yolks, yogurt, and nuts

Vitamin B6

-Called pyridoxine and comprises a group of compounds including pyridoxal, pyridoxine, and pyridoxamine ---All three forms can be converted into pyridoxal phosphate, which is required for many enzyme reactions in the body -Vitamin B6 deficiency may result in anemia due to impaired hemoglobin synthesis and neurotransmitter issues -A toxicity from supplements can cause irreversible nerve damage

Niacin

-Can be synthesized in the body from the essential amino acid tryptophan if the diet is adequate in tryptophan -Plays an important role in the production of energy and in general metabolism -Two forms of niacin are nicotinic acid and nicotinamide -Two active coenzymes are nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP)

Vitamin B6: Dietary Sources

-Chicken, pork, lentils, beef, brown rice, trout, sunflower seeds, walnuts, whole wheat bread, milk, OJ, asparagus, spinach, kiwi, apple, peanut, corn, oatmeal, spaghetti, cheese, white bread -meat, poultry, fish, nuts, beans, rice potatoes, bananas, spinach, sweet red peppers, broccoli

Niacin: Dietary Sources

-Chicken, trout, peanuts, pork, beef, lentils, brown rice, whole wheat bread, spaghetti, white bread, sunflower seeds, corn, asparagus, OJ, kiwi, spinach, oatmeal, apple, milk, walnuts -protein foods, enriched grains, peanuts

Riboflavin

-Easily destroyed by heat and exposure to light -An important component in the citric acid cycle and for assisting the body with the absorption of other vitamins -Flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) are the coenzyme forms -Ariboflavinosis—a deficiency of riboflavin

Choline: Dietary Sources

-Eggs, beef, salmon, pinto beans, chicken, milk, yogurt, broccoli, spinach, sunflower seeds, almonds, peanuts, brown rice, oatmeal, corn, orange, banana, whole wheat bread, apple, cheese

Enriched Foods

-Enrichment ---Adding nutrients back to foods that have lost nutrients due to processing ---An example is the addition of B vitamins to white rice

Thiamin

-First B vitamin to be identified -Also called vitamin B1 -Assists in energy production, carbohydrate metabolism, the production of ribose and the health of the nervous system -Beriberi—a deficiency of thiamin -Wernicke-Korsakoff syndrome—a deficiency of thiamin in alcoholics

Finding Vitamins in Foods- Fruits

-Folate -Vitamin A -Vitamin C

Folate (Folic Acid)

-Folate coenzymes are needed for DNA synthesis and the metabolism of some amino acids -Low folate intake in early pregnancy is associated with an increased risk of neural tube defects -Low folate intake has been associated with an increased risk of heart disease related to the metabolism of the amino acid homocysteine

Fortified Foods

-Fortification ---Process of adding nutrients to foods ---The added nutrients are generally not found in the food or are added in much larger amounts, such as fortifying orange juice with calcium

Thiamin's Role in Glucose Metabolism

-Glucose---> pyruvate---> acetyl-CoA---> neurotransmitter synthesis and ATP

Vitamin C

-Known as ascorbic acid or ascorbate -Can be destroyed in food by oxygen, light and heat, as well as contact with copper or iron cookware -Functions ---Antioxidant in the body ---Helps maintain the immune system ---Important in the production of collagen ---Aids in iron absorption

Folate: Dietary Sources

-Lentils, spaghetti, asparagus, OJ, spinach, white bread, sunflower seeds, peanuts, corn, whole wheat bread, kiwi, walnuts, trout, milk, cheese, oatmeal, brown rice, pork, beef, chicken, apple -enriched grains, green vegetables, legumes, liver

Riboflavin: Dietary Sources

-Milk, pork, trout, beef, lentils, cheese, chicken, white bread, spaghetti, whole wheat bread, spinach, asparagus, kiwi, OJ, corn, oatmeal, brown rice, walnuts, peanuts, apples -milk, mushrooms, spinach, liver, enriched grains

Vitamin B12

-Necessary for metabolism of folate and fatty acids and maintaining myelin around nerves -Found almost exclusively in animal products ---Vegan diets require supplements or foods fortified with B12 -Atrophic gastritis - low stomach acid reduces B12 absorption -Pernicious anemia - lack of intrinsic factor prevents the absorption of B12 -High intake of folic acid can mask B12 deficiency

B6 and Myelin

-Nerve cell -Cell nucleus -Myelin

Folate Deficiency

-Neural Tube Defects ---spine with spina bifida

Vitamin C: Dietary Sources

-OJ, kiwi, strawberries, cantaloupe, broccoli, tomato, spinach, potatoes, apple, corn, lentils, milk, walnuts, trout, sunflower seeds -citrus fruits, strawberries, broccoli, greens

What Are Vitamins?

-Organic compounds essential in the diet to promote growth and health maintenance -Water-soluble vitamins include the B vitamins and vitamin C ---B vitamins were originally thought to be one chemical substance but are actually many different substances, that is the reason for B1, B2, B12, etc. -Fat-soluble vitamins include A, D, E and K

Niacin 2

-Pellagra—a niacin deficiency ---Symptoms include the 3 Ds: dermatitis, diarrhea and dementia, and eventually the 4th D: death -Niacin toxicity from overuse of niacin supplements can result in elevated blood pressure, cardiac arrhythmia, nausea, vomiting, elevated blood sugar levels and impaired liver function

Thiamin: Dietary Sources

-Pork, lentils, whole-wheat bread, spaghetti, white bread, oatmeal, trout, OJ, brown rice, peanuts, sunflower seeds, asparagus, milk, chicken, beef, walnuts, kiwi, spinach, apple, corn -pork, whole grains, enriched grains, legumes

Finding Vitamins in Foods- Veggies

-Riboflavin -Niacin -Vitamin B6 -Folate -Vitamin A -Vitamin C -Vitamin E -Vitamin K

Finding Vitamins in Foods- Dairy

-Riboflavin -Vitamin A -Vitamin B12 -Vitamin D

Vitamin C 2

-Scurvy—vitamin C deficiency -UL is 2000 mg

Pantothenic Acid: Dietary Sources

-Sunflower seeds, lentils, trout, chicken, pork, milk, peanuts, brown rice, oatmeal, corn, beef, OJ, kiwi, whole wheat bread, white bread, walnuts, cheese, asparagus, apple, spinach -widespread in foods, meats, whole grains

Is Fresh Really Best?

-The high temp used in canning reduce nutrient content. However, because canned foods help for a long time, do not refrigeration, and are less expensive than fresh or frozen foods, they provide an available, affordable source of nutrients that may be best choice in some situations. -Sometimes "fresh" produce is lower in nutrients than some would expect because it has spent a week in a truck, traveling to the store, several days on a shelf, and another week in ones refrigerator. -Frozen foods are often frozen in the field in order to minimize nutrient losses. Thus, frozen fruits and veggies supply more vitamins than "fresh" ones.

Finding Vitamins in Foods- Grains

-Thiamin -Riboflavin -Niacin -Pantothenic Acid -Vitamin B6 -Folate -Vitamin E

Finding Vitamins in Foods- Protein

-Thiamin -Riboflavin -Niacin -Biotin -Folate -Pantothenic Acid -Vitamin A -Vitamin B6 -Vitamin B12 -Vitamin D

Vitamin B12: Dietary Sources

-Trout, beef, pork, milk, cheese, chicken -Only animal-based products: Meat, fish, shellfish, milk, egg

Bioavailability of Vitamins

-Vitamins must be absorbed by the body in order to perform their functions -Fat-soluble vitamins require fat in the diet to be absorbed -Water-soluble vitamins may require transport molecules or specific molecules in the GI tract -Some vitamins are absorbed in inactive provitamin or vitamin precursor forms that must be converted into active forms by the body

Storage and Excretion

-Water-soluble vitamins are easily excreted from the body (except B12) -Because stores can be rapidly depleted, they must be consumed regularly -Fat-soluble vitamins are stored in the liver and fatty tissue so it takes longer for a deficiency to develop

Vitamin C Functions as...

-an Antioxidant LOOK ON PP -Without vitamin C free radicals can damage DNA and other molecules -Vitamin C neutralizes free radicals so they can no longer damage molecules such as DNA

Absorption of Vitamins

1. In the mouth, chewing breaks food into small particles, helping to release vitamins 2. In the stomach, digestion of food releases vitamins. Some niacin is absorbed here 3. The gallbladder releases bile, which emulsifies fat and helps absorb fat-soluble vitamins 4. The pancreas secretes digestive enzymes that releases vitamins from food 5. In the small intestine, fat-soluble vitamins are incorporated into micelles and absorbed by simple diffusion. Inside the mucosal cells, they are packaged in chylomicrons, which enter the lymph. 6. Water-soluble vitamins are absorbed from the small intestine directly into the blood. Many depend on energy-requiring transport systems or must bind to specific molecules in the gastrointestinal tract to be absorbed. 7. In the large intestine, bacteria synthesize small amounts of vitamins, some of which are absorbed.

B Vitamins Act as Coenzymes

1. The vitamin combines with a chemical group to form the functional coenzyme (active vitamin) 2. The functional coenzyme combines with the incomplete enzyme to form the active enzyme 3. The active enzyme binds to one or more molecules and accelerates the chemical reaction to form one or more new molecules. 4. The new molecules are released, and the enzyme and coenzyme (vitamin) can be reused or separated.

Absorption of Vitamin B12

1. Vitamin B12 in food is bound to protein 2. In the stomach, acid and pepsin help release vitamin B12 from food proteins 3. Cells in the stomach lining release intrinsic factor 4. In the upper portion of the small intestine, intrinsic factor binds to vitamin B12 5. In the lower part of the small intestine, the vitamin B12- intrinsic factor complex binds to receptors on cells, allowing for absorption 6. In the colon, vitanin B12 in synthesized by microorganisms but cannot be absorbed

Coenzymes Are Essential for...

Energy Metabolism

Homocysteine Metabolism

LOOK ON PP -Proteins---> methionine---> homocysteine (high levels of homocysteine in the blood increases risk of heart disease)---> cysteine -vitamin B6- (if vitamin B6 is deficient, homocysteine cannot be converted to cysteine, so levels rise) OR ---> methionine -vitamin B12 folate- (if folate or vitamin B12 is deficient, homocysteine cannot be converted to methionine, so levels rise)

Vitamin B6: Functions

LOOK ON PP -Transamination reactions synthesize nonessential AA by transferring an amino group to a carbon group compound -Deamination reactions remove the amnio group from AA so they can be used to produce ATP or to synthesize glucose -Decarboxylation reactions remove the acid group from AA so they be used to synthesize neurotransmitters

Fat soluble vitamins

Vitamins A, D, E, K