Wardlaw's Perspectives in Nutrition Ch. 13

Which vitamins are added to grains in the enrichment process?

Thiamin, B1. Riboflavin, B2. Niacin, B3, and Iron. Folate now added. Because we loose vitamins in the bran and germ during processing.

How can Niacin be synthesized endogenously?

60mg tryptophan = 1 mg Niacin. 1g of Protein = 10mg tryptophan. Body won't do this readily because it needs tryptophan for protein synthesis.

Why would raw egg whites consumption produce Biotin deficiency?

Biotin binds to the protein Avidin in raw egg white which limits its absorption.

Which B vitamin is supplied primarily in foods of animal origin?

B12

Which individuals are more likely to experience poor B12?

Those with digestive disorders, Vegans, Atrophic gastritis

Which water soluble vitamins have a UL?

Niacin, B-6, Folate; to not mask B12 deficiency, Vitamin C, Choline

Name two B vitamins required for mature red blood cell development and avoidance of megaloblastic anemia

B12 and Folate. B6 also important for mature red blood cells but not in avoidance of megalobalstic anemia.

Symptoms of scurvy

After 20-40 days, pinpoint hemorrhages around hair follicles, gums and joints bleeding, impaired wound healing, bone pain, fractures, and diarrhea, depression.

Effects of smoking on Vit C needs and why

The RDA increases by 35mg/ day to counteract oxidative stress. Smokers Vit C serum levels are a third less than non-smokers.

Why is folic acid so important in the early stages of pregnancy

Rapid cell development.

White rice vs brown rice

Fat in the bran goes rancid in warm environments so it made sense to remove the bran, resulting in loss of vitamins. Brown Rice has more B6, potassium, zinc, magnesium and fiber than white rice.

Thiamin food sources

Pork, sunflower seeds and legumes like navy beans and peas. Pork one of highest sources.

Why do men have a higher RDA of B vitamins?

B vitamins are coenzymes that help break down food. Men tend to have greater energy requirements and therefore need more b vitamins to break down the higher intake.

Functions of Thiamin

Coenzyme form: thiamin pyrophosphate- has 2 phosphates added. Required for carbohydrate and branched chain amino acid metabolism and decarboxylation. When a carbon is taken off and we see CO2 in the CAC, Thiamin is the helper.

Use of thiamin in energy metabolism

Needed in the conversion from pyruvate to acetyl CoA. Included in the enzyme reaction with NAD.

Thiamin deficiency

Beriberi comes from not eating thiamin in the diet. Symptoms include peripheral neuropathy and congestive heart failure. Wernicke-Korsakoff Syndrome from alcohol use. Shakiness is a sign of nerve damage. alcohol inhibits use and absorption and causes secretion of vitamins.

Riboflavin foods

Milk, enriched grains, eggs and meat. Riboflavin is destroyed by UV light. No milk in glass bottles.

Functions of Riboflavin B 2

Coenzymes FMN and FAD. Carrier to bring energy or released electrons to the electron transport chain. Citric Acid Cycle, Beta Oxidation- breaking the fatty acid chain into 2 carbon pairs, oxidizing fat for energy. Antioxidant function: part of glutathione synthesis.

Riboflavin deficiency

ariboflavinosis: cracks on the side of mouth, tongue large and glossy, sore throat

Niacin B3 rich foods

Poultry, meat, fish, mushrooms, wheat bran, peanuts, coffee, tea and bread products.

Overview of Water soluble vitamins

Storage in body tissues is minimal. Easily destroyed in cooking. Form coenzymes. Freed during digestion; released not digested. Absorbed easier because doesn't have to be packaged in chylomicron.

B vitamins and Coenymes

B 1 Thiamin: TPP. B 2 Riboflavin: FAD and FMN. B 3 Niacin: NAD and NADP. B 9 Folic Acid: THFA. B 5 Pantothenic Acid: CoA. B 6: PLP. B12: Methylcobalamin

Niacin B3

Available as niacin or synthesized by the body from the amino acid tryptophan. Tryptophan generally used for protein synthesis so body won't readily use this pathway.

Niacin B3 Absorption, Transport, Storage and Excretion

Readily absorbed in the stomach and small intestine by active transport and passive diffusion. After absorption it is transported via the portal vein to the liver where it is stored or delivered to the body. Excess is converted to coenzyme forms or excreted in the urine.

Niacin B3 toxicity

This has an Upper Level; 35mg. Can be stored or cause problems in liver. High amounts cause flushing- dilates blood vessels only on upper parts of the body. Can happen with energy drinks or Pharmacological doses.

Functions of Niacin B3

Coenyzmes NAD and NADPH, required for catabolism of carbs, fats and proteins, oxidation reduction reactions, required in at least 200 reactions.

Niacin B3 deficiency

Pellagra, generally symmetrical, skin rough or red sickness. 4 Ds: Dermititis, diarrhea, dementia, death. Associated with corn based diets. Corn has to be soaked in lime water to release protein bound to the niacin to make it bioavailable.

Pharmacological uses of Niacin B3

Used for cholesterol therapy because blocks fat released from cells or synthesized so the body can't use them. Nicotinic acid lowers triglycerides and increases HDL-C.

Pantothenic Acid

From the Greek word meaning From Every Side. It is present in all cells of the body and in a wide variety of foods.

Food sources of Pantothenic Acid

meat, milk, mushrooms, peanuts, egg yolks, yeast, broccoli, and soy milk, avocado, sunflower seeds.

Pantothenic Acid Absorption, Transport, Storage and Excretion

The pantothenic acid portion of any coenzyme A is released during digestion in the small intestines. It is absorbed and transported through the body bound to red blood cells. Storage is minimal and is in the coenzyme form. Excretion is via the urine.

Functions of Pantothenic Acid

Essential for ATP. Grabs the double carbons and throws them into the CAC then leaves. Does not actually enter the CAC. Also important building block of fatty acids, cholesterol, bile acids and steroid hormones.

Pantothenic Acid deficiency and toxicity

Rare.

Functions of Biotin

Enzyme that participates in carboxylation; adding carbon dioxide. Required for metabolism of carbs, fats and proteins. pyruvate to oxaloacetate,

Sources of Biotin

Food: Whole grains, eggs, nuts and legumes. Strawberries, mushrooms and cauliflower low sources. Microbial Synthesis: flora in the large intestines

Biotin Absorption, transport, storage and excretion

In the small intestine the enzyme biotinidase releases biotin from protein and lysine. It is absorbed in the small intestine via a sodium dependent carrier. Stored in small amounts in the muscles, liver, and brain. Excreted mostly in urine though some in bile.

Biotin deficiency

Genetic biotinase enzyme deficiency. Excessive consumption of raw eggs. Avidin binds with biotin and prevents absorption.

Food source of B 6

Muscle tissue of animals; meat, fish, poultry. Whole grains also good source. B 6 lost in refinement and not added back in during enrichment. Carrots, potatoes, spinach, bananas and avocados. fortifed cereals.

Metabolism Functions of B6

Need B6 to process proteins. PLP coenzyme involved in Amino acid metabolism. In metabolism helps to break off nitrogen. Helps move nitrogens around to help liver. Deamination and transamination. Glycogenolysis.

Synthesis functions of B6

PLP catalyses steps in the synthesis of heme, neurotransmitters like dopamine, serotonin, norepinepherine, and GABA, and vitamins.

Other B6 functions

Supports normal immune function and regulation of gene expression. May help prevent colon cancer.

B6 deficiency and toxicity

deficiency Rare. microcytic hypochmic anemia. Toxicity: UL is 100mg. Irreversible nerve damage. Peripheral- feet impaired gait

Food sources of folate

liver, legumes, and leafy green vegetables, avocado and oranges. Foods fortified with Folic Acid.

Folate B9

Folate is the natural form. Folic Acid is the synthetic form. Folic acid is easier to absorb. Has an upper limit because can mask a B12 deficiency. Almost direct parallel with B12 in many functions.

Functions of folate

DNA synthesis- rapid division of cells like pregnancy. Amino acid metabolism, neurotransmitter synthesis, and coenzyme THFA.

Folate deficiency

Megaloblastic anemia; cells unable to divide leaving large immature red blood cells that still have nuclei. Neural tube defects: Maternal deficiency plus genetic predisposition. Pregnant capable 400mg.

Food sources of B12

Only Animal products

Vitamin B12 Absorption

Unique absorption requirements. Free vitamin binds to R protein. Released from protein by panreatic lipases. Has to have HCL to get it off the proteins. If problem with HCL production possible problems with B 12 - hyperthyroidism. IF- Intrinsic Factor- made in the stomach. IF connects with B12 in the ileum and then can be absorbed into the blood.

B 12 storage and excretion

Body recaptures and recycles. if deficient it could take years to show.

Functions of B12

Create and protects healthy myelin sheaths- only function it doesn't share with Folate. Cofactor in 2 enzymatic reactions.

Reasons for B12 Deficiencies

Primary: if not in diet. Secondary: if something else intereferes like atrophic gastritis: less HCL- without size, intrinsic factor deficiency, alcohol consumption, Elderly can have dystrophy issues meaning doesn't work as well.

Manifestations of B12 deficiency

Pernicious (eventual death) anemia, macrocytic anemia, neurological changes; needed for nervous system, elevated plasma homocysteine concentrations.

High homocysteine levels

High protein diet can lead to high homocysteine levels which cause inflammation, injury and heart disease. Homocysteine comes from amino acid when there is an excess of methionine. Folate, B12 and B6 can convert it back to amino acid.

Treatment for malasborption of B12

Monthly injections. Nasal gel. Very high oral doses 1-2 mg; only very small amount is absorbed through passive diffusion.

Food sources of Vitamin C - Ascorbic Acid

Citrus fruits, peppers, and green vegetables, papaya, strawberries, broccoli, potatoes

Toxicity issues for Vitamin C

UL 2g. Can interfere with absorption of other vitamins like zinc and B12. If saturated by high doses body kicks in enzyme to break down. When dose stops enzyme continues and can cause rebound scurvy. Need to taper off doses.

Functions of Vitamin C

Reduction-oxidation reactions. Donates electrons. Cofactor for metalloenzymes. Collagen synthesis. Synthesis of nuerotransmitters and viral compounds. Iron absorption. Immune function. Big helper for chemical reactions. Antioxidant functions.

Deficiencies of vitamin C

Scurvy, Cancer and heart disease due to lack of antioxidant reactions.