VitaminsChapter 8

What are Vitamins?• Vitamins : Essential nutrients needed in tiny

amounts to regulate body processes. There are 13 known vitamins.

• As a nutrient group, vitamins assist with the following functions :

• Nutrient Metabolism• Energy production and release• Tissue maintenance• Normal digestion• Infection resistance

What are Provitamins?

• Provitamins : Several vitamins have provitamin forms. Provitamins are compounds that are not vitamins, but the body can convert them into the active form of a vitamin.

• Example : Beta-carotene is a provitamin for vitamin A. It is a deep yellow, dark green compound found in vegetables.

How much of the vitamins are needed?

• You need only about one ounce of vitamins for every 150 lbs of food that you eat.

Vitamin Deficiency

• There are two main causes for vitamin deficiencies :

• An insufficient amount of a vitamin in the diet. In cases of poverty, people may lack the variety of foods that would provide all the vitamins they need.

• The failure of the body to absorb vitamins. For instance, changes in the body that occur with age can affect a persons ability to absorb vitamin B12.

Vitamin Classification• All vitamins are grouped into two categories :• Fat soluble (These vitamins are dissolved through

the intestinal walls with fats from foods)• Water soluble ( Lean tissues may store surpluses

of these vitamins for short periods)• Some vitamins dissolve in fats, the four fat

soluble vitamins are : vitamins A, D, E, K. • Other vitamins dissolve in water, the nine water

soluble vitamins are : B complex vitamins ( Thiamin, ribolflavin, niacin, pantothenic acid, biotin B6, folate, and B12) and vitamin C.

Toxicity

• Toxicity: A poisonous condition. Vitamins A, and D are especially toxic if consumed in large amounts over long periods. Toxicity does not occur from eating vitamin- rich foods. It occurs when people take large amounts of vitamin supplements.

Deficiency

• Vitamin A deficiency is the leading cause of blindness in children living in Africa, Asia, and South America. Up to 500 000 children go blind each year b/c their diets lack vitamin A.

• Functions of Vitamin A• Vitamin A is necessary for the formation of

healthy epithelial tissues. The epithelial cells are the surface cells that line the outside of the body. They cover the eyes, passages to the lungs, reproductive organs. Because of this function, vitamin A plays a role in keeping skin and hair healthy. Adequate amounts of vitamin A help keep the eyes free from dryness and infections.

Vitamin A

• Vitamin A also helps the linings of the lungs and intestines stay moist and resistant to disease. Without sufficient Vitamin A the cells in the eyes cannot make the compound needed by the eyes to see well in dim light. That means the eyes adapt slowly to darkness and night vision becomes poor. This condition is called night blindness.

•

Meeting Vitamin A Needs• Vitamin A in foods exists in two basic forms : • Animal Sources• Plant Sources• Animal foods usually provide vitamin A as a

preformed vitamin (this is an active form of a vitamin that the body can use).

• Plant foods provide vitamin A is a provitamin carotenes. Including alpha and beta carotene. The body can convert these compounds into the more usable form of vitamn A.

Effects of Vitamin A Deficiencies and Excesses

• Symptoms of the deficiency may include night blindness, dry, scaly skin, and fatigue.

• Getting too much Vitamin A can cause health problems.

• Symptoms of Vitamin A toxicity are :• Severe Headaches• Bone pain• Dry skin• Hair loss• Vomiting• Liver damage

Vitamin DVitamin D is a unique fat soluble vitamin. With direct exposure to

sunlight, your body can make all the vitamin D it needs.• Functions of Vitamin D• Vitamin D helps to regulate the levels of calcium in the bloodstream.

Normal amounts of calcium in the blood are needed for healthy nerve function, bone growth and maintenance.

• Vitamin D also controls the absorption of calcium from the intestines.

• Meeting Vitamin D Needs• As was previously mentioned, with exposure to sunlight the body can

make vitamin D. When sunlight shines on skin, a cholesterol like compound in the skin forms a provitamin. The liver and kidneys change the provitamin into vitamin D.

Effects of Vitamin D Deficiency

• A lack of vitamin D can cause rickets. This disease causes bones to become misshapen, by a lack of vitamin D reaching bones.

• The leg bones may bow in or out. The chest bones may bulge outward.

• A similar vitamin D deficiency in adults is called osteomalacia. It can cause the leg and spine bones boned to soften and bend.

Vitamin D Continued

• Too much vitamin D can be poisonous and toxicity occurs most quickly in children.

• Toxic intakes of vitamin D occur as a result of consuming supplements in the amount greater than the normal limit.

• Overdoes of vitamin D can not be caused by prolonged sun exposure or by eating foods that contain vitamin D.

• Excessive amounts of vitamin D cause too much calcium to be absorbed into the bloodstream. This surplus calcium is then deposited in the kidneys and other soft organs.

• This causes the organs to become hard and unable to perform their vital functions.

Vitamin E

• Function of Vitamin E• Helps maintain healthy immune and nervous

systems.• Main function is to act as an antioxidant.• Antioxidants are substances that react with

oxygen to protect other substances from harmful effects of oxygen exposure. Vitamin A/C are also antioxidants.

• Protects the cells of the lungs

• Meeting Vitamin E Needs• Research provides no strong support for

consuming large amounts of vitamin E. Therefore you do not need to take supplements, you can receive daily amounts from foods.

• Effects of Vitamin E Deficiencies and Excesses• Deficiencies are not common, however,

deficiencies have been seen in premature babies.

• These deficiencies cause red blood cells to break, a condition called erythrocyte haemolysis, this makes babies weak and listless.

Vitamin K

• Vitamin K• Functions of Vitamin K• Main function is to make proteins needed in

the coagulation of blood. (Coagulation means clotting).

• Also needed to make a protein that helps bones collect minerals they need for strength.

Vitamin K

• Meeting Vitamin K Needs• The need for vitamin K increases throughout

childhood, the teen years, and young adulthood.• Bacteria in the intestinal tract help meet a

significant part of your vitamin K needs. • Food sources of vitamin K include : • green leafy vegetables and liver• fruits, milk, meat, eggs, and grain.

• Effects of Vitamin K Deficiency• Deficiencies usually occur to people who take

antibiotics to kill intestinal bacteria.• Newborns may also have a vitamin K

deficiency as they do not yet have bacteria in their intestines to synthesize the vitamin.

Water Soluble Vitamins

• Water Soluble Vitamins• Includes all B vitamins, and vitamin C. • Excesses of these vitamins can be excreted in

urine.

B Vitamins• The B Vitamins are as follows :• Thiamin• Riboflavin• Niacin• Pantothenic Acid• Biotin• B6• Folate • B12• Coenzyme : a nonprotein compound that combines with

an inactive enzyme to form an active enzyme system.

Thiamin• Thiamin• Functions• Plays a vital role in energy metabolism• Required for normal functioning of the nerves and the

muscles they control.• Meeting Thiamin Needs• Whole grain breads and cereals are sources of thiamin as

well as several other B vitamins. • Refined grain products are commonly enriched with these

vitamins and iron. • Enriched foods have had vitamins and minerals added

back that were lost in the refining process.

Effects of Thiamine Deficiencies and Excesses

• Without thiamine the body cannot perform the tasks required for everyday living. Symptoms include weakness, loss of appetite, and irritability.

• Beriberi is a thiamine deficiency disease.• Alcoholism increase the risk of thiamine

deficiency b/c alcohol diminishes the body's ability to absorb and use thiamine.

Riboflavin

• Functions• Helps the body release energy from carbohydrates. • Needed for healthy skin, and normal eyesight.• Meeting Riboflavin Needs• Milk and milk products, enriched and whole grain

cereal, meats, poultry and fish are excellent sources for meeting these needs.

• People who do not drink milk or eat milk products may be at risk for developing a deficiency.

Effects of Riboflavin Deficiency and Excesses

• Symptoms include :• inflamed tongue• cracked skin around the mouth• various eye disorders• mental confusion• Toxicity symptoms have not been reporter,

extra riboflavin is excreted in the urine.

Niacin• Functions • Involved in energy metabolism• Helps keep the skin and nervous system healthy, and promotes normal digestion.• • Meeting Niacin Needs• Whole grain and enriched breads and cereals, meat, poultry, and nuts are popular

sources of niacin • Effects of Niacin Deficiencies and Excesses• Pellagra is the niacin deficiency disease. The four systems of pellagra are known

as the 4 Ds :• Diarrhoea• Dermatitis• Dementia• Death• Early disease symptoms include poor appetite, weight loss, and weakness.

Pantothenic Acid

• Functions• Promotes growth• It is part of a coenzyme that is critical to the

metabolism of the energy nutrients.• Effects of Pantothenic Acid Deficiencies and

Excesses• Is found in many foods therefore deficiency

symptoms are rarely a problem. Toxicity is also rare.

Biotin

• Gets its name from the Greek word for sustinence, which means something that supports life

• Functions of Biotin• Helps activate several enzymes involved in the release

of energy from carbohydrates, fats, and proteins. • Biotin also helps the body make fats and glycogen.

• Meeting Biotin Needs• There is no RDA for biotin. • Is widespread in foods :Egg yolks, yeast, beans, nuts,

cheese, and liver.

• Effects of Biotin Deficiencies and excesses• Deficiencies are uncommon as biotin is widely

available in foods. • However if a deficiency was to occur the

symptoms would be : abnormal heart rhythms, pain, weakness, fatigue, and depression. Nausea; loss of appetite; dry scaly skin; and hair loss are other symptoms.

Vitamin B6• Functions of Vitamin B6• Plays a key role in synthesizing non-essential amino acids• It is needed to convert the amino acid tryptophan into

niacin. • Helps make protein that allows red blood cells to carry

oxygen.• Affects the health of the immune and nervous systems.• • Meeting Vitamin B6 Needs• B6 is found in many foods such as : meats, fish, and poultry,

dairy products, fruits, vegetables, and spinach.

Effects of Vitamin B6 Deficiencies and Excesses

• Deficiencies are rare and are related to poor amino acid and protein metabolism.

• Symptoms include skin disorders, fatigue, irritability, and convulsions.

• People who have taken large amounts of b6 have reported symptoms of toxicity. These include walking difficulties and numbness in the hands and feet.

• Irreversible nerve damage can also result from excessive intakes of this vitamin.