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Chapter 7

The Vitamins
Summary - Chapter Seven focuses on the individual Vitamins. Grouped according to solubility in water or fat, each vitamin is characterized by a deficiency disease. The physiological and biochemical properties of each vitamin are discussed along with a description of the deficiency diseases and their symptoms. Good dietary sources of each vitamin are outlined. Controversy 7 deals with vitamin supplements.

“To know that we know what we know, and that we do not know what we do not know, that is true knowledge.” [Henry David Thoreau]

 

Vitamins 226
Vitamins are non-caloric essential nutrients, organic compounds vital to life, indispensable to body function, and are needed in minute amounts. Also, the body can biochemically convert precursors or provitamins to vitamins so these also will meet our needs for the vitamins.

 

Classification 226
Based on solubility in water or organic solvents.

Water Soluble - B Vitamins and Vitamin C

Excess excreted by kidneys Excess accumulates, can be toxic

Fat Soluble - Vitamins A, D, E and K

Absorbed directly into blood Transported and stored like fats

 

Fat Soluble      Vitamin A 228
vitamin A Vitamin A - Needed everywhere. Three active forms: retinol, retinal and retinoic acid.

Functions:
Eyesight- A is part of rhodopsin, the visual pigment
Epithelial tissues need A to protect integrity.
A is needed by immune system to fight infections.
A is needed for bone growth.

Deficiency Diseases: Keratinization, xerosis, xerophthalmia. Infections. Weak bones, poor teeth.

Toxicity: Hyper A vitaminosus.

Average RDA: 800 - 1000 RE/day

Sources: ß-Carotene. Plant pigment, precursor of A. Converted to A.
Green and yellow fruits vegetables.

Vitamin A Vignette
Sir Douglas Mawson, the Antarctic explorer whose likeness appears on the Australian $20 bill, was the leader of an ill fated expedition to travel to the South Magnetic Pole by dogsled. His party set out with several teams of sled dogs. An accident caused the loss of the sled with the food supplies into a crevasse. To survive, the party had to eat the remaining dogs. The dog livers were large and healthy looking, so Mawson fed these to his men. They became sicker and eventually died. Mawson, who denied himself any liver so to give them to the men, was the sole survivor. We now know that men died of Vitamin A poisoning, as a result of consuming the dog livers which were very rich in Vitamin A.

 

Fat Soluble      Vitamin D 233
Vitamin D - Synthesis in body from precursor sterols stimulated by sunlight.

Functions: Bone growth. Helps to maintain blood calcium levels.

Deficiency Diseases: rickets, osteomalacia (weak bones).

Toxicity: 5 X RDA = symptoms of D poisoning. Diarrhea, headache, nausea.

Adult RDA 5 µg/day.

Sources: Cod liver oil, butter, cream, egg yolks, fatty fish, and sunlight.

Vitamin D

 

Fat Soluble      Vitamin E 236
Vitamin E Vitamin E - Antioxidant. Prevents oxidative damage to PUFAs and vitamin A.

Functions: Protects lung membranes. May reduce risk of heart disease.  May help heal burns, may help prevent sunburn, may promote tan.

Deficiency Diseases: Premature babies have erythrocyte hemolysis. Adults have anemia,neuromuscular disorder, fibrocystic breast disease, intermittent claudication, and malabsorption of fat.

Toxicity: Rarely seen. Maybe free bleeding.

Average RDA 8 - 10 mg/day.

Sources: Widespread in plant kingdom. Wheat germ oil, fruits and veggies.

Vitamin E Vignette
Much controversy exists regarding the possible role of Vitamin E in protection against sunburn. Proponents claim that daily vitamin E supplements can reduce the chances of painful summer sunburns. Dr. Wolfe has heard of Canadian cruise ships that recommend that their guests prepare for midwinter Caribbean holidays by taking 400 to 800 units of Vitamin E daily for 8 - 10 weeks before the cruise. The crew in sick bay claim fewer bad cases of sunburn happen if the people follow these instructions.

 

Fat Soluble      Vitamin K 238
Vitamin K - Involved with blood clotting. Mice lacking K hemorrhage easily.

Functions: Needed for synthesis of blood clotting proteins.

Assists A in bone formation function.

Deficiency Diseases: Possibly uncontrolled bleeding.

Toxicity: Rarely seen.Jaundice.

Average RDA 45 - 80 µg/day.

Sources: Dark green leafy vegetables (spinach) and liver.

 Vitamin K

 

Water Soluble   B Vitamins   Thiamin 243
Thiamin Thiamin (Vitamin B1)

Functions: Energy metabolism,
appetite and nervous system function

Deficiency Diseases: Beriberi

Symptoms: Weakness, pain, low morale,
nervous disorders, mental confusion.

Toxicity: None reported

Average RDA 1.1 - 1.5 mg/day

Sources: Meat, grains, beans, nuts.

Thiamin Vignette

Dr. Eijkman, a Dutch physician working in Indonesia at the end of the last century, noticed that some people and some chickens in his neighborhood were afflicted with beriberi, a disease characterized by stiffness and weakness. He also noted that diseased chickens fed on rice bran (the roughage created when the hull of the rice grains is removed by abrading the grains) recovered rapidly from the disease. So he followed his observations with an experiment. He fed rice polishings to people with beriberi, and discovered the same nearly miraculous recovery took place as with the chickens. He had discovered that thiamin, present in rice bran, prevented beriberi. Later on, it was discovered that beriberi was caused by a lack of thiamin in the diet, so beriberi could be defined as a thiamin deficiency disease.

 

Water Soluble   B Vitamins   Riboflavin 243
Riboflavin (Vitamin B2)

Functions: Energy metabolism, vision and skin health.

Deficiency Diseases: Ariboflavinosus.

Symptoms: Chielosis, photophobia, skin rash, nervous disorders, and confusion.

Toxicity: None reported

Average RDA 1.2 - 1.8 mg/day

Sources: Meat, milk, green vegetables, grains.

 Riboflavin

 

Water Soluble   B Vitamins   Niacin 244
Niacin Niacin (Vitamin B3)

Functions: Energy metabolism, skin health, and nervous system.

Deficiency Diseases: Pellagra

Symptoms: Diarrhea, irritability, confusion, and psychosis skin rash.

Toxicity: 10 X RDA = "niacin flush"

Average RDA 15 - 20 mg/day

Sources: Meat, milk, eggs, fish, grains, high protein foods.

Niacin Vignette

The Niacin deficiency disease is called Pellagra. Among the symptoms of this malady is dementia. People in the southern United States relied on corn as a staple food, and corn is notoriously low in niacin. Many people in the South who were suffering from pellagra exhibited symptoms of dementia, and hence were confined to insane asylums. In 1936, the State of South Carolina passed legislation to fortify corn meal with niacin, and the consequence was that large numbers of the insane asylum inmates were miraculously cured of mental illness and released back to family and friends. Niacin had cured their pellagra, and their mental illness!

 

Water Soluble   B Vitamins   B6 248
Vitamin B6 (Pyrodoxine)

Functions: Amino acid metabolism, red blood cells.

Deficiency Diseases: Nameless collection of symptoms.

Symptoms: Anemia, irritability, skin rash, nervous disorders, confusion.

Toxicity: Depression, fatigue.

Average RDA: 1 - 2 mg/day

Sources: Meat, milk, green vegetables, beans, grains.

 Vitamin B6

 

Water Soluble   B Vitamins   Folate 245
Folate Folate (No common names)

Functions: New cell synthesis.

Deficiency Diseases: Megaloblastic anemia

Symptoms: Anemia, red tongue, nervous disorders, and confusion.

Toxicity: None reported

Average RDA: 50 - 200 µg/day

Sources: Beans, grains, liver.

Folate Vignette

Recently, we have come to understand that folate deficiency in pregnant women can lead to neural tube defects. Neural tube defects are characterized by lack of proper development of the spinal cord, ranging from slight spinal problems all the way to aencephaly, a birth defect that results in babies being born without a brain. Folate is named after foliage, where it is found in abundance. A sound diet, with the recommended servings from the vegetable group, will guard against neural tube defects.

 

Water Soluble   B Vitamins   B12 246
Vitamin B12

Functions: New cell synthesis, nerve maintenance.

Deficiency Diseases: Vitamin B12 deficiency anemia

Symptoms: Anemia, fatigue, and paralysis.

Toxicity: None reported

Average RDA: 1 - 2 µg/day

Sources: Meat, milk, fish, and poultry.

 Vitamin B12

 

Water Soluble   B Vitamins   Pantothenic Acid 249
Pantothenic Acid Pantothenic acid (No common name)

Functions: Energy metabolism.

Deficiency Diseases: Nameless collection of symptoms.

Symptoms: Vomiting, insomnia, fatigue.

Toxicity: None serious

Average RDA: 4 - 7 mg/day

Sources: Ubiquitous.

 

Water Soluble   B Vitamins   Biotin 249
Biotin (No common name)

Functions: energy, amino acid and fat metabolism.

Deficiency Diseases: Nameless collection of symptoms.

Symptoms: Abnormal heart rate, nausea, fatigue, nervous disorders, confusion.

Toxicity: None reported

Average RDA: 30 - 100 µg/day

Sources: Ubiquitous.

 

Water Soluble      Vitamin C 250
Vitamin C Vitamin C (Ascorbic acid)

Functions: Collagen synthesis, antioxidant, amino acid metabolism.

Deficiency Diseases: Scurvy.

Symptoms: Anemia, bleeding gums, weakness, muscle pain, slow healing.

Toxicity: Headache, rashes

Average RDA: 160 mg/day

Sources: Citrus fruits, vegetables and fruits.

Vitamin C Vignette

In 1756, Dr. James Lind conducted a classic experiment on sailors with scurvy. He divided them into groups, and treated each group with a different food. He discovered that those fed diets containing citrus fruits soon regained robust health, but the sad outcome of this experiment was that the remainder of his experimental patients became more ill, and many died! He was a dedicated scientist, and so he finished the experiment, losing many of his subjects. Nonetheless, his discovery that citrus fruits prevented scurvy changed the dietary habits of the British Navy and Maritime fleet. The chemical structure of Vitamin C was not elucidated until over 150 years after Dr. Lind's classic experiments.