B Vitamins

• Soluble in water and contain nitrogen
• Thiamin (B1)
• Riboflavin (B2)
• Niacin
• Pyridoxine (B6)
• Pantothenic Acid
• Folic Acid
• Biotin
• Choline
• Cobalimin (B12)

Thiamin

Disease Beriberi

Also heart disorders and CNS dysfunction

Children lack knee reflex

Alcoholics often show deficiency

Increased need with increased CHO intake

Functions

Carbohydrate metabolism

Make ribose to form RNA

Maintenance of normal appetite and in normal muscle tone in G. I. tract

Called the "Morale Vitamin"

Deficiency became widespread with advent of polished rice. Was thought to be an infectious disease.

• Area Affected	Main Effects
  Nervous system	Mental confusion
  	Peripheral paralysis
  	Loss of ankle & Knee Jerk
  Muscle	Weakness
  	Wasting
  	Painful calf muscles
  Cardiovascular	edema
  	Enlarged heart
  	Death from cardiac failure

Requirements

• Beriberi is rare in the U.S.
• In times of growth, pregnancy, lactation or with alcoholics, marginal deficiencies are sometimes observed.
• Thiamin status can be determined by measuring its level in the urine or the level of the enzyme, transketolase.
• Need is calculated to be about 0.5 mg/1,000 kcal

Riboflavin

• Functions as part of a coenzyme involved in oxidation - reduction reactions
• FAD and FMN

Functions

• The main function of riboflavin is as a cofactor for a number of enzymatic reactions.
• Commonly called flavin adenine dinucleotide and abbreviated FAD.
• Functions in oxidation - reduction reactions as a carrier of hydrogen.

• Human deficiencies are almost never seen.

Niacin

• Pellagra- "rough skin"
• 60 mg. tryptophan = 1 mg.of Niacin.

Function

•         Component of two coenzymes involved in oxidation - reduction reactions: 

•         NAD        NADP            

•         Corn poor in tryptophan

•         Pellagra  was widespread in southern United States

The symptoms of a niacin deficiency are listed below:

• 4 D's Dermatitis - especially on areas exposed to sun
• Dementia Irritability Mental confusion progressing to psychosis or delirium
• Diarrhea
• Death

Requirements

• The Food and Nutrition Board recommends 14 mg/day for college age women and 20 mg/day for college age men.
• Also recommend 6.6 mg/1,000 kcal
• Clinical signs of deficiency are seen in significant numbers of persons in the U.S., especially in low-income aged, where the incidence may approach 10%.

Niacin and Tryptophan

• Some synthesis of Niacin occurs by intestinal flora
• Niacin can be synthesized from the amino acid, tryptophan. It requires 60 mg of tryptophan to produce 1 mg on Niacin.
• Diets rich in foods, like corn, that are low in both Niacin and tryptophan can lead to Pellagra

Toxicity

• Consumption of 30 times the RDA has no effect
• Nicotinic acid can function as a drug in doses of from 2 to 3 grams/day.
• May be prescribed for certain cardiovascular problems and to lower serum cholesterol
• Results in flushing and chest pain.

Flour Enrichment
Refining of grains removes B vitamins and has resulted in historical deficiencies. The United States requires that such grains contain nutrients added back to the level that would be found in whole grain. This has also been used as a vehicle to add other nutrients that were not removed during processing.

Vitamin B6

Pyridoxine

• Pyridoxol
• Pyridoxal
• Pyridoxamine

Functions:

• Metabolism of amino acids
• Conversion of glycogen to glucose
• Deficiency - rare
• RDA adult = 2 mg.
• Increased need for B6 in pregnancy

Deficiency
In 1951 6 infants fed an infant formula diet began to develop irritability, muscular twitching and convulsions. Heat sterilization of formula had destroyed all of Vitamin B-6. First demonstration of human requirement.

Pantothenic Acid

• Deficiency is rare
• Part of Coenzyme A

Biotin

• Functions in fatty acid synthesis
• Deficiencies are rare

Requirements

• Extrapolation from animal data suggests that 50 to 75 Mcg/day should be adequate.
• The Food and Nutrition Board has not made a recommendation because intestinal flora produce considerable amounts of Biotin.
• The average American excretes more Biotin in urine than is consumed in a day.
• For labeling purposes, the USRDA is set at 300 Mcg/day.

Folic Acid

Metabolic Role

• Coenzyme form is tetrahydrofolic acid.
• Functions in transfer of formyl and hydroxymethyl groups.
• Required for synthesis of purines and pyridines and for efficient utilization of the amino acid, histidine.

Requirements

• Incidence of deficiency most likely seen towards the end of pregnancy.
• Food and Nutrition Board recommends intake of 400 mcg/day.
• Canadian recommendation is 200 mcg/day.
• Average western diet contains from 200 to 1,500 mcg/day.
• Recent evidence has linked low consumption during pregnancy to neural tube disorders.
• New requirement to fortify foods with folic acid

Pregnancy
Women of reproductive age who are considering becoming pregnant or who might become pregnant should be sure that they have an adequate intake of folic acid. The crucial stage where a folic acid deficiency affects a pregnancy is very early in the pregnancy. by the time a person realizes that she may be pregnant, it is usually to late to reverse the effects of a possible deficiency.

A deficiency of folic acid results in a type of anemia known as megaloblastic anemia . The RDA for folic acid is about 400 mcg. day.

Choline

Became a vitamin in 1998

Deficiencies very rare

Most people make all they need

Cobalamin ( B12 )

• Very large molecule
• Some storage in body - 5 years supply
• Sensitive to acid
• Absorption from intestine requires intrinsic factor

Functions

Coenzyme in all body cells

Nucleic acid synthesis

Neural function - odd chain fatty acids required for myelin

Amino acid synthesis

Blood cell formation

Megaloblastic anemia - first symptom. Excess folic acid can mask this symptom.

Pernicious anemia (Deadly Anemia) - loss of neural function

Often due to a lack of intrinsic factor

Child vegans - risk of deficiency - no body stores

Many vitamins function as cofactors. Cofactors are small molecules necessary for the function of some enzymes. For example in the reaction:

The enzyme, lactic dehydrogenase, adds two molecules of hydrogen to a molecule of pyruvic acid to form a molecule of lactic acid. The enzyme requires a source of hydrogen. In this case it utilizes the cofactor Nicotinamide Adenine Dinucleotide ( NAD ). The enzyme alone or NAD alone can not cause the reaction to occur. The enzyme with the reduced form of NAD ( NADH ) does cause the reaction to proceed. In this reaction NADH is functioning as a cofactor. Your body can make NADH if it is given a source of Niacin. Thus, the vitamin, Niacin, is utilized by the body to produce the coenzyme NADH which is required for some oxidation - reduction reactions. Many other B vitamins also function as parts of coenzymes. If we can not determine a cofactor role for a putative nutrient, it is probably not required by the body and is not a real nutrient.

Many substances are promoted and sold as vitamins when in fact these substances are not vitamins. In addition to the obvious promotional benefits to this, there are also legal benefits because vitamins are regulated differently than drugs. In some states, laetrile has been declared to be a vitamin by state statute even though it does not meet the scientific criteria for a vitamin.

There are two main classes of compounds that are not vitamins for humans, but that sometimes get confused for human nutrients:

1. Microbial (but not human) growth factors:

• Inositol (we make all that we need)
• PABA (para - amino benzoic acid) - 5% solutions make a great sun screen some bacteria use this instead of Folic Acid
• Lipoic Acid (we make all that we need)
• Ubiquinone (we make all that we need)
• Bioflavinoids ( once called Vitamin P ) - humans don't need them.

2. Miracle ( $ ) Non - Vitamins

Laetrile® is the registered trade mark of a compound patented by E. T. Krebs. Preparations contain amygdalin which is generally obtained from apricot pits, belongs to a class of compounds called cyanogenetic glycosides . Under certain conditions these compounds release cyanide which is poisonous. Numerous cases of sub-lethal poisoning have been reported. The use of laetrile to treat cancer flourishes in Mexico in spite of overwhelming evidence that laetrile is useless as an anti-cancer drug.

Pangamic Acid ( non-vitamin B15 ) This non-vitamin, like laetrile, was discovered by E. T. Krebs in the 1940's. Commercial preparations appear to contain either diisopropylamine dichloroacetate or dimethyl glycine both of which have some pharmacologic effect. These compounds are mild stimulants. Pangamic acid

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