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biology

The water soluble vitamins

Overview of Water-Soluble Vitamins
• Dissolve in water
• Generally readily excreted
• Subject to cooking losses
• Function as a coenzyme
• Participate in energy metabolism
• 50-90% of B vitamins are absorbed

3.

B Complex Primary Functions
• Energy metabolism
– Thiamin (B-1), Riboflavin (B-2), Niacin (B-3),
Pyridoxine (B-6), Biotin, Pantothenic Acid
• Red blood cell synthesis
– Folate, B12, B6
• Homocysteine metabolism
– Folate, B12, B6

4.

Thiamin
• Part of nerve cell membranes—synthesize and
regulate neurotransmitters
• Functions in energy metabolism

5.

Thiamin Deficiency
• Thiaminase found in raw fish also in tea and
coffee
– Destroys thiamin
• Heavy alcohol consumption with inadequate
food consumption ; alcohol interferes with
absorption (Wernicke-Korsakoff syndrome);
poor and elderly at risk for not eating
sufficient energy

6.

Thiamin Deficiency
• Beri Beri
• Impaired muscle contractions
• Impaired cardiac function, edema and muscle
twitches
• Decreased neurological function and memory
loss

7.

Wet and Dry BeriBeri

8.

Food Sources of Thiamin
• Wide variety of food
• Pork, meat, cereal
• Enriched breads and grains/ whole grains
• Green beans, milk, orange juice, organ meats,
peanuts, dried beans and seeds

9.

Riboflavin (B2)
• Coenzymes
• Participate in many energy-yielding metabolic
pathways
– Fatty acids broken down and burned for energy

10.

Deficiency of Riboflavin
• Ariboflavinosis
– Glossitis, cheilosis, seborrheic dermatitis,
stomatitis, eye disorder, throat disorder, nervous
system disorder

11.

Ariboflavinosis

12.

Food Sources of Riboflavin
• Milk/products
• Enriched grains
• Ready to eat cereals
• Liver
• Oyster
• Brewer’s yeast
• Vegetables (asparagus, broccoli, greens)
• Sensitive to uv radiation (sunlight)
Stored in paper, opaque plastic containers

13.

Niacin (B3)
• Nicotinic acid and nicotinamide
• Coenzymes
• Important for fatty acid synthesis

14.

Deficiency of Niacin: Pellagra
• 3 Ds
– Dementia
– Diarrhea
– Dermatitis (worse with sun exposure)
• Poor appetite, weight loss, weakness

15.

Pellagra

16.

Food Sources of Niacin
• Enriched grains, ready to eat cereals
• Beef, chicken, turkey, fish
• Asparagus, peanuts
• Heat stable; little cooking loss
• Niacin in corn is bound by a protein(not a good
source)

17.

Pyridoxine (B6)
• 3 compounds
• Coenzyme
• Activate enzymes needed for metabolism of
CHO, fat , protein
• Synthesize nonessential amino acid via
transamination
• Synthesize neurotransmitters
• Synthesize hemoglobin and WBC

18.

Other Roles of Vitamin B-6
Homocysteine
• Produces toxic effect on arterial walls
(atherosclerosis)
• Metabolized by vitamins B-6, B-12 and folate

19.

Food Sources of Vitamin B-6
Well absorbed
• Meat, fish, poultry
• Enriched cereals
• Potatoes
• Milk
Less well absorbed
• Fruits and vegetables: Banana, spinach, avocado
Heat and alkaline sensitive

20.

B6 Deficiency
Widespread symptoms
• Depression
• Vomiting
• Skin disorders
• Nerve irritation
• Impaired immune system
• Anemia

21.

B6 Toxicity
• Nerve damage
• Difficulty walking
• Numbness in hands/feet

22.

Folate
• Coenzyme
• DNA synthesis
• Homocysteine metabolism
• Neurotransmitter formation

23.

Deficiency of Folate
• Similar signs and symptoms of vitamin B-12
deficiency
• Anemia
– RBC grow, cannot divide
– Megaloblast: large, immature RBC
• Pregnant women
• Alcoholics
• Megaloblastic Anemia

24.

Neural Tube Defects
• Neural tube closes first 28 days of
pregnancy
• Forms brain and spinal cord
• By the time pregnancy is confirmed,
damage is done

25.

Neural Tube Defects
• Spina bifida
– Spinal malformation
– Paralysis
• Anencephaly
– No brain cortex
– Stillborn or die within hours
• Importance of folate before and during pregnancy
• Government requires folate enrichment of flour and
cereal
• May prevent 50% neural tube defects