Transcript The Vitamins

Chapter 8
THE WATERSOLUBLE VITAMINS
Vitamin Talk
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Vitamins are organic compounds essential in
the diet to promote growth and health
maintenance.
Water-soluble vitamins include the B vitamins
and vitamin C.
Fat-soluble vitamins include A, D, E and K.
B vitamins were originally thought to be one
chemical substance but are actually many
different substances. That is the reason for
B1, B2, B12, etc.
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The Vitamins
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Finding Vitamins in Foods
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Fortified and Enriched Foods
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Fortification: process of adding nutrients to
foods. The added nutrients are generally not
found in the food, such as fortifying orange
juice with calcium.
Enrichment: adding nutrients back to foods
that have lost nutrients due to processing. An
example is the addition of B vitamins to white
rice.
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Fortification
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Health Canada regulates which foods must
be fortified and which nutrients should be
added.
Example:
 table salt with iodine
 milk with Vitamin D
 grains with thiamine, riboflavin, niacin, iron
and folic acid
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Dietary Supplements
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Dietary supplements can be another source of
vitamins in the modern diet.
Dietary supplements contain some combination
of vitamins, minerals, herbs, botanicals, amino
acids, enzymes or extracts.
Dietary supplements cannot replace the benefits
of a diet containing a wide variety of foods.
Dietary supplements are regulated by Health
Canada’s Natural Health Products Directorate.
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Dietary Supplements (continued)
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There is a concern that natural health
products in food format may confuse the
consumer.
Dietitians of Canada is concerned that the
consumer may perceive these products as
food, be unaware that there are maximum
doses and exceed the ULs for some
nutrients, with potential adverse effects, as
there are no nutritional facts on these
products’ labels.
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Absorption
of Vitamins
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Bioavailability of Vitamins
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Vitamins must be absorbed by the body in order to
perform their functions.
Approximately 40-90% of vitamins are absorbed in
the small intestine.
Fat-soluble vitamins require fat in the diet to be
absorbed.
Water-soluble vitamins may require transport
molecules or specific molecules in the GI tract.
Some vitamins are absorbed in inactive provitamin
or vitamin precursor forms that must be converted
into active forms by the body.
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Thiamin
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Thiamin was the first B vitamin to be
identified and is also called B1.
Thiamin is widely available in foods,
especially in enriched grains, whole grains,
legumes, nuts and seeds.
Thiamin assists in energy production,
carbohydrate metabolism, the production of
ribose and the health of the nervous system.
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Thiamin
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Riboflavin
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Dairy products are a good source of riboflavin.
Plant sources of riboflavin include mushrooms, broccoli,
asparagus, whole grains and green, leafy vegetables.
Animal sources include red meat, poultry and fish.
Riboflavin is easily destroyed by heat and exposure to
light.
Riboflavin is an important component in the citric acid
cycle and for assisting the body with the absorption of
other vitamins.
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Riboflavin
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Niacin
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Niacin is added to enriched flours in North America.
A niacin deficiency disease is pellagra.
Niacin can be synthesized in the body from the essential
amino acid tryptophan if the diet is adequate in
tryptophan.
Niacin plays an important role in the production of
energy and in general metabolism.
Two forms of niacin are nicotinic acid and
nicotinamide.
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Niacin
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Niacin
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Advanced pellagra’s symptoms include the 3
D’s: dermatitis, diarrhea and dementia.
Niacin toxicity from overuse of niacin
supplements can result in elevated blood
pressure, cardiac arrhythmia, nausea,
vomiting, elevated blood sugar levels and
impaired liver function.
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Pantothenic Acid
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Vitamin B6
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Vitamin B6
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Vitamin B6 is also called pyridoxine and
comprises a group of compounds including
pyridoxal, pyridoxine, and pyridoxamine.
All three forms can be converted into
pyridoxal phosphate, which is required for
many enzyme reactions in the body.
Vitamin B6 deficiency may result in anemia
due to impaired hemoglobin synthesis and
neurotransmitter issues.
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Folate or Folic Acid
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Folate or Folic Acid
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Folate coenzymes are needed for DNA
synthesis and the metabolism of some amino
acids.
Low folate intake in early pregnancy is
associated with an increased risk of neural
tube defects.
Low folate intake has been associated with
an increased risk of heart disease related to
the metabolism of the amino acid
homocysteine.
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Folate Deficiency and Neural
Tube Defects
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Folate Fortification
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Neural tube defects have decreased by 50%
in Canada since food fortification.
Newfoundland rates have dropped by 80%.
Alberta and Quebec have found a reduction
in the number of congenital heart defects.
Ontario reported a reduction in
neuroblastoma.
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Folate Fortification
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Some studies have shown an increase in
colon cancer since folate fortification began in
1998.
This maybe the result of folate stimulating
DNA synthesis and promoting growth of preexisting cancerous cells.
When considering food fortification it is
important to consider that what may benefit
one segment of the population may harm
another segment.
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Macrocytic Anemia and Folate
Deficiency
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Calculating Dietary Folate Amounts
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Vitamin B12
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Vitamin B12
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Pernicious anemia is a form of anemia that does not
respond to iron supplementation.
Vitamin B12 is necessary for the proper absorption of iron
in the body.
Excessive intake of folic acid can mask B12 deficiencies.
Vitamin B12 is most readily absorbed from animal
products.
Vegan diets need to be supplemented with readilyabsorbable forms of B12.
Atrophic gastritis may lead to B12 deficiencies.
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Absorption of
Vitamin B12
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Vitamin C
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Vitamin C
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Vitamin C is also known as ascorbic acid or
ascorbate.
Vitamin C in foods can be destroyed by
oxygen, light and heat, as well as contact
with copper or iron cookware.
Vitamin C functions as an antioxidant in the
body, helps maintain the immune system, is
important in the production of collagen and
aids in iron absorption.
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How Antioxidants Work
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Summary of Water-Soluble Vitamins and
Choline
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Summary of Water-Soluble Vitamins and
Choline (continued)
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Summary of Water-Soluble Vitamins and
Choline (continued)
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Benefits and Risks of Water-Soluble
Vitamin Supplements
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Copyright
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