The Clinical Nutrition Service is responsible for advising and adapting diets for various disease conditions to hospitalized patients or patients visiting outpatient clinics. The staff of the unit includes clinical nutritionists qualified in various fields of specialization such as: diabetes, gestational diabetes, digestive system diseases, geriatrics, surgery and heart, among others.
2. The vitamins – an overview
Vitamins
are organic, essential nutrients required in tiny amounts to perform
specific functions that promote growth, reproduction, or the
maintenance of health and life.
vita = life
amine = containing nitrogen
3. The vitamins – an overview
Water soluble vitamins Fat soluble vitamins
B vitamins: 1. Vitamin A
1. Thiamin B1 2. Vitamin D
2. Riboflavin B2 3. Vitamin E
3. Niacin B3 4. Vitamin K
4. Biotin B7
5. Pantothenic acid B5
6. Vitamin B6
7. Folate B9
8. Vitamin B12
9. Vitamin C
4. The vitamins – an overview
Vitamins differ by:
•Vitamins are individual units; they are not
linked together
Structure
•Vitamins do not yield energy when broken
down; they assist the enzymes that release
energy from carbohydrates, fats, and proteins.
Function
•The amounts of vitamins people require are
measured in micrograms (μg) or milligrams
(mg), rather than grams (g)
Food
contents
5. The vitamins – an overview
Bioavailability:
The amount of vitamins available from foods depends not only on the
quantity provided by a food but also on the amount absorbed and
used by the body “vitamins’ bioavailability”.
The quantity of vitamins in a food can be determined relatively easily.
Researchers analyze foods to determine their vitamin contents and
publish the results in tables of food composition.
6. The vitamins – an overview
Determining the bioavailability of a vitamin is a more complex task
because it depends on many factors, including:
• Efficiency of digestion and time of transit through the GI tract
• Previous nutrient intake and nutrition status
• Other foods consumed at the same time
• Method of food preparation (raw, cooked, or processed)
• Source of the nutrient (synthetic, fortified, or naturally occurring)
Experts consider these factors when estimating recommended intakes.
7. The vitamins – an overview
Precursors
Some of the vitamins are available from foods in inactive forms
known as precursors, or provitamins.
Once inside the body, the precursor is converted to an active form of
the vitamin.
8. The vitamins – an overview
Organic Nature
Being organic, vitamins can be destroyed and left unable to
perform their duties. Therefore, they must be handled with care
during storage and in cooking.
Prolonged heating may destroy much of the thiamin in food.
Riboflavin can be destroyed by the ultraviolet rays of the sun or by
fluorescent light, foods stored in transparent glass containers are most
likely to lose riboflavin.
Oxygen destroys vitamin C, so losses occur when foods are cut,
processed, and stored; these losses may be enough to reduce its
action in the body.
9. The vitamins – an overview
Solubility
Hydrophilic: water-soluble vitamins
Hydrophobic: fat soluble vitamins
Solubility is apparent in the food sources of the different vitamins, and it
affects their absorption, transport, storage, and excretion by the body.
The water-soluble vitamins are found in the watery compartments of foods;
the fat-soluble vitamins usually occur together in the fats and oils of foods.
On being absorbed, the water soluble vitamins move directly into the blood.
Like fats, however, the fat-soluble vitamins must first enter the lymph, then
the blood.
10. The vitamins – an overview
Once in the blood, many of the water soluble vitamins travel freely,
whereas many of the fat-soluble vitamins require protein carriers for
transport.
Upon reaching the cells, water-soluble vitamins freely circulate in the
water-filled compartments of the body, but fat-soluble vitamins are
held in fatty tissues and the liver until needed.
The kidneys, monitoring the blood that flows through them, detect
and remove small excesses of water-soluble vitamins.
Fat soluble vitamins tend to remain in fat-storage sites in the body
rather than being excreted, and so are more likely to reach toxic levels
when consumed in excess.
11. The vitamins – an overview
Because the body stores fat-soluble vitamins, they can be eaten in
large amounts once in a while and still meet the body’s needs over
time.
Water-soluble vitamins are retained for varying periods in the body.
Although a single day’s omission from the diet does not bring on a
deficiency, the water-soluble vitamins must still be eaten more
regularly than the fat-soluble vitamins
12. The vitamins – an overview
Toxicity
As an inadequate intake can cause harm, so can an excessive intake.
Even some of the water-soluble vitamins have adverse effects when
taken in large doses.
The effects of every substance depend on its dose, and this is one
reason consumers should not self-prescribe supplements.
The Committee on Dietary Reference Intakes (DRI) addresses the
possibility of adverse effects from high doses of nutrients by
establishing Tolerable Upper Intake Levels.
13. The vitamins – an overview
An Upper Level defines the highest amount of a nutrient that is likely
not to cause harm for most healthy people when consumed daily.
The risk of harm increases as intakes rise above the Upper Level.
Niacin, vitamin B6, Folate, choline, and vitamin C have Upper Levels.
14.
15. The B vitamins
Without B vitamins the body would lack energy.
The energy-yielding nutrients are used for fuel; the B vitamins help the body
to use that fuel.
Several of the B vitamins—thiamin, riboflavin, niacin, pantothenic acid, and
biotin—form part of the coenzymes that assist certain enzymes in the release
of energy from carbohydrate, fat, and protein.
Other B vitamins play other indispensable roles in metabolism.
• Vitamin B6 assists enzymes that metabolize amino acids.
• Folate and vitamin B12 help cells to multiply. Among these cells are the
red blood cells and the cells lining the GI tract—cells that deliver energy to
all the others.
16. The B vitamins
The vitamin portion of a coenzyme allows a chemical reaction to
occur; the remaining portion of the coenzyme binds to the enzyme.
Without its coenzyme, an enzyme cannot function.
Thus symptoms of B vitamin deficiencies directly reflect the
disturbances of metabolism incurred by a lack of coenzymes.
18. In each vitamin we will discuss the following:
Definition
Recommendation
Deficiency
Toxicity
Food sources
19. Thiamin B1
Thiamin
Is the vitamin part of the coenzyme TPP (thiamin pyrophosphate),
which assists in energy metabolism.
Thiamin occupies a special site on the membranes of nerve cells.
Consequently, processes in nerves and muscles, depend heavily on
thiamin.
21. Thiamin
Deficiency
Inadequate thiamin intakes have been reported among the nation’s
malnourished and homeless people. Similarly, people who derive most
of their energy from empty-kcalorie items.
Prolonged thiamin deficiency can result in the disease beriberi, which
was first observed in Indonesia when the custom of polishing rice
became widespread. “Rice provided 80 % of the energy intake”.
The symptoms of beriberi include damage to the nervous system as
well as to the heart and other muscles.
22. Thiamin
Toxicity:
No adverse effects have been associated with excesses of thiamin; no
Upper Level has been determined.
Food sources:
Whole-grain, fortified, or enriched grain products.
Moderate amounts in all nutritious food
Easily destroyed by heat
23. Riboflavin B2
Riboflavin
serves as a coenzyme in many reactions, most notably in the release of
energy from nutrients in all body cells.
Riboflavin Recommendations
Most people meet or exceed riboflavin recommendations.
24. Riboflavin
Riboflavin Deficiency
Lack of the vitamin causes inflammation of the membranes of the
mouth, skin, eyes, and GI tract.
Riboflavin deficiency is called ariboflavinosis
Toxicity
Excesses of riboflavin appear to cause no harm; no Upper Level has
been established
25. Riboflavin
Food Sources
The greatest contributions of riboflavin come from milk and milk
products , Whole-grain or enriched bread and cereal products are also
valuable sources because of the quantities typically consumed
Dark green, leafy vegetables (such as broccoli, turnip greens,
asparagus, and spinach)
Ultraviolet light and irradiation destroy riboflavin. For these reasons,
milk is sold in cardboard or opaque plastic containers, and precautions
are taken when vitamin D is added to milk by irradiation.
In contrast, riboflavin is stable to heat, so cooking does not destroy it.
26. Niacin B3
Niacin
The name niacin describes two chemical structures: nicotinic acid and
nicotinamide.
The body can easily convert nicotinic acid to nicotinamide, which is the
major form of niacin in the blood.
The two coenzyme forms of niacin, NAD (nicotinamide adenine
dinucleotide) and NADP (the phosphate form), participate in numerous
metabolic reactions.
They are central in energy-transfer reactions, especially the
metabolism of glucose, fat, and alcohol.
27. Niacin
Recommendations
The body can make it from the amino acid tryptophan.
Average niacin intakes in the United States and Canada exceed
recommendations.
Deficiency
Pellagra, produces the symptoms of diarrhea, dermatitis, dementia,
and eventually death “the four Ds”.
28.
29. Niacin
Toxicity
Naturally occurring niacin from foods causes no harm, but large doses
from supplements or drugs produce a variety of adverse effects, most
notably “niacin flush.”
Have been used to help lower blood cholesterol and prevent heart
disease.
People with liver disease, diabetes, peptic ulcers, gout, irregular
heartbeats, inflammatory bowel disease, migraine headaches, and
alcoholism may be particularly susceptible to the toxic effects.
30. Niacin
Food sources:
Meat, poultry, legumes, and enriched and whole grains contribute
about half the niacin people consume.
Mushrooms, potatoes, and tomatoes are among the richest vegetable
sources, and they can provide abundant niacin when eaten in
generous amounts.
Niacin is less vulnerable to losses during food preparation and storage
than other water-soluble vitamins. Being fairly heat-resistant, niacin
can withstand reasonable cooking times, but like other water-soluble
vitamins, it will leach into cooking water.
31. Biotin (vitamin H)
Biotin
Biotin plays an important role in metabolism as a coenzyme that
carries activated carbon dioxide. This role is critical in the TCA cycle.
also participates in gluconeogenesis, fatty acid synthesis, and the
breakdown of certain fatty acids and amino acids
Recommendations
Needed in very small amounts. Instead of an RDA, an Adequate Intake
(AI) has been determined.
32. Biotin
Deficiency
Rarely occur, symptoms include skin rash, hair loss, and neurological impairment.
More than two dozen egg whites must be consumed daily for several months to
produce these effects, however, and the eggs have to be raw; cooking denatures
the binding protein.
Toxicity
No adverse effects from high biotin intakes have been reported,
but some research indicates that biotin supplementation damages DNA.5 Biotin
does not have an Upper Level.
Food Sources
Biotin is widespread in foods (including egg yolks), so eating a variety of foods
protects against deficiencies.
33. Pantothenic acid B5
Pantothenic Acid
It is part of the chemical structure of coenzyme A—the same CoA that forms
acetyl CoA.
it is involved in more than 100 different steps in the synthesis of lipids,
neurotransmitters, steroid hormones, and hemoglobin.
Recommendations
An Adequate Intake (AI) has been set. It reflects the amount needed to
replace daily losses.
Deficiency
Rare. Its symptoms involve a general failure of all the body’s systems and
include fatigue, GI distress, and neurological disturbances.
34. Pantothenic acid
Toxicity
No toxic effects have been reported, and no Upper Level has been
established.
Food Sources
Pantothenic acid is widespread in foods, and typical diets seem to
provide adequate intakes. Beef, poultry, whole grains, potatoes,
tomatoes, and broccoli are particularly good sources.
Losses during food production can be substantial because it is readily
destroyed by the freezing, canning, and refining processes.
35. Vitamin B6
Vitamin B6
Vitamin B6 occurs in three forms—pyridoxal, pyridoxine, and
pyridoxamine. All three can be converted to the coenzyme PLP
(pyridoxal phosphate), which is active in amino acid metabolism.
Helps to convert tryptophan to niacin and to serotonin; helps to make
red blood cells.
vitamin B6 influences cognitive performance, immune function, and
steroid hormone activity.
Unlike other water-soluble vitamins, vitamin B6 is stored extensively in
muscle tissue.
36. Vitamin B6
Recommendations
Because the vitamin B6 coenzymes play many roles in amino acid
metabolism, previous RDA were expressed in terms of protein intakes;
the current RDA for vitamin B6 is not.
Deficiency
Without adequate vitamin B6, synthesis of key neurotransmitters
diminishes, and abnormal compounds produced during tryptophan
metabolism accumulate in the brain.
Early symptoms of vitamin B6 deficiency include depression and
confusion; advanced symptoms include abnormal brain wave patterns
and convulsions.
37. Vitamin B6
Toxicity
Neurological damage in people who had been taking more than 2
grams of vitamin B6 daily (20 times the current Upper Level of 100
milligrams per day) for two months or more.
Some people have taken vitamin B6 supplements in an attempt to cure
carpal tunnel syndrome and sleep disorders even though such
treatment seems to be ineffective or at least inconclusive.
38. Vitamin B6
Food sources:
meats, fish, and poultry, potatoes and a few other vegetables , and
fruits offer vitamin B6.
Foods lose vitamin B6 when heated.
vitamin B6 bioavailability from plant-derived foods seems to be lower
than from animal-derived foods.
39. Folate
known as folacin or folic acid
Its primary coenzyme forms, THF (tetrahydrofolate) and DHF
dihydrofolate helps convert vitamin B12 to one of its coenzyme forms
and helps synthesize the DNA required for all rapidly growing cells.
40. Folate
Folate Recommendations
The bioavailability of folate ranges from 50 % for foods to 100 % for
supplements.
The need for folate rises considerably during pregnancy and whenever
cells are multiplying, so the recommendations for pregnant women
are considerably higher than for other adults.
41. Folate
Folate and Neural Tube Defects
Folate has proven to be critical in reducing the risks of neural tube
defects. The brain and spinal cord develop from the neural tube, and
defects in its orderly formation during the early weeks of pregnancy
may result in various central nervous system disorders and death.
Folate supplements taken one month before conception and
continued throughout the first trimester of pregnancy can help
prevent neural tube defects.
It’s recommendation can be met through a diet that includes at least
five servings of fruits and vegetables daily, but many women typically
fail to do so and receive only half this amount from foods.
42. Folate
Mandatory fortification of grains
High intakes of folate complicate the diagnosis of a vitamin B12
deficiency, folate consumption should not exceed 1 mg daily.
43. Folate
Folate and Heart Disease
One of folate’s key roles in the body is to break down homocys-teine.
Without folate, homocysteine accumulates, which seems to enhance
blood clot formation and arterial wall deterioration.
Fortified foods and folate supplements raise blood folate and reduce
blood homocysteine levels to an extent that may help to prevent heart
disease.
44. Folate
Folate Deficiency
It impairs cell division and protein synthesis processes critical to growing
tissues, the replacement of red blood cells and GI tract cells falters.
first symptoms of a folate deficiency are anemia and GI tract deterioration.
The anemia of folate deficiency is characterized by large, immature red blood
cells. Without folate, DNA damage destroys many of the red blood cells as
they attempt to divide and mature. “macrocytic or megaloblastic anemia.”
The result is fewer, but larger, red blood cells that cannot carry oxygen or
travel through the capillaries as efficiently as normal red blood cells.
45. Folate
Folate deficiencies may develop from inadequate intake and have been
reported in infants who were fed goat’s milk, which is low in folate.
Folate deficiency may also result from impaired absorption or an
unusual metabolic need for the vitamin, such as pregnancies involving
twins and triplets; cancer; skin destroying diseases such as chicken pox
and measles; and burns, blood loss, GI tract damage.
46. Folate
Folate Toxicity
Naturally occurring folate from foods alone appears to cause no harm.
Excess folate from fortified foods or supplements, however, can reach
levels that are high enough to obscure a vitamin B12 deficiency and
delay diagnosis of neurological damage.
For this reason, an Upper Level has been established for folate from
fortified foods or supplements
47. Folate
Food Sources
abundant in legumes, fruits, and vegetables.
With fortification, grain products also contribute folate.
Heat and oxidation during cooking and storage can destroy as much as
half of the folate in foods.
48. Vitamin B12
Vitamin B12 and folate are closely related: each depends on the other
for activation.
The regeneration of the amino acid methionine and the synthesis of
DNA and RNA depend on both folate and vitamin B12.
Vitamin B12 maintains the sheath that surrounds and protects nerve
fibers and promotes their normal growth.
Bone cell activity and metabolism also depend on vitamin B12.
49. Vitamin B12
In the stomach, hydrochloric acid and the digestive enzyme pepsin
release vitamin B12 from the proteins to which it is attached in foods.
The stomach also secretes a molecule called intrinsic factor.
As vitamin B12 passes to the small intestine, it binds with intrinsic
factor. Bound together, they travel to the end of the small intestine,
where receptors recognize the complex.
There the intrinsic factor is degraded, and the vitamin is gradually
absorbed into the bloodstream.
50. Vitamin B12
Vitamin B12 Deficiency and Toxicity
Most vitamin B12 deficiencies reflect inadequate absorption, not poor
intake.
Inadequate absorption typically occurs for one of two reasons:
1. A lack of hydrochloric acid
2. A lack of intrinsic factor.
Without hydrochloric acid, the vitamin is not released from the dietary
proteins and so is not available for binding with the intrinsic factor.
Without the intrinsic factor, the vitamin cannot be absorbed.
51. Vitamin B12
Many people, especially those over 50, develop atrophic gastritis, a
common condition in older people that damages the cells of the
stomach.
Atrophic gastritis may also develop in response to iron deficiency or
infection with Helicobacter pylori, the bacterium implicated in ulcer
formation. Without healthy stomach cells, production of hydrochloric
acid and intrinsic factor diminishes.
Even with an adequate intake from foods, vitamin B12 status suffers.
The vitamin B12 deficiency caused by atrophic gastritis and a lack of
intrinsic factor is known as pernicious anemia.
52. Vitamin B12
Some people inherit a defective gene for the intrinsic factor.
In such cases, or when the stomach has been injured and cannot
produce enough of the intrinsic factor, vitamin B12 must be injected to
bypass the need for intestinal absorption.
53. Vitamin B12
A prolonged inadequate intake, as can occur with a vegan diet, may
also create a vitamin B12 deficiency.
People who stop eating animal-derived foods containing vitamin B12
may take several years to develop deficiency symptoms because the
body recycles much of its vitamin B12, reabsorbing it over and over
again.
Even when the body fails to absorb vitamin B12, deficiency may take up
to three years to develop because the body conserves its supply.
54. Vitamin B12
Because vitamin B12 is required to convert folate to its active form,
one of the most obvious vitamin B12–deficiency symptoms is the
anemia of folate deficiency.
This anemia is characterized by large, immature red blood cells, which
indicate slow DNA synthesis and an inability to divide.
When folate is trapped in its inactive (methyl folate) form due to
vitamin B12 deficiency or is unavailable due to folate deficiency itself,
DNA synthesis slows.
55. Vitamin B12
First to be affected in a vitamin B12 or folate deficiency are the rapidly
growing blood cells.
Either vitamin B12 or folate will clear up the anemia, but if folate is
given when vitamin B12 is needed, the result is disastrous: devastating
neurological symptoms.
vitamin B12, but not folate, maintains the sheath that surrounds and
protects nerve fibers and promotes their normal growth. Folate
“cures” the blood symptoms of a vitamin B12 deficiency, but cannot
stop the nerve symptoms from progressing.
By doing so, folate “masks” a vitamin B12 deficiency.
56. vitamin B12
Marginal vitamin B12 deficiency impairs performance on tests
measuring intelligence and short-term memory.
Advanced neurological symptoms include a creeping paralysis that
begins at the extremities and works inward and up the spine.
Early detection and correction are necessary to prevent permanent
nerve damage and paralysis. With sufficient folate in the diet, the
neurological symptoms of vitamin B12 deficiency can develop without
evidence of anemia.
58. Vitamin B12
Food Sources
Vitamin B12 is unique among the vitamins in being found almost
exclusively in foods derived from animals.
Microwave heating inactivates vitamin B12. To preserve this vitamin,
use the oven or stovetop instead of a microwave to cook meats and
milk products.
59. Non-B Vitamins
Choline
Essential nutrient?!
DRI established AI
The body uses choline to make the neurotransmitter acetylcholine and
lecithin.
During fetal development, choline supports the structure and function
of the brain and spinal cord.
Sources: Milk, liver, eggs, peanuts
Inositol and Carnitine
60.
61. it is often difficult to tell which vitamin is truly responsible for a given
effect because the nutrients are interdependent; the presence or
absence of one affects another’s absorption, metabolism, and
excretion.
62. B Vitamin Deficiencies
Vitamin B deficiencies affects the whole body
Deficiencies of single B vitamins seldom show up in isolation
Only in beriberi and pellagra deficiencies associated with single B
vitamins
The skin and the tongue appear to be especially sensitive to B vitamin
deficiencies
Two symptoms commonly seen in B vitamin deficiencies:
1. Glossitis an inflammation of the tongue
2. Cheilosis a condition of reddened lips with cracks at the corners of
the mouth.
63.
64. B Vitamin Toxicities
Toxicities of the B vitamins from foods alone are unknown, but they
can occur when people overuse supplements.
With supplements, the quantities can quickly overwhelm the cells.
3000
bananas
6600 cups
rice
3600
chicken
breast
2 mg of vitamin B6
65. B Vitamin Food Sources
Whole grains, vegetables, fruits, meat, fish, poultry, eggs, legumes,
nuts, and milk and milk products.
66.
67. Vitamin C
it was named ascorbic acid.
Vitamin C serves as a cofactor helping a specific enzyme perform its
job
it acts as an antioxidant participating in more general ways.
68. Vitamin C Roles
As an Antioxidant
In the body, antioxidants defend against free radicals.
A free radical is a molecule with one or more unpaired electrons, which
makes it unstable and highly reactive. By donating an electron or two,
antioxidants neutralize free radicals and protect other substances from
their damage.
In the cells and body fluids, vitamin C protects tissues from oxidative
stress and thus may play an important role in preventing diseases.
In the intestines, vitamin C enhances iron absorption by protecting iron
from oxidation.
69. Vitamin C Roles
As a Cofactor in Collagen Formation
Vitamin C helps to form the collagen.
Collagen serves as the matrix on which bones and teeth are formed.
When a person is wounded, collagen glues the separated tissues
together, forming scars.
Cells are held together largely by collagen; this is especially important
in the artery walls, which must expand and contract with each beat of
the heart, and in the thin capillary walls, which must withstand a pulse
of blood every second or so without giving way.
70. Vitamin C Roles
As a Cofactor in Other Reactions
vitamin C helps in the hydroxylation of carnitine, a compound that
transports long-chain fatty acids into the mitochondria of a cell for
energy metabolism.
It participates in the conversions of the amino acids tryptophan and
tyrosine to the neurotransmitters serotonin and norepinephrine.
Vitamin C also assists in the making of hormones, including thyroxin,
which regulates the metabolic rate; when metabolism speeds up in
times of extreme physical stress, the body’s use of vitamin C increases.
71. Vitamin C Roles
In Stress
The adrenal glands contain more vitamin C than any other organ in the
body, and during stress, these glands release the vitamin, together
with hormones, into the blood.
physical stresses raise vitamin C needs; infections; burns; extremely
high or low temperatures; intakes of toxic heavy metals such as lead,
mercury; the chronic use of certain medications, including Aspirin and
oral contraceptives; and cigarette smoking.
When immune system cells are called into action, vitamin C steps in as
an antioxidant to control this oxidative activity.
72. Vitamin C Roles
As a Cure for the Common Cold
Research supporting such claims has been conflicting and
controversial.
74. Vitamin C Deficiency
Two of the most notable signs of a vitamin C deficiency:
1. The gums bleed easily around the teeth
2. Capillaries under the skin break spontaneously, producing pinpoint
hemorrhages
When the vitamin C pool falls to about a fifth of its optimal size (this may take
more than a month on a diet lacking vitamin C), scurvy symptoms begin to
appear.
Inadequate collagen synthesis causes further hemorrhaging. Muscles,
including the heart muscle, degenerate. The skin becomes rough, brown,
scaly, and dry. Wounds fail to heal because scar tissue will not form. Bone
rebuilding falters; the ends of the long bones become softened, malformed,
and painful, and fractures develop.
Sudden death is likely, caused by massive internal bleeding.
75.
76. Vitamin C Toxicity
side effects of vitamin C supplementation such as nausea, abdominal
cramps, and diarrhea are often reported.
Large amounts of vitamin C excreted in the urine obscure the results of
tests used to detect diabetes, giving a false positive result in some
instances and a false negative in others.
People taking anticlotting medications, vitamin C may counteract.
Those with kidney disease, a tendency toward gout, genetic
abnormality that alters vitamin C’s breakdown to its excretion products
are prone to forming kidney stones.
77. Food sources
Fruits and vegetables can easily provide a
generous amount of vitamin C.
Grains , milk (except breast milk), legumes,
and meats are notoriously poor sources of
vitamin C.
