The Comprehensive Guide to Vitamin C:
Benefits, Sources, and Importance for Health
Introduction
Ascorbic acid or vitamin C is among
the most popular and most needed nutrients that the human body needs. It is
also important in different physiological activities, such as immune support,
collagen production, antioxidant defense, and wound healing. Humans, unlike
many other animals, are unable to endogenously produce vitamin C, and therefore
must get it exogenously through foods or supplements.
This paper gives a detailed discussion
of vitamin C, its biochemical characteristics, health effects, food sources,
adequate intake, deficiency signs, and possible adverse effects of its overuse.
1. What is
Vitamin C?
Chemical
Structure and Properties
Vitamin C is water soluble vitamin;
this means that it dissolves in water and is not stored in the body. Its
chemical name ascorbic acid was obtained due to its property of preventing
scurvy (a disease that results due to vitamin C deficiency). The molecular
structure of vitamin C is C6H8O6 and it occurs in 2 active forms:
·
L-ascorbic
acid (the active form).
·
Dehydroascorbic
acid (an oxidized form which can be reduced back to ascorbic acid).
Vitamin C is very labile to heat,
light, and oxygen, which may destroy its activity in foods during storage.
Biological
Functions
Vitamin C serves as:
·
An enzyme
cofactor (e.g., in collagen formation, in the production of neurotransmitters).
·
It is a powerful
antioxidant that neutralizes free radicals and decreases oxidative stress.
·
An immune
modulator, an enhancer of the activity of white blood cells,
2. Health
Benefits of Vitamin C
A. Immune System
Support
Vitamin C has been largely known to
boost the immune system. It enhances:
·
Function of white
blood cells (lymphocytes and phagocytes).
·
Antibody
production.
·
Collagen
formation to strengthen the skin barrier defense.
Research indicates that vitamin C
supplementation can lessen the morbidity and duration of cold especially among
people who are physically stressed (e.g., athletes, soldiers).
B. Antioxidant
Properties
Vitamin C acts as an antioxidant,
reducing the damage of cells caused by free radicals (reactive oxygen species,
or ROS). This safeguard assists in the prevention of:
·
Chronic
inflammation.
·
Mutations of DNA
(can reduce risk of cancer).
·
Cardiovascular
diseases through inhibition of oxidation of LDL cholesterol.
C. Collagen
Synthesis and Skin Health
Collagen is the most profuse protein
in the body, which is imperative in:
·
Wound healing and
elasticity of the skin.
·
Integrity of bone
and cartilage.
·
Vasculature
architecture.
Vitamin C acts as a cofactor to prolyl
and lysyl hydroxylase, which are enzymes needed to stabilize collagen. In the
absence of vitamin C, collagen will be weak and this will result in symptoms of
scurvy (e.g., bleeding gums, poor wound healing).
D. Cardiovascular
Health
Studies show that vitamin C can:
·
Reduce blood
pressure through enhancing the formation of nitric oxide (a vasodilator).
·
Inhibit the
oxidation of LDL cholesterol, which reduces the risk of atherosclerosis.
·
Blood flow,
promote endothelial function.
E. Iron
Absorption Enhancement
Vitamin C transforms non-heme iron
(found in plant foods) into a form that can be readily absorbed, and this
checks iron-deficiency anemia. To increase iron absorption, vitamin C rich
foods should be taken with iron rich food (e.g. spinach with lemon juice).
F.
Neuroprotective Effects
The brain is concentrated with vitamin
C and can:
·
Neuroprotective (e.g. Alzheimer, Parkinson)
·
Neurotransmitter synthesis (e.g., dopamine, norepinephrine)
G. Eye Health
Vitamin C rich intake is associated
with reduced chances of cataracts and age-related macular degeneration (AMD)
because of its antioxidant properties in the lens and the retina.
3. Dietary
Sources of Vitamin C
Best Natural
Sources
Fruits and vegetables are good sources
of vitamin C, among them:
Fruits
·
Citrus fruits
(oranges, lemons, grapefruits)
·
Kiwi (more per
gram than oranges)
·
Strawberries
·
Guava (extremely
high, ~200 mg each fruit)
·
Papaya
·
Pineapple
Vegetables
·
Bell peppers
(particularly red pepper)
·
Broccoli
·
Brussels sprouts
·
Spinach
·
Tomatoes
Cooking and
Storage Considerations
·
Heat labile: Up
to 50 percent of vitamin C can be destroyed by boiling.
·
It is best eaten
raw or steamed slightly.
·
Vitamin C is
destroyed by exposure to air- keep fruits and vegetables in good condition.
4. Recommended
Daily Intake
The Recommended Dietary Allowance
(RDA) of vitamin C depends on the age, gender and the stage of life:
|
Group |
RDA (mg/day) |
|
Infants (0-12 months) |
40-50 |
|
Children (1-18 years) |
15-75 |
|
Adult Men |
90 |
|
Adult Women |
75 |
|
Pregnant Women |
85 |
|
Breastfeeding Women |
120 |
|
Smokers |
+35 mg (extra) |
Higher Doses for
Therapeutic Use
Higher doses (200-1000 mg/day) have
been associated in some studies to be beneficial, especially:
·
Athletes
(lowers oxidative stress)
·
Prevention
of chronic diseases
·
Support of
wound healing
Yet, at a high dosage (>2000
mg/day), side effects can occur (see below).
Read Also: - Iodine and Vitamin C: Essential Nutrients and Their Roles in the Body
5. Vitamin C
Deficiency (Scurvy)
Causes of
Deficiency
·
Unhealthy
nutrition (absence of fresh fruits/vegetables)
·
Malabsorption
diseases (e.g. Crohn disease)
·
Smoking
(oxidative stress, vitamin C)
Symptoms of
Scurvy
·
Weakness and
fatigue
·
Bleeding and
swollen gums
·
Easy bruising
·
Delayed wound
healing
·
Joint pain
·
Corkscrew hairs
(perifollicular hemorrhes)
Treatment
·
Oral ascorbic
acid (100-200 mg/day)
·
Dietary changes
(more citrus fruit, leafy vegetables)
6. Risks of
Excessive Vitamin C Intake
Although vitamin C is fairly safe,
high doses of the vitamin (most often in supplements) may:
·
Diarrhea and GI discomfort
(osmotic effects)
·
Kidney stones (in
predisposed people, due to the formation of oxalate)
·
iron overload (in
individuals with hemochromatosis)
·
Very high doses
(>1000 mg in some conditions) Pro-oxidant effects.
Tolerable Upper Intake Level (UL) of
adults is 2000 mg/day.
7. Vitamin C
Supplements: Forms and Absorption
Common Supplement
Types
1. Ascorbic Acid (standard form, acidic)
2. Buffered/Easier-on-the-stomach forms of Mineral
Ascorbates (e.g. sodium ascorbate).
3. Liposomal Vitamin C (enhanced absorption)
4. Ester-C
(calcium ascorbate and metabolites to enhance retention).
Absorption and
Bioavailability
·
Sodium-dependent
transporters in the small intestine absorption.
·
Bioavailability
is lower when the dose (>200 mg at a time) is higher.
·
Absorption is
promoted by split doses.
8. Conclusion
Vitamin C is an essential nutrient
that has various health effects, which range Immune support, collagen
production, and antioxidant protection. Although in developed countries
deficiency is not common, it is necessary to maintain adequate intake by
consuming a balanced diet with plenty of fruits and vegetables.
It may be supplemented in those that
are at risk of being deficient or those that have an increased need (e.g.,
smokers, athletes, elderly), but they must be consumed in moderation, as they
can also cause negative effects.
With this knowledge of the science of
vitamin C, people will be able to make informed decisions to ensure that they
get the best of their health and wellbeing.
Final
Recommendations
·
Consume
different foods that contain vitamin C every day.
·
Supplements
may be considered when the dietary intake is inadequate.
·
Do not take
large amounts (>2000 mg/day) unless recommended by a medical practitioner.
·
To maintain
vitamin C, store foods in good ways.
Vitamin C is the nutrient that has
been studied the most and that is needed by the body, and sometimes, simple
vitamins have the most significant effects on health.
Post a Comment
0Comments