What is vitamin C? Vitamin C is a water-soluble vitamin
which cannot be stored in the body, so a regular intake is
essential. Most animals make their own, but we lack the enzyme
(L-gulonolactone oxidase) needed for its synthesis. This is
probably because cavemen obtained good amounts from berries and
green leaves, so there was little evolutionary pressure to acquire
this metabolic trick.
Requirements
Different authorities have suggested different levels of
adequate intake for vitamin C that range between 30-100mg per day.
These were based on criteria such as prevention of deficiency
disease (scurvy), turnover rates or tissue saturation. But when
vitamin C function is taken into account, higher intakes are
justified. Adult goats, for example, which are similar in weight to
man, produce between 2g and 13g per day, depending on their level
of stress and illness. Higher doses of vitamin C appear to have a
therapeutic effect that may protect against common illnesses.
Smokers and those with diabetes need twice as much vitamin C as
non-smokers and those with normal glucose control, as their
metabolism generates many more free radicals which consume vitamin
C more rapidly.
Cardiovascular health
Vitamin C is the main antioxidant in body fluids and regenerates
vitamin E, which protects lipids such as cell membranes. Vitamin C
increases levels of beneficial HDL-cholesterol and reduces uptake
of harmful LDL-cholesterol by the scavenger cells which deposit
cholesterol in artery walls. As well as protecting against
hardening and furring up of the arteries, vitamin C improves
dilation of diseased arteries, lowers blood pressure and reduces
levels of fibrinogen a circulating protein that increases the
likelihood of blood clots. It therefore helps to protect against
heart disease and stroke.
Immunity
High levels of vitamin C block the replication of viruses inside
cells to lower the frequency and severity of the common cold. It
also reduces the duration of herpes cold sores. Its antihistamine
action is helpful against allergies.
Joint health
Vitamin C is essential for the synthesis of collagen, a major
structural protein in bone and cartilage. It reduces cartilage loss
and disease progression in osteoarthritis, while its
anti-inflammatory action reduces joint inflammation.
Bone health
Vitamin C stimulates bone-building cells (osteoblasts), enhances
vitamin D activity and boosts calcium absorption to improve bone
mineral density and reduce the risk of osteoporosis.
Types of vitamin C supplements available
Vitamin C with Bioflavonoids: these natural
antioxidants found in fruits such as oranges, rose hips and acerola
cherries increase absorption of vitamin C and work with it to
strengthen body tissues and reduce inflammation.
Vitamin C sustained release: provides a
constant delivery of vitamin C over six to eight hours so blood
levels stay consistently higher for longer.
Effervescent Vitamin C: dissolves in water to
produce a pleasant-flavoured drink for rapid absorption.
Ester-C: contains the active, non-acidic,
breakdown products of vitamin C which are more rapidly absorbed
into cells. It does not cause indigestion at higher doses
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