Vitamin C – does it cure colds?
Vitamin is also known as ascorbic acid. It’s a water soluble vitamin which means it’s found
in the watery compartments of food, and is quickly absorbed into the blood stream when
consumed. Water soluble vitamins travel freely throughout the body and are taken up by
cells as needed. Excess water soluble vitamins are excreted, generally via the kidneys.
This means you need to have a regular intake of foods with water soluble vitamins to keep
levels up.
Humans cannot synthesis vitamin C, so it must be obtained through the diet, or
supplements if the diet is inadequate. Vitamin C is dose dependent i.e the more you take
the less the body takes up the vitamin. So if you choose to supplement with vitamin C,
don’t take one or 2 large does, spread the dose out. Better yet, consult a practitioner
qualified in nutrition as they will be able to prescribe a dosage regime that will ensure
uptake of the vitamin.
The recommended daily allowance of vitamin C is between 75mg and 90mg per day.
Smokers need an additional 35mg per day. You’ll find vitamin C in citrus fruits, green leafy
vegetable (cabbage etc, lettuce), capsicum, broccoli, strawberries, black currants, rosehips
and parsley.
Vitamin C and the Immune System
So, does vitamin C prevent colds and flu? There is no short answer to this question.
Vitamin C is an immunomodulator i.e it regulates immune function through enhancing the
activity of immune cells. Vitamin C increases immunity a number of ways, e.g influencing
T-cells, stimulating the production of interferons (proteins that protect cells against
viruses), stimulating production of antibodies, and stimulating production of humoral
thymus factor. Vitamin C also improves the function of leucocytes (white blood cells).
Think of Vitamin C as a nutrient that primes the internal army that fights viruses and other
pathogens. To achieve this effect you need to take vitamin C beyond the recommended
daily intake (RDI). This should only be done under the supervision of a suitably
qualified practitioner. Taking vitamins and other supplements in high does can be
dangerous, so don’t do it without seeking advice first.
A maintenance dose of vitamin C, along with specific herbs, is a standard preventative of
colds and flu over the winter months.
Vitamin C is also useful in the prevention and management of seasonal allergies as is
inhibits the release of histamines.
Other functions of Vitamin C
Vitamin C is an antioxidant i.e it mops up excess free radicals produced as part of the
metabolic process, and those that make their way into the body in other ways e.g smoking,
exposure to pollution.
Vitamin C is also needed for the formation of collagen, the matrix which holds tissue,
including teeth, together. Collagen holds cell walls together, so is really important for all
tissues, particularly blood vessels. When you think about what vitamin C does for collagen
production, you can see the link between low vitamin C levels and scurvy, symptoms of
which include bleeding gums. Other symptoms of vitamin C deficiency include muscle
degeneration, pin-point haemorrhages and skin becomes scaly, dry and rough.
Vitamin C enhances iron absorption.
Bioavailability of Vitamin C
A very important consideration with vitamins sourced from food or supplements, and other
nutrients, is bioavailability. While it’s easy to determine how much vitamin is present in a
particular food, it’s difficult to say how much of that vitamin is absorbed by the body once
the food is consumed. An efficient digestion will break down the food so that the nutrients
are readily available for absorption. This will depend on nutritional status, what
foods/nutrients are consumed at the same time, how the food is prepared (cooked,
processed, raw) and whether the nutrient comes from a natural source or is synthetic. The
best way to get vitamin C is from fresh food on a daily basis. Supplement if your diet is low
in vitamin C rich foods, but only to the recommended RDA.
Adverse Reactions to Vitamin C
Too much vitamin C (usually taken as a supplement) can lead to symptoms including
nausea, abdominal cramps, and diarrhoea.
Excessive doses of vitamin C can adversely effect warfarin and other anti-coagulants, as
well as being detrimental to people with iron overload.
Inadequate Vitamin C
British sailors of the later 1700s and early 1800s who were known to have a daily ration of
lime juice to prevent scurvy – a classic sign of vitamin C deficiency. However, British navy
physicians did know that a daily dose of lime juice prevented scurvy. Scurvy was the
scourge of sailors back then. leading to an early death due to vitamin C deficiency, that is
if they managed to survive the other risks of taking to the open sea in wooden boats with
sails, not to mention pirates etc.
Other symptoms of vitamin C deficiency include fatigue, malaise, chronic stress,
weakness, wounds that heal slowly, bruise easily, nosebleeds (weak blood vessels);
joint/muscle pain & swelling; weak connective tissue & bone.
Extremely low levels of vitamin C can lead to oedema, which is an indication that blood
vessels are not reabsorbing fluid correctly.
Vitamin C Supplements
If you feel that you may be at risk of vitamin C deficiency, or you want to use vitamin C
supplementation to prevent colds and flu, consult a health care professional trained in
human nutrition. If you are in the Canberra Region you can make an appointment to see
me to discuss your vitamin C status & the need for a supplement. Contact World of
Wellbeing on 6260 4774 to make an appointment. If you live in another part of Australia,
then contact the National Herbalists Association of Australia (NHAA) or the Australian
Traditional Medicine Society (ATMS) to find a naturopath, herbalist or nutritionist who can
correctly prescribe vitamin supplements.
Reference: Herbs & Natural Supplements: An evidence based guide (3rd Edition), by
Lesley Braun and Marc Cohen. The Nutrient Bible (6th Edition), by Henry Osiecki.
Understanding Nutrition (11th Edition) by Ellie Whitney and Sharon Rady Rolfes