It's time to turn our attention to perhaps the best known and most controversial vitamin of the lot. Although renowned as the 'anti-cold' vitamin, the truth is rather more complex. Vitamin C does more than boost immunity, but more is not always better.
What is vitamin C?
Pure vitamin C is a water-soluble, white crystalline powder. You sometimes hear it referred to as ascorbic acid or ascorbate. Chemically, it is quite closely related to the sugar glucose. Unlike most animals, humans lack the enzyme required to synthesise ascorbate, hence its status as a vitamin. Along with monkeys and guinea pigs, we need to obtain it from our diet. It's is a fairly fragile molecule; oxygen in the air easily destroys it and heat also quickly breaks it down. As a result, fresh foods rich in vitamin C lose so much when cooked and processed.
Why do I need it?
Vitamin C plays an important role in the synthesis of collagen; required for connective tissue, bones, teeth, skin, tendons and scar tissue. It's important for making and releasing neurotransmitters and hormones. Thirdly, it's involved in nutrient absorption and metabolism, like in the case of iron and folic acid. Lastly, vitamin C is a crucial component of the antioxidant defence system. This system protects us from molecular damage at a cellular level. Thereby lowering the risk of degenerative diseases such as cancer while also slowing the ageing process.
How much vitamin C do I need?
The Recommended Daily Intake (RDI) for vitamin C is 45mg per day for adults in Australia. The UK advises 40mg per day whereas in the USA, the RDA for men is 90mg and 75mg for women. There's a growing consensus that higher than recommended levels are required to produce maximum antioxidant protection. Leading nutritionists in antioxidant research believe 250-500mg would be optimum.
Where can I find vitamin C?
All fruits are rich in vitamin C. This is especially true for citrus fruits (oranges, grapefruit, lemons), berries and currants. Certain vegetables are also very rich in C. Examples include cabbage, new potatoes, broccoli, capsicum, tomatoes, watercress and Brussels sprouts. Most animal produce and cereals lack and real vitamin C content.
What happens if I don't get enough?
A severe deficiency can cause scurvy. Symptoms include bleeding gums, joint swelling, skin lesions, ulceration and even gangrene. Milder deficiencies cause excess bruising and increased susceptibility to viral infections. An increased risk of cancer and heart disease can also result.
Who should take most care to regulate their intake?
Anybody whose intake of fresh fruit and vegetables is low risks sub-optimal vitamin C intake. The elderly and long-term hospitalised are also at risk. Those who rely heavily on processed, takeaway and fast foods are particularly at risk.
Can I get too much?
Yes, although it is relatively non-toxic, even at very high doses. Regular intake above 2000mg per day is not recommended. At such levels, vitamin C is capable of acting as a 'pro-oxidant'. In the presence of iron and copper, this is especially true. In this case, it will actually damage our body's cells rather than protect them.
Am I getting enough?
The best sources by far are fruits and vegetables. Meat, fish, dairy, grains and cereals provide very little.
Vitamin C Content (per 100g)
Kiwi fruit, peeled, raw
Red cabbage, raw
Broccoli, fresh, microwaved
Sweet potato, baked
Mango, peeled, raw
Potatoes, new, peeled, boiled
Carrots, peeled, raw
*Figures supplied by Australian Food Composition Database - FSANZ