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Vitamin C crystals

Spike Walker

Download this image from Wellcome Collection.

Light micrograph of crystals of oxidised vitamin C (L-ascorbic acid). To make vitamin C crystals, vitamin C powder that had begun to oxidise was dissolved in water and a drop spread onto a microscope slide. This was warmed until enough water had evaporated to leave a thin film of solution packed full of vitamin C, which was then scratched with a needle to initiate crystal growth. As the crystals are colourless and more or less transparent, they were imaged using polarised light microscopy with crossed polars to enhance the contrast and colour of the image. The crystals are needle-shaped, but at low magnifications you can only see the final form their groupings take. Our bodies cannot make vitamin C, so we have to obtain it from food and drink. Vitamin C is used to make collagen, a protein found in many different tissues in the body. Too little vitamin C means that not enough collagen can be made, which causes skin, cartilage, bone and blood vessels to start to break down. This rare disease is called scurvy. The width of the image is 8 mm.

Where can you find vitamin C?

Fruit and vegetables are good sources of vitamin C; good examples include citrus fruits such as oranges and grapefruits, kiwifruit, strawberries, red and green peppers, potatoes, and green leafy vegetables such as spinach and broccoli. Some foods such as cereals and milk may be fortified (enriched) with nutrients including vitamins and minerals. The recommended daily amount of vitamin C for adults in the UK is 40 to 60 mg. In the US it is 75 mg per day for women and 90 mg for men. Children will need less depending on their age and pregnant or breastfeeding women will need more. Smokers or people exposed to second-hand smoke will also need more vitamin C. Vitamin C is an antioxidant and protects cells from damage, improves absorption of iron and helps the immune system to work properly.

What is scurvy?

People who get little or no vitamin C can develop scurvy. Scurvy is now a rare disease, but it was once prevalent among mariners and was known as the 'scourge of the seas'. It causes inflammation of the gums, joint pain, fatigue, poor healing of wounds, and small red or purple spots on the skin. Depression, bleeding gums and loss of teeth can also occur. People with scurvy can also develop anaemia, a condition in which the number of red blood cells or the amount of haemoglobin being carried by red blood cells is lower than normal. This means that not enough oxygen can be carried to other cells in the body. Scurvy is ultimately fatal if not treated.