Also known as ascorbic acid. As well as being a naturally occurring vitamin, vitamin C is also used as an approved food additive, where it acts as an antioxidant. It is needed for the structure of connective tissue, muscle and blood vessels. It helps maintain healthy gums. Vitamin C is also needed for the absorption of iron from plant sources.
Sources
Many fruits and vegetables. Good sources are strawberries, citrus fruits, peppers and potatoes.
The recommended daily amount for vitamin C is 60mg for adults and children over the age of 5. Use of high-dose supplements (over 1g a day) can cause nausea, stomach cramps and stomach upsets.
Vitamin C is sensitive to light and heat, as well as being soluble in water. To maximise the amounts in food when eaten, it's best to store fruits and vegetables away from direct light, cook for the minimum amount of time needed, and only use small amounts of water for cooking.
Vitamin C is widely recognised to have antioxidant properties. This means it can help 'mop up' reactive substances that are naturally produced by our bodies and which can also be found in smoke and pollution. These reactive substances are known as free radicals, and are thought to play a part in the development of heart disease and possibly some cancers.
Antioxidants - such as vitamin C, vitamin E, vitamin A and its precursor betacarotene - may therefore help reduce the risk of heart disease and some cancers. Fruits and vegetables provide these vitamins, and thus it is important to try to achieve the recommended five or more portions of fruit and vegetables a day.
Also known as cholecalciferol, vitamin D is needed for healthy bones and teeth, as it aids the absorption of calcium. It also plays a role in the normal functioning of the nervous system.
Sources
Between the months of March and September we make our own vitamin D by exposure of small areas of skin (such as the forearms and face) to sunlight. This can be stored by our bodies in fat, as vitamin D is fat-soluble. Vitamin D is also found in fish, eggs and butter, and it is also added to many margarines and fat spreads, so these products can provide useful amounts too.
For people who do not get much exposure to sunlight, such as those who wear enveloping clothing for religious beliefs or the housebound, there may be some risk of deficiency. Children, pregnant women and women who are breast-feeding also have higher requirements for vitamin D. Food sources are important in these cases and supplements may be necessary for some.
The recommended daily amount is 5 micrograms for adults and children over the age of 5. High intakes may cause stomach upsets.
Also known as tocopherol.
Vegetable oils, egg yolks, avocados, fortified breakfast cereals.
The recommended daily amount is 10mg for adults and children over the age of 5. There is little risk of toxic effects.
Vitamin K is needed for the clotting of blood.
Sources
Mostly made by the body. Food sources include green leafy vegetables, plus some dairy and grain products.
There is no recommended daily amount for vitamin K. A deficiency is unlikely as it is found in so many foods, and also because it can be made by bacteria in the large intestine.
