The Open University Nutrition
The Open University Nutrition, Both vitamins and minerals are essential in the diet in small quantities. Learn about the two main vitamin groups and the major mineral elements. This free course, Nutrition: vitamins and minerals, looks at the two main groups of vitamins: the fat-soluble vitamins, A, D, E and K; and the water-soluble vitamins, the B group and vitamin C. It also examines the major mineral elements, and the importance of fluid balance in the body.
Course learning outcomes
After studying this course, you should be able to:
- Understand certain minerals are required in the body and that some minerals form essential structural components of tissues
- Understand that sodium, potassium, calcium and chloride ions are important in maintaining the correct composition of cells and of the tissue fluids around them (homeostasis)
- Understand that some minerals are essential components of important molecules such as hormones and enzymes
- Understand that the correct fluid balance is essential for normal functioning of the body
- Understand that tapwater, and not just mineral water, contains minerals.
Nutrition: vitamins and minerals
This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.
1.1 Introduction to vitamins and why we need them
Before the 19th century, one of the hazards of long sea voyages was a condition called scurvy, whose symptoms were loss of hair and teeth, bleeding gums, very slow healing of wounds, and eventually death. Hundreds of sailors and explorers died from scurvy until a Scottish physician, James Lind, in the 1750s discovered that adding a daily portion of citrus fruit to the rations of those at sea could prevent the condition, whereas adding cider, vinegar or various other substances that he tested, could not. In those days, it was considered that a disease was caused by something bad in the diet, or in the air, but not by the absence of something good, so despite Lind’s evidence, his ideas were not accepted by his fellow physicians. Additionally, he was unable to confirm his work by experiments on land since, although he tried to restrict the types of food eaten by a group of volunteers to attempt to produce scurvy in them, he was unable to do so, probably because it can take several months for the condition to develop, and in that time his volunteers occasionally cheated on their diet. However, though he died disillusioned, Lind had actually discovered the importance and source of vitamin C.
Before their detailed chemical structures were known, vitamins were named by being given a letter. They are generally still referred to by that letter, as well as by their chemical name; for example, vitamin C or ascorbic acid. There are two main groups of vitamins: fat-soluble vitamins and water-soluble vitamins. The body can store fat-soluble vitamins, but any excess water-soluble vitamins are easily removed from the body in the urine, so regular intake is necessary. Vitamins are, however, needed in only very small quantities.
The daily requirement of certain vitamins is much less than 1 mg (1mg is one-thousandth of a gram), and so is measured in micrograms per day, written as μg per day, where 1 μg is one-thousandth of a milligram. The values for the daily requirements of vitamins are regularly updated as more information becomes available. The values given in Table 1 are those recommended by the UK Government’s Food Standards Agency early in 2005.
Table 1 Vitamins essential for human health, reference nutrient intake (RNI) values taken from the UK Food Standards Agency website, and the main dietary sources of these vitamins.
|Name||RNI values for adults per day||Main dietary sources|
|vitamin A||0.6 mg for women; 0.7 mg for men||liver, cheese, eggs, butter, oily fish (such as mackerel), milk, fortified* margarine, yoghurt|
|vitamin D||0.01 mg (10 μg) for certain groups, e.g. pregnant women, those who rarely go outside, etc.||oily fish, liver, eggs, margarine, some breakfast cereals, bread, powdered milk|
|vitamin E||3 mg for women; 4 mg for men||plant oils (such as soya,corn and olive oil), nuts, seeds, wheat germ, some green leafy vegetables|
|vitamin K||0.07 mg(70 μg), or 1 μg per kg of body weight||green leafy vegetables (such as broccoli and spinach), vegetable oils, cereals; small amounts can also be found in meat (such as pork),and dairy foods (such as cheese)|
|thiamin (vitamin B1)||0.8 mg for women; 1 mg for men||pork, vegetables, milk, cheese, peas, fresh and dried fruit, eggs, wholegrain breads, some fortified* breakfast cereals|
|riboflavin (vitamin B2)||1.1 mg for women; 1.3 mg for men||milk, eggs, fortified* breakfast cereals, rice, mushrooms.|
|niacin (vitamin B3)||13 mg for women; 17 mg for men||beef, pork, chicken, wheat flour, maize flour, eggs, milk|
|vitamin B6 (pyridoxine)||1.2 mg for women; 1.4 mg for men||liver, pork, chicken, turkey, cod, bread, whole cereals (such as oatmeal, wheatgerm and rice), eggs, vegetables, soyabeans, peanuts, milk, potatoes, breakfast cereals|
|folate (folic acid, vitamin B9)||0.2 mg, but 0.4 mg extra for women who are, or plan to be, pregnant||broccoli, sprouts, spinach, peas, chickpeas, potatoes, yeast extract, brown rice, some fruit (such as oranges and bananas),breakfast cereals, some bread|
|vitamin B12 (cobalamin)||0.0015 mg (1.5 μg)||meat (particularly liver), salmon, cod, milk, cheese, eggs, yeast extract, some breakfast cereals|
|pantothenic acid (vitamin B5)||none given – should be sufficient in normal diet||chicken, beef, potatoes, porridge, tomatoes, liver, kidneys, eggs, broccoli, wholegrains (such as brown rice and wholemeal bread), some breakfast cereals|
|biotin (vitamin H)||0.01–0.2 mg||meat (such as kidney and liver), eggs and some fruit and vegetables, especially dried mixed fruit|
|vitamin C (ascorbic acid)||40 mg||wide variety of fruit and vegetables, especially peppers, broccoli, sprouts, sweet potatoes, cranberries, citrus fruits, kiwi fruit|