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Vitamins and minerals and the athlete

For a long time it was believed that the body only needed proteins, fats, carbohydrates and a number of minerals to stay fit and healthy. But then it was discovered that these dietary components were not enough - tiny amounts of other materials were essential to keep the body functioning. These vital ingredients were named vitamins.

Vitamins - what are they?

Vitamins are organic compounds that help regulate fat, carbohydrate and protein metabolism in the body. They cannot be made by the body and have to be provided by the food we eat - fortunately we only need tiny amounts of these vitamins.

Vitamins are not an energy source, but they play a vital role in releasing the energy stored in the other foods we eat. In addition, our enzyme, nervous, hormonal and immune systems are dependent on vitamins for regulation and control. Because of this vitamins are essential for good health, wellbeing and growth.

Vitamins are divided into two types: water-soluble and fat-soluble.

Water-soluble: These vitamins cannot be stored in the body and need to be replaced regularly through our diet.
Fat-soluble: These vitamins are stored in the body and include vitamins A, D, E and K. Although these vitamins can be stored, they should still be part of a healthy diet

Minerals - what are they?

Minerals are inorganic elements that have many roles in the body's functioning. Apart from their more well-known roles in the formation of strong bones and teeth, they also help to control the nervous system, fluid balance in tissues, muscle contractions, some hormonal functions and enzyme secretion.

Minerals are as essential as vitamins and, just like most vitamins, they cannot be made in the body. All our bodies' mineral needs have to be supplied from our diets.

Where do we get our vitamins and minerals from and what role does each play?

Vitamins	Function	Food sources
Vitamin A (found in two forms: retinol and beta carotene)	Necessary for vision in dim light, for healthy skin and surface tissues, especially those which excrete mucus (for example the intestines, lungs and vagina). In addition, it prevents infections and is necessary for the immune system	Fish liver oils (for example cod or halibut liver oil), liver, carrots, fortified margarine, cheese and dark green leafy vegetables
Vitamin D (found in two main forms: cholecalciferol and ergocalciferol)	For the growth and maintenance of bones and teeth through regulation of absorption and metabolism of calcium	Oily fish, eggs, milk, fortified breakfast cereals and fortified margarine. Also created in the body by action of sunlight on the skin
Vitamin E (found as a group of compounds called tocopherols)	Protection of cell membranes and fats from oxidative damage; protection of vitamin A, immune system and nervous system	Vegetable oils, eggs, whole grains, green vegetables and nuts
Vitamin K (covers a number of compounds, including phylloquinone)	Is necessary for normal blood clotting and energy metabolism	Dark green leafy vegetables, liver, meat, potatoes and cereals
Vitamin B1 (thiamin)	For energy metabolism, especially from carbohydrates	Bread, potatoes, milk, meat (especially pork), offal, whole grain cereals and fortified breakfast cereals
Vitamin B2 (riboflavin)	Essential for the utilisation of energy from foods, especially fats and proteins	Milk, meat (particularly liver) and eggs
Niacin (also known as vitamin PP) (nicotinic acid)	Necessary for energy metabolism	Meat, potatoes, bread and fortified breakfast cereals
Pantothenic Acid (also known as vitamin B5)	Energy metabolism and production of neurotransmitters for the nervous system	Yeast, liver, whole grains, greens and nuts. In fact it is found in virtually all foods
Vitamin B6 (found as a group of compounds, including pyridoxine)	Necessary for protein metabolism, particularly of haemoglobin	Potatoes, vegetables, meat, milk and fish
Vitamin B12 (found as a group of compounds, including cyanocobalamin and hydroxocobalamin)	For the production of blood (red cells), nervous system, synthesis of DNA	Liver, milk, fish and eggs
Folic Acid (also known as vitamin B_c or M)	Necessary for the production of blood (red cells), nervous system, synthesis of DNA	Offal and raw green vegetables
Biotin (also known as vitamin H)	For protein and fat metabolism	Liver and kidneys, whole grains and nuts
Vitamin C (found as a group of compounds, including ascorbic acid)	Necessary for the maintenance of connective tissues (including tendons, ligaments and cartilage). In addition, it helps wound healing, production of hormones, the immune system and protects vitamins A and E	Fresh fruit, especially citrus fruits and vegetables (particularly potatoes)

Minerals	Function	Food sources
Sodium	Helps regulate body fluids and is involved in energy release, functioning of nerves and muscle contraction. Increases blood pressure	Salt, bread and cereal products, bacon, ham, shellfish, smoked fish, soy sauce and foods that have been preserved by using salt
Potassium	Is used in the body's fluid balance and is involved in membrane functions, muscle function and reduces blood pressure	Potatoes, vegetables, greens, pork, dairy products, fruit (especially bananas) and juices
Calcium	For bones and teeth, blood clotting, hormone secretion, muscle and nerve function	Milk, cheese, bread and flour, green leafy vegetables and small oily fish with bones
Magnesium	Involved in muscle tone and activates enzymes	Milk, bread, potatoes and vegetables
Iron	Necessary for the manufacture of haemoglobin in blood (red cells) oxygen transport and transfer to tissues, activates enzymes	Red meats, liver, flour and cereal products, potatoes and vegetables
Zinc	For growth, bone metabolism, activation of enzymes, release of vitamin A from liver, immune system, taste and insulin storage	Meat, liver, seafood (especially oysters) milk, bread and cereals
Copper	Essential for enzyme function, especially blood formation, bone metabolism, immune system, nerve function and energy metabolism	Oysters, mussels, whelks, liver, brewer's yeast, whole grains, nuts and cocoa
Manganese	Necessary for enzyme activation and cell structure (works with calcium and iron)	Wholemeal bread, wheat germ, nuts, avocados, peas and tea
Molybdenum	Involved in enzyme functions	Liver, kidney, wheat germ, lentils, sunflower seeds, eggs and beans
Selenium	Has an enzyme function protecting cell membranes and fats from oxidative damage (works with vitamin E)	Nuts (especially brazils), seeds, bread, fish and meat (especially pork)
Chromium	Enhances the action of insulin on glucose uptake by cells	Egg yolk, liver, cheese, wholemeal products, molasses and brewer's yeast
Iodine	A necessary component of thyroid hormones	Oily fish, seaweed, meat, milk and iodised table salt
Phosphorus	Accommodates energy stores, bones, membrane function and growth	Dairy products, eggs, meat, fish, soya beans, soya products, pulses and wheat bran

Am I getting enough?

Most experts now agree that a balanced diet should provide you with all the vitamins and minerals you need. This is provided you eat a variety of foods from each of the food groups (see section on balanced diet) and, of course, in sufficient quantity. By quantity, we mean enough food for you to maintain a healthy body weight. To check that your body weight is in the correct range for your height, why not try our online body mass index (BMI) calculator.

Clearly, different people have different requirements and, because of this, helpful guidelines have been established by the Department of Health.¹ These are called Dietary Reference Values or DRVs. For any particular nutrient (where the scientific information is available) there are three values.

LRNI (Lower Reference Nutrient Intake): This is for a small number of people who have low needs and represents about three percent of the population. Most people will need more than this.
EAR (Estimated Average Requirement): Is the amount of a nutrient needed by an average person. So many people will need more and many will need less.
RNI (Reference Nutrient Intake): The amount of a nutrient that should cater for the needs of 97 percent of the population. It is more than most people require and only very few people (3 percent) will need more. This is also known as the Recommended Daily Amount or RDA. It is this value you will see on the sides of cereal packets.

It is important to remember that DRVs are aimed at populations of people, not individuals. As such they are guidelines and not targets for you to aim for.

Athletes - do they have different requirements?

Generally speaking, like the rest of us, athletes should get all the vitamins and minerals from their diet. Because athletes use up more energy than inactive people, they probably eat more too, and so any increased requirement for vitamins or minerals should be met by their increased food intake (providing the diet is balanced).

However, some studies^2,3,4 have shown that many athletes don't have adequate vitamin and mineral intakes. This may be because they restrict calorie intake in order to manage weight. Other reasons for inadequate vitamin and mineral intake include irregular training routines that making meal planning difficult and following a dietary "fad" that is not providing a balanced diet.

Will vitamin and mineral supplements enhance athletic performance?

A lot of work has been carried out to try to establish whether vitamin and mineral supplements improve athletic performance. So far, there is little evidence that any improvement occurs in athletes who are well nourished. The only improvements observed have been in people whose diets were previously deficient in one nutrient or another, adding supplements just brought them up to their optimum level.

In summary, if you are not deficient in any vitamins or minerals, then supplementing your diet will not bring about any improvement in performance. Nevertheless, if you do have some sort of deficiency, then correcting this may well be of benefit.

Choosing a supplement

Most people will probably not be aware of any minor vitamin and mineral deficiencies as the symptoms may be slight, while gross deficiencies are very uncommon in this country.

Nevertheless, you may want to take a supplement as an "insurance policy", based on the principle that, at the very least, it will not harm you and may possibly be of benefit. If you do decide to take a supplement then it is best to choose a well formulated multi-vitamin and mineral supplement that contains all the main vitamins and minerals.

What about specific vitamins or mineral supplements?

It is best not to use supplements that contain just one or two specific vitamins or minerals. This is because vitamins and minerals work in harmony and an excessive amount of just one can impair the absorption or effectiveness of others. Correct balance is important.

Furthermore, some vitamins, particularly the fat-soluble vitamins, can be harmful in excess quantities as they tend to build up in the body and cause problems. With water-soluble vitamins, amounts over and above the body's requirements are simply lost from the body in urine and do not provide any additional benefit - so you will be wasting your money!

You will notice on the packaging of supplements that for each particular vitamin or mineral it may list the "% of RDA". RDA simply means the Recommended Daily Amount so, for example, if say for Vitamin C it says "100% RDA", this means that it contains 100 percent of your daily allowance. The RDA is similar to the RNI in Dietary Reference Values.

You will probably notice that many supplements exceed the RDA, however, this is not necessarily harmful as the safety margins are very high and well-formulated supplements are well within the acceptable range. RDAs were formulated to cater for the vast majority of a population (nearly 100 percent). This means that many people will require less. However, RDAs were also set at a level where it was known that there were no adverse effects.

Key points

Most vitamins and all minerals cannot be made by the body, so need to come from your diet
A balanced diet should provide you with all vitamins and minerals you need
If you are well nourished already, supplements will not improve performance
If you are slightly deficient in some nutrients, a supplement may benefit performance
Gross vitamin deficiencies are rare in this country
The fat-soluble vitamins, A D E and K, may cause side-effects if taken in very high quantities
When choosing a supplement choose a well-balanced multi-vitamin and mineral supplement
Supplements containing a single vitamin or mineral are best avoided because it is difficult to get the balance right

References

Department of Health. Dietary Reference Values for Food and Energy and Nutrients for the United Kingdom. Report of the Panel on Dietary Reference Values of the Committee on Medical Aspects of Food Policy. HMSO, 1991.
Short SH, Short WR. Four year study of university athletes' dietary intake. J Am Diet Assoc 1983; 82: 632-45.
Steen SN, McKinney S. Nutrition assessment of college wrestlers. Physician and Sports Med 1986; 14: 100-106.
Bazzare TL. Incidence of poor nutritional status among triathletes, endurance athletes and controls. Med Sci Sports Ex 1986; 18: 590.