Athlets diet and nutrition

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Vitamins, minerals and the athlete

 

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 found that these dietary components were not enough and some amounts of other materials were essential to keep the body functioning. These ingredients were named vitamins.

Vitamins

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

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	Necessary for the production of blood (red cells), nervous system, synthesis of DNA	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

Minerals

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.

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

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 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.
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.
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 .
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.
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.