Vitamins and minerals form the micronutrients in the diet. Although we need these substances in much smaller amounts than the macronutrients (CHO, protein and fats), they remain a vital part of our diet if we are to maintain our health.
Minerals are necessary for structure and for the normal regulation of metabolic, hormonal and nervous interactions within the body. In simple terms, they enable our bodies to function correctly on a daily basis. They do not provide energy themselves but may allow our bodies to ‘unlock’ the energy contained within our diet. Minerals form approximately 4% of our body mass, mostly within the skeletal system. Plants extract the minerals from the soil, which enables us in turn to ingest them, assuming we have a varied diet. Although most minerals are important to the body, the four macrominerals are required in greater amounts.
Other minerals are needed for a healthy functioning body, but are required in much smaller amounts. These are referred to as the trace minerals:
Vitamins also come under the category of micronutrients and consist of a group of organic compounds (all containing carbon), which are required for normal growth and metabolism. All vitamins are synthesised by plants and can be obtained in the diet by either eating the appropriate plants themselves or by eating animal products that have derived their vitamin content from plants. We are capable of synthesising some of the B vitamins, i.e. biotin and riboflavin, and vitamin K ourselves, from the action of bacteria found within our GI tract. Our bodies are also capable of assembling certain vitamins from precursors called pro-vitamins often referred to as ‘inactive vitamins’. For example, beta-carotene is a pro-vitamin found in yellow and dark green vegetables from which our bodies synthesise vitamin A.
Fat soluble vitamins:
Vitamins A, D, E, and K are termed as fat soluble, meaning that they can only be absorbed, transported and utilised in the presence of fat. Their main function is to have a protective effect on our cell membranes (cell walls). These membranes are important because they enable our cells to ‘breathe’ and to receive the nutrients necessary to maintain our health and normal functioning. A diet too low in fat will lead to a severe deficiency in the fat-soluble vitamins, which will lead to ill health.
Water soluble vitamins:
The B group of vitamins and vitamin C are all water-soluble and are absorbed, transported and utilised within water. They are all absorbed along the length of the digestive tract and tend to have an effect within the cells themselves. These vitamins cannot be stored within the body in any great quantity and therefore, we need to include them daily in our diet if we are to avoid an eventual deficiency resulting in ill health. A diet rich in refined simple carbohydrates containing an excess of sucrose will eventually lead to such a deficiency.
These are chemicals synthesised by plants, which appear to have an important effect upon human health. One important phytochemical found in tomatoes and other brightly coloured fruit and vegetables, is lycopene, an effective antioxidant.
|Key components of 1cup of cherry tomatoes|
For every physiological change in the body a specialised protein molecule known as an enzyme provides the stimulus. Its job is to catalyse or speed up chemical reactions within the cells so that the physiological changes that support life can take place more quickly. The rate at which these reactions take place is totally dependent upon the enzyme, often increasing them by one hundred thousand to one million times.
How does an enzyme work?
An enzyme has a precise three-dimensional structure. By adjusting or altering the structure of the enzyme, the body can use it as a switch to turn on and off the reaction that it catalyses or other reactants involved in the process. These reactants, that bind to the enzyme, are known as substrates, and the point on which the substrate binds onto the enzyme itself is known as the active site. The two fit together almost like a lock and key, thus only an appropriately fitting substrate can bind to the specific enzyme. Once this binding process has taken place, it can now promote the desired reaction and cause the eventual outcome.
Each enzyme is specific for only one substrate. There is a ‘one lock’ and ‘one key’ principle, where the active site of the enzyme also has a unique fit for one specific substrate and no other.
Since this whole process relies on a unique fit between the substrate and the active site in the enzyme, it often requires assistance, which almost customises the substrate in order to achieve a perfect fit. This assistance comes from either co-enzymes, which are derivatives of vitamins, or co-factors, which are minerals. Therefore, vitamins and minerals play a vital role in helping enzymes to function appropriately and sustain life.
Research has linked exercise with increased production of damaging chemicals called free radicals, which cause a variety of diseases such as cancers, cardiovascular disease, autoimmune disorders and even the ageing process itself (Pullen, 2002).
What is a free radical?
A free radical is strictly defined as ‘an entity with one or several unpaired electrons in the outer electron orbit of an atom or molecule’ (Karlsson, 1997).
This explanation may sound a little confusing, but in essence, it is fairly simple. Atoms have within them, small particles called electrons and protons, which play a role in creating the attraction to form a chemical bond. Generally, atoms or molecules have equal numbers of protons and electrons to remain balanced and stable. In a chemical reaction, this balance may be changed and leave an unpaired electron. With unequal numbers of protons and electrons, the atom is unbalanced and must achieve stability. The unbalanced ‘free radical’ is highly reactive and quickly seeks out a spare electron. If one can’t be found, it quickly steals an electron from an intact molecule causing damage in the process. This may initiate a chain reaction that continues for several days (Colgan, 1993).
Free radicals are produced in the body in a number of ways, but a large contributor (especially for regular exercisers) is oxygen. Most energy is produced within the body via an aerobic process, which requires the break down of the food we eat along side the use of oxygen. 95% of energy is produced through controlled oxidation, resulting in “clean” reactions, which cause no free radical damage. However, the remaining 5% of energy production, results in the formation of a mass of free radicals, each capable of causing damage within the body (Colgan, 2002).
Examples of the damaging effect of oxygen or oxidisation include the rusting of untreated metal, the browning of a cut apple and the rotting of meat. Inside the body the radicals can attack cell membranes leading to wrinkles and skin diseases, such as eczema and psoriasis. Arterial walls become damaged, leading to the beginning of blocked arteries of atherosclerosis. Double bonds found in unsaturated fats and in DNA are attacked leading to an increased risk of cancer and arthritis (Golan, 1995).
The damage caused by free radicals is also the major source of delayed muscle soreness, or DOMS, felt for several days after intense exercise (Gerutti et al, 1998). Links have also been made between free radicals and Alzhemer’s disease, diabetes, hypertension, rheumatoid arthritis, mental illness and macular degeneration of the eye (Patrick Holford, 1997). On a positive note, free radicals are utilised by some cells within the immune system in order to kill harmful microbes.
Exercise can create a 10-15 fold increase in oxygen consumption and along with it, increased free radical damage (Pullen, 2002).
Defence mechanisms – antioxidants:
As the human body evolved to utilise oxygen, it has also evolved elaborate defences in order to limit free radical damage. These come in the form of antioxidant enzymes, which the body produces naturally within the cells, such as superoxide dismutase. Dietary antioxidants can also be acquired from the food that we eat. People with poor diets, depleted of nutrients, may be at greater risk, as the body’s antioxidant enzymes require nutrients such as vitamins A, C, E and minerals including zinc, selenium, copper and manganese in order to function properly.
Antioxidants are substances that slow oxidation by neutralising free radicals (mayo Clinic, 2003) and work by being able to donate or receive electrons. Both the enzymes and the nutrients play a role in breaking the damaging chain reactions. Research suggests that regular exercisers do have a much higher level of their natural antioxidant enzymes to help protect them (Cardwell, 1999).
|Sources of antioxidant nutrients|
|vitamin C – citrus fruits, green veg, peppers, tomatoes, potatoes|
vitamin E – veg oils, egg yolks, whole grains, almonds, nuts, green leafy veg
zinc – oysters, ginger root, lamb, nuts, grains, eggs, peas
selenium – grains, meats, fish, brazil nuts, tuna, shellfish, dairy
As we get older, we lose the battle against environmental damage from radiation, pollution and increasingly poor diets. Exercise also increases oxidative stress through increased oxygen consumption, so it is important to stress that those engaging in regular and especially intense exercise, need to ensure that their diet is better than the average to ensure high nutrient densities. A variety of vitamins and minerals from many different sources will ensure that the body can function nearer it’s optimal level. This should help limit any damage caused by exercise, including injuries, and to help promote recovery caused by myofibril damage (DOMS).
Although not all the research with supplementation is favourable, one thing is agreed among scientists. Consumption of a diet rich in fruit and vegetables is recommended as a protection against the risk of developing a number of degenerative diseases associated with age, including cardiovascular diseases and cancer (Food Standards Agency, 2001).
|limiting food choices|
‘fresh’ produce from overseas
fortified foods – lack quality
processed fruit and vegetables
cooking at high temperatures
|eat variety of fresh fruit, vegetables, and animal produce|
eat seasonal, local produce – freshest
eat raw fruit and veg where possible
broaden tastes – try new foods
Key learning points
Minerals are necessary for:
- the regulation of metabolism
- act as co-factors to assist enzymes
- many act as antioxidants
- water soluble = B, C
- fat soluble = A,D,E,K
- act as co-enzymes to assist enzymes
- many act as antioxidants
- important chemicals synthesised by plants
- a protein molecule that acts as a catalyst for the body’s reactions
- they speed up chemical reactions without entering the reaction itself
- they activate by the presence of a substrate binding with the active site – Work in conjunction with co-enzymes and co-factors
A free radical is a molecule which is:
- unbalanced and unstable
- highly reactive
- they are mostly formed by 5% rogue oxygen
Free radicals cause damage to:
- cell membranes
- DNA in the nucleus of the cells
- LDL cholesterol
Diseases linked with free radicals:
- coronary arterial disease
- alzheimer’s disease
- macular degeneration of the eye
Ames, BN. (1983). Science: 221:1256
Cardwell, G. (1999). Antioxidants and sport, from ptonthenet.com
Colgan, M. (1993). Optimum sports nutrition, Advanced Research Press.
Colgan, M. (1995). The new nutrition, Apple Publishing.
Colgan, M. (2002). Sports nutrition guide, Apple Publishing Company Ltd.
Food Standards Agency, (2001). Antioxidants in food, Crown Copyright
Gerutti, A. et al. (1998). Oxy-radicals in molecular biology and pathology, New York: AR Liss
Giovannucci, E. Rimm, E.B, Liu, Y, Stanpfer, M.J, Wilett, W.C, (2002). A prospective study of tomato products, lycopene and prostate cancer risk. Journal of the National Cancer Institute, Vol.94, No. 5: 391-398.
Harman, D. (1956). Aging: A theory based on free radical and radiation chemistry. J Gerontol, 1956: 11: 298-300
Hirayama, T. (1985) A large-scale cohort on cancer risks by diet with special refernce to he risk reducing effects of green-yellow vegetable consumption. Prncess Takamatsu Symp, (USA), vol 16, 41-53.
Holford, P. (1997). The Optimum nutrition bible, Judy Piatkus (publishers) Ltd.
Karlsson, J. (1997). Antioxidants and exercise, Human Kinetics.
Kawai, Y. Shomomitsu, T. Takanami, Y. et al. Vitamin E level changes in serum and red blood cells due to acute exhaustive exercise in collegiate women. J Nut Sci Viaminol (Tonkyo), Jun:46 (3): 119-24
Mayo Clinic information, (2003). Mayoclinic.com
Meydani, M. Evans, WJ. Handelman, G. et al. (1993). Protective effect of Vitamin E on exercise induced oxidative damage in young and older adults. Am J Physiol May: 264
Pryor, WA. (1986). Ann Rev Physiol, 48:657-667
Pullen, S. (2002). Exercise; free radicals and antioxidants, from ptonthenet.com.
Qunitanilha, A. (1989). Handbook of free radicals and antioxidants. CRC Press.
Singh, A. Faila, ML. Deuster, PA. (1994). Exercise induced changes in immune function:effects of zinc supplementation. J Appl Physiol Jun:76(6): 2298-303
Thompson, D. Williams, C. McGregor, SJ. Et al. (2001). Prolonged vitamin C supplementation and recovery from demanding exercise. Int J Sport Nut Exer Metab Dec: 11(4):466-81