Nutrition - Free Fitness Library
The maze of nutritional supplements
Dr R E Lister
"Why should I take nutritional supplements?", "Will they do me any good?" and "IF I take them, which ones should I take?". These are questions that I am constantly being asked. In this article, I will try to provide brief answers to these questions by covering the major nutritional or dietary supplements that are readily available in high street stores or by mail order. The price of these products can vary widely. Some companies can offer products cheaply by avoiding undertaking proper analytical control procedures and minimising the amount of active ingredient. Products from quality manufacturers will usually include information on the pack about the levels of quality control used and as with many products you get what you pay for. All makers of supplements must state the nature and amounts of active ingredients in the preparation. For vitamins and minerals the RDA (the Recommended Daily Allowance) determined by the EU must be stated where these have been determined. The RDA is the minimum amount considered to be needed by the average person in order to remain healthy. However every individual has a different requirement, those following tough exercise regimes have different requirements from a chair-ridden pensioner.. This has been recognised by the Department of Health who have provided Recommended Nutrient Intakes (RNI) for some nutrients for which a RDA has not been established.
Supplements can be divided into two groups, essential and non-essential. The essential nutrients can be further classified into MACRONUTRIENTS, those that are required in large amounts to build and maintain the body e.g. protein and calcium and MICRONUTRIENTS that are required in smaller amounts e.g. most vitamins and minerals. Non essential nutrients are not necessary for existence but can help to provide optimal nutrition, these include the Superfoods that are complete foods that can make up for multiple deficiencies e.g. Spirulina. The major macronutrients, proteins, fats and carbohydrates will not be dealt with.
Below is a brief guide to the type of nutrition supplements which are widely available and for which exists well established evidence for health benefits.
Vitamins are natural substances derived from food that are required
by the body in small amounts if it is to function normally. The majority
of the 15 vitamins must be provided in the diet but four of these can
be made by the body from other nutrients but only in small quantities
which are often insufficient to meet the needs of a healthy active body.
| Boron | Works with calcium | Most foods | May be toxic; enough in diet | |
| Calcium | 800mg | Build bones and teeth, needed for cell function and blood clotting | Milk, cheeses, yoghurt, fish, nuts, pulses, cereals, flour | Pregnant and nursing mothers, children, inhured athletes, vegans, post menopausal women, the elderly. |
| Chromium | Sugar metabolism | Eggs, meat, wholemeal bread, yeast | Low and high blood sugar, slimmers, high fat and cholesterol levels | |
| Cobalt | Part of vitamin B12 | Vegetables, seafood, meat | No need for supplement of this mineral | |
| Copper | 1.2mg | co-factor of many enzymes, aids iron absorption | Liver, seafood
pulses, olives, nuts, cereals, yeast |
Anaemia, arthritis, poor hair |
| Fluoride | Builds teeth and bones | Tea, some drinking water | Prevents cavities in children | |
| Iodine | 150mg | Regulates energy production, part of thyroid hormone | Fish, kelp, meat | Children, usually only needed for thyroid deficiency, on medical advice |
| Iron | 14mg | Essential for blood production and oxygen utilisation | Seafood, red meat, yeast, soya, cereals | Tiredness, lack of stamina due to anaemia, women with heavy periods, vegans, vegetarian |
| Magnesium | 300mg | Needed by nerves and to release energy from food | Soya, nuts, wholewheat flour, seafood, rice, yeast | Pregnancy, athletes, anyone on poor diet or under stress or taking many prescribed drugs |
| Manganese | Growth co-factor for enzymes and hormones | Cereals, nuts, pulses, tea | May help in heart disease and diabetes | |
| Molybdenum | Works with iron and fluoride | Vegetables, wheat germ, liver | Dental cavities, anaemia, sexual dysfunction in males | |
| Phosphorus | 800mg | Needed for bones and burning sugar to give energy | Milk, yeast, soya, nuts, wheatgerm | Pregnancy, children, the elderly. Diet gives enough except for in some diseases |
| Potassium | Balances body fluid levels, nerve function, energy production | Dried fruits, coffee, tea, fruit juices, vegetables, flour | Before and after hard exercise, those taking diuretic drugs and for children and adults with chronic diarrhoea | |
| Selenium | 75mg | Acts as an antioxidant | Liver, seafood, garlic, onions | Arthritis, mercury poisoning, cataract, angina, cancer |
| Silicon | Needed for bone, hair and cartilage | Equisetum, many plants | Poor hair, skin and nails, stomach upsets | |
| Sodium | Controls nerve and muscle activity | All meats, fish and vegetables | Not needed unless for medical conditions | |
| Sulphur | Used to make proteins; in blood clotting and cell walls | Present in all proteins, garlic, onions, green leaves | Sulphur containing amino acids can help skin and nail disorders | |
| Zinc | 15mg | Needed for growth and many enzymes | Seafood, liver, yeast, meat, cheese, fish | Can help remove toxic metals, vegans, aids wound healing, improves appetite, loss of taste |
Essential nutrients are substances that the body cannot make or can only make in amounts that may be less than required to remain healthy and which normally come from the diet. There are two classes; essential amino acids and essential fatty acids. These do not have RDAs.
A good mixed diet normally supplies adequate amounts of the essentials amino acids; vegans should insure that they eat some grain based and some pulse (bean)based foods as this will provide all the essential amino acids needed for good health. Certain medical conditions can be helped by taking specific amino acids but these should only be taken following advice from a qualified medical or nutritional practitioner.
Western diets and low fat diets may be deficient in essential fatty
acids (EFAs) that are needed to build and maintain nervous tissue and
as the starting materials more complex fatty acids and making for hormones
known as prostaglandins (PGs). Stress, drugs and pollutants can impair
the synthesis of the higher fatty acids and supplements containing them
can be helpful in a number of conditions.
| EFAs | |||
| Linolenic acid;
(an omega 6 EFA) |
Provides energy, makes cell walls | Cooking oils, nuts, algae, meat, milk, soya, margarine | Dry skin, atherosclerosis, arthritis |
| a-linolenic
acid (an omega-3 EFA) |
Part of cell membranes and nervous skin tissue | Cooking oils, algae, leaves, margarine, milk, butter | Skin disorders, helps wound healing |
| y-linolenic acid (GLA) (an omega 6 EFA) | Converted to PGs | Evening primrose & borage oils, spirulina | PMS, diabetes, eczema, thrombosis, alcoholism |
| EPA (an omega-3 EFA) | Converted to PGs | Oily fish, cod liver oil | High cholesterol and blood fats, arthritis, thrombosis, high blood pressure |
| DHA (an omega-3 EFA) | Part of cell membranes inc. brain and retina | Oily fish, cod liver oil | Pregnancy, lactation, arthritis, poor vision |
Superfoods is the name coined for those foods that contain all or most of the necessary nutrients to sustain life. Only a limited number of these are available commercially. They can be taken in addition to a normal diet to provide nutritional insurance. The most readily available are:
Spirulina is a microscopic blue-green algae originating from tropical Africa where it is still used as a total food by the local inhabitants of the region. Modern methods of cultivating and processing spirulina have led to an increase in it's nutritional value. It contains more and better quality protein than meat or soya beans and a full spectrum of vitamins, including vitamin B12, minerals, enzymes and essential fatty acids. A major advantage over many other foods is that it is easily digested and the nutrients are readily assimilated. Spirulina is free from saturated fats and the amino acids present can help to suppress appetite, it is a valuable supplement for use as a dietary aid for athletes and for vegans.
Chlorella is an algal product grown in cooler waters than spirulina. It contains a similar spectrum of nutrients to spirulina but as it's cell walls are tough it may need processing for maximum assimilation.
Aphanizomemum flosaqua is another blue-green algal product with similar constitution and nutritional properties to the previous two.
Barley and Wheat Grass concentrates have less protein, fatty acids and iron than the algae but more carbohydrates, vitamin C and folic acid. They are devoid of vitamin B12.
The above information is provided as guide only and is not intended as a substitute for professional medical care. If in any doubt about any health issue you should consult a health care professional.