Nutrition - Free Fitness Library
Are you a pill popper? the ins and outs of vitamins
By Anita Bean BSc
There is such a bewildering array of vitamin and mineral pills on the shelves. Do you really need to take them and how would you decide which one is best for you?
Can a balanced diet provide all the vitamins and minerals I need?
Yes, in theory you should be able to get all the vitamins and minerals you need from a well-planned diet that includes a wide variety of foods from each of the main food groups in roughly the proportions recommended by the Department of Health (see below).
However, in practice many people do not plan their diets well or they restrict their calorie intake so it can be difficult to obtain sufficient amounts of vitamins and minerals from food. Vitamin losses also occur during food preparation and cooking, thus further reducing your actual intake.
Achieving a Balanced Diet*
Portions / Day
Cereals and Starchy Veg / 5 - 11
Fruit and Vegetables / > 5
Milk and Dairy Products / 2 - 3
Meat, Fish, and Vegetarian Alternatives / 2 - 3
Oils and Fats / 0 - 3
* National Food Guide, DoH, 1994
When may supplements be useful?
Eating a balanced diet may not always be easy and you may wish to take a supplement as a form of insurance. For example, if you are travelling a lot or eating on run and unable to purchase and prepare your own meals. Also, if you eat less than 2000 calories a day for a period of time it is unlikely that you can get enough vitamins and minerals. Remember: Aim to get your vitamins and minerals from your diet rather than relying on supplements.
Who may benefit from taking supplements?
If you think you may be lacking in vitamins and minerals, adjust your diet to include more vitamin and mineral rich foods. Supplements are not a substitute for poor eating habits. However, you may benefit from taking a supplement if :
* You have erratic eating habits
* You eat less than 2000 kcal a day
* You are pregnant (folic acid)
* You are out a lot/ rely on fast foods
* You are a vegan (Vitamin B12)
* You are anaemic
* You have a major food allergy or intolerance (e.g. milk)
* You are a heavy smoker or drinker
* You are ill or convalescing
Does exercise increase my requirements?
Regular intense exercise increases your requirements for a number of vitamins and minerals, particularly those involved in energy metabolism (e.g. B vitamins), tissue growth and repair (e.g. vitamin A, zinc), red blood cell manufacture (e.g. iron) and free radical defence (e.g. beta-carotene, vitamins C and E). However, you should be able to meet these needs by a corresponding increase in your food. There is a direct relationship between food intake and vitamin/mineral intake - the more you eat, the more vitamins and minerals you get.
Will supplements improve my physical performance?
While a deficiency will adversely affect your performance, there is no strong evidence that taking supplements in excess of your requirements will improve your physical performance. To find out if your diet is deficient in any nutrient, you should consult a qualified nutritionist (look for the initials BSc or SRD) for a dietary analysis. He or she will then be able to advise you about your diet and supplementation if necessary.
Can supplements be harmful?
Some vitamins and minerals taken in high doses can be toxic. For example, excess vitamin A can cause nausea, skin changes, liver damage and birth defects in unborn babies. Too much vitamin D can cause high blood pressure and kidney stones, excessive doses of vitamin B6 may lead to numbness and unsteadiness, and high doses of iron can cause constipation and stomach discomfort. Always follow the guidelines on the label and never take more than 10 time the RDA of any of the above nutrients.
Can supplements cause imbalances?
Taking large doses of selected vitamins or minerals can lead to imbalances because many micro nutrients interact with each other. For example, iron, zinc and calcium share the same absorption and transport system so taking large doses of iron can reduce the uptake of zinc and calcium. It is safest to choose a multivitamin and mineral formulation rather than individual supplements. If in doubt, you should consult a doctor or nutritionist.
Is it worth taking antioxidant supplements?
There is good evidence that antioxidant nutrients (e.g. beta-carotene, vitamins C and E, selenium, bioflavanoids) found chiefly in fresh fruit and vegetables may help protect against heart disease, certain cancers and post-exercise soreness. However, supplements may not be the best solution since we do not know the optimal dose nor whether it is possible to replicate all the other substances in foods which have antioxidant properties. Aim to get as much as possible from your diet (at least 5 portions of fruit and vegetables a day). If you do decide to take a supplement choose one which contains several antioxidants in moderate rather than high doses.
Are natural vitamins better than synthetic?
Natural or food source vitamins claim to be better absorbed but, for the majority, there is no difference. One exception is vitamin E which is better absorbed in its natural form, called d alpha tocopherol.
Are time release supplements better?
Time release vitamins are coated with protein and embedded in micropellets so, in theory, may take longer to dissolve and get absorbed. There is little evidence they are better for you; best advice is to take any supplement with a meal.
How should I choose a supplement?
Here are some basic guidelines:
* If in doubt, choose a multivitamin/mineral supplement
* Check it contains all the main vitamins and minerals (vitamins A,
C, D, E, beta- carotene, thiamin, riboflavin, niacin, pyridoxine, vitamin
B12, folic acid, pantothenic acid, biotin, calcium, iron, zinc) in amounts
roughly equivalent to the RDA. This will be stated on the label
* Avoid high dose supplements - they won't do you more good and they
cost more
* Multivitamin, mineral supplements which highlight their antioxidant
content are worth looking out for
* Expensive brands are not neces sarily better for you.