Supplements are nutrients that enhance the dietary requirements for optimal health. Supplements are also used to provide specific nutrients for specific conditions, for example Coenzyme Q10 in heart disease. Supplements are necessary in many cases where the dietary intake is lacking in essential nutrients due to poor quality food, stress, overwork, increased demand due to sporting activities, when recovering from disease, during pregnancy and lactation, food grown in suboptimal soils, for example in Australia our soil is poor in selenium and magnesium, increased need of nutrients related to social habits such as smoking and alcohol consumption and in many more situations.
Supplements are usually grouped as Vitamins, minerals and trace elements and most supplements come in combinations that are suited for specific conditions or target specific organs and systems, eg hormonal.
One should always get professional advice before taking supplements and to make sure that the supplements are of high quality. Some of the cheaper supplements do not deliver what they claim. For example, one should always source fish oils from fish that have been harvested in the wild as they have optimal levels of omega 3 fatty acids, whereas fish oils derived from farmed fish do not have adequate levels of these acids and may also contain traces of antibiotics and other contaminants.