What are supplements?

Supplements are normally tablets, capsules, potions and powders that are designed to correct for a deficiency or to enhance health. They are classified by the companies that sell them in different ways, some of which are quite arbitrary. Below, I've classified supplements so that you can see how they originate, what function they serve in the body and learn some more useful facts about them.  Next week I'll address the question of when and how it is sensible to supplement, as well as looking at which suppliers are most reliable.

Vitamins along with minerals are sometimes referred to as micronutrients. This distinguishes them from macronutrients such as protein, fat and carbohydrate. Note that virtually all supplements, except for some herbs and synthetic vitamins, are likely to be found in commonly consumed foods.

Classes of supplement.


  • These are chemicals produced by plants, fungi, animals and bacteria. They are needed in our diet because we cannot produce them ourselves.  If we were able to produce enough of them they would no longer be called vitamins, and would join the very long list of organic chemicals that we produce naturally in our bodies. So vitamins can be produced by other forms of life, but not us. For instance, vitamin C is produced by oranges and also by cats. However, cats don't need to consume vitamin C, but we do, and we get it by consuming plants that make it such as the orange.
  • Looking at the diagram to the right you can see there are two different types of vitamin, those that dissolve easily in water and those the dissolve best in fats. This has important consequences, as to absorb fat soluble vitamins most effectively, it is best to consume them with foods containing fats. Nature does this for us. For instance vitamins A and D are found in fat containing foods like cheese, milk, liver and oils. Vitamin C is found in watery foods such as fruit and vegetables.
  • Because vitamins were discovered by scientists in a certain order the letters used to name them are essentially random, and don't indicate any ordered relationship. The vitamin B group contains chemicals that are quite different. They include B1, B2, B3 , B5, B6 and B12 as well as biotin and folic acid. Other vitamins, such as D, contain different chemicals, e.g. D2, D3, but they are all chemically quite similar. Note that most vitamins have other chemical names. So vitamin B1 is called thiamin and vitamin C, ascorbic acid etc.


  • These are chemical elements that are impossible for us to produce. In fact you can only produce these from scratch in a particle accelerator on the sun. We need them in our diet as they also help our body function normally. Iron for example is needed to enable oxygen to be transported in our blood to the muscle fibres. Sodium and potassium enable our nerves to transmit the nerve signals that allow us to have a sense of touch. Minerals like vitamins can be termed, micronutrients. The following minerals are essential in our diet: Sodium, potassium, calcium, magnesium, zinc, iron, iodine, chromium, selenium and manganese. The ones that are most regularly supplemented are iron, especially for women of child bearing age.
  • There are minerals that are toxic and that we wish to avoid. These are the heavy metals such as cadmium, aluminium and lead as well as mercury.


  • These are proteins, fats and carbohydrates. The carbohydrate found in grains, sugars and root vegetables are not essential for the human body. It's true they are handy as a source of energy, but we can produce them from fat and protein. This explains how eskimos survive, and how many of our ancestors, living in colder climates would have survived. When it comes to fats there are some components called essential fatty acids that we need to consume in our diet. There are also some components of protein called essential amino acids that we need to consume. Eating meat or fish provides all these things, although not necessarily in optimal amounts.
  • You will find both amino acids and fatty acids are available as supplements. For instance, amino acids are a popular supplement with bodybuilders. They try to maximise the rate at which their muscles create protein by consuming the building blocks of protein, amino acids. Another supplement you'll often come across is omega 3 oils, such as cod liver oil or flaxseed oil. Omega 3 fatty acids are used by our body to produce eicosanoids. These help control our bodies response to injury and illness. They also control aspects of our circulatory system, such as our blood pressure and the ability of our blood to clot. This is why omega 3 fish and their oils are often marketed as being able to improve the health of our heart and circulation.

Animal biochemicals 

  • These are chemicals naturally produced in us, or sometimes inside the bodies of other animals. If we needed them to remain in good health and couldn't produce them, then they'd be called vitamins. As naturally occurring substances, we may have enough of them for our needs or we may be deficient. In some instances as we age some of these substances become a bit thin on the ground. Examples include carnitine, lipoic acid and coenzyme Q10, all of which serve multiple functions throughout the body. You'll find plenty of these sold by supplement companies, and it is worth knowing that you actually do produce them naturally.
  • Digestive enzymes are another type of organic chemical produced in human bodies that can be supplemented. They are designed to work in the digestive tract.
  • In contrast, glandular products are most often taken from pigs or cows. I'm sceptical about glandular products as they are essentially proteins that get digested (broken down) when you eat them. How these broken down proteins can then affect our own glandular functions is unclear. I've not seen any valid science that suggests they have an effect.

Naturally occurring bacteria

  • Our guts normally contain about one thousand trillion bacteria. That is a lot, and more than 10 times the total number of cells in our body. These bacteria start to appear in our guts shortly after birth and many come from the mother's milk. They are generally good for our health, helping to boost our immune defenses and keeping our digestive system healthy. However sometimes disease-causing bacteria are introduced from outside, or develop within us when our defences are weak. When this happens a condition called gut dysbiosis occurs (literally meaning bad bacteria in our gut).
  • Probiotics are supplements that contain gut friendly bacteria. They are used when people have digestive problems, have taken antibiotics, or to improve immunity. Probiotics are also found in various foods such as yoghurts. The commercial yoghurts that contain live cultures of bacteria are normally termed probiotic, Biolive or live yoghurts.
  • Prebiotics are foods that feed the good bacteria, encouraging them to proliferate at the expense of bacteria that are harmful. Such foods include Jerusalem artichokes, leeks, onions and bananas. Although they exist, there are not currently many prebiotic supplements. As such, knowing what foods to eat to encourage your good bacteria, is rather useful.


  • These are organic chemicals found in plants and algae, that are often beneficial for our wellbeing. There are many different types of phytonutrient. The best known are the flavonoids and carotenoids. 
  • Flavonoids come in many different types such as the anthocyanins found in berries, flavanols found in tea and cocoa, isoflavones found in soya and tofu, flavonols found in onions and apples and flavanones found in citrus fruit. They are not well absorbed in most people, with absorption rates typically of about 5%. Despite this they are able to change the way our body's cells communicate with each other. They induce changes that can be beneficial for blood pressure and reduce the risk of certain cancers. They also are associated with a reduced risk of neurodegenerative diseases like Parkinson's and Alzheimer's. For younger people, flavonoids have been associated with improved brain function.
  • The presence of good bacteria in the gut allows more flavonoids to be absorbed.
  • Carotenoids are pigments that typically give plants yellow, orange and red colours. However, although they are red, yellow and orange pigments they can be hidden by other colours in vegetables, and so some are also contained in green vegetables. Examples include the lycopene in tomatoes, beta carotene in carrots and lutein in spinach. The health benefits of carotenoids include reduced likelihood of eye degeneration, including cataracts and reduced likelihood of some cancers. All carotenoids are fat soluble, meaning that they can be stored in the body for extended periods of time. Being fat soluble they are best consumed with fats, to ensure their absorption from the intestines. So tomatoes fried lightly in olive oil will provide more carotenoids than cold tomatoes. Carotenoid supplements are generally better absorbed than carotenoids in food as they are specially mixed in with oils. Note that cholesterol reducing drugs such as cholestyramine (Questran) and colestipol (Colestid), can reduce absorption of fat-soluble vitamins and carotenoids.


  • Herbs are plants that we use for medicinal purposes. They can have beneficial effects on our health, but they are not required for us to function properly. Well known examples include echinacea, ginkgo biloba and silymarin. Because whole plants are involved the quality of herbal remedies can vary enormously with different parts of the plant being used and different strains of a plant being used. Varying the parts of the plant or the strain used normally makes a big difference to the quality of the herb.
  • Herbs that are used orally are administered in a variety of forms. These include tinctures (soaked in alcohol), infusions (soaked in boiling water) and decoctions (simmered for 30 minutes). As with all supplements it is important to get the dosage correct. Being aware of the size of a teaspoon, dessertspoon, tablespoon and standard cup are all vital to the correct administration of herbal remedies.
  • While herbs are safer than most medicines it is wise to exercise caution when using them. Several herbs interact with common medicines in a way that makes them potentially dangerous. For instance, St John's Wort (anti-depression) should not be used with antibiotics, other anti-depressants or immune suppressants. Ginkgo biloba and angelica should not be used with anti-coagulant medications such as warfarin and heparin.
  • It is also possible that herbs will induce allergic reaction in some people. If you have suffered allergic reactions before it would be wise to consult a qualified herbalist before taking any.
  • Please note that most nutritional therapists, dieticians or nutritionists are not qualified to administer herbal remedies. There is a lot of knowledge involved in the safe selection of herbs, and unless the herbal remedy you are taking has a good safety record it is always best to consult somebody who has some specialist knowledge about them.


So are supplements worth taking? That would depend on which of the views below you hold?

  • Sceptical - Some people think that all their nutrition should come from their diet. This is an attitude that is often encountered in the medical profession and some Government sponsored nutritional bodies. Sceptics would only supplement if they knew they were clinically deficient in a particular vitamin or mineral.
  • Cautious user - Others will supplement if there is an established need. If there is good evidence from scientific studies or personal experience that suggests a health benefit, then supplements would be used. I would put myself in this category.
  • Enthusiast - You will also find many people, including many of my colleagues in the nutrition and alternative health industries, that will have a try it and see approach. They often use multi vitamins as a sort of health insurance policy and may end up taking a wide range of supplements as they all offer the potential for major health benefits.

My experience is that people seem to mostly sceptical or enthusiastic. A cautious and studied approach is less common. This is entirely understandable, as the research required to be sure you are not, 1) Being duped by product marketing for a supplement or 2) are deficient in an important nutrient, is potentially  vast.

There are several things to bear in mind when choosing which of the above camps you should sit in.

  1. The price of supplements can add up quickly, so if you aren't wealthy it is prudent to be sure you are getting some benefit.
  2. Some supplements can interact with medications or even foods. Are you sure what you are doing is safe for you?
  3. What is good for one person is not very likely to be good for you. We are all different, and our needs for supplements varies enormously.
  4. If you are completely sceptical, I would remind you that there are a huge number of good quality scientific studies supporting the use of most types of supplement in certain circumstances.
  5. Supplement and sports product companies are out to make money and their marketing can be misleading. Many scientific studies are subject to bias, and especially if they are industry funded.