Have you ever wondered why nutrient units are written in grams, milligrams, micrograms, and why you sometimes read about international units ‘i.u’s?
From the very first days when vitamins were isolated, at around the turn of the century, scientists have been working out how much of any certain vitamin or mineral was needed by the body.
It soon became apparent that some are needed in bigger quantities than others. Some are needed in microgram quantities; selenium, for example. Others are needed in larger mg amounts; zinc, calcium whilst others are sometimes expressed in grams – think of vitamin C – where, in the early days of nutritional therapy, it wasn’t unusual to see information from practitioners quoting ‘2g of vitamin C’. This is 2000mg.
Have you ever looked at a vitamin E product and noticed that it’s expressed as ‘international units’. Well, it might surprise you to know that there is no such thing as ‘vitamin E’ – no one single entity that exists in nature that we can pin the ‘vitamin E’ tag onto.
In fact, there are many different biochemical structures that have ‘vitamin E activity’. The technical name for for most common form of the vitamin E family is ‘tocopherols’; alpha-tocopherol, delta-tocopherol and others, and each of these gives a different amount of vitamin E activity.
In nature, tocopherols are often found together – in wheat germ oil, for example, or soya oil – and sometimes, on product labels, you will see the individual tocopherols listed in the nutrition information table. The amount of ‘international units’ in the product is the combined total of the different contributions that each tocopherol makes to the total activity.
You might like to know that there are strict rules about how nutrients should be written on packaging and the ‘units of measurement’ are included in these. This is to make sure that consumers get consistent information from product to product, helping you to compare strengths and helping with product safety too, by quick identification of the amounts within the product.