When one or more of these micronutrients are lacking, metabolic reactions may slow down or even fail, so your cells cannot function properly. Despite their importance, most of these micronutrients cannot be made in the body and so must come from your diet. The few that can be made (niacin, vitamin D) are rarely produced in sufficient amounts to meet your needs, and are also classed as ‘essential’. Although vitamins are necessary for health, you only need to obtain tiny amounts from your food. The quantities needed are measured in milligrams (mg) or micrograms (mcg). VITAMIN UNITS 1 milligram = one thousandth of a gram (1/1,000 or 10−3 grams) 1 microgram = one millionth of a gram (1/1,000,000 or 10−6 grams) 1 milligram therefore = 1,000 micrograms. How do you know how much you need? Everyone has different, individual needs for each vitamin and mineral, depending on their age, weight, level of activity and the metabolic pathways and enzyme systems they have inherited. Some people need more vitamins and minerals, while some need fewer.
