Micronutrients and the food you eat
Published: September 05, 2014
Micronutrients are vitamins, and minerals, which are required by your body in small amounts. Vitamins and minerals are essential nutrients which in most cases cannot be synthesised within your body and must come from the food and beverages that you consume.
Vitamins are organic coumpounds that have specific functions within your body. Vitamins support growth, reproduction and the maintenance of body functions which contribute to health and life. Vitamin deficiencies can result in less than optimum body function; the greater the deficiency of a specific vitamin the greater the loss of a specific body function.
Unlike carbohydrates, proteins and fats, vitamins are not an energy source; instead vitamins contribute to the many metabolic reactions which release energy from carbohydrates, fats, and proteins as well as the many other metabolic reactions that occur in your body. Specific vitamins are required for various processes within your body such as your eye sight, and the synthesis of your skin, hair, and bone.
Vitamins are generally required in very small amounts measured in micrograms (mcg) or milligrams (mg). All the vitamins that you require are available from a variety of food.
However, the bioavailability of vitamins (the amount of the vitamin that is absorbed and utilised) is dependent on a number of factors including: the efficiency of your digestive process, nutrient intake, nutrient status, the combination of foods you consume at the same time, and how you prepare, cook and store your food.
Vitamins are divided into two groups:
- Fat soluble: vitamin A, vitamin D, vitamin E, and vitamin K
- Water soluble: Thiamine (B1), Riboflavin (B2), Niacin (B3), Biotin (B4), Pantothenic acid (B5), vitamin B6, Folate, vitamin B12, and vitamin C
Although your body produces "vitamin D" when your skin is exposed to direct sunlight this "vitamin" is considered essential as it is a necessary metabolite in several important metabolic processes and some people, for a variety of resons, may not synthesise sufficient vitamin D. In addition, despite its designation as a vitamin, vitamin D has hormone-like properties.
Vitamin K is produced by bacteria in you intestine, but as with vitamin D, the amount may not be sufficient to meet a person's daily requirement thus a dietary source of the vitamin is required.
Within the body, water soluble vitamins are contained in watery fluid compartments of your body cells and fat soluble vitamins are stored in your fat tissue and your liver.
In general, water soluble vitamins are not stored in your body and excess water soluble vitamins are excreted in the urine on a regular basis. Therefore, water soluble vitamins need to be consumed regularly.
Although it is unlikely that you will consume toxic amounts of vitamins when the only source is food, in some instances, particularly if excessive doses of supplemental vitamins are consumed on a regular basis, vitamin toxicity may occur which may be harmful to your body.
Minerals are inorganic elements such as calcium, iron, sodium, zinc, and potassium which cannot be altered in any way and once in your body remain in your body until excreted.
Minerals may combine with other elements to form salts, but the chemical identity of the mineral is not changed. For example, sodium and chloride together form sodium chloride (table salt), but sodium remains sodium and chloride remains chloride.
Minerals are easily preserved during food preservation and cannot be destroyed by heat, acid, air or mixing. When food is burned the resulting ash contains the minerals that were in the food.
However, minerals can leech into water or other fluid cooking mediums during the cooking process. If the liquid is discarded then the minerals will be lost.
Major and Trace Minerals
You need major minerals, calcium, phosphorus, potassium, sulphur, sodium, chloride, and magnesium in amounts measured in 100s of milligrams or grams. You need trace minerals, iron, zinc, copper, manganese, iodine, and selenium in smaller amounts which are measured in 10s of milligrams or micrograms.
Both major and trace minerals are essential for your health and the importance of a mineral is not determined by the amount of the mineral required. Trace minerals are as important as major minerals.
As with vitamins, minerals have various roles in your body.
Minerals do not have the same bioavailability. The way in which your body absorbs and excretes minerals varies according to each mineral. In some foods, minerals are bound with other minerals or substances (phytates and oxalates) which impair absorption.
For example, although spinach is a good source of calcium it contains oxalates which reduce calcium bioavailability to less than 5% of the total amount of calcium contained in a serving of spinach.
Interactions between minerals may also affect the bioavailability of certain minerals especially when there is an excess of one mineral over another.
When sodium intake is high, both sodium and calcium excretion increases. High intakes of phosphorus impair magnesium absorption.
Mineral toxicity is unlikely to occur if your mineral source is unprocessed food. However, consumption of large amounts of supplemental minerals may become toxic and lead to adverse health effects.
A group of non-nutrient plant compounds, phytochemicals,have biological activity in your body and also contribute to your metabolic processes and health.
In general, the majority of the vitamins and minerals that you require for your body to function optimally are available in food and beverages. Eating well by consuming adequate amounts of the foods that contain these essential vitamins and minerals will help you maintain a healthy body.
Whitney, E. & Rady Rolfes, S. (2005). Understanding Nutrition. Belmont, CA: Thomson Wadsworth
Gropper, S.S., Smith, J.L. & Groff, J.L. (2005). Advanced Nutrition and Human Metabolism (4thEd.). Belmont, CA: Thomson Wadsworth.