Minerals
Minerals
Minerals are inorganic substances. At least 20 mineral elements are essential to our diet. We need minerals for the normal management of our bodies systems. They are an essential component of our teeth and bones (calcium, phosphorus, and magnesium), they help to regulate body fluids (sodium, potassium, and chlorine) and they are components of enzymes and hormones which regulate body functions, especially the nervous system. For example without calcium muscles quite simply cannot contract.
Minerals are absorbed by plants from the soil. To get access to minerals we eat the plants, or we eat the animals that have eaten the plants. However, minerals can vary in our diet depending on soil quality. As farming has become more intensive the soils are more vulnerable to mineral depletion and fertilising has become necessary to ‘top up’ the soil.
However problems such as run off (water running off the land) due to the size of soil particles once they have been turned and broken up a lot, can result in many of the nutrients being leached away into the waterways nearby (hence the often abundant growth of weed in some waterways) and not transferred through the food chain.
The age old method of farming (or cropping) by rotation was to plant a different crop in a field each year, thereby reducing the stress on the soil as different plants take differing amounts of nutrients from the soil. Every few years the farmer would grow some legumes (peas, beans) because they put nutrients back into the soil. It was much better for the food chain but not as much food could be produced, so as intensive farming grew to feed the nations, soil quality suffered.
So while there may be mineral deficiencies in the soil of your country you should check with your national nutrition guidelines to determine if any mineral supplementation is required. Often minerals are added to the soil or to food products to ensure that deficiencies in the soil are not transferred to the human food chain.
The following table highlights the major functions and common food sources of the major minerals required by the human body:
|
|
Functions |
Common Sources |
|
Iron |
Transport oxygen to body tissues and picks up CO2 for expulsion |
Meat (esp. red) and poultry, seafood, wholegrain breads & cereals, some green leafy vegetables |
|
Calcium |
Supports bone & teeth formation and remodelling, assists muscle contraction, blood clotting, cardiovascular health & iron metabolism |
Milk & dairy products, wholegrain breads & cereals, |
|
Potassium |
Helps conduct nerve impulses, is vital for muscle contraction, helps maintain normal heart rhythm and regulates fluid balance |
Green leafy vegetables, lean meat, some fruits, wholegrain breads & cereals |
|
Zinc |
Important for growth & neurobehavioural development, immune & sensory function and reproduction |
Lean meat and poultry, some seafood, nuts and seeds, wholegrain breads & cereals |
|
Magnesium |
Important for structure of bones and teeth, transmission of nerve impulses and muscle contraction |
Wholegrain breads & cereals, nuts, lean meat, poultry & seafood, some fruits & vegetables |
|
Sodium |
Important for energy transfer, fluid balance, nutrient uptake and the maintenance of a normal heart rhythm. |
Common salt whether added to food or in processed food |
|
Iodine |
Required for normal growth and development and the maintenance of normal metabolic rate |
Iodised table salt, low fat milk products, eggs & seafood |
|
Selenium |
Has important roles in control of thyroid hormone metabolism, reproduction and immune function |
Seafood, lean meat & poultry, eggs, wholegrain breads & cereals |
|
Fluoride |
Has role in bone mineralisation and protects teeth from dental caries |
Fluoridated water and toothpaste |
A few of these minerals do require special mention namely; sodium, calcium and iron.
Sodium
High sodium intakes are directly related to high blood pressure, one of the two major risk factors attributed to over 70% of premature deaths due to heart disease or stroke.
Because we often add salt directly to our food and increasingly eat more foods high in salt (takeaway foods, any heavily processed foods) our sodium intakes often dramatically exceed what is deemed to be healthy. Based on this it is quite obvious that encouraging clients to reduce or eliminate any additions of salt to their food and reduce their intake of highly processed foods is extremely important for their health and longevity.
Calcium
Calcium is the most abundant mineral in the body, at any one time it makes up about a kilogram of our weight. It forms part of the matrix of our bones and teeth, it is required to support the bone formation phase of bone remodelling, a process that continues throughout life. It is vital in muscle contraction and is needed for blood clotting.
Regular moderate (weight bearing) physical activity is good for calcium retention in bones whereas excessive physical activity with an inadequate diet is detrimental to bones. Everyday we excrete about 500mg of calcium in our urine so we need to replace it.
Rather than encouraging the supplementation of calcium, most national nutrition guidelines simply recommend people consume the recommended low fat intakes of milk and milk products and other foods containing calcium, such as wholegrain breads and cereals.
Calcium loss can also be minimised by reducing alcohol intake and ceasing smoking, two activities that if adhered to will provide numerous benefits for you and your personal training clients.
Iron
The percentage of iron absorbed and utilised by the body can vary from less than 1 percent to more than 30 percent. The main factor controlling iron absorption is the amount of iron stores in the body. Iron absorption from the gastrointestinal tract increases when the body’s iron stores are low, and decreases when stores are sufficient.
Because the iron from plant based foods is poorly absorbed it is often thought that vegetarians and vegans would be vulnerable to iron deficiency. If untreated iron deficiency can lead to iron deficiency anaemia where a person simply has less than the normal number of red blood cells or amount of haemoglobin in the blood.
Symptoms of iron deficiency include; abdominal pain, black faeces (signs of peptic ulcer), brittle nails, a sore mouth or tongue in conjunction with fatigue or a headache. Also pale complexion is sometimes anecdotally linked to iron deficiency (haemoglobin gives blood the red colour, so when it’s low, our complexion can appear pale).
Iron deficiency anaemia is actually very rare and iron supplementation is rarely required. Most national guidelines simply advise people who may be vulnerable to deficiency to include foods high in vitamin C at mealtimes (such as spinach!) as this helps increase the absorption of non-haem iron by two to three times, and to minimise the consumption of tea and coffee at mealtimes as substances called polyphenols within these actually hinder the absorption of iron, as well as ensuring they adhere to the guidelines for intake of all the major food groups.
