It is also required for maintaining the integrity of the cell's membrane and keeping junctions between cells intact which is critical for absorption. These are all highly important functions and thus serum levels of calcium are precisely controlled. If external sources of calcium are not available, the body will requistion calcium from the bones.

Natural food sources include dark leafy greens, broccoli, dairy products and yogurt (no surprise), oranges and asparagus. Absorption is the key to efficient utilization of calcium and requires vitamin D and a parathyroid hormone to ensure good absorption.

Calcium is one of the most important of all minerals in food but it is important to know that it is absorbed better is some foods than others. Calcium in milk and diary products are easily absorbed but not so much in the green vegetables.

Without phosphorus, the acid-base balance, called the pH factor, in our body would be out of kilter and our nerves, muscles and kidneys wouldn't work right.

Without potassium, the water level in the body would be out of balance and couldn't regulate blood pressure.

Phosphorus is found in most foods but dairy products, meat, and fish are particularly rich sources.

Bananas have a reputation as being rich in potassium but in reality they are pretty far down the list. Foods containing a much higher content of potassium would be soy flour, fresh apricots, tomato puree, figs, raisins and wheat bran.

If that weren't enough, about 300 different enzymes depend on magnesium to perform their duties; particularly those that make adenosine triphosphate (ATP), the fuel that powers our body and those that assist in the construction of DNA and RNA.

In relation to bones, about 50% of our body's magnesium is stored in our bones with the rest residing in the cells of tissue and organs. Magnesium and Calcium work together as partners in that Mg enhances the absorption of Ca in the intestine. This wonderful mineral has also been used to treat or prevent cardiovascular disease, diabetes and hypertension.

Another use for magnesium is in the mitigation of migraine headaches. For a very detailed discussion of Mg and migraines, go to http://www.help-for-migraines.com/magnesium-migraine.html.

In general, green vegetables (those containing chlorophyll) will contain magnesium; for example just a half cup of cooked spinach contains 66 mg of Mg.

Most people do not get enough Mg in their diets so supplementation is called for in many cases. If taken as a supplement, an upper limit of 350 mg/day has been established however, it is difficult, if not impossible, to get a magnesium overdose from food.

Most of our sodium comes from normal table salt (NaCl); about one-third from the salt shaker. Another third we get from processed foods and the last third from the food itself.

Copper is obtained from organ meats, shellfish, lamb, pork, tofu and nuts. Whole grain cereals, dairy products, lentils, mushrooms, dried beans, canned tomatoes, curry powder and chocolate are also great sources for copper.

Spices and brewers yeast contain the highest concentrations and meat, dairy products and eggs are also good sources.

Since most food is low in flouride, many communities fluoridate their municipal water supply. A few foods that are higher in flouride include tea, grape juice, sardines, fish and chicken.

The thyroid gland, kidneys, salivary and gastric glands all compete for free iodide. In fact the thyroid must trap about 60 ug of iodide per day to maintain thyroxine levels. Thyroxine is the major hormone excreted by the thyroid and function to increase the number and activity of mitochondria in cells by binding to the cells' DNA, increasing the basal metabolic rate.

Thyroxine causes an increase in the rate of carbohydrate metabolism and a rise in the rate of protein synthesis and breakdown. Thus a deficiency of iodine can lead to major problems with our metabolism.

When it comes to minerals in food, the iodine content of food (and water) is related to the iodine content of the soil. The primary food source is seafood but most people get adequate intakes of iodine from using iodized salt.

When the cell completes its job, it dies. Wouldn't it be a good idea to be able to replace all those dead cells. That's where iron comes in. Blood cells are pretty important to our well being and iron is critical to making new red cells and white blood cells in the immune system.

Iron also promotes normal brain function. Hmm, maybe Congress could use a little more iron.

There are two forms of dietary iron known as heme and non-heme and without going into detailed explanations, let's just say that the importance of which it is relates to absorption by the body.

Heme iron is found only in meat, fish and poultry and is absorbed much more easily than non-heme iron, mostly found in fruits, vegetables, dried beans, nuts and grain products.

It has received a lot of attention for the prevention of prostate cancer but the evidence shows that the apparent benefit is limited to men with low basal plasma selenium and/or those who smoke.

An upper limit of 400 ug per day has been set to avoid the possibilty of selenium toxicity.

The best sources are Brazil nuts and kidney although neither are common foods in most diets. Moderately good sources are fish, shellfish, organ meats and whole grains while fruits and vegetables are poor sources of selenium. Organic selenium minerals in food are absorbed best while inorganic is poorly absorbed. If supplementing with selenium, be sure to use a brand that is plant sourced.

Zinc mainly comes from protein rich foods such as beef, lamb, pork, crab, turkey, chicken, lobster, clams and salmon. Vegans have to get their zinc from milk, cheese, yeast, peanuts, beans, whole grain cereals, brown rice, whole wheat bread, potato and yogurt. Even so, vegans would be wise to supplement for adequate zinc intake.

Manganese helps process blood sugar; makes DNA, connective tissue, cholesterol, and energy to help with brain function.

Molybdenum helps fat burn and works to keep the liver, kidneys, teeth and bones healthy.

Manganese and Molybdenum both come from green leafy vegetables, tea, whole grain cereals, beef liver, blackberries, lima beans, pinto beans and sweet potatoes.

Some possible health benefits include support of growth, healthy skin and bone structure. It influences absorption of iron and may also play a role in production of red blood cells.

Nickel is found in oatmeal, dried beans and peas, nuts, and chocolate.

Before leaving the introductory page to minerals in food, it would be good to show what the government recommends as a Dietary Reference Intake (DRI) for some of the minerals listed above.

A DRI isn't just one number, it is a set of guidelines that includes Recommended Dietary Allowances (RDA), Adequate Intakes (AI) and Estimated Average Requirements (EAR); all segregated by age group, sex and lactation/pregnancy.

For our purposes, we will only give the RDA for some of the macro and trace minerals for male and female adults strictly to bring home how small the actual requirements really are.

Given the small amounts of dietary minerals we need, it becomes very easy to consume an excess of one or more minerals through supplementation.

An excess of particular minerals can create a host of collateral problems in absorption and bioavailability resulting in deficiencies and other issues that affect our homeostasis (balance in total bodily functions).

The important point is that an "RDA is the average daily dietary intake sufficient to meet the nutrient requirements of nearly all healthy individuals in a group". The key words here are "average" and "healthy".

The numbers will not apply to malnourished or sick people who will in all likelihood need to adjust their intakes depending on their medical condition with guidance from a qualified health provider.

If anyone wants to study the tables developed and published by the Food and Nutrition Board of the National Academy's Institute of Medicine just click on DRI Tables and away you go.

Recommended Dietary Allowances for 31 - 50 Year Old Adults

Note that a mg is 1000th of a gram; a ug is one millionth of a gram. There are 28.4 grams in an ounce so with many of these elements we are seeing some very, very small amounts.

That concludes our peek at the 17 essential minerals in food; and believe me, it was just a peek. The physiology of minerals in the body is extremely complex with vast implications for our health.

In general, it is imperative that we supplement our diets with natural, plant sourced vitamins and minerals...but even this statement is too simplistic.

For example, as was mentioned above, iron from red meat (animal sources) is heme-iron. Iron from vegetable sources is non-heme iron. The source of the iron greatly affects how well it is absorbed in the body.

Animal sourced iron is readily absorbed but not so with plant sources. As a general rule, plant sourced vitamins and minerals in food are superior for absorption but there are exceptions to every rule.

the next logical step in the study of essential nutrients is amino acids. However, before jumping to amino acids, be aware that a few of the minerals in food that were presented above have been singled out for more extensive coverage in separate pages.

You can navigate to them by clicking on magnesium, selenium and zinc.

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