Encouraged by reports linking the mineral to cancer protection, people are buying – and taking – selenium supplements. In some Asia countries, they call selenium as the king of anti-cancer substances.  But, a few words of caution are in order.

At high doses, selenium can cause health problems. Fatigue and irritability, as well as brittleness or loss of hair, have been seen in patients suffering from toxic amounts of selenium. A research scientist exposed to too much selenium developed bronchitis and skin problems.

How Much is Too Much?

According to the Food and Nutrition Board of the National Research Council, a long term intake of 2400 to 3000 micrograms of selenium per day would be expected to cause a toxic reaction.

It is very unlikely that the diet could provide such a high level of selenium. In fact, there is only recorded instance of selenium toxicity caused by food. It dates back about seventy five years and occurred among people living in an area of the country where the soil was unusually rich in this mineral.

To overdose on selenium, you would probably have to work with it or take supplements. In 1977, the Food and Nutrition Board (U.S.) advised:

There is no justification at this time for the use of selenium supplements by the general population. Should selenium supplements eventually be condidered desirable for those persons living in low-selenium areas, or for those consuming vegetarian diets, a daily supplement of 50 to 100 micrograms could probably be taken safely. (Emphasis added.)

Five years later, in 1982, the Committee on diet, Nutrition, and Cancer (U..S.) seemed to agree with the Food and Nutrition Board’s opinion. “Increasing the selenium intake to more than 200 micograms a day…….. by the use of supplements has not been shown to confer health benefits exceeding those derived from consumption of  a balanced diet,” said tyhe panel.

Selenium in Our Diet

It is not easy to list the selenium content of common foods. The amount of selenium in meat, for instance, can vary. It depends partly on the amount of the mineral in the animals’ diets.

The selenium content of the soil also varies throughout the regions of each country. The soil content, inturn, greatly affects the amount of selenium in grains. But most of us  now eat foods grown from many parts of our country; no longer do we eat only foods grown nearby. Furthermore, recently so many foods were imported from Asia and other countries.

As a result, nutritionosts rarely see signs of selenium deficiency among Americans. The average selenium intake in the United States, for instance, is 150 micrograms per day, which is considered more than enough  for most people.

Good sources of selenium are:

• Meat and seafood
• Grains, unless, grown in soil low in selenium
• Asparagus and mushrooms
• Garlic
• Meats and seafood are the richest source of this mineral.

Fruits and most vegetables contain little selenium. The selenium content of dairy products and eggs varies.

Can Iron Help, Too?

Adequate iron in the diet prevents a condition called Plummer-Vinson syndrome. This condition has been linked to increased risk of developing stomach cancer and cancer of the esophagus.

Probing these findings, scientists have found that iron deficiency allows bacteria to grow in the stomach. It is possible that these bacteria turn nitrites into the cancer causing substances called nitrosamines.

But, as is the case with selenium, there is still not much evidence to go on. It certainly makes sense, though, to eat iron-rich foods (unless your doctor has advised against it. Some people, though not many, have a disorder that causes them to retain too much iron).

Iron deficiency is not truly widespread in some countries. But many people, such in case of Americans, don’t get the RDA for iron. This hardly means that all of these people have iron deficiency. The RDA is set higher than about 96 % of us need. It is not a requirement, but rather a “better-safe-than-sorry” approach.

The Best Sources of Iron

If you are concerned about your iron intake, consider some of these sources:

• Lean meats and shellfish
• Whole grain or enriched cereals
• Dried apricots, prunes, or raisins
• Nuts and wheat germ
• Dried beans and peas
• Leafy green vegetables

(  Next Story, the Part III )

It is an alluring idea. Some have even proposed that the quick fix already does exist – in the form of a mineral called selenium.

But the wishful thinking is a little premature. There is some evidence that the minerals in our food play a role in preventing cancer. More research is needed, though, before we can draw any conclusions.

The Minerals in Food

Food contains a wide range of minerals. We need some of them in large amounts. Other minerals are required in very small amounts.

Nutritionists refer to the minerals needed in large amounts as major minerals. Those that we need in small amounts are known as trace minerals or trace elements.

The most important major minerals are:

• calcium
• magnesium
• sodium
• chloride
• phosphorous
• potassium

There are many trace minerals. Scientists know a great deal about some of them, and very little about others. Some of the trace minerals include:

• copper
• chromium
• fluorine
• iodine
• iron
• manganese
• molybdenum
• selenium
• zinc

When it comes to minerals and cancer, research has focused only on trace minerals. None of the major minerals have been the focus of cancer research.

Too Soon to Tell

Most cancer institutions and foundations, including Committee on Diet, Nutrition, and Cancer (U.S.), made no recommendation about minerals. In general, the scientists found too little evidence for making judgment.
Some of them cited selenium and iron as the best-studied minerals. But though they found evidence that selenium may protect both humans and animals against some forms of cancer, the evidence was ruled preliminary.
Similarly, they found evidence that an adequate iron intake protects both humans and animals against cancer in the upper part of the digestive tract. But this findings, too, were considered inconclusive.

In this case, the Committee on Diet, Nutrition, and Cancer said that no conclusions could be drawn at all about the role of the following minerals in cancer prevention:

• copper
• zinc
• molybdenum
• iodine
• arsenic
• cadmium
• lead

It may surprise you to read the committee’s conclusions about these last three minerals – arsenic, cadmium, and lead. You may be aware that these minerals have long been linked to excessive cancer rates among workers who are heavily exposed to them. But occupational exposure to these minerals is many times higher than the levels that occur in food. For this reason, too, the committee declined to make any judgments.

The Selenium Story

Chances are that you have heard reports about the ability of selenium to prevent cancer. A few enthused promoters have inspired some people to take selenium supplements as a preventive measure.

The evidence that selenium helps to prevent cancer is promising but far from final. Research has shown, for instance, that:

1. Areas of the world where selenium intake is high have lower cancer rates than countries where the diet is low in selenium.
2. Blood selenium levels are higher in healthy people than in cancer victims.
3. Selenium added to the diet or drinking water of laboratory animals helps to protect against cancer-causing chemicals.

One problem with these findings is clear. Scientists can rarely know whether a cancer patient always had a low blood level of selenium. It is possible that the disease, once developed, cause a normal selenium level to drop suddenly.
Some research has yielded opposite results, showing no relationship between the selenium in the blood and the risk of cancer. But on the whole, the research on this mineral must be considered promising.

Oddly enough, there were once concerns that selenium might promote cancer. These fear have not been supported by the most recent research.
But research has shown that selenium can be toxic in other ways. Scientists hardly want to advocate a measure that will help prevent one disease but cause others instead.

By the way, I would be very grateful if you have some latest valuable information regarding this subject, never hesitate to write down on the comment board below.

( Next Story, the Part II )