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United States Department of Agriculture

Agricultural Research Service

Nutrients keeps immune system in balance
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By Forrest Nielsen

The human body has a defense system called the inflammatory response, which is activated when the body is infected with bacteria and viruses, or is injured by trauma, toxins and other causes.

The response tells the body to make messengers called inflammatory cytokines. The cytokines tell special cells to go to places where they are needed to kill the bacteria and viruses and repair damaged tissue. These cells kill the invaders by making a reactive form of oxygen.

Fortunately, the inflammatory response is under tight control -- preventing it from making too many cytokines and too much reactive oxygen. Otherwise, damage to normal tissue will create problems that lead to degenerative diseases. Such diseases include arthritis, heart attacks, diabetes, some cancers and perhaps Alzheimer's disease.

Scientists now are checking to see if some medicines that lower the inflammatory response, such as ibuprofen (Advil) and naproxen (Aleve), also have an effect on preventing some of these diseases. However, these drugs often have unwanted side effects.

Significantly, some nutrients are involved in preventing the manufacture of too many inflammatory cytokines and too much reactive oxygen. These nutrients include the minerals magnesium, zinc, copper and boron.

But not all nutrients act in the same way to control the inflammatory response, so eating high amounts of one may not prevent the bad response caused by the lack of another. This means that gobbling single-nutrient supplements may not be the best plan to fight disease.

As an example, taking zinc supplements may help prevent colds and help fight infections when your diet is low in zinc. But taking high amounts of zinc will not prevent too many unwanted cytokines caused by a lack of adequate magnesium in the diet. Instead, the high zinc intake may make the low magnesium effect worse.

Research findings in the Grand Forks Human Nutrition Research Center have shown that a high zinc intake results in the body being less able to absorb magnesium it needs from food. A high zinc intake also results in higher amounts of magnesium being lost in urine.

Research in the center also has shown that some nutrients actually work in concert to keep the inflammatory response in check. For example, boron and the omega-3 fatty acids help each other to give good effects.

Nutrition scientists also have found that some foods themselves are very helpful in controlling the inflammatory response. Foods such as grape juice, chocolate, green tea and wine contain chemicals called phytonutrients that prevent the formation of too many cytokines caused by a poor diet.

One poor diet would be eating too much omega-6 fatty acids. These fatty acids spur the making of too many of the cytokines used in the inflammatory response. Safflower oil and corn oil are high in omega-6 fatty acids.

On the other hand, foods high in omega-3 fatty acids make different kinds of cytokines that replace those made by omega-6 fatty acids. This replacement helps control the inflammatory response. Flaxseed, fish and canola oil are high in healthy omega-3 fatty acids.

Much has been written about eating properly to prevent degenerative diseases. However, many articles talk about just one food or nutrient. It is important to pay attention to more than just one item in the diet for protection from disease. A good diet provides all nutrients in needed amounts and contains foods with high amounts of good fatty acids and phytonutrients.

You can get help in creating such a balanced diet online by going to, sponsored by the U.S. Department of Agriculture. At this Web site, you can enter information about yourself to get a personalized guide in pyramid form. The pyramid shows the amounts of various food types of foods to include in your diet.

The Web site also provides good tips such as make at least half of your grains whole grains, vary your vegetables beyond just potatoes and iceberg lettuce, eat whole fruits, not just fruit juice, and go lean on your protein foods. I would add that some of these protein foods should be rich in omega-3 fatty acids. You also can get good fatty acids from a daily serving of tree nuts. A serving is about the amount you can hold in a hand when you close your fingers.

A diet guided by these tips and your pyramid should ensure that your defense system is attacking invading bacteria and viruses, not you.

Last Modified: 8/2/2006